/diy/ - Do It Yourself

I thought resistive biased class A amplifiers had 25 percent theoretical efficiency? Now some individuals are telling me it’s 50 percent? What is the truth

>>2670318
Do the calculations. Assume sinusoid, then integrate, and compare.
25% is realistic. 50% is maybe B or AB.

anyone know if the Fnirsi 1014d oscilliscope is ok? it's cheap chinese shit but im not using it for anything professional

>>2670325
the answer is 6v, this is a stupