/ohm/ - electronics general

[Anonymous No.1834622]

Previous: >>1825788

>I'm new to electronics. Where to get started?
It is an art/science of applying principles to requirements.
Find problem, learn principles, design and verify solution, build, test, post results, repeat.

>Project ideas:
http://adafruit.com
http://instructables.com/tag/type-id/category-technology/
http://makezine.com/category/electronics/
Don't ask, roll:
https://github.com/Rocheez/4chan-electronics-challenges/blob/master/list-of-challenges.png.png (embed) (embed) (embed)

>Principles (by increasing skill level):
Mims III, Getting Started in Electronics
Geier, How to Diagnose & Fix Everything Electronic
Kybett & Boysen, All New Electronics Self-Teaching Guide
Scherz & Monk, Practical Electronics for Inventors
Horowitz and Hill, The Art of Electronics

>Design/verification tools:
LTSpice
MicroCap
falstad.com/circuit/circuitjs.html
NI Multisim
CircuitLab
iCircuit for Macs
KiCAD (PCB layout software, v5+ recommended)

>Components/equipment:
Mouser, Digi-Key, Arrow, Newark, LCSC (global)
RS Components (Europe)
eBay/AliExpress sellers, for component assortments/sample kits (caveat emptor)
Local independent electronics distributors
ladyada.net/library/procure/hobbyist.html

>Related YouTube channels:
mjlorton
w2aew
jkgamm041
eevblog
EcProjects
greatscottlab
Photonvids
sdgelectronics
BigClive

>Li+/LiPo batteries
Read this first: http://www.elteconline.com/download/pdf/SAFT-RIC-LI-ION-Safety-Recommendations.pdf
>I have junk, what do?
If you have to ask, nothing. Get rid of it.

[Anonymous No.1834625]

>>1834603
Changing the timing capacitor won't make a shred of difference to the output voltage, it will just change the frequency at which it switches. You'd need to change the voltage feedback or voltage reference side of the circuit. Read the relevant datasheet/appnote for the relevant IC.

I read the datasheet for the IC on my powerbank. Turns out all of the buck/boost circuitry is internal so I can't modify jack fuck anyway.
There might be an alternative, though. The actual lithium cell inside of it is a nominal 3.7 volt battery, which is exactly what I need. Would I be able to tap the battery directly at the + terminal, power my circuit with it, return it to the powerbank's ground, and still have the IC deal with under/overvoltage and overcurrent protection?
Something tells me it doesn't quite work like that.

[Anonymous No.1834629]

>>1834603
>Changing the timing capacitor won't make a shred of difference to the output voltage, it will just change the frequency at which it switches. You'd need to change the voltage feedback or voltage reference side of the circuit. Read the relevant datasheet/appnote for the relevant IC.

I read the datasheet for the IC on my powerbank. Turns out all of the buck/boost circuitry is internal so I can't modify jack fuck anyway.
There might be an alternative, though. The actual lithium cell inside of it is a nominal 3.7 volt battery, which is exactly what I need. Would I be able to tap the battery directly at the + terminal, power my circuit with it, return it to the powerbank's ground, and still have the IC deal with under/overvoltage and overcurrent protection?
Something tells me it doesn't quite work like that.

[Anonymous No.1834638]

What could be the purpose of this circuit?

[Anonymous No.1834676]

>>1834629
>Would I be able to tap the battery directly at the + terminal

most definitely. only the voltage wont be 3.7V. it'll vary from something like 3.2 to 4.2 depending on the state of charge. (also, you may be bypassing the low-voltage cut-off which protects the battery from destruction.) if that's unacceptable, just use 2 diodes in series with the 5V to drop 1.3V. or use a low dropout voltage regulator. a very common type puts out 3.3V.

>>1834638

insufficient data.

[Anonymous No.1834679]

>>1834622
i dont understand the math in holowitz' book, wat do?

[Anonymous No.1834682]

>>1834679

if you dont get the formulas (on the right) look at the pictures (on the left). same thing!

[Anonymous No.1834701]

>>1834679
anyone who says they understand integrodifferential equations is lying

[Anonymous No.1834706]

So is Pin 6 3.3V Power? Pin 2 just carries data right?

[Anonymous No.1834707]

>>1834706
yea. look at applications notes

[Anonymous No.1834908]

>>1834676
the powerbank would be powering a GameBoy Advance SP, which does have its own internal power circuitry. I think it might just be able to do low voltage cutoff itself.

the only reason why I don't just wire the battery directly into the GBA SP and forego the USB portion of the circuit entirely is that the battery is 3.7 volts whereas a normal GBA battery is 3.8 volts. My friend said that you can't charge the two the same way, so I didn't want to risk exploding the battery

[Anonymous No.1834924]

>>1834682
Yeesh, that's kinda complex math for a beginner, though I'd say it's pretty helpful to know. It's about the level of high-school calculus and differential equations, so if he's going to the trouble to read AoE, he should read up on that too.

>>1834701
I have to understand it to some degree, I took a paper focused on Maxwell's equations and the Einstein rate equations. But if you showed me an equation in a similar format I'd take some time to work out its nuances.

>>1834908
If your GameBoy is expecting to see a 3.2-4.2V signal from a lithium cell anyway, then yes you can probably wire the BAT+ and BAT- wires directly to your GBA's voltage input. But if you're doing that, you might as well ditch the charge/discharge/boost PCB in exchange for a TP4056 PCB. Probably one of the ones that has overdischarge protection.

However, the GBA might be a bit older than common lithium cells and use NiMH/NiCd instead. So research that first.

[Anonymous No.1834981]

>>1834682
This specific example is very odd.
I know how to derive V=Vi(1-e^-t/RC) which is a solution of a simple differential equation. However the formula on the right is not a step in the solution. It is some kind of an improper integral which looks a lot like a convolution which would be an a lot more advanced concept.

[Anonymous No.1835018]

>>1834679
Read a book that actually explains like Scherz & Monk.

[Anonymous No.1835171]

I want to make a 1W @ 220V heater like pictured. What kind of resistance element are they using inside of these to achieve this wattage at such high voltage?

Considering Ohms = Volts squared / Watts, then they are using a ~48.400 ohm resistance. How would I achieve that in the cheapest way, similar to what they are using inside the heater in the picture?

[Anonymous No.1835173]

I want to make a 1W @ 220V heater like pictured. What kind of resistance element are they using inside of these to achieve this wattage at such high voltage?

Considering Ohms = Volts squared / Watts, then they are using a ~48k ohm resistance. How would I achieve that in the cheapest way, similar to what they are using inside the heater in the picture?

[Anonymous No.1835175]

>>1835171

It's probably a metal or carbon film element.

Would be a little tricky to make your own with any similar method. Way easier to just get something like:

https://www.digikey.com/product-detail/en/te-connectivity-passive-product/ROX5SJ47K/A138102-ND/2384741

...and pot it in thermal epoxy.

[Anonymous No.1835179]

>>1835175
Thanks!

[Anonymous No.1835192]

>>1835173
>>1835175
Could use an NPN TO-220 transistor with a fixed base resistor instead. While it would be beta-dependant and more expensive, it would come with a handy thermal tab to just clamp onto whatever you want. An appropriately-sized PTC thermistor would also probably handle the 1W and it would be self-regulating to some degree.
Not sure if there are small power resistors with thermal tabs.

[Anonymous No.1835194]

>>1835192
A transistor is indeed a good idea, due to its shape. But how would I go connecting it to 220V to generate 1W?

[Anonymous No.1835202]

>>1835194
>bridge rectifier to 220VDC (bumpy but it doesn't matter)
>collector to V+
>emitter to V-
>base to V+ through a resistor
>I_base = 220/R_base
>I_collector = I_base * hFE
>P = I_collector * 220
>work backwards from P = 1W to find R_base

It will also give you a good way of toggling it, just pull the base to ground with another transistor.
Might be better to use two transistors instead of a bridge rectifier, using complimentary NPN + PNP transistors will mean you'll only need one resistor.

But 220V BJTs aren't that common.

[Anonymous No.1835207]

>>1835202
Complexity goes up significantly if I want the transistor, doesn't it. Still, that's awesome. Definitely going to consider going with it. Thanks!

[Anonymous No.1835241]

>>1834622
These people built an atomic force microscope:
https://newatlas.com/lego-arduino-nanometer-resolution-atomic-force-microscope-lego2nano/29238/
does anyone have an idea of how they did it and how much it would cost to make one?

[Anonymous No.1835259]

Hi guys! I need some advice in finding a replacement speaker for Beats Solo 2 wireless in Europe(or somewhere with cheap shipping to EU). Apparently it's the same as solo 3 wireless. I found some but they are all in the USA with 20+ euro shipping.


Pics in case you can identify what they rebadged:
https://lewd.pics/p/AyvI.jpg
https://lewd.pics/p/Hkuz.jpg

[Anonymous No.1835269]

>>1835241

https://www.instructables.com/id/A-Low-Cost-Atomic-Force-Microscope-%E4%BD%8E%E6%88%90%E6%9C%AC%E5%8E%9F%E5%AD%90%E5%8A%9B%E9%A1%AF%E5%BE%AE%E9%8F%A1/

It might help if you can read Chinese.

[Anonymous No.1835270]

I don't know a lot about electronics, so bear with me.

Testing capacitors. Multimeter set to high ohm range. Two read low and slowly go up to infinity. From quick online research, this is apparently what you'd expect from working capacitors. Two read high and go down to 1.12 (with the multimeter set to "20M" I assume this means 1.12 Mohm). Are these fucked or am I doing something wrong?

The "working" capacitors are 184j (0.18uF if google is to be believed), the other two are EN132400. At least that's the info I can find.

[Anonymous No.1835330]

>>1835270
>Two read high and go down to 1.12

that would be odd if you were doing it correctly. to do it correctly means (1) you discharge the cap before testing by shorting the leads, (short it again before you do a second test) and (2) if it's polarized, you apply red lead to + of cap.

[Anonymous No.1835335]

>>1835270
This is how you read capacitors:
>1 - first significant digit
>8 - second significant digit
>4 - number of zeros you tack on to the first two
>J - this is usually tolerance but can indicate voltage rating or tempco
The value is in picofarads. So in this case:
>184 - 180000pf, 180nf or 0.18uf, pick your flavour they mean the same thing.

[Anonymous No.1835338]

>>1835270
>EN132400
Type of capacitor. The value should be printed on those, looks like a safety type and is usually written in uf, for example 0.18uf. Usually good up to 275vac / 400vdc, and surprisngly good for audio.

[Anonymous No.1835345]

>>1834638
need more info, this could be anything

[Anonymous No.1835385]

There is surprisingly very little information about how comparators work. Nothing in the datasheets so have to look for various websites for examples. I mean I know in general but I am never sure if I need to set the reference on the positive or the negative input. And if the other input needs to go above or below the reference for the output to go high. I am assuming one can achieve many different variations, i.e. pull In+ to zero, compare to In-, pull In+ to VCC, compare to In-, set In+ as a Vref, compare to In-, set In- as a ref and compare to In+ etc? Is there like a truth table for all possible combinations? Something like this but for the analog comparator?

[Anonymous No.1835397]

>>1835270
>>1835330
>>1835335
>>1835338
So I tested them again, making sure to discharge, and the result is the same.
The two EN132400 seem to be broken. The only difference between the writing on them is that one has .1uFM and the other .01uFM.
So I'll try to get some replacements and see if that fixes it.

[Anonymous No.1835398]

>>1835385
Play with it on a breadboard or in a simulator. Practical, on hands experience is the best teacher.

[Anonymous No.1835400]

>>1835397
Those capacitors rarely fail, they are "self healing"; if the dielectric is punctured the resultant arc fuses the film back together. Of course there are limits, if those failed I would be leery of a surge or spike that could have destroyed other components.

[Anonymous No.1835412]

>>1835400
Hmm shit. So what else is likely to be fucked?
It's an electronic sewing machine pedal -- something similar to pic related.

There's a voltage regulator (one you can modify with a small plastic screw -- possibly to adjust the minimum or maximum speed?), a triode, a transformer these four capacitors and a couple of resistors.
The TRIAC controls the voltage the motor gets and it's controlled by a sliding component that is actuated by the pedal pressing down and moving the moving part front/back.

The sliding component's feet had come lose so I resoldered these. Unfortunately it still didn't work. However with some wiggling, the motor spun up for a second sometimes. I can't reliably reproduce that though and all the contacts seem fine on the rest of the board. I reflowed them regardless.

So, given that the motor did spin up for a moment, can the TRIAC even be the problem?
Anyway, I can't seem to find this sliding component (I have no idea what it's called) so I'm inclined to order another TRIAC.

I do have another sewing machine pedal I could solder to this proprietary connector, but I'd like to fix this one if only for the experience/learning effect.

[Anonymous No.1835416]

can you just... buy the wire that resistor/diode/capacitor leads are made of?
The really resilient, bendy stuff? What is it called?

[Anonymous No.1835426]

son of a bitch

[Anonymous No.1835433]

>>1835426

That's no way to make a vernier, anon.

[Anonymous No.1835436]

>>1835416
Wire?

[Anonymous No.1835438]

>>1835436
solid wire?

[Anonymous No.1835439]

>>1835416
>>1835438

I'd say lead wire just to be a smartass but I checked wikipedia, and it has some info on the material.

https://en.wikipedia.org/wiki/Lead_(electronics)

[Anonymous No.1835440]

>>1835436
>>1835438
well, duh
but like, what gauge? What chemistry?
The best I'm seeing is steel wire, copper-claded steel wire, and tin-coated copper-clad steel wire

[Anonymous No.1835442]

>>1835439
nice, reading this now

[Anonymous No.1835444]

>>1835440
>but like, what gauge? What chemistry?
I doubt gauge and alloy even matter as long as it conducts electricity.

[Anonymous No.1835446]

>>1835444
I'm asking because the 22 gauge wire I have, both stranded and solid, are stiff as a corpse and just as hard to work with. It might just be because it's cheap chinese shit, I don't know.
Meanwhile I find myself saving resistor/capacitor/diode leads because they're so malleable and easy to work with for jumpers and etc.
So I just want to grab a spool to have off-hand instead of having to sacrifice resistors for it

[Anonymous No.1835448]

>>1835440
You can test if they're steel by putting a magnet to it.

[Anonymous No.1835455]

>>1835446
Oh, I didn't realize that you were asking for gauge for the malleability. Why don't you just measure the resistor leads?

[Anonymous No.1835485]

>>1834622

A good place to start:

https://www.youtube.com/watch?v=SuKkRB7BBjY

[Anonymous No.1835523]

>>1835440
The good stuff is made of copper plated in tin.

[Anonymous No.1835544]

>>1835412
>>1835270
Success!
The third pin of the sliding potentiometer was broken off, but it was hidden under the component so I didn't notice until I rechecked everything now. Bridged it with the brown wire. As the component was now unsupported on one end and the spring puts an upward force on that end, I strapped a ziptie on there -- works great!

[Anonymous No.1835551]

>>1835416
Buy a set of 100000 resistors and cut the leads and solder them together and wind them on a spool. Done.

[Anonymous No.1835700]

What's the best way to design a high voltage regulated power supply?
I can do a basic bitch linear design (pic related), but a switch mode design would have better performance, right?

Pic related is only able to do about 50 watts, mainly limited by the maximum voltage the transistor can drop and the expense of buying a larger capacitor.

[Anonymous No.1835708]

>>1835700
Fixed or variable voltage? What voltage or voltage range? Maximum desired power at maximum voltage? Current limiting or no?

[Anonymous No.1835715]

>>1835385
If + is greater than - the output is '1'; otherwise its zero. Both inputs can be fluctuating waveforms, there's no need for one to be a stable "reference". There isn't really an A==B since variations between analog signals can be so small. To detect that you need to use two comparators to construct a "window comparator". It goes high if one input is close to another.

The outputs of comparators are usually open drain meaning you need a pullup resistor.

Comparators are a subset of op-amps. It's assumed everyone looking at a datasheet knows how to use those.


Here's an analog vector to raster converter I built by running a huge number of 2D window comparators in parallel. Each point is produced by comparing two voltages representing x,y to the vector input.

[Anonymous No.1835728]

>>1835708
Fixed +/- 300v, although I wouldn't be opposed to being able to adjust the voltage.
I haven't decided exactly how many watts I need yet, but probably in the 50 to 80 watt range.
No need for current limiting.

[Anonymous No.1835733]

>>1835728
Center tapped mains step up transformer. You want the output to be around +/-210Vrms. That gives you a peak output voltage of about +/-300V. Rectify that and honestly, I wouldn't even bother to regulate it.
No load that requires a 300V power supply is going to be super sensitive to a few volts of variation. By trying to regulate it all you're doing is wasting power. Doesn't sound like your application needs any particular regulation.

[Anonymous No.1835734]

What the hell are all these symbols? V-sub-I-K? Where's the symbol glossary for datasheets?

Also, is the current draw for this damned thing even listed?

[Anonymous No.1835741]

>>1835734
Datasheets usually assume you're not retarded. Perhaps YouTube tutorials are more your speed if this is too hard for you.

[Anonymous No.1835742]

>>1835741
I don't get any useful results when I google search "VIK electrical engineering symbol". I know Volts and milliAmps and all that shit, I just don't understand what's under the "parameter" header.

[Anonymous No.1835748]

>>1835700
You can buy HV adjustable linear regulators. Also consider a capacitive dropper if heat waste becomes a problem. A transformer as the other guy said is a good idea, but a dedicated SMPS might end up cheaper. A 400V 1mF cap isn't too expensive, btw.

>>1835715
How many comparators exactly? Looks like a 16x16 or something ridiculous, which I think numbers out to be 64 comparators total, unless you've got dedicated window comparator ICs that cut that number in half.

[Anonymous No.1835766]

>>1835741
here's a hearty "go fuck yourself"

[Anonymous No.1835769]

>>1835734
read the datasheet, the first mention to sub-IK it's the Input Clamp Current (I-sub-IK) it would be safe to assume these are related

[Anonymous No.1835784]

>>1835748
32 LM339s (generic quad comparator chips). It's not obvious in the picture but there's a stack of two boards. Each 2D window takes four comparators.

They're not arranged in a grid like a bitmap. The position of each rectangle is analog. It's pixely because there are only 32 rectangles.

[Anonymous No.1835789]

I'm a retard, how do I measure the voltage of a battery?
I got some 18650 LiFePO4 cells and I want to test them before I put them into this OpenUPS2 device

[Anonymous No.1835791]

>>1835734
Pretty sure V_IK is the voltage dropped from input to output with the specified current going through the switch. Though it might be something to do with clamping to the rails as the other anon mentioned.
The quiescent current is Icc = 3µA. Nice and low.
The "cc" in "Icc" and "Vcc" means "collector collector", as voltages are described as "Vab", where a and b are different nodes in a circuit. For example, Vbe = voltage from base to emitter, or Vds = voltage from drain to source. By having the same initial twice, it's the special condition where we're talking about a voltage referenced to GND. Vcc is common for supplies because the collector most positive pin in a standard NPN BJT, which ICs contain many of, but for CMOS parts it's often replaced with Vdd, referring to the drain of a standard N-channel MOSFET. Hence Icc refers to the current going into that power pin that Vcc refers to.

>>1835784
Boy that's something. Are the diodes for ANDing all the comparators for each window? Because if so, you could just swap the comparator inputs, OR them with the open-collectors and a single resistor, followed by an inverter for each window. Less parts, I think.

Also those curvy traces are looking nice.

[Anonymous No.1835809]

>>1835791
I'm doing the ANDing for each window by connecting the four comparator outputs directly together with a single pullup resistor. I then need to OR all 32 windows together and run that to the TV. The diodes are for that OR operation.

[Anonymous No.1835811]

>>1834622
DON'T TAZE ME BRO! reverse phase me, dude. Voltages and shit.

[Anonymous No.1835814]

what connector is this? couldn't find anything useful briefly browsing through molex's site
it's not a 4-pin fan connector, and it's designed for power output on a SBC. Issue is the people that made this board don't provide anything better than a block diagram of the board so I'm down to probing it with a multimeter

[Anonymous No.1835815]

>>1835809
Ah, I thought there were too few diodes to be doing the ANDing.

[Anonymous No.1835828]

Roast me. Its the first pcb I have done in a while.

[Anonymous No.1835883]

>>1835269
I remember hyping myself up tho this but theres no actual information on how to make one. Its just a chinglish "lookatme how cool i am" monument.

[Anonymous No.1835895]

>>1835828
whats with all the via?

[Anonymous No.1836005]

>>1835895
On that topic do PCB fab houses still put limits on the number of vias ? I remember years ago being charged extra for having too many and since then I've always been trying to keep it down as much as possible.

[Anonymous No.1836014]

>>1835883
this. I've been looking for info, and there is nothing concrete.

[Anonymous No.1836083]

>>1835895
Vias are for making a small patch of proto board. Design need to suit multiple applications.

[Anonymous No.1836149]

>>1835828
Pretty sure VR1 is a voltage regulator, and the ADSXXX is an ADC. The diodes are for overshoot protection, the R1s are small value resistors for dropping voltage across when the diodes are conducting, and the R2s are large value pulldowns? I'd guess 10k and 1M, but maybe it's closer to 1k and 100k.

>>1835895
Those aren't vias, the only vias are under and next to VR1.
The dotboard holes look too small for a standard 1N4007 though.

[Anonymous No.1836164]

>>1835828
P1, P2 you have silkscreen on the edge. Is there a reason why you've put connectors so close to the edge? Does your ADS1115 module include input anti aliasing filters? Why THT resistors and diodes? Do you really need external diodes? Chip already has internal ones with 10 mA capability, just put resistor in series with input, then add a capacitor to ground for LP filter as most ebay modules won't have additional resistors/capacitors to save on cost. I would also try separating analog and digital as much as possible and use groundfill around analog stuff.

[Anonymous No.1836174]

>>1836149
Almost correct. R1 is 150ohm and provides a voltage from a 4-20ma sensor, R2 is 10k for input resistance to the ADC and the diodes clamp voltage on the ADC pin from going over/under Vcc/gnd is something goes wrong with the 24v circuit. x4 for four ADC channels.

Dotboard holes are on 100mil pitch which should fit dip chips and the like.

[Anonymous No.1836209]

How hard with no experience would it be to get a gamecube controller to tell me how fast I Press the ABYX buttons in button presses per second through a LCD screen

[Anonymous No.1836283]

>>1836209

you can get an approximation by using a calculator that counts up if you do 1+1= then keep smashing the = key. use stopwatch software to count down 10 secs, then divide count by 10.

[Anonymous No.1836299]

Why do other transistors even exist?

[Anonymous No.1836330]

>>1836299
Different frequency ranges and/or power requirements.

[Anonymous No.1836339]

>>1836299
Because you'd need a shitload of those to drive my 5kW brushless DC motor.

[Anonymous No.1836345]

>>1835715
thanks i understand better now. i was overthinking the whole thing. the only thing i need to know is
>If + is greater than - the output is '1'; otherwise its zero
basically just like a rail to rail op amp in an open loop mode. and also the reference can be either + or - so it doesn't really matter. depends on what i need it to do. i think i can now consciously configure a comparator to operate in a certain way instead of searching for examples on the web.

cool video. are you that anon who built an analog pythagoras solver and posted some other analog stuff?

[Anonymous No.1836392]

>>1836174
Oh, current-sensors. I assumed it was an ADC for general-purpose use, seeing as you added perf-board instead of a dedicated circuit. What sensors are you using? 24V sounds faintly automotive/marine, but I guess it could be any power system under the sun with the right AC-DC power supply.
>Dotboard holes are on 100mil pitch which should fit dip chips and the like.
I assumed so, but I was more wondering about the holes' inside-diameter as opposed to the pitch.

>>1836299
>not 2N3904
>THT

[Anonymous No.1836395]

>>1836345
>basically just like a rail to rail op amp in an open loop mode
That's almost exactly what it is. The only difference is that op-amps have output stages specialised for linearity and analog signal outputs, while comparators have outputs specialised for slew-rate and digital signal outputs. Many old circuits just use a 741 op-amp as a comparator, and in some cases it could even a better way to go if you're lacking more specialised hardware (i.e. you need the push-pull output). However, if you try to use an LM393 as a linear element with negative feedback you'll probably get distortion. Could be fun for guitar pedal shit.

I seperate them as follows:
>op-amp: negative feedback loop, + ≈ -
>comparator: no feedback or positive feedback loop, + ≠ -
Because the positive feedback loop (i.e. schmitt trigger) is a very useful circuit to know. Usually for noise immunity (debouncing, etc.), but also for making an oscillator. The single comparator oscillator is a pretty simple circuit that I use somewhat often, it uses a comparator with its + input hooked up for positive feedback via some resistors, while its - input is hooked up for negative feedback via an RC low-pass filter. But this circuit is frequently made with op-amps too, even though the + and - inputs do not equal one another.

[Anonymous No.1836484]

>Making an analog VCO for synth
>Finally get the exponential converter to track 1 volt/octave
>Get Octaves 1, 2, 4, and 5 in almost perfectly in tune on the VCO
>Octave 3 stubbornly remains a quarter tone flat
Honestly, how? Everything above and below is just fine
I get A1=109.5Hz, A2=220.6Hz, A4=439Hz, A5=1755Hz, which is all pretty close to ideal, but A3 winds up at 850Hz

[Anonymous No.1836496]

>>1836484
Post circuit? I probably can't help you but I'm just interested in VCO circuits in general.

[Anonymous No.1836509]

>>1836484
It's nothing crazy, but here's what I've got.
The tuning resistor sets the frequency for a given input voltage, and the tracking resistor is used to trim out the exponential converter to 1V/Oct.
The tuning process goes like this:
>Set CV to 0.833V (A1)
>Set the tuning resistor so that the frequency is 110Hz
>Set the CV to 4.833V (A5)
>Set the tracking resistor so that the frequency is 1760Hz
>Repeat until tuned.

[Anonymous No.1836521]

anybody here work with fpga's? Got an entry level fpga engineer coming up next week. Just been reviewing my projects and also some basics about digital design. Anybody got some good tips?

[Anonymous No.1836534]

>>1836521
Just recently interviewed for some entry level FPGA jobs and stuff I wasn't prepared for was setup & hold time, bash scripting, rest is just basic C, (VHDL/Verilog), (Xilinx/Altera) questions. If you've got projects put them on Github. During my interviews they brought it up and asked me to walk them through my projects and design decisions. Seems like you have a pretty solid plan though, good luck and I hope you get it! :)

[Anonymous No.1836537]

>>1836392
>What sensors are you using?
Got a bunch of sensors, pressure, tank levels, water flow rates, differential pressure. I also have optocouplers for sensing 240/415V sates so I can monitor things like solenoids, pumps and motors being on. I also have some DS1820 temp sensor which seem to work well.
> I was more wondering about the holes' inside-diameter
The id of the dotboard holes are 40mil with 60mil pad. I am hoping this big enough to take standard dip packages/resistors. But also the dotboard needs to isolate 240/415v from the IC's. It could just blow up in all honesty.
Over all I have made the PCB to fit in this case which is ~85x75x30mm and clips into a din rail. These will be put in machine control cabinets, most of which have 24vdc control power. Also most of the 4-20ma sensors run on 24v too, so running off 24v makes powering the sensors easy too. Its going to be like a budget SCADA system.

[Anonymous No.1836681]

Anyone here use LTSpice? I can't figure out one simple thing: do I need a capacitor after a sine voltage source? Sometimes it only works when I add it. And some other times (feeding an non inverting amp) it only works when I remove it. Makes no sense. In general I think I shouldn;t ever need it since the Voltage source doesn't even have a DC offset. I am talking about simulating a simple op amp in this case. I get conflicting results with inverting and non-inverting amps. And I am not even talking about the single supply related chicanery where you need to add a cap to the voltage divider in some cases otherwise it wont work which has nothing to do with real life.
For example this simple example will stop working if I add a capacitor after the V2. Is there anything obvious that I miss in this schematic that makes it behave this way?

[Anonymous No.1836689]

Also I absolutely hate it how the opamp symbols have criss crossed +- and Vcc connectors so you have to rotate it to avoid messy connections but ground on top looks odd. I wish there were different pin layouts for inverting / non-inverting configurations.

[Anonymous No.1836712]

>>1836681
adding a cap there gives a floating node. computers really don't like floating nodes.
stability depends entirely on whatever it thinks the starting voltage should be, which is chaotic/unpredictable/at the whims of the algorithm.
Just add a 1Meg pulldown or something

[Anonymous No.1836720]

>>1836681
Those are some funky looking symbols. What version of LTSpice are you using? Depending on how TL071 model is built there could be a floating node as >>1836712 says. Check if there is anything in View>SPICE Error Log.

[Anonymous No.1836748]

>>1836712
>>1836720
Well the non-inverting amp doesn't work at all until I add a capacitor. Then it works fine, nothing is floating, no need to add a resistor. So it is exactly the opposite.

> funky looking symbols
which ones? this is the latest version XVII. But the old one had exact same symbols.

pic related doesn't work

[Anonymous No.1836753]

But this suddenly works fine

[Anonymous No.1836757]

>>1836753
op amps want both inputs to be equal
try setting the sine's DC offset to 2.5V

[Anonymous No.1836759]

>>1836753
Well, it's way out of phase, and the first pic is in phase. Try lowering your resistor values.

[Anonymous No.1836760]

im confused more

[Anonymous No.1836776]

>>1836748
>which ones?
I just got confused due to your GUI scaling as everything looks thicker. This is not a SPICE problem. If you connect voltage source with 0 V DC you're essentially shorting R2 to GND which basically gives you non inverting amplifier with gain of 11 (top pic). Because there is 2.5 V on noninverting input the whole thing goes into saturation and you get nothing on the output. If you put capacitor in series you block DC which results in voltage follower for DC signals so you get 2.5 V on the output (bottom pic) which you can use to superimpose AC signals using a capacitor in your second example.
>>1836759
It's inverting amplifier, you'll have 180° of phase shift because of negative sign.

[Anonymous No.1836801]

>>1836757
This, you should be setting your GND node to be at 0V, with your power rails being at ±2.5V. At the moment you've got one power rail at 0V, so any DC-free signal that's referenced to ground will be constantly hitting the negative rail, and op-amps don't behave well near the rails. By using a capacitor in series it's basically a high-pass filter that lets the voltage equalise to between the rails.
Also you're shorting across C1, which is way too high a value capacitor to be driving with an op-amp anyhow.

[Anonymous No.1836806]

>>1836801
In addition to this, if you're using a single-supply 5V rail for logic (i.e. USB) you'll need to make yourself a virtual ground circuit. This can be a simple voltage divider with some large caps on it, or a voltage divider or voltage reference being buffered by a spare op-amp. I'd lean towards the latter if you happen to have a spare op-amp.

[Anonymous No.1836807]

>>1836757
Not sure what you mean. It is a single supply. So + is biased to 1/2Vcc and - is the virtual ground. The opamp will do its thing to make sure V- = V+ right?
>try setting the sine's DC offset to 2.5V
even if I wanted to do that just for the sake of a simulation, the real signal in a real curcuit is pure AC.

[Anonymous No.1836808]

>>1836807
>the real signal in a real curcuit is pure AC
Then add an actual high-pass filter to bias the AC properly. You can't just inject an AC signal bouncing below your op-amp's negative rail and expect it to fucking work.

[Anonymous No.1836812]

>>1836807
>>1836808
And why does your signal's ground have to be referenced to the PSU's 0V rail anyhow? Can't your just connect it to the 2.5V virtual ground circuit?

[Anonymous No.1836813]

>>1836808
it is not bouncing below the negative rail precisely because V+ is biased to Vcc/2. I was just lazy and connected a +2.5V power supply but typically you just use a voltage divider. It is a pretty standard building block not sure what the issue is.

[Anonymous No.1836815]

>>1836813
Yes it is, because the AC voltage source in >>1836748 is connected to the GND node, which is connected to the negative rail on the op-amp.

[Anonymous No.1836816]

>>1836815
well this circuit : >>1836748 because there is no capacitor.
this circuit works fine: >>1836753

here is an example i found. that is what i mean.

[Anonymous No.1836817]

>>1836776
>everything looks thicker
yeah i think there is an option for that.

[Anonymous No.1836821]

>>1836757
>op amps want both inputs to be equal
It makes them equal via the negative feedback. Thats the whole point.

[Anonymous No.1836825]

>>1836816
>because there is no capacitor
Yes, a capacitor in series makes a high-pass filter, which is exactly what you need in order to turn a signal doing this: >>1836815 into a signal within your op-amp's range.

That's a kinda shitty example. No cap(s) on the voltage divider, and no definite reference after the first high-pass either. It's also specialised for taking a signal bouncing about the -ve rail, amplifying it, and putting it back against the -ve rail, hence the high-pass filter at the end as well as at the beginning. It isn't exactly a typical example of an inverting amplifier. Also
>741

What is the physical circuit going to do? Is there anything stopping you from doing this: >>1836801 and connecting the ground of the AC signal to the Vcc/2 divider? Because it's not always that your PSU's 0V rail is connected to your AC signal's ground in the first place. If you have the luxury to, I'd ditch the high-pass filters as they're just making things more complicated.

[Anonymous No.1836827]

>>1836825
Something like this I guess

[Anonymous No.1836829]

>>1836825
>What is the physical circuit going to do?
well a generic example of a voltage amplifier
>Is there anything stopping you from doing this: >>1836801
well thats a dual supply. i don't have a dual supply. i've never done dual supply. i am interested in a single supply.

[Anonymous No.1836833]

>>1836827
I get that. but it is a dual supply. How else do you achieve this with a single supply.

[Anonymous No.1836839]

>>1836816
I think there was a confusion with voltage sources. All sources are DC coupled. Even if it's just a sine it still has 0 V DC component which is basically wire or short to GND. If you omit coupling capacitor that 0 V DC is just a wire to GND which makes your circuit a non-inverting amplifier that amplifies your bias voltage. Coupling capacitor disconnects everything after R1 and makes a voltage follower which gives you Vcc/2 on output. When you then feed in AC it amplifies it around Vcc/2.
>>1836827
You only have to ask yourself. Do you want to amplify the DC component of your sine input (probably not)? That voltage divider PSU is pointless if you don't need DC amplification. You also need to be sure that you meet your current requirements.
>>1836833
You can't. You need AC coupling capacitor in series with sine source. Replace sine source with short and put bias voltage on non-inverting input. What do you get?

I don't know why are you all complicating things into oblivion. Perform analysis separately for DC and AC.

[Anonymous No.1836844]

>>1836839
>I don't know why are you all complicating things into oblivion
Well I am not sure what we are arguing about in the first place. I just noted that I am doing a single supply not a split supply.

[Anonymous No.1836846]

>>1836844
>Well I am not sure what we are arguing about in the first place
Why >>1836748 can't work.

[Anonymous No.1836852]

>>1836846
Ah you are right I confused myself. I switched back and forth from inverting to non-inverting and also from a split to a single power supply which does need both input and output decoupling capacitors. I know that all stages of op amp-like audio amp designs are direct coupled since they are based on a split power supply.

[Anonymous No.1837000]

>try new idea on breadboard
>doesn't work
Ah well, guess I'll try again next month

[Anonymous No.1837001]

Anons please bear with me one more time, I am learning. So the most confusing of the four combinations for me is the single rail non-inverting setup. What is the purpose of C3? It is not shown on a typical schematic but the simulation won't work without it. Why?
Also it is not clear to me, should I think about C1 R3 as a decoupling capacitor plus a load resistor, or should I consider them as a whole, i.e a high pass filter? or as an AC voltage divider? Since the AC voltage drop on C1 depends on its value and the frequency. So should I make sure 1/2pi*f*C << R3 so most voltage would drop on R3?

[Anonymous No.1837006]

>>1837001
>What is the purpose of C3?

this has been explained several times in several ways. but you keep rejecting the answers, so fuck you.

[Anonymous No.1837010]

>>1837001
Exactly the same as C2. It's basically equivalent to replacing R2 with two resistors, one to 5V and one to 0V. Without the cap or divider, R2 points right into the negative rail of the op-amp, and an op-amp won't run down that low, neither its inputs nor its output.

You should put a little more thought into how a standard split-rail schematic is converted to work on a single supply, and how you'd go about doing the opposite.

[Anonymous No.1837017]

>>1837010
OK, thanks. We talked about the purpose of C2 but I didn't make the connection that it is the same C2.

[Anonymous No.1837020]

Are there MCU dev-boards out there with integrated H-bridges? A high-precision ADC would be good too, be it in the MCU or external. I'm thinking about buying/making a bunch of these for DSP, PWM, and PID uses. Because an H-bridge or half-bridge is a DAC if you add filtration and feedback.
Maybe just an H-bridge driver and slots to solder in your own MOSFETs, as you'd want slots to solder in your own optional LC filter anyhow. Maybe a buck converter too.

[Anonymous No.1837079]

>>1836005
>On that topic do PCB fab houses still put limits on the number of vias ?
no. i've nearly covered oshpark and elecrow boards in vias and they don't seem to give a fuck. as far as i can tell you can also use a dozen different drill sizes.

[Anonymous No.1837140]

I'm trying to make an ir blaster, the blaster emitter doesn't light up when the blaster is connected to an audio source. I didn't think it was getting enough volts, so I added a 386 amp and it lights up now, but when I connect 386 output to a speaker its very noisy. Will this affect the blasters ability to send signals correctly?

[Anonymous No.1837152]

>>1837020
The PIC16f15344 has an H-bridge mode for its PWM mode. It's just controlling two pins with one the inverse of the other and a defined High-Z dead time in between. The pins are still 20mA microcontroller IO though.

[Anonymous No.1837172]

>>1837001
Always remember these basic rules:
>capacitors are infinite resistors for DC - open circuit
>capacitors are shorts for AC - short
>since you're dealing with linear system you can use superposition, calculate gains for different frequency components separately
Using this you can calculate output voltage for two cases:
>First, forget about supply voltages, you will only use them after analysis to check if you're in saturation
>DC circuit, replace capacitor with infinite resistors, set V2 to 0, voltage at the output of opamp is then
Vout = (1+R1/(R2+inf))*V+ = 1*V+ = 10 V (divider)
>AC circuit, replace capacitor with shorts, put other voltage sources to 0
Vout = (1+R1/R2)*V+ = (1+20k/1k)*V+ = 21*V+ = 21*V2
>use superposition
Vout = 10 V + 21*V2
As you can see you get a signal with fixed DC component of 10 V which you then filter with C1 R3 HP filter.

>or as an AC voltage divider?
Exactly, first crude approximation is that C1 is short for AC signals so all the voltage drops on R3. For accurate analysis you replace C1 with it's impedance value
>Zc1 = 1/(jwc)
Calculating output voltage is then same as normal voltage divider
Vout = Vin * R3/(R3+Zc1)
After some algebra...
R3/(R3+1/(jwc)) = (j w R3 C1)/(j w R3 C1 + 1)
for amplitude we're interested in absolute value of that expression
w R3 C1 / sqrt(1 + (w R3 C1)^2)
Now what happens if w R3 C1 is significantly larger than 1? We can approximate that expression with:
w R3 C1 / sqrt((w R3 C1)^2) = 1
What about if w R3 C1 is significantly smaller than 1?
w R3 C1 / sqrt(1) = w R3 C1
What if w R3 C1 is exactly 1, we can then say we transition between previously defined cases, and amplitude is equal to
1 / sqrt(2)
or in dB scale 20*log(1/sqrt(2)) = -3.0103 dB, that's where you get that famous -3 dB point. Cutoff frequency is defined by calculating frequency at which w R3 C1 is equal to 1 or your
1 = w R3 C1
w = 1/(R3 C1)
if w = 2*pi*f
f = 1/(2*pi*R3*C1)

cont.

[Anonymous No.1837178]

>>1837172
From f = 1/(2*pi*R3*C1) you can then calculate what value of R3 you need. If you want to get all voltage above f you need to consider lowering f sufficiently
f << 1/(2*pi*R3*C1) which you can achieve by increasing value of R3 (or C1) as you said yourself. Remember at f you have -3 dB of gain or 0.707 of output signal. You can safely assume that at 10*f you get all the signal on the output. For numbers in schematic that means f = 3.18 Hz which means that above 31.8 Hz all the signal will pass through your filter. You can use ac analysis in SPICE to get bode plot of your amplifier. You also need to consider impedance of your feedback network as gain won't be constant for transitional frequencies, but that's probably not too important, depending on your application.

[Anonymous No.1837207]

>>1837140
>Will this affect the blasters ability to send signals correctly?
Probably not if noise is less than threshold voltage of your IR diode. Make sure you have decoupling/bypass capacitors on your amplifier power inputs. Ideally you would use comparator instead of amplifier since your signals are digital.

[Anonymous No.1837225]

>>1837140
Are you trying to send an amplitude-modulated analog signal with the IR blaster, or just on-off-keying?
If it's the former (which it should be if you're trying to receive a good sounding audio signal), it will be pretty difficult to get a good SNR (not to mention hard to filter out the 120Hz from the lighting). So much so that I'd recommend driving an array of IR LEDs (an LED strip maybe?) with a class-D amplifier (one that can handle the DC offset). Maybe with a feedback loop that includes an IR LED and the same kind of receiver that you've got on the other end, for linearity's sake. On that note, the standard receivers that IR blasters use are tuned to receive a certain frequency (2-40kHz IIRC) because they expect an AC IR signal (to avoid the 120Hz from the lighting as well as the DC ambient), so you won't be able to use a standard IR receiver, but rather will have to use a photodiode or phototransistor. In my experience it doesn't really matter which. Any noise in your amplifier will be noise in the IR signal, so long as you're measuring them with the same load impedance (your speaker's impedance may be too low for the 386).
If it's the latter, just use a comparator driving a MOSFET (with a BJT or two in there I guess), probably with a tiny bit of positive feedback.

If you want to transmit the best sounding audio you can via IR, you may want to consider some other form of modulation, be it analog like FM or PWM, or digital like FSK. Note that your IR LEDs will have a max switching frequency.

>>1837152
>The pins are still 20mA microcontroller IO though
Kinda useless for anything other than a low-power audio output, in fact it's two orders of magnitude lower than the H-bridge driver I was looking at. RIP PSU caps. But it's an interesting feature to see, as I imagine trying to emulate the same thing in software would result in a tiny bit of delay between one pin going high and the other pin going low.

I think I'll start designing the circuit in KiCAD.

[Anonymous No.1837229]

>405nm "UV" LEDs light up the phosphor on my oscilloscope screen
This actually makes the grid lines more visible, especially when it's dark in my room. Maybe I should hook up a few of these permanently to the periphery of my scope's screen. I'd keep them as dim as possible for keeping the traces nice and visible though.

[Anonymous No.1837260]

>>1834603
>The wires have a thin enamel insulation on them which you'll need to somehow strip o

nope
you solder them directly with the enamel and the solder will just burn it
it's great actually for soldering small wires

[Anonymous No.1837273]

>>1837172
>>1837178
Wow, this is awesome. Thank you anon!
A separate AC and DC analysis sounds like the way to go. I am just not good at it analyzing circuits except for the most basic ones with only a few passive elements.

[Anonymous No.1837438]

I really hope I'm just retarded and smacked a few knobs around to cause this...
But I think my oscilloscope might be goofed. A few days ago there was a lightning strike very, very close to my house (close enough to make several small salvaged speakers on my desk make an audible pop). The oscilloscope was unplugged during all of this and I never lost power to anything else.

I haven't used my scope in a few weeks, but I go to turn it on - and it's only showing a thin, bright line on the far left of the screen (I used the horizontal position adjustment to move it to the middle in the pic)
Is this me fucking up the settings, or did the lightning fuck it up?

[Anonymous No.1837448]

>>1837438
Connect your probe to CALIBRATOR signal on the scope and see what happens.

[Anonymous No.1837451]

Hey XD we are nonymus Xd

[Anonymous No.1837453]

>>1837448
It shows a split waveform.
Using the 10x magnification, it does show the square calibration waveform almost normally.

I switched the gross sec/div knob, and the beam started going across the full screen. However, other than that, it doesn't look like the gross sec/div knob is having any affect on the appearance of the waveform (until I get to the nanosecond scale, where it looks like a capacitively distorted square wave.) Now that I think about it, I'm not sure if the calibration oscillator changes its frequency to correlate with the sec/div knob so it might not actually be an issue.

The fine sec/div knob, however, does extend/contract the waveform.

I'll post pics for all of these in a second.

[Anonymous No.1837455]

>>1837453
after twiddling the gross sec/div knob

[Anonymous No.1837457]

>>1837453
>I'm not sure if the calibration oscillator changes its frequency
It probably does as stated above pin
>5 Hz - 5 MHz

It's probably working just fine. What were you trying to measure? You have channel 1 on AC coupling so maybe that's the problem?

[Anonymous No.1837461]

>>1834622
What's the best way to program a PIC12F675 from linux? Preferably something with a command-line interface

[Anonymous No.1837482]

>>1837455
god damn, focus that scope

[Anonymous No.1837483]

>>1837482
that's about as focused as I can get it unfortunately

[Anonymous No.1837540]

what do they mean by that?
dq/dt is the current right? how can it be zero? Why should it be zero?
Context: this is a bulb filament (a lumped abstraction)

[Anonymous No.1837542]

>>1837540
oh wait i just noticed it is a partial derivative. what?

[Anonymous No.1837551]

How does one git gud with analog design using transistors?
I'd say I'm a pretty intermediate analog designer, but I definitely lean on op-amps as a crutch.
It feels like my solution to most problems is to just sprinkle more op-amps on the design and count on feedback and gain to make the issues go away.

[Anonymous No.1837555]

>>1837551
But high quality discrete amplifiers are based on op amp design as they use the same building blocks which you are already familiar with. Unless you want to design basic common emitter AC coupled stages with no current sources etc.

[Anonymous No.1837562]

>>1837540
What kind of modern art masterpiece is this slide?
>comic sans
>3 different math fonts
>3 different shades of red
>no alignment

Judging by the looks of the slide it's probably something stupid like current can be only 0 because there is no complete circuit between filament points.

[Anonymous No.1837566]

>>1837260
You get a residue left on the conductors, but with flux it should be fine.

>>1837540
dq/dt is the buildup of charge in the wire. if I_A ≠ I_B then some charge would be building up in the wire. Of course, the electric field of these charges would prevent any appreciable amount of charge building up. It's a crude way of explaining a reduced version of Kirchhoff's current law that doesn't delve into Maxwell's Equations. Fucking engineers.

[Anonymous No.1837567]

>>1837540
q is charge of the filament. If dq/dt=0 then no charge accumulates in the wire, therefore current in = current out

[Anonymous No.1837572]

>>1837551
>>1837555
Yeah, pretty sure there's little reason to use transistors for small signal amplifiers/filters/etc. outside of RF use. Even for high-power amplifiers the class-D is showing some amount of dominance over ABs, but it's less straightforward there.

[Anonymous No.1837574]

>>1837555
Right, just about everything is made up of current mirrors, differential pairs, and class A/B amplifiers on some level.

I guess what I'm trying to say is that I would like to make better use of transistors when possible to save cost on designs with dozens of op-amps, since not everything requires the precision of an op-amp.
Also, I would like to do some VHF radio design, and op-amps aren't really an option at those frequencies, at least not at a reasonable price.

[Anonymous No.1837581]

>>1837574
I can see where you're coming from. Nice simple transistor circuits like you find in cheap chinese microphones would be nice to learn, but because the difference between input and output impedance is so much lower than with op-amps, you can't just assume that slapping any two building blocks together will result in a usable circuit.

Also DSP.

[Anonymous No.1837587]

>>1837581
>because the difference between input and output impedance is so much lower than with op-amps, you can't just assume that slapping any two building blocks together will result in a usable circuit.
Right, that's true, but you can always slap a buffer between stages if needed.

I probably just need to read through the Art of Electronics again and get a better understanding of how to bias common emitter and common base amplifiers.
I can manage the textbook problems, but most of the things I've designed on my own seem to have the wrong bias to work correctly.

[Anonymous No.1837606]

>>1837587
Yeah biasing is the most tedious part since you need to check the datasheet and choose the collector current and the base current and set the operating point and set the gain by the Rc/Re ratio then make sure Ve is within a certain range then calculate the bypass capacitors and coupling capacitors etc then as soon as you add the second stage you realize it is loading your previous stage so you have to mess with impedance matching and recalculate your biasing resistors then you run a simulation and notice that as you add more stages you add more distortion etc etc

[Anonymous No.1837609]

>>1837562
dunno some random handout. the style is horrible yes but seems legit as far as the formulas etc

>>1837566
>>1837567
ah makes sense, thanks

[Anonymous No.1837614]

>>1837587
>>1837606
I'm guessing that you have to AC-couple all your stages to be unaffected by the bias levels of the next and previous stages, and to counteract the transistor's own drop, right? I can't imagine what it would be like to try and amplify and filter a DC signal with discrete transistors.

[Anonymous No.1837625]

>>1837614
Sure you will need to AC couple them. But you may still have some issues due to impedance matching or at least thats how I remember it.

[Anonymous No.1837630]

>>1837562
lol it is actually an MIT course
https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-002-circuits-and-electronics-spring-2007/video-lectures/6002_l1.pdf

[Anonymous No.1837716]

>>1834622
Sorry if this is a really stupid question but I wanted to be sure as I'm still learning.

I'm playing around with LEDs making lights because I find it interesting, and I wanted to make a bigger one from those 100W crap cheap chink chips.


If I'm powering it from a battery that produces the voltage required by the chip, I don't need a constant voltage/current LED driver right?

If I have a 24v DC source, and the chip requires 24v and I should need is a resister in series to make it operate just fine, correct?

[Anonymous No.1837741]

>>1837716
if the battery is capable of producing more current than the LED can handle, you need to limit the current some how.
that's why resistors in series with LED on your first blinky project are current limiting resistors.

LEDs are not linear devices. Once you reach the threshold voltage, they will conduct. And as they heat up, they will conduct more.

If you sit right around the forward voltage of the LED, you MIGHT get away with it, but you're banking on how the LED was fabricated, which is not a good decision.

In short, you should always limit current through an LED.

[Anonymous No.1837763]

>>1837741
gotcha, another stupid question.

As long as the positive and negative terminals are intact on the sides can you shave down those chips?

like take some of the excess plastic/metal off the top and bottom to make it more compact? (not touching the inner area of course) and assuming I have adequate cooling.

[Anonymous No.1837769]

>>1837763
You can probably shave down on the aluminium parts, but you'd have to be careful not to hit any traces if you go any further in. Also you'd still need to connect it to a heat-sink, which the screw holes help with unless you're using thermal epoxy.

[Anonymous No.1837783]

>>1837769
I was going to put like 4 fairly close together and hold them firm against the heat-sink with a small metal bracket on top of them around the rim to eliminate the need for the screw holes and allowing the emitters to be closer

I was looking at this particular one because as far as I can tell the top/bottoms are purely there just to hold the screw holes and provide a little extra thermal conductivity via surface area.


the heat dispersion part i'm extremely comfortable with, I just don't know much about consumer electronics so I'm learning the fun way via fucking around and having fun.

[Anonymous No.1837786]

>>1837783
It should be fine, but I'd first carve away the layer atop just to be sure there aren't any traces below it.

[Anonymous No.1837787]

>>1837769
>>1837783
sorry 1 other stupid question, this im like 99% sure yes but yah want to be certain.

If they take 36V and 3amps to power up to McFull...

The most compact way to arrange 4 of the chips would be to hook them up in Parallel with a 36V 12amp driver, correct?

Because that arrangement would deliver 36v and 3 amps to each chip, right?

[Anonymous No.1837789]

>>1837786
will due, I ordered 10 extra just to screw around with just for that purpose.

[Anonymous No.1837796]

Anyone got suggestions for what to do with these? I yanked them out of the trash and dismantled them when my roomie tossed them. I was thinking a kind of walkie-talkie style setup (they'd have shite range but this is mostly just for fun anyway)

[Anonymous No.1837798]

>>1837787
For 4 units, you can do series (144V, 3A) or parallel (36V, 12A).

If you want full blast, you have to deliver full power (Volts * amps, aka 36*3) somehow to each device. Of specifically if you have 4 100W devices, you would need to deliver 400W.

In series, you split the total voltage 4 ways, in parallel, you split the amps 4 ways.

Parallel means if one blows, the other say on, so that's slightly better.

[Anonymous No.1837799]

>>1837787
>that arrangement would deliver 36v and 3 amps to each chip, right
In theory, yes. But the LED COBs will each have slightly different specs, so each one will pull a slightly different amount of current. The higher current in one will cause it to heat up slightly, decreasing its effective resistance, increasing its current, and so-on in a positive feedback loop. The result being, all your LEDs will die. This is why you'll need a constant-current driver (or some form of current limiting) for each parallel element.

Also 12A is quite a lot, you may well find it cheaper to buy a 72V PSU rated at 6A, or a 144V PSU rated at 3A. But above 30-60V you're entering the realm of HV electronics (as far as silicon is concerned), which also start to jack the price up. Either way you'll need a switching power supply unless you plan on running them on some lipos.

You can buy switching power supplies designed for powering LEDs that have their own constant-current outputs, which you may well want to look into.

[Anonymous No.1837802]

>>1837799
>>1837798
I did get this chart from actual lumens test off a youtube vid, at the very least it can stand up to some decent +/- amps as long as the cooling is good (which I plan to go overboard with regardless)


But yah, so if I understand yall correctly (obv simplified for laymen aka me) a "driver" is just a limiter that caps the amount of current that can go through it correct?

One thing I've had trouble finding on ebay if yall know of any or even keywords (maybe im looking for the wrong thing) to look for is a driver for a battery to the led, most everything I'm seeing is for AC sources.


thank you both for the info btw

[Anonymous No.1837803]

Maybe ya’ll can help.

I’m trying to find a suitable replacement for the center switch in pic related. It’s for the seat adjustment on an old Thunderbird. It has 5 positions; up, down, left, right, and center (which is just off/open). It’s effectively just 4 Momentary SPST switches with a common actuator. The closest I could find were joystick switches but they all seemed way too large. The one I’m trying to replace has a roughly 1-1.5” square housing with a roughly 1” long shaft.

[Anonymous No.1837806]

>>1837802
Here's one rated for one LED:
https://www.ebay.com/itm/100W-30-36V-High-Power-Supply-LED-Constant-Current-Driver-110-220V-With-Heatsink/301735903111?hash=item4640dc7f87:m:m8yQCIDI20NgkRbSssxhPLQ

You could get 4, 1 for each LED.

"constant current driver 36V 100W" is what I searched, and you can fuck around with the wattage rating or whatever to try to find other shit.

[Anonymous No.1837809]

>>1837806
Sorry that's what I was talking about before and what I'm not fully understanding.

>Input Voltage : AC 85-265V 50/60hz

>Output Voltage: 30-36V DC

>Output current : 3000MA+/-5%


Every one I find are AC input, I plan to run it off big fat batteries

[Anonymous No.1837815]

>>1835241
>>1835269
>>1835883
turns out they had a website (openafm.com) of which the domain name expired, but the blog is still there: https://openafm.wordpress.com/
no idea if all the the info needed to build the AFM is there, but they also have a github repo that seems to have a lot of info, including some software: https://github.com/openafm

BTW, while looking for info on how to build cheap microscopes, by following that project and reading random articles, I found from one of the same authors:
"Hacking CD/DVD/Blu-ray for Biosensing" https://pubs.acs.org/doi/10.1021/acssensors.8b00340 (supplementary info has a 5 minutes video)

I then started reading about graphene:
https://en.wikipedia.org/wiki/Graphene_production_techniques
Effects of amount of graphene oxide and the times of LightScribe on the performance of all-solid-state flexible graphene-based micro-supercapacitors https://www.researchgate.net/publication/315590626_Effects_of_amount_of_graphene_oxide_and_the_times_of_LightScribe_on_the_performance_of_all-solid-state_flexible_graphene-based_micro-supercapacitors
Laser-induced porous graphene films from commercial polymer https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4264682/ (if I'm not mistaken, best results were 4.8W cutting lasers on polyimide (Kapton); also, check the supplementary info)
Scientists demonstrate first color-tunable and first graphene-based LED https://phys.org/news/2015-07-scientists-color-tunable-graphene-based.html

[Anonymous No.1837822]

>>1837802
The fundamental limit, which you approach with increased cooling, is the thermal resistance from the LED silicon chips/dies themselves to their surroundings. Even if the heat-sink is at 4 kelvin, with enough power through the LEDs there will still be enough of a temperature difference such that the dies are overheating. The same applies to power MOSFETs and such.
But when you'll have to consider this will be something you'll have to read from the datasheet.

>>1837809
It's a switching power supply so it has a rectifier in it anyhow, it can handle 100-350VDC easily.
But if you are planning to use batteries, you may be able to simply use an LM2596 module (like $1 each for 3A output) for each LED, with a 12S lithium setup. These modules already have trimpots in them for current and voltage, so they actually make pretty nice benchtop power supplies. Some even have a third trimpot to set a battery charging threshold.

>>1837815
>Hacking CD/DVD/Blu-ray for Biosensing
That looks absolutely incredible, not just for bio but for anything small.
>Although off-the-shelf OPUs can be easily obtained, manufacturers protect their datasheets under nondisclosure agreements to impede their availability to the public
>Thus, OPUs are black boxes that few people can use for research, and only experienced researchers can access all their functions
Bugger. Think there are noname chinese OPUs out there? I want to get my lithography game on.

[Anonymous No.1837826]

>>1837822
>Model/Name: LM2596S DC-DC Buck Module
>Input voltage: 3.2V~46V (recommended for use within 40V)
>Output voltage: 1.25V~35V
>Output current: 3A (max.)
so If Im reading these correctly basically I would just have 1 for each led, and hook each one up to the battery directly?

And run a say 36-40V battery and each would throttle the energy going from the battery to the led to 35V and 3A?


Please excuse my artistic retardation but pic related, trying to make sure I understand the concepts correctly.


And could this basically scale to any led amount barring heat and weight?

[Anonymous No.1837828]

there are TONS of interesting projects here: http://physicsopenlab.org/low-cost-diy-scientific-equipment/ haven't checked for easiness or even factibility, though...

>>1837822
>Bugger. Think there are noname chinese OPUs out there? I want to get my lithography game on.
well, I'm not really knowledgeable, just starting some research for fun, but there is also this:
https://hackaday.com/2014/10/30/reverse-engineering-a-blu-ray-drive-for-laser-graffiti/ (still haven't watched it all)
I also wonder if this could be of help: https://superuser.com/a/1194170
looks like these guys may have more interesting stuff:
https://forum.hackteria.org/t/laser-optical-pickup-unit-hacking/771

[Anonymous No.1837833]

>>1837826
>so If Im reading these correctly basically I would just have 1 for each led, and hook each one up to the battery directly?
Yup.
>And run a say 36-40V battery and each would throttle the energy going from the battery to the led to 35V and 3A?
Yes, though in reality you'd set the current down to 3A and leave the voltage no less than what that will give. By using it in a mode where the current limit results in a lower voltage than the voltage limit, it will remain pulling that same current. On the other hand, if you tuned the voltage limit to 20V or so, you'd have the LEDs staying at a constant 20V, with the current being lower than 3A and changing somewhat over time.
They're switching regulators, so heat shouldn't be too big an issue. Your pic looks fine, though I'd possibly desolder all the trimpots and replace them with one single potentiometer for each use (current, voltage) connected to all four modules.

>>1837828
>all those neat links
I'll check those out when I'm not cooking 12 servings of curry to eat within 5 days.
If nothing else, an OPU should be able to have its driving circuitry replaced with standard stepper/servo drives to use as a more macroscopic CNC. Like for a plotter that draws graphics on the backs of CDs.
Also a floppy disc magnetic (analog?) delay, I guess.

[Anonymous No.1837843]

>>1837833
Thank you a ton for all the info from everyone, exp for keeping it in fairly laymens terms so I can actually understand it.

>Yes, though in reality you'd set the current down to 3A
the module is 3A max so wouldn't I just turn it up all the way or whatnot? (not sure exactly how it works)

The ones I'm looking at are...
https://www.ebay.com/itm/10-PCS-LM2596-DC-DC-buck-adjustable-step-down-Power-Supply-Converter-module/221920170517
to make sure I'm getting the correct thing


And another just to make sure I understand the base concept...if I got a say 36v 4.4 amphour lithium battery for pic related,
running full blast it would draw (3amp x 4) 12 amps, which means a 4.4 amphour battery would last theoretically given a perfect battery, 22 minutes right?
Being ( 4.4 / 12 ) amphours
I'm actually going on a month long trip in 2 days so I'm planning on ordering a pile of chinkshit before I leave so when I get home i'll have everything to play with.


Besides the leds, the regulators and the battery is there anything else electronic wise I really need?
>besides the cooling, mounting, ect... just talking about the pure zappy zapp parts the others I'm actually not retarded with unlike this lol

[Anonymous No.1837845]

>>1837833
read the biosensing paper and also download the supplementary info. they even have technical info for the OPUs in PS3 and XBOX 360
also, apparently the last link I posted talks about the same researcher that made the AFM and coauthored the biosensing paper :)

[Anonymous No.1837850]

>>1837843
>the module is 3A max so wouldn't I just turn it up all the way or whatnot
I'd still turn it slightly below its maximum (which may well turn out to be a bit above 3A) just to ensure it's running in current-limiting mode.
>The ones I'm looking at are...
That one only has one trimpot on it (the blue cuboid with a brass screw atop it), you need one with two or three. The ones with one only do constant-voltage, the ones with two do cc and cv, while the ones with three do cc, cv, and battery charging (which you don't need).

>22 minutes
Sounds right to me.
>36V 4.4Ah
I'd recommend getting a 12S battery, which I think is a bit above than 36V, because it's a relatively common setup and the higher voltage gives you a little overhead if your LED array happens to want a bit higher of a voltage.

>is there anything else electronic wise I really need?
Potentiometers to replace the trimpots with. Trimpots are fine for setting and forgetting, but if you want dynamic brightness regulation (I bet you will with those 100W LEDs) you'll want to change the value often. Trimpots are only good to a few hundred uses, and those little screws are a pain to adjust. Can't remember if it should be 10k or 100k (or 1k?) you want, I can check my module if I can find it if you can't see it on any listings or datasheets.

[Anonymous No.1837851]

>>1837815
https://www.youtube.com/watch?v=5bqujaldaCQ
holy FUCK I wish I had read that paper and seen this video before

[Anonymous No.1837853]

>>1837850
>That one only has one trimpot on it (the blue cuboid with a brass screw atop it), you need one with two or three. The ones with one only do constant-voltage, the ones with two do cc and cv, while the ones with three do cc, cv, and battery charging (which you don't need).
Gotcha let me look around to try to find the cheapest bulk ones

>Potentiometers to replace the trimpots with. Trimpots are fine for setting and forgetting, but if you want dynamic brightness regulation (I bet you will with those 100W LEDs)
I actually don't.
At this point my only goal is to produce the sun.


I might look into that for my next build, don't want to bite off too much at once you know. first thing i'll be doing is just running a single 1, then im going to try to smash 4 together as close as I can and mill a casing for it.


Down the road though I'll def be doing that, so thanks for the info on that I've copied it all for later

[Anonymous No.1837854]

>>1837850
finding just 2 seems to be hard, I'm retarded, or both.
This is what your talking about with the 3 right?
>https://www.ebay.com/itm/2-5-10PCS-LM2596-DC-DC-Step-down-CC-CV-Power-Supply-Module-Converter-LED-driver/202038428306?var=502035049729

granted I don't need the 3rd, if it's cheaper than the 2 for whatever reason, it wont actually hurt to have it right?

[Anonymous No.1837863]

>>1837853
>At this point my only goal is to produce the sun
In that case, best of luck to you.

>>1837854
Yeah that one is the 3. The ones I have are the 3 too, so maybe the 2s don't exist at all.
I buy all my shit on aliexpress though, which I think in general has a better selection. Prices can go either way though. Look for ones with the most buyers and high reviews though, as opposed to lowest prices. Going for low prices alone just nets you "dear friend, we put the price wrong so you need to pay extra shipping, can you paypal us $5? please understand" or words to that effect.

[Anonymous No.1837872]

>>1837863
thanks for all the help famalam.

I just want to create a portable McSun, No real reason just really want to do it.

[Anonymous No.1837896]

>>1837863
one thing I just thought of.

Can those little LM2596 chips also supply less than the 3amp 36v, can it step down the voltage off the 36v batteries?

Like can I use one to power the 12v cooling system?

[Anonymous No.1837897]

>>1834638
If I look like this, this looks like a current controlled output. The triangle being a buffer or amplifier, the resistor to ground on the right being the load, the other resistor in series being a current measurement resistor with two taps for measurement.

[Anonymous No.1837916]

>>1837803
Got a picture of the innards?

[Anonymous No.1838140]

>>1834622
what is the best brand for a mouse switch replacement? Is there anything better than Japanese omron?

[Anonymous No.1838163]

>>1837796
>suggestions for what to do with these?

spy on your new roomie. listen to him fuck; listen to him tell his GF how much he hates his creepy roommate (you). you can hide the handset inside a wall, next to a power socket for power, or a piece of furniture, or a gadget you say the last tenant left behind. an alarm clock is ideal. i bought a Sony clock radio at a thrift store that has a huge empty space behind each speaker. DVD players also have lots of empty space, but nobody uses them anymore.

[Anonymous No.1838189]

>>1837896
Definitely. You could use one to power a 3V LED if you stayed below the 3A limit.

[Anonymous No.1838228]

>>1835700
Linear or switching? For linear you either need linear fets or vacuum tubes, switching can be flyback. BJT”s have Poor SOA so forget about using those.

[Anonymous No.1838243]

>>1837916
These are the broken pieces that hold spring loaded pins which engage the contacts. You can see how they used to fit together. One piece was pinned to the actuator shaft and the other was held in by friction by a ball feature at the end of the shaft. I’ll post the contacts next.

[Anonymous No.1838250]

>>1838243
This is the contact plate assembly. There are 9 pins total. Moving the actuator up would depress the left and right contacts and short the left center pin to the left top pin and the right center pin to the plate which is connected to the centermost pin.

You can see my godawful repair attempt to the broken pieces. I first tried using a hot knife to melt them back together. I found they would melt far too quickly causing them to deform while at the same time reharden too quickly to create a proper bond. I then tried using heatshrink to hold them together, which was too weak so I also tried focusing heat on the points of contact with the heatshrink keeping them together with a heat gun which resulted in the plastic just bubbling up and oozing out of the heat shrink. I then tried reinforcing it with some craft pins and that didn’t work at all. I could potentially make some new ones out of some scrap delron at work with a rotary tool but at this point I kind of just want a new switch.

The new switch wouldn’t have to be the same set up internally nor would it need the same connections on the back. I can easily just make a new wiring harness. The only thing I need is for the new switch to fit the old housing.

Also I just realized these contacts would actually be SPDT, right?

[Anonymous No.1838335]

What the fuck happened to this fuse?

[Anonymous No.1838377]

>>1838335

zeus happened!
(the fact that lightning is real means that zeus is real. take that atheists.)

[Anonymous No.1838458]

>>1834679
>>1834679
anon, I'm in school for EE rn.
Get a book on calculus. Then get the book after that.
As the book says, those are RC circuits. You can find much more basic ones that only use algebra, but they lack the accuracy of the differential ones.

[Anonymous No.1838470]

>>1838335
well im no scientist or mathamagician but the board says 350w so ima take a stab in the dark and say it took 350 wats no lube then shit its guts out

[Anonymous No.1838478]

>>1838335
Scientist here. It looks like a pretty standard case of fusal prolapse after rigorous stimulation.

[Anonymous No.1838484]

Ah yes, the classic protection plan for thermal paste.

[Anonymous No.1838496]

>>1838484
what kind of subhuman approves this shit?

[Anonymous No.1838513]

>>1838496

probably a feller named myfirstscript.py

[Anonymous No.1838763]

>>1838496
>>1838513
>frequently bought together
>another item that does the same thing
that shit gets me every time.

[Anonymous No.1838782]

on a scale of suicide to saving money where would you put buying a huge lithium battery off aliexpress?

https://www.aliexpress.com/item/4000926688224.html?spm=a2g0o.productlist.0.0.661d18cbY4sAPx&s=p

[Anonymous No.1838784]

I'm trying to find a digital switch that looks and acts like an 'ignition' key-turn. Does anyone know of anything like that? My search-skills seem to not be doing the job and I'm not exactly sure what keywords I should be looking for.

[Anonymous No.1838785]

>>1838784
A key switch?

[Anonymous No.1838787]

>>1838785
Oof... That's embarrassing. I don't know why I didn't try searching for that.

Thanks anon

[Anonymous No.1838870]

>>1838782
Just buy the 18650s and make the pack yourself. Who knows how many shitty cold joints the chinks made underneath that plastic wrap.

[Anonymous No.1838954]

>>1838870
Thanks for the tip, do you know of a chink model number for 30A constant discharge? 18650 seems to be 20 only

[Anonymous No.1838955]

>>1838954
>>1838870
Ideally I'm looking for
>36v 3amp cont
>36v 12amp cont
>36v, 27amp cont

[Anonymous No.1838956]

>>1838954
https://en.m.wikipedia.org/wiki/List_of_battery_sizes

[Anonymous No.1838960]

>>1838956
I'm sorry I had no idea that it was a standardized size I assumed it was one of the Chinese model numbers.

Thanks senpai

[Anonymous No.1838961]

>>1837461
>PIC12, linux
Microchip has MplabX that runs native under Linux. When installing, you can also install a stand-alone programming application, Mplab IPE, that interfaces their programming hardware.
>command-line
I've only used everything under their GUI, I believe you can operate the programming from a CLI if you dig deep enough.

[Anonymous No.1838974]

>>1838956
>>1838870
so I've been reading about the 18650s and everything I'm reading says they are all 20A max, but I'm also seeing people build shit that draws far more than 20A with them.

How exactly does that work?
Will the batteries output more than 20A but the battery life is reduced or something?
Is it just hyper dangerous to draw say 30A?

[Anonymous No.1839134]

>>1838782
Buy the name-brand lipos instead, like CNHL. Also get a brand-name charger (SkyRC?) and brand-name XT60 connectors too.
t. anon who asked similar questions over at >>>/diy/rcg

[Anonymous No.1839168]

>>1839134
I'll look into it, what about
>>1838974
?
I'm looking at a constant draw of about 28-30amps

[Anonymous No.1839179]

>>1839168
A small 1300mA CNHL lipo will do like 100A. Also you don't have to worry about spot-welding the cells together.

[Anonymous No.1839213]

lower impedance in a speaker means it's louder?
so headphones have much higher impedance than say room speakers?

[Anonymous No.1839242]

Im not sure what this means. This is a breakout board for stepper controllers that has an added PWM circuit for a VFD. I have both a 5v and 12v power supply to control it.
Is this telling me not to daisy chain ground cables between the two power supplies?

[Anonymous No.1839245]

>>1839213
>lower impedance in a speaker means it's louder
No, just that they take more current (and hence more power) at the same voltage. You could drive a 10kΩ speaker with 100kV and it would be louder than many room speakers. But in general, speakers run at around 12-36V (an arbitrary guess), so the comparison sticks. Headphones driven off a normal headphone output will only run up to 1V (also an arbitrary guess) or so, which is why some (lower impedance or leakier) headphones need an external headphone amplifier. I usually run my IEMs at 1-4 bars out of 16, which assuming it's a logarithmic scale puts my voltage way below 1V, and they're 32Ω headphones. On the other hand, room speakers will be 8Ω or 4Ω run at a higher voltage, so the reason for the difference in loudness is both due to voltage and due to impedance.

Note that impedance values are calculated at a certain frequency or as an average of certain frequencies, and that in reality this impedance (and hence the current that will flow through a speaker for a given signal amplitude) will vary as a function of frequency. Ordinary speakers (made with a diaphragm that has a coil of wire on it that produces a force relative to a stationary permanent magnet) are inductive loads, hence their impedance increases with increasing frequency. Capacitive loads on the other hand, like piezo tweeters or crystal earpieces or ultrasonic transducers, have their impedance decrease with increasing frequency.

And as you might expect, the main limiting factor of a speaker is a thermal one. Too much power dissipated in them as heat and they start to degrade. Unless you drive it hard enough for a short enough time that you deform the diaphragm before it overheats. And tolerance to thermal power is proportional to size. So regardless of its impedance, similarly sized speakers will be able to handle similar power outputs, you just have to run them at a different voltage. This exact same principle applies to electric motors.

[Anonymous No.1839251]

Curious does anyone use gucci soldering irons or does everyone just use stupid harbor frieght shit

[Anonymous No.1839256]

>>1834908
>>1834924
Can confirm the SP uses a standard LiIon, and you can pop in an 18650 and be all good. Your friend clearly doesnt know what he is talking about - as the other anon said, it ranges from 3.2v to about 4.2v depending on charge.

What is your end goal here? USB chargers have existed for the SP forever, and are under $1. This will let you plug your SP directly into the power banks USB output as intended, and will charge it no worries

[Anonymous No.1839259]

>>1839251
I use ORIGINAL Giccu soldering irons from China

[Anonymous No.1839260]

>>1835173
They typically use Nichrome wire for heating elements. As a bonus, they are typically rated for 240v mains. For something that low, its probably a high power resistor though

[Anonymous No.1839282]

>>1839242
Yes, don't connect the negative rail of the +12V supply to the rest of your circuit's ground. In addition, ensure that they aren't indirectly connected together, say via the ground prong on the mains power cables.

>>1839251
I use a KSGER T12 OLED STM32, no complaints here. It's a brand name, but a cheap chinese brand name.

[Anonymous No.1839287]

>>1839251
i would not even touch anything that doesn't start with TS

[Anonymous No.1839288]

>>1839287
>

[Anonymous No.1839314]

>>1839251
Dumped money on a Hakko FX-888D, don't regret it for a second. Very sturdy and holds temps beautifully. Soldered a QFP-48 with 0.5 lead spacing by hand.
I had another soldering station from china that was decent for a year or two, but started getting loose and the element/feedback would keep getting disconnected from its contacts if you held it the wrong way.

[Anonymous No.1839330]

>>1839314
How does it compare to weller stations? I have an older analog weller I am pretty happy with it except the tip holder (the metal screw-in part of the iron) got loose as the thread got stripped with time which sucks. May need to buy a replacement iron but not sure if they are still available.

[Anonymous No.1839333]

>>1835173
tungston osmium alloy or something equally absurdly hard for something that is just going to get hot and not be shot at

[Anonymous No.1839336]

>>1836299
pfff . my c945s are better and in the same to92 package. get mhz noise if you run one in reverse bias and you can do it with 3 lithium ion cells in series

[Anonymous No.1839357]

>>1839336
I'm partial to the 2n5551. Curve tracers are fun toys.

[Anonymous No.1839370]

>>1839251
No soldering station will ever replace soviet ingenuity.

To be honest, chinkshit irons, even with temperature control, are shit compared to German mains iron. Tips don't last, ergonomics are shit. If I had a choice between meme T12 station or TS100 or whatever and Ersa mains 20W iron, I'd select Ersa.

[Anonymous No.1839407]

>>1839370
looks like you'd need a bunch of potentially expensive and/or unobtainable wood working tools to build this thing. unless those tools were also hand made. but what tools do you use to make the tools?

[Anonymous No.1839419]

>>1839251
I use pic related. Nice pencil grip with short tip and it heats up in 9 s.

[Anonymous No.1839422]

How long can you let a soldering iron like a Hakko sit and idle. Will you destroy a tip by using it for 10 minutes, let it sit running for 20-30, then keep using it for 10 in a cycle. Would you turn it off in between?

[Anonymous No.1839426]

>>1839422
You tip will corrode eventually so there is not much you can do. Corrosion is accelerated at high temperatures so yes, idling will eat your tip faster.
http://kb.hakkousa.com/Attachments/Checklist%20to%20Maximize%20Soldering%20Iron%20Tip%20Life-GUIDe235e20050694447802eac655acbaa81.pdf
Your manufacturer says that you shouldn't
>Increase tip temperatures
>Leave the iron idling at high temperatures
>Leave the soldering iron on continuously without use

[Anonymous No.1839577]

>>1839370
>tips don't last
Been on my first chinky T12 tip for the last two years, no signs of wear. You can use it with legit Hakko tips if you want.
>ergonomics are shit
They feel fine to me, I think they're just copied from a jap iron alongside the tips. I have the thin pencil-style handle with rubber grip.
TS100/80 ergonomics are much more hit-and-miss, you have people having to 3D-print their own grips for those.
>20W
have fun soldering ground planes.

>>1839426
This is why it's good to have a soldering station with automatic standby and sleep modes. I've set my T12 to 150C standby after 8 minutes, with the tilt-switch in the pencil tip being used to wake it up. After 20 minutes the iron goes to sleep, where no power goes to the element. Because it heats up so quickly I'm tempted to disable the standby mode completely and have it go to sleep much faster, but that would mean much more thermal cycling.
My boost settings are +80C for 3 minutes (or until I disable it, which is more likely).

[Anonymous No.1839606]

>>1839422
>he doesn't have a nitrogen flow soldering station to prevent oxidation

[Anonymous No.1839609]

Do you guys ever think about what you'd do if disaster struck and you found yourself in a lawless/collapse of order/post apocalyptic situation? Like, the power grid and the internet are down; how would you use your skills with electronics to survive?
With the power down, how would you rig up some sort of solution to charge small devices?
If the collapse lasted for the rest of your life would you open an electronics repair business? Fixing toasters, setting up custom diy generators, and buying scavenged components for bottles of everclear and cigarettes.
You'd need a lot of components, and you'd have to scavenge them from trash and discarded appliances.
Even worse, you'd be without datasheets from the internet.
I once tried to back up the entirety of that transistor datasheet archive site(alltransistors? I forget the name), but it ended up being absolutely massive and beyond my capabilities at the time. I currently have a fairly good stockpile of databooks, textbooks, and common datasheets in pdf form (well, a couple textbooks in physical form), but if the power went down it'd be a bitch to maintain access to them. Tablets, phones, and laptops would be able to access them and don't require much power so I'd probably just try and rig up a small generator to charge those, then go from there.
When I get the money I'm gonna try and buy several more car batteries and maybe an old car and try and rig up a diy generator / battery charge controller just for fun. Probably not the best solution, but I always thought it's an aesthetically pleasing one for such circumstances.
I like to think about this sort of thing. I wish there were more books on this issue, but all I could find was Simon Monk's zombie survival book which is a little to meme-y and unrealistic for my taste.
I apologize if this is too far out for this thread, but I'd love to hear if anyone else has thought about this and what sort of things they've come up with.

[Anonymous No.1839615]

>>1839609
In the past the electronics manufacturers used to annualy publish databooks for all the components they produced. At least Siemens did so since I have two of three volumes from 1976/77.
They're basically all the datasheets with some supplementary use examples in one book.

Don't know if that is still being done though.

[Anonymous No.1839617]

>>1839609
>how would you use your skills with electronics to survive?
Well I don't have any batteries, nor solar panels, so by myself I'd be screwed. But I know a few things about circuit repair and simple radio modulation and demodulation, so I may be able to cobble together useful circuits alongside allies.

>>1839615
Those books are so useful. A book full of appnotes is pretty good too, I got one from a lainchan pdf sharing thread IIRC.

[Anonymous No.1839643]

>>1839617
You can pick them up quite cheap on ebay.
I purchased them for a couple of bucks at a second hand store. Mostly as a curiosity and a nerdy grown ass man picture book.....

[Anonymous No.1839685]

>>1839643
I got some old TI CMOS data books that my university was throwing out.
I also got an old AMD PAL data book, which is pretty neat.

[Anonymous No.1839706]

>>1834622

we're making a wiki out of the old mims books

https://robots-everywhere.com/re_wiki/pub/web/Cookbook.Cookbook.html

[Anonymous No.1839713]

I long time ago I bought some connectors and I lost part of the one I want to use. Im planning on 3d printing it but I don't know the dimensions. Its the part seconds to the far right.

[Anonymous No.1839720]

>>1834622
little off topic but the /eng/ generals on /sci/ suck

Im starting my first power engineering job in a month, and while i have been reviewing the textbook i used for my two power courses (doing more systems stuff for a desgin/build company rather than electronics) anyone have some books they would recommend

[Anonymous No.1839753]

>>1839713

that's most likely rubber, for water resistance, which you cant 3D print. to make it you can use 2 rubber punches made from pipe that's been ground into being sharp at the end. or make a negative and fill it with silicone.

or pull the rubber ring from one of these cable glands.

or ignore it coz it doesnt matter 90% of the time.

[Anonymous No.1839772]

how do I light up this led I got from a cheap flashlight without sticking it back in the case?

[Anonymous No.1839807]

>>1839772
nvm found the fix.

[Anonymous No.1839826]

>>1839426
not him but I bought a chink knock off JBC station kek
I want the legit shit but they're a lot of money for who knows if the performance is that much better

[Anonymous No.1839861]

Might be wrong thread/not enough info but I bought one of these for my gas mask and I'm wondering if there is possiblly a way to make it louder? It runs off a single CR123 battery.

[Anonymous No.1839882]

>>1839407
No, all you need is random ferrite core, two NPN transistors that are rated for mains voltage, couple film capacitors, diac.
Case cam be whatever you want (if you live in first world) or can steal (if you're from ex-soviet part of the world).
>>1839577
>Been on my first chinky T12 tip for the last two years, no signs of wear. You can use it with legit Hakko tips if you want.
I had used 900-M clone station before, and coating on original hakko tips is much more robust, than on clones. Also manufacturing tolerances are different too.
Yes, I'm the nigger who does scrapy-scrapy on PCB. Chinks tips get stripped to bare copper if you do this. And you're lucky if it is copper.
>They feel fine to me, I think they're just copied from a jap iron alongside the tips. I have the thin pencil-style handle with rubber grip.
I think it is better to get original handpiece since it would be much nicer mold, spared no expense on heat insulation. It gets annoying when you use iron entire day.
With all chink irons I have one problem, they get hot. You really need asbestos gloves or something in order to use them comfortably.
>have fun soldering ground planes.
You're forgetting that classic irons have large thermal mass. This is way better than most temperature control algorithms on chinkshit stations that measure temperature once a second, and tip thermal mass is nothing.
>>1839419
I stole pic related from my colleagues for a week, and man, it worth $300 they want for it.

[Anonymous No.1839888]

>>1839643
Man I wish I found that sort of thing at 2nd hand bookstores.

>>1839713
>seconds to the far right
Are you including the barely visible white piece in that evaluation? Either way, both the rubber piece and the metal piece with the O-ring will be very hard to 3D print and retain functionality.

>>1839861
We're not psychic. Take it apart and post pics of internals. Measure the DC resistance through the speaker and the maximum voltage amplitude going into the speaker.
>inb4 don't have a DMM

>>1839882
>scrapy-scrapy
You do you. If I were doing that sort of stuff I'd get an iron/station that just uses those solid copper tips, since they're like 99c each anyhow.
>nicer mold
There's the barest hint of flashing around my handle's plastic, and none around the rubber grip. It could be better (the rubber grip is a teensy bit loose) but I'm in no hurry to replace it.
>heat insulation
I've no idea how they do it, but even though the pencil grip is pretty thin (15mm) with nothing but plastic in there and a rubber grip atop it, it's never more than slightly warm to the touch. Certainly colder than 35C, and that's after soldering for a good hour or two.
>thermal mass
I couldn't tell you the response rate of my T12 soldering station, but I suspect it's greater than 1Hz. It only takes 5-8s to heat up and the screen shows a continuous decrease in duty-cycle when it does this, and the screen appears to update this ~4 times per second. I also never see the tip's temperature dip by more than ~1C while I'm soldering, though I am usually not looking at the temperature display while doing so. I could maybe figure out how to chuck my scope on it, if you're interested, though measuring would be a bit tedious.

Assuming that the temperature sample-rate is significantly faster than the temperature changes, I'd much prefer to solder via temperature control, compared to soldering via heat capacity. Not to mention it doesn't work if your ground plane is thermally bigger than your tip.

[Anonymous No.1839894]

I have a 300w inverter. I’m thinking of buying a 100w solar panel plus that comes with a controller and then maybe a car battery from Walmart. From what I gather I can just hookup the car battery to the solar panel and then boom, free power as long as I charge it for 14 hours, right? I just don’t wanna get jewed

[Anonymous No.1839899]

>>1839894
Car batteries aren't what you want, unless you're going to crank a starter motor with it. You want a deep-cycle battery instead. And you will want a charge controller between your battery and your solar panels. MPPT charge controllers are preferred.

Also note that an inverter may be a waste of power, as many appliances have no need for AC power as they just use internal SMPSs; 150VDC will suit many applications just fine.

[Anonymous No.1839903]

>>1839899
Will a 7ah deep cycle battery be okay for a laptop? How will I utilize the internal SMP? Is it possible to plug it in without using an inverter?

[Anonymous No.1839904]

>>1839903
SMPS*

[Anonymous No.1839905]

>>1839899
>MPPT charge controller
Is this a scam? It looks too good to be true
https://www.wish.com/product/5ddf7b2bd691bc5caf935be0?hide_login_modal=true&from_ad=goog_shopping&_display_country_code=US&_force_currency_code=USD&pid=googleadwords_int&c=%7BcampaignId%7D&ad_cid=5ddf7b2bd691bc5caf935be0&ad_cc=US&ad_curr=USD&ad_price=23.00&campaign_id=10083230814&utm_campaign=10083230814&utm_source=pdp_install&gclid=Cj0KCQjwiYL3BRDVARIsAF9E4Gd0zgEN9xxnxjPdZ4vpmPySTTCmG_L6Z3m1bZ2SN4RoaKb3j4UNVxkaAq-OEALw_wcB&share=mobileweb

[Anonymous No.1839914]

>>1839888
OK I figured as much. I'll take it apart when I get back to my shop. I'm a retard when it comes to electronics but I do have an 87V for troubleshooting.

So what will resistance and peak amplitude tell me? I also don't have a reference frame for the magnitude of those numbers either.
Am I looking to increase voltage to the speaker to make it louder? V=IR so am I looking to reduce resistance in the circuit as (probably) the easiest way to increase voltage without changing the battery?

[Anonymous No.1839918]

>>1839903
A simple 12V-19V boost converter should be sufficient for a laptop, check the output specs on your power brick. Might want to add some overcurrent protection though.

>>1839905
>wish
Don't even need to click to know that it's garbage.

>>1839914
>what will resistance and peak amplitude tell me
If peak-to-peak amplitude is below Vcc-Vee then you'll be able to just increase the gain of the amplifier. If not, then replacing the speaker or increasing the voltage to the system may be able to increase the volume for you. Increasing the voltage might not be supported by the electronics, so you may want to simply replace them with your own amplifier circuit. Speaker resistance isn't too important, but you'd need to know it to calculate the total power usage (for battery life calculations and rough loudness comparisons) and whether the output stage can handle sourcing that much current.
>87V
Good man.

[Anonymous No.1839922]

>>1839905
>read reviews
>see this
>5 stars anyway
Imagine being a Wish cuck.
Aliexpress is the way to go for most things, but for solar panels and charge controllers I wouldn't chink out in the first place unless you really know what you're getting.

[Anonymous No.1839923]

>>1839918
>12-19v boost converter
This is perfect for my tablet, seems way more efficient, thanks man. Will it be okay for my thinkpad as well? It says 20v on the power brick

[Anonymous No.1839926]

>>1839923
You'll probably want a seperate converter for the 20V, but I'm no authority on the subject. Google something along the lines of "20V laptop with 19V power brick".

Also on that pic I think I can see a 5V written on it, is it a charge cable with more than 2 pins on it? If so you'll probably need a more complicated power supply or array of power supplies, and I'm unsure whether that would comply with what the tablet's power-management IC is expecting. If it were a simple DC barrel jack it should be fine to just use a boost converter, since I don't think any information is transmitted from computer to charger at all.

As for the battery size, a 7Ah 12V battery means it's got about 84Wh of energy in it. Check your computer's specs to see how much power it uses in idle and in more intense use.
I'd personally go for a battery (or array of batteries) that will take on the order of half a day to charge fully via your solar cells, that way you're not wasting a high-power solar array by charging your batteries to the top within quarter of an hour of sunlight. So if you have a 100W solar panel, go for something like 200-500Wh. Depending on how you mount the panel (fixed at an angle is probably most cost-efficient) and on how much sun you expect to get on average.

[Anonymous No.1839928]

>>1839926
On the other hand, if you're fine with a 84Wh battery, a 50W solar panel is probably more than sufficient.

[Anonymous No.1839931]

>>1839926
That works great, 200wh deepcycle batteries are relatively inexpensive and half a day works just fine. Both the tablet and the laptop only have two pins. Would it be possible to use a 19v boost converter for a 20v laptop? I’m wondering if it’s possible to charge them both while I have the battery plugged into the solar panel

[Anonymous No.1839943]

>>1839931
>use a 19v boost converter for a 20v laptop
As I said, google it. But you're more likely to be able to run a 19V tablet on 20V than the other way around, since I believe the voltage requirement is for the dropout to the buck converter that charges the batteries; higher dropout should be acceptable but not lower.

[Anonymous No.1839948]

>>1839943
I see

[Anonymous No.1839995]

Anyone have any idea what type of cap these are?
One of them failed spectacularly and needs replacing.
Judging by the ratings and polarity I assume it's Aluminium / possibly tantalum but I've never seen them in a package like that.

[Anonymous No.1840001]

>>1839903
>Will a 7ah deep cycle battery be okay for a laptop
7ah is pretty shit, lead acids are usually 12v so that is 84 watts for one hour, desktop pc is like 200w when not gaming so laptop will be around 100 i reckon so you get like one hour of power, get at least a 20ah AGM battery, ideally several of them so you can build a small say 100AH bank. Then you can actually run some shit from it

[Anonymous No.1840014]

>>1839995
I don't think they have vents, and their energy capacity / volume ratio looks a little low for aluminium electrolytic, so I'd guess they're tantalum. A 25V 33µF al-electro would only be about 6mm wide and 12mm tall. There don't seem to be any standard yellow tantalums on the PCB either, though the same can be said for standard al caps from what I can see. If you hunt about on digikey you may be able to find those exact capacitors. Not that I'd buy them unless they're actually new stock, I've heard tantalums age poorly. Considering the price of tantalum caps, it may be cheaper to replace them with film caps instead, though I've never seen 25V film caps before.

>unusual capacitor packages
>QFP sockets
>resin-dipped SIP resistor arrays
>MELFs
>possibly a ceramic SOIC or two
That board is a goldmine for interesting packages. Looks like no expense spared with all those sockets, plus it's made in Germany. The layout is also really nice to look at, nice thin elegant traces, and the components aren't cluttered either. What's it from?

>LM339
I was going to guess it's from around the year 2000, but now I'm not sure. I guess you can swap out those comparators for ones from a different IC, either because they age or wear down or for slightly different behaviour.
>LF__
I think that means it's a JFET op-amp, at least from the few LF ICs I've seen.

[Anonymous No.1840018]

>>1840014
It's out of an old Leitz silicon wafer inspection system.
The boss bought a load of stuff from Intel back in the day (late 90s, early 2000s) and it's been sitting in a warehouse since.
Local hospital wanted to rent the warehouse during the pandemic so this was brought over to the factory.
I was asked to power it up and the power supply immediately blew a bunch of through hole tantalums.

Power supply itself was quite interesting, big ass toroidal with different secondaries.
There's a separate PCB plugged into it for each of the voltage rails and it was the +12V and -12V boards that shit themselves.
Besides the tantalums having exploded, most of the aluminiums had vented, the BJTs that were push/pulling the main MOSFET blew, few TVS diodes and zeners blew and the switch driver got fried.
I fixed them, powered it up today and one of the caps from my previous pic burst.

I'm after replacing it with an aluminium and a board further down the line is after spectacularly blowing a huge cap (Can't even tell what it is anymore it's charged so badly).
Half the factory got filled with thick white smoke so I've stopped working on it for the time being.

It's not really critical for me to get working but it's an interesting piece of kit so I'll keep tinkering with it until I'm told to stop.

[Anonymous No.1840023]

>>1840014
Power supply

[Anonymous No.1840024]

>>1840023
Driver boards

[Anonymous No.1840026]

>>1840024
Board I originally posted

[Anonymous No.1840027]

>>1840026
This chunky bastard seems to be a driver for the light source

[Anonymous No.1840031]

Point me in the right direction please.

Have decent professional tool skills and electrician and fair amount of java and c++ and a major in aerospace engineering. Installing correct to speck isn't even an issue. However parent's big family room is going to get wood to replace carpet. I want to make a 270 ° pitching and 180 ° roll welded cage that can be disassembled with pins and attached to a "pilot seat" with straps. Prying up specific wood plates reveal hidden anchors well into the studs for firm attachment. Would prefer to use IMT or heavy wall if it can be ordered certified for structural. Will literally just fill in Comsci for stresses and tack in emt cut reinforcements to cut weight for the moving parts.

The idea is we put a long baby gate around when under a load for accidents, but moving the couch and table back should be enough for room. Can this be done also by expoxying a Teeter Hangup to a gamer chair with 4 angle iron, 4 actuators, and 4 arduinos? I feel proper shocks so you don't shake loose fasteners by house builders since I'm not already in a earthquake zone.

…

[Anonymous No.1840034]

>>1840031
…
Point me in the right direction please.


…
Full roll is a later concern, just like to pull up and at least be pulled at the proper simulated net vector of gravity on the fictional pilot. The feel of decent by leaning forward in the seat to straight down to simulate diving at terminal velocity before pulling out as you pitch back down to parallel with the horizon. Pulling up making you literally lie on your back. Banking will not just orient my ass to the map but lean inversely as if pinned gently to the seat. Eventually a linear shake would be cool for ablation simulation. Batteries and bluetooth will make the VR and joystick work fine with a server, but I am going to probably pipe a 240 branch right there into the floor from the basement. The pitching will need not many amps by counter weighing until center of rotation overlaps personal center of mass, but for entertainment really, the roll may need to resist "intensive" use back and forth dynamically with the virtual without having the momentum of a rotating strapped in adult to burn it out when sudden repeated fights itself.
PS, Ace Combat for PS4 implementation by just siphoning existing coefficients in game would make it so much faster. I also want to explore drone piloting for seniors to feel AS MUCH AF POSSIBLE like they're flying for real by lessening it being a drone by picking up or designating override while feeling like they actually moving with what the see. And of course, limited actuator speeds and torques so if something breaks, its likely a safety braided non-metallic cable that can be cut from a spindle if crimped correctly.

[Anonymous No.1840054]

>>1839995
So the logo on the caps is apparently Siemens but still haven't found anything about that package or what dielectric is

[Anonymous No.1840055]

>>1840054
Maybe tantalums actually
https://www.ebay.ie/itm/Lot-of-10-pcs-of-Siemens-tantalum-electrolytic-capacitor-22-F-16V-FREE-SHIPP-22u-/332978524923

Makes sense that the anode is marked rather than the cathode

[Anonymous No.1840061]

>>1839888
>You do you. If I were doing that sort of stuff I'd get an iron/station that just uses those solid copper tips, since they're like 99c each anyhow.
Those plated tips are still cheaper, $5 for 10 pieces. More expensive chink ones, btw, are exact same quality.
>I couldn't tell you the response rate of my T12 soldering station, but I suspect it's greater than 1Hz. It only takes 5-8s to heat up and the screen shows a continuous decrease in duty-cycle when it does this, and the screen appears to update this ~4 times per second. I also never see the tip's temperature dip by more than ~1C while I'm soldering, though I am usually not looking at the temperature display while doing so. I could maybe figure out how to chuck my scope on it, if you're interested, though measuring would be a bit tedious.
I wonder how fast this is happening on original Hakko. Because on all chinkshit stations I wasn't satisfied with way how they work, they would stick to plane and then overshoot. And overshoot is something I don't like.
T12 based one was better than 900-M crap, but still, brainboxery was slow.

[Anonymous No.1840064]

>>1839606
HVAC faggots fuck off. I'm not wasting money on nitrogen.
>t. Brazed fridges and ACs without nitrogen

[Anonymous No.1840084]

>>1834622

I'm a noob. This is a laser pointer/led light I scavenged from a pen. The pen was metallic on the inside, with three LR41 connected to the spring and nothing connecting their back to the mechanism. How do I complete the circuit?

[Anonymous No.1840120]

>>1840023
Hmmm, seems one in my 12v supplies isn't working after repair actually.
It's dropping even under a tiny load.
All the output caps are new so I'm not sure what's causing it.
The schotky maybe?

[Anonymous No.1840263]

FUCK WHY THE FUCK IS THE FUCKING IC NOT WORKING I REUPLOADED AND CHECKED THE CODE 10 FCUKING TIMES BUT THE SCOPE IS SHOWING A FUCKING FLATLINE
...
wait if the dot in on the top left corner that means the pin i'm outputting on is on the... other side of the chip...

yeah thats it, i'm fucking done for today, fucking stupid ass faggot electronics shit i wish we still used gears and steam

[Anonymous No.1840266]

>>1840084
looks like just a lead with a resistor, so make sure the connection goes through the resistor

battery + -- resistor -- led anode leg (very important don't connect the led backwards) -- battery -

[Anonymous No.1840301]

>>1840266
>(very important don't connect the led backwards)

absolutely nothing will happen, good or bad, if you connect an led backwards at 4.5V
i just now hooked one up to 28Vdc, and the current was 0.0uA. and it lights as good as ever.

[Anonymous No.1840306]

>>1840031
A single arduino is probably all you need as far as controlling everything. Though personally I'd go for a board with an ATmega32U4 on it (or just a bluepill) for the native USB. For bluetooth (or wifi) an ESP32 alone can probably do all the work you need it to.
Motor-wise, no clue. You're talking about pretty high torques, and you can probably get stepper motors that do that, but gear-motors with encoder feedback are probably cheaper, and they probably waste less current when braking (which is most of the time). Whether you go for brushed or brushless is just a question of how much you want to spend and how much effort you put into it.

You'll also need to spec your bearings (or bushings) well, but that should be no stranger for you. For that and all other structural questions this is not the correct thread.
As for actually interfacing with your software, you'd have more luck asking /g/.

[Anonymous No.1840345]

>>1839918
OK thank you for the info, I'll have to look up some of that and take it apart and test it.

[Anonymous No.1840383]

>>1834622
I'm working on a project, this is my first time designing a circuit, so be gentle
trying to work out an i/o switcher for audio. idea is to be able to chose from 2 different inputs, and select one of two outputs. is this all I need for the circuit?

[Anonymous No.1840416]

>>1840383
You should make sure the grounds a switch as well, if they aren't all the same ground.
If they are the same ground, you need to add that on the circuit by grounding the third pin.
Sorry, I don't know audio jacks so I don't know what S, R, and T are. Is T ground?

[Anonymous No.1840421]

>>1840416
TRS - Tip, Ring, Sleeve. Tip is ground.
the T pins would be grounded, I guess to the same ground? just didnt know how to specify that in kicad, still figuring that out too.

[Anonymous No.1840444]

>>1840421
>>1840416
whoops, got that backwards. Sleeve is ground, I'm a dingus. lets pretend it's wired that way for now though, since i dont feel like fixing it right now

[Anonymous No.1840478]

>>1834622
What am I doing wrong? Shitty pic, but basically:

>Trying to troubleshoot MC74HC00 NAND gate
>Two circuits, 12v to 4v (Vcc) and 5v to .4v (Vin)

No matter what the Y output remains high and it's bullshit.

Before I was feeding everything (Vcc and Vin) using a single 5v circuit and received the same error. I thought I had maybe overloaded the chip since the min-max Vin per the doc was -.5v - .5v but I've received the same error on four of these chips.

>New to electronics plz no bully.

[Anonymous No.1840479]

>>1840478
Forgot pic

[Anonymous No.1840481]

>>1840479
The Ohm ratings for the 12v-5v circuit are r1 = 300 and r2 = 220, and r1=1000 and r2=100 for the 5v-.43v circuit.

[Anonymous No.1840491]

>>1840481
>The Ohm ratings for the 12v-5v circuit are r1 = 300 and r2 = 220, and r1=1000 and r2=100 for the 5v-.43v circuit.

using a voltage divider to power a circuit is supremely dumb. dont do it. ever.
how is it possible that a human doest have several 5V power bricks in 2020?

>>1840444

your project is dumb. what you wanna do instead is to make a general purpose patch bay that you can expand later. it's very flexible and will be used your entire life for audio, video, and smell-o-rama.

[Anonymous No.1840499]

>>1840491
Why is it dumb? Like I said, noon here.

[Anonymous No.1840504]

>>1840499

2 reasons it's dumb.
1) the 220ohm is in parallel with your chip, which effectively reduces the resistance by some factor. so your calculations are meaningless.
2) the chip will take varying amounts of current as you play with it, so the 5V will be jumping around. you need a steady supply, +-5%, not something that's jumping around.

[Anonymous No.1840509]

>>1840504
Ok, thanks for the advice

[Anonymous No.1840511]

>>1840084
the metal housing connects to the other side of the battery and where ever it was touching it connects the circuit. most likely the copper heatsink on the laser diode since most of those have negative on the can housing

however it looks like a bad driver circuit. you could just get the momentarys off it and the laser diode and get a better driver . zandelion has some vids on laser drivers and you can see the circuits from green laser pointers in his vids and just copy it but at the same time between a 20 ohms resistor and 100 ohms resistor with a single 3.7 lithium ion cell will let most dvd laser diodes work at near or at burn level. so the circuit isnt really all that important

point is if you cant figure it out take it to bits and make a new circuit that you understand. its not that complicated

[Anonymous No.1840512]

(almost) noob here, I tried to do a small project of an automatic fan with a comparator, used the LM35 because of the direct equivalence of degrees to mV.
In simulation everything works fine, but in the circuit the fan is always on regardless of the temperature
>I forgot to place 1K pullup resistor on the output in the first test run nothing happened but I fear the comparator is toasted (measuring constant 0.62V on the output)

any pointers on what I'm doing wrong?

[Anonymous No.1840516]

>>1840512

there's a strategy so simple even babies know it called ''divide and conquer''
disconnect fet from comparator. test if works as expected.
apply appropriate gate voltage and see if fet works as expected.

[Anonymous No.1840537]

>>1840512
so if you pull it up, your fet is always on?

[Anonymous No.1840543]

>>1840512
nm, comparator will pull it down to the gnd when the output is low, right?

[Anonymous No.1840546]

>>1840516
thanks I will try it

>>1840543
yeah that's the idea, although I'm not sure if it's fine at all, R3 is supposed to limit the current that the LM393 can sink

[Anonymous No.1840548]

>>1840491
i want to be able to use this to switch between amps on one set of headphones, or switch between headphones on one amp. having to flip a switch is nicer than plugging and unplugging cables, unless i misunderstood

[Anonymous No.1840636]

Does this cap look bad to you guys?
It's not raised or bumpy but that assembly glue is black when all the others have clear glue at their base.

[Anonymous No.1840680]

>>1840306
Imagine someone with a major in aerospace engineering using an arduino to control anything.
The absolute state of /ohm/

[Anonymous No.1840682]

>>1840120
I would need to see the whole board to get an idea for the topology used, but assuming some form of SMPS, check out the primary driver for the coil. If that is good, check your feedback loop.
A high current pull that causes the output to crash would most likely be due to the driver not being able to saturate the coil enough, or the feedback from the output voltage to the coil driver isn't working correctly, if at all.

[Anonymous No.1840684]

>>1840680
I never said it was the best or the cheapest way of going about controlling those motors. It's just the quickest to get working, the lowest hassle. I was operating under the assumption that he doesn't already have more advanced MCUs and programmers lying about.

And for a 1-off project, leaving an arduino in there isn't as bad as it could be, especially if there's no need to design a full PCB anyhow.

[Anonymous No.1840687]

>>1840548
Your project is fine, you just need to make sure to keep all the lines connected correctly (all tips connect to tips, all sleeves connect to sleeves, all rings connect to rings).
You could get a couple 3PDT (3-pole, Double Throw) switches to switch all 3 lines. Or keep the DPDT switches you already have and connect all of the grounds together so they never disconnect.
Be warned that this style can be bad for pops in audio when switching sources. Also, you technically should turn off your amp before you connect/disconnect anything, so this setup would make it easy to change connections when everything is off, no swapping cables.

[Anonymous No.1840691]

>>1840383
You'll want to ground the signal (perhaps with a series resistor) coming from the unused audio sources (preamps, instruments), and probably use pulldowns on unused audio sinks (headphones, amps), for noise reasons. Because you can get capacitive coupling through a mechanical switch like that.

Actually I'd recommend splitting that into a two-to-one splitter and a one-to-two splitter, to make things easier. Because you'd be able to and combine them to have a one-to-three splitter since they're reversible.
And/Or:
I'd also recommend using analog switch ICs instead of mechanical switches, so long as the voltage ranges you're talking about will fall within the rails. Using a proper virtual ground circuit, none of that high-pass filter bullshit. A 9V battery should last pretty long with just the 20-80µA q-current of a 4053 (http://pdf.datasheetcatalog.com/datasheets/150/109160_DS.pdf).). Maybe even add a smart MOSFET timing circuit in order to have it turn off when there's no audio signal after a while, or something like that.

[Anonymous No.1840716]

This is my first diy project. I want to build an electrical standing desk. I have already ordered the parts and have drawn a plan of the table.
I really have no clue about electronics though.
I watched this video: https://www.youtube.com/watch?v=jMzbfN492LA [Embed] where he had 2 actuators, one power supply and a double pole, double throws switch. I have understood it like pic rel where the middle poles are used for power supply and the poles at the top are for actuators going up and the poles at the bottom are for the actuators going down.
Will this even work?

[Anonymous No.1840722]

>>1834622
howdy, somewhat new
i've got a synthesizer running on a knockoff Pi. I'd like for an atmega328p to handle encoders and buttons (all digital) and send signals to the Pi, which will interpret them any which way, mainly incrementing/decrementing parameter values, and i'd like those values to be sent back into the arduino to be drawn to a GUI on a screen. can firmata handle rotary encoders? can i use firmata and draw stuff to a screen at the same time?

[Anonymous No.1840750]

>>1840722
Why not have the Pi knockoff draw the GUI?
It would be much more suited to doing graphics than the atmega.

[Anonymous No.1840757]

>>1840750
i'm retarded and don't know anything about GPIO, programming a GUI or drawing directly to a framebuffer. my programming language of choice is pure data, for reference. I don't think theres a way of drawing directly from there to a screen and I'd rather not learn C just to draw text and pixel graphics to a screen

[Anonymous No.1840792]

The class I am taking says I need an oscilloscope and function generator. Which should I get? Any chinkshit brands that are pretty good?

[Anonymous No.1840793]

>>1840792
rigol

[Anonymous No.1840848]

How hard would it be to figure out the supporting circuitry for a one channel mic recorder? I'm thinking mic xlr>preamp>CS5364 ADC with SPI out>raspi zero w>uSD card
Maybe some small screen and navigation/record buttons.

[Anonymous No.1840859]

>>1840516
well it turned out it was a shorted MOSFET can't believe I burned it somehow. Thanks!

[Anonymous No.1840876]

I'm looking to get an upgrade from my soldering iron I've used which is a $5 Walmart piece of shit.

Is there a well liked chink one or something that a lot of people use maybe something in the $40 range?

Looking for the best bang for my buckkind of thing more than a top of the line one, willing to wait for some ali shit if needed

[Anonymous No.1840888]

>>1840757
>i'm retarded and don't know anything about GPIO, programming a GUI or drawing directly to a framebuffer.
How do you plan on getting the atmega to draw a GUI then?
The atmega has pretty limited ram for a frame buffer, an you're probably going to have to use C to do so, since it's a microcontroller.

The Pi knock-off on the otherhand likely has a relative surplus of RAM and processing power, and probably has python graphics libraries if you would prefer.

[Anonymous No.1840891]

>>1840876
depends what you're looking for
I've never had trouble with my $15 60W iron. Owned it for 2-3 years now, tip's fine, heat's fine, crank the temp up ~20C and it can do ground planes.

[Anonymous No.1840893]

>>1840888
idk, gui stuff just seems simpler with arduino. if it doesn't go well i'm thinking about fucking with raylib even though it's C, it seems kind of easy though. but getting an ILI to work with this Pi (nanopi neo) seems janky as fuck

[Anonymous No.1840945]

>>1840682
I managed to fix it while comparing it to the other working one, looks like somebody had attempted a repair before me.

It's a basic buck converter with a UC3524 driving a BJT pair which are driving the main FET.
There are two Wiha film caps right beside each other on the board, one of which is the timing cap for the PWM of the UC3524.
The other cap has a marking of 100 and is 100 nanos when I pulled it off and measured it.
The timing one has a marking of 1000 (Same manufacturer, shape, colour, voltage, etc) so someone replaced it with a 1micro cap (1000 nanos).
When I pulled the one off the good board though it was 1 nano (1000 picos) so I put a 1 nano on the bad board and it's sorted

[Anonymous No.1840968]

>>1840792
Tektronix AWG70001B
Vres: 16 bits,
analog bw: Up to 15 GHz
freq: 20 GHz
Sample rate: 50 GS/s
record length: 32 GS

It is pretty good. Everyone in your class should have one.

[Anonymous No.1841001]

If I take this and hold the germanium diode to a metal outlet plate and hold the other wire from the crystal earpiece in my hand I can hear am stations. Now if I take the bare wire and also hold it to the plate I can hear different stations and they're much louder. I'm guessing it's capacitance that is causing this but what would be the range of of capacitance if I were to put a trim cap instead ?

[Anonymous No.1841036]

>>1840876
>>1840891
I was thinking about something like this
https://a.aliexpress.com/_dVoM3xY

I was told silicone cords were the way to go, it all less annoying and I was just looking for something like a little station or some shit.

that one looks like a clone or probably the same thing of when I saw an Amazon for 55 that seemed real popular.

[Anonymous No.1841083]

>>1840716
>Will this even work?

not even. circuit makes no sense. e.g. when the switch is up it applies + to + of the top actuator, and - to + of bottom actuator. no current will flow anywhere.

>>1840848
>Maybe some small screen and navigation/record buttons.

so you're trying to recreate a gadget you can get at the dollar store? see pic

>>1841001
>what would be the range of of capacitance

you need both a coil and a cap to tune. google ''crystal radio circuit'' for 1 million examples.

[Anonymous No.1841086]

>>1840512
1k is a bit small for a 12V supply, it's getting close to the 1/4W limit of a standard resistor. I usually stick to 10k or higher. It's also getting similarly close to the comparator's output current limit.
As the other anon said, divide and conquer.

[Anonymous No.1841089]

>>1840876
Go for something with digital temperature control. A T12 is a good one, but there are others.

[Anonymous No.1841147]

>>1841083
Not quite, something to record high quality audio from a shotgun mic with xlr out

[Anonymous No.1841152]

>>1840968
could I borrow yours for a couple weeks?

[Anonymous No.1841166]

I'm not particularly good with electronics and trying to learn more. I've got a few things for projects going, including a couple of CRTs to repair/test.
What I'm not sure about, is what to do when shit hits the fan. So hypothetically let's say I plug one of these fuckers in and it explodes/starts an electrical fire. Is it enough to just hit it with an electrical extinguisher then unplug from mains? Should I be using an isolation transformer or something? I play around with high drain IMR batteries too so if something went wrong there would a similar course of action suffice?

[Anonymous No.1841168]

>>1840876
I'm not an expert but I picked up a Yihua 939D, China clone of some other brand. Was about 30-40 dollarydoos and had no issues with it
I wanted a model up that had a heatgun but apparently it autofires and the thing isn't properly grounded, so beware (was only a few dollars more)

[Anonymous No.1841175]

What is the technical difference between a regular AC cable and this polarized audio cable?

I ask this because I need to use it as an AC cable, and would like to know the technical benefits or drawbacks (risks?) of using an audio cable as an AC cable for common appliances.

It reads TIAFLEX POLARIZED AUDIO CABLE 2x1.50mm2.

So why don't I just use a proper AC cable to run AC electricity? Because I mistakenly bought this a long time ago and I have no other use for it, except as an extension cord which I need right now, and I already have the male and female plugs to make the whole thing immediately. But I want to know what I'm getting into first.

It will run a small thermal blanket warmer which peaks 75W @ 220V.

Thanks in advance.

[Anonymous No.1841189]

>>1841175
probably just black line to distinguish one cable from another

[Anonymous No.1841212]

>>1841189
You're right.

My cheap multimeter couldn't detect any meaningful difference in resistance on the polarized audio cable when compared to an identical gauge regular AC cable I have here. Its section also seems quite generous to the current I'll be running.

I just connected the plugs here and no issues, as it should. My electrical blanket is running great connected to it.

It might be silly to think there would be any meaningful difference for this application, but I always assume there might be something I don't know. I've actually read Wikipedia's Speaker Wire page just to make sure, and I'm now inclined to think audio cables would actually run any kind of DC or AC electricity technically (but not noticeably) easier than a cheap electrical wire, since audio is more demanding when it comes to low resistance and long distance transmission. So they usually employ higher purity copper and, in some cases, RF shielding.

[Anonymous No.1841216]

>>1841212
>My cheap multimeter couldn't detect any meaningful difference in resistance on the polarized audio cable when compared to an identical gauge regular AC cable

you're measuring the wrong thing. what counts is voltage rating and strength of the insulation. speaker cable is typically rated 30-50V.

[Anonymous No.1841218]

Hi /ohm/
I'm trying to learn more about weird C++ stuff and I want to create a "GuiButton" struct which contains some visual info and a callback function to execute when the user clicks on it. The thing is, I want to have a class that inherits from "GuiScreen" to be what actually executes the callback stored in GuiButton, and if the callback can accept a lambda expression that would be even better. I can't figure out a way to do this without using a singleton or using std::function, and I think that you can't use the functional header in Arduino or Platformio due to porting issues? What do I need to google for this one?

[Anonymous No.1841221]

>>1840687
this is the corrected version, with the sleeves as the ground, as intended. everything runs to everything else, T-T, R-R. I dont really see how a 3PDT would help here, as I want to be able to choose either in from either out at any given time, how would that work in this case? Sorry if its simple. I'm tired and not really thinking it through, probably.

For ground, if I just wire up each S to each other, then ground out on the enclosure, should be fine, right? or is that not really how ground works?
I've never had any pops on either of the amps in question when hot plugging/unpluging, is there any way to prevent that? a buffer circuit, or something of the sort? Hadn't really though of that, in all honesty.

[Anonymous No.1841244]

>>1840792
Don’t buy a new oscilloscope for your first scope. Get a 2nd hand scope, probably a CRT. If you’re not willing to drop $300 or more then you’ll just end up with a piece of junk that you’ll need to replace anyhow. CRT scopes are a bit different to modern digital scopes, but they’re perfectly usable and a good learning experience.

[Anonymous No.1841266]

Trying to fix some cheap ass headphones but I have to solder to fix them. I figure that this is as good of a time as any to get into it, is there a babby's first soldering kit I should grab or just the first thing I see on eBay?

[Anonymous No.1841279]

>>1841266
Headphones aren't fun to solder. What kind of price range are you looking for?

[Anonymous No.1841280]

>>1841279
I mean, I'd like the cheaper the better but I know things usually don't work that way. I haven't soldered anything before, so I can't comment if it'll be fun, but it's only two wires. Hopefully not that bad.
A guy in another thread recommended a Hakko but they're a bit pricey. I could be falling for a meme and not even know it.

[Anonymous No.1841282]

Hi /ohm/,
I want to do some audio work (amps, etc.) and while I want to get a used analog scope, I was wondering whether I could convert a microphone into a second oscope that offers me FFT and such stuff through software. As an example, chinkexpress item/4000257491925.html is a 24bit 192kHz microphone for 30$. Since it's going to be for audio only, 192kHz should be enough for the low frequencies I actually need and 24bits is much better than most low cost digital scopes. Obviously, I need some stuff before feeding the signal into the sound card of the microphone, but as a first approximation a pot should do the trick. In a second step adding something like a unity gain buffer would be in order to avoid drawing too much current and changing the circuit under consideration. Am I missing something obvious here?

[Anonymous No.1841287]

>>1841266

Get some used stuff from fleabay, much better than the cheap new chink crap. Some used Weller soldering station should not cost you more than 50€ or so.

[Anonymous No.1841290]

>>1841280
Hakko is not a meme, but it is pricy. What are memes but still potentially good are the chinese soldering irons/stations. The T12 soldering station is pretty damn good for the price (cheaper than the TS100 but not as portable), but more expensive than those digital temp-controlled mains irons with a 7-seg display on the handle. The T12/TS100 tips are also more expensive than those smaller ones that don't have an integrated element. While others would say it's not necessary, I would personally recommend an iron with temperature control. Digital temp control is nice (plus you can get other neat features like standby timers and boost modes), but a soldering iron with an analog temperature dial on the side should work mostly fine once you work out their quirks, and they're only like $7 on alibay. And no, they don't just have a TRIAC inside, I checked. Something similar to that is what I used for a couple of years without issue, but it was a more obscure model that I couldn't find replacement tips for.
When you do get a soldering iron and want to decide what tips to go for, I'd recommend a K tip (5mm ~45° chisel tip) for larger work, and a D12 tip (1.2mm screwdriver tip) for smaller/SMD work. A 2-3mm screwdriver or chisel tip would be a passable compromise if you just want to buy one tip.

Then you'll want solder wire (diameter is entirely up to preference, all the way from ~1.2mm to ~0.4mm, I prefer the thin stuff), external flux, a solder sucker and/or wick, some form of workpiece clamping, and all the connectors and hardware you're going to need. I'd advise practicing solder joints on lengths of fine stranded wire (32awg maybe), so get a reel of that I guess. Proper flush-cutters and small needle-nose pliers are a must too. As for wire-strippers, I just use my flush cutters.

A DMM for testing would be good too, the ANENG AN8009 is the top meme at the moment.

>>1841287
Never tried used soldering stations, but I'd be prepared to replace the element and tip.

[Anonymous No.1841291]

Okay, after several more months of procrastinating it's time to finish up this puppy
I finally wrote the code for both of the micros and now all that is remaining is to design the PCB and then mill it
And then i will finally be able to get them blinks on to some tunes
This is my biggest project so far, so i hope it works, because nothing is more suicide inducing than designing a pcb, soldering all the shit on and then you find out it doesn't work because you fucked up some fundamental somewhere

[Anonymous No.1841297]

>>1841282
Is a microphone like that really a better choice than buying a USB sound card? Assuming you can get one with those specs, that is. Also assuming you aren't also going to use that mic as a mic.
>24b
Yeah that's what you want to go for. There may be software out there that's already designed to use your computer as a real-time oscilloscope, so hunt about for that sort of thing. Sound card oscilloscopes are nothing new.
Actually, if you find a good external USB sound card on alibay, please post it here. Not to turn into a scope, probably. I've had enough of trying to use my laptop's TRRS mono audio input and filtering out the mic phantom power.

>a pot should do the trick
I'd add TVS diodes at the very least. Both zener and overshoot diodes to both rails. An op-amp buffer in case the signal's impedance is too high for the ADC is a good idea too, along with a virtual ground circuit to ensure your signal is right in the middle of the ADC's range. Shielding might be nice too.

Personally I'd install an analog optocoupler (be it a photoFET or dual feedback opto) before the computer stage so you can have an entirely electrically isolated USB side, and run a much higher voltage for the input side to better avoid the rails of any op-amps and the like that you install. Maybe even chuck an MCU or two in there to control the V/div and such. With any luck you can use stereo channels for a dual-channel oscilloscope, or even add an automatic or USB-controlled multiplexing via analog switches to add even more channels at the expense of your sample-rate.

Also to use a sound card as an oscilloscope you'll probably want it to convey DC, with no capacitors in series, which might require some desoldering on the existing PCB.

[Anonymous No.1841319]

I have this converter thing I want to re purpose. It has a 6 pin jst gh female connector from what I can tell. I dont want to cut the wires on it but I'd like it to plug it into a breadboard.
Its there something that converts 1.25mm pitch to 2.54mm pitch easily

[Anonymous No.1841320]

>>1841319
I'd crimp a custom cable to convert from one to the other. With male duponts on the end so I can plug it into a breadboard, I guess.

[Anonymous No.1841323]

>>1841320
Usually I would, but I dont want to cut the original wires.

[Anonymous No.1841324]

>>1841323
Or were you referring to crimping some of the jst gh connectors? Those are really tiny and seem like a pain to deal with. But it might be the only option.

[Anonymous No.1841332]

>>1841297
>Is a microphone like that really a better choice than buying a USB sound card?
No, I don't need the mic as mic, but I have a hard time finding USB sound cards with those specs.

>Actually, if you find a good external USB sound card on alibay, please post it here.
Will do

>There may be software out there that's already designed to use your computer as a real-time oscilloscope, so hunt about for that sort of thing.
Software is around, I've seen some stuff already, but as I'm a software engineer by trade, I have no problem with doing some coding myself.

>I'd add TVS diodes at the very least. Both zener and overshoot diodes to both rails. An op-amp buffer in case the signal's impedance is too high for the ADC is a good idea too, along with a virtual ground circuit to ensure your signal is right in the middle of the ADC's range. Shielding might be nice too.
Yeah, fully agree with that. Don't want to kill my pc with a voltage spike. And thanks for the remaining hints. I'll check and see what I want to implement. Should be a nice project with plenty of stuff to learn.

[Anonymous No.1841359]

>>1841175
something to do with the electron magnetic dipole moment. those cables are tricky. you have to burn them in slowly for best results.

[Anonymous No.1841431]

>>1841359
The vendor is laughing his ass off.

[Anonymous No.1841489]

>>1841166
Watch shango066 on youtube, he explains things well and is hilarious. What you should have is a variac, a light socket and incandescent bulb to make a dim bulb tester, and isolation transformers are a great idea. Depending on the age of the crt chassis, it could be live at mains potential. If something does eat the dirt sandwich an extinguisher is a good idea but unplug it first. As for the batteries, a metal box is important if you plan on pushing limits but if they really go bad, get them outside, extinguished and covered. Consider using a BMS to prevent your day being ruined.

[Anonymous No.1841614]

Does /ohm/ have a preferred circuit for discrete flip-flops?

This one I made (bottom left) keeps getting loaded down when I make it on breadboard

[Anonymous No.1841651]

>>1841332
>I have a hard time finding USB sound cards with those specs
As am I. TI's page for USB audio converters only has 16bit ADCs by the look of things, so I'll check mouser or octopart next.
>Don't want to kill my pc with a voltage spike
It's also an option to just put a bunch of digital optocouplers (or maybe one single multi-pin optocoupler) after the ADC. Though for USB's differential pairs I think you'd need to use an isolation transformer, which may or may not be class-compliant.
But I suspect that the slight nonlinearity of a standard ADC will be similar to or greater than that of an analog opto anyhow.

>>1841614
It's been ages since I looked at the makings of a flip-flop, and only did so in terms of logic gates, but last I checked the easiest way to get something remotely synchronous was with a master-slave design. Though what you've build looks more to just be a simple SR latch, not a flip-flop. And that looks nothing like a 1Hz or 2Hz clock, not with that 330Ω that's probably pulling at the rails a bit much.

[Anonymous No.1841652]

>>1841614
>>1841651
Oh no wait that's a T-FF that exploits the difference in propagation delay of an SR latch and a very short pulse. Never seen a design like that (outside of minecraft), I'd consider putting capacitors across those diodes, maybe 100p-1nF, in case it isn't asymmetric enough.

As for your oscillator, instead of having a 100k going to two 10ks, just have two 200ks going to each rail. And using a larger value resistor than a 330 is still a really good idea, and a comparator would be better than an op-amp since V+ ≠ V-. Comparators often need a pullup resistor too.

[Anonymous No.1841675]

>>1841651
>And that looks nothing like a 1Hz or 2Hz clock
you don't use placeholder values? it's actually 90kHz and 45 kHz, but big numbers make my eyes cross

[Anonymous No.1841684]

>>1841175
Cables have at least two properties that need to be taken into consideration.
1: The diameter of the copper, this determines how much the conductor temperature will rise when a given current passes through it.
2: The insulation material and insulation thickness, this determines how well the cable can withstand voltage transients.

Speaker wires usually operate at a low-voltage with a high-current, and as such, have thick conductors and thin insulation to minimise heat buildup.
Mains cables usually operate at high-voltage low-current, and as such, have thin conductors and thick insulation; as a result, they can withstand high transients in voltage.

Don't be a dumb, just cut the end and re-use a old IEC-C13 or IEC-C7 cable.

[Anonymous No.1841695]

>>1841684
I'd like to say that speaker cables are usually twisted together more for noise avoidance, but from my experience mains cables often have more of a twist. The audio cable in question was a figure-8 cable (I assume for heat dissipation), but surely they could have added some twist to the insulation.

[Anonymous No.1841722]

>>1841489
Thanks anon, will look him up.
With the CRTs, one is completely mains isolated and will run but it's been arcing (Wells Gardner D9200) and the other is untested and I'm thinking isolated stepdown is the way to go (Nanao MS9-29A), it has a SMPS on the board but I've been told the chassis is only partially isolated (don't want a jolt when adjusting pots)
Batteries aren't being really pushed anymore and used for vaping (under 10A) but at one stage was pushing 2 25Rs in parallel upwards of 50A (since replaced).

[Anonymous No.1841803]

>>1841332
>>1841651
Ok I've done some digging, looks like there aren't any direct USB (CODEC?) ADCs or DACs that do 24bit 192kS/s. So either that microphone uses a seperate ADC IC to its USB interface (likely) or it's bullshitting (also likely).

I'd quite like to know how to combine a common (cheap) ADC with a USB interface so it acts as a class-compliant microphone.

[Anonymous No.1841871]

>>1841869
>>1841869
>>1841869
>>1841869
>>1841869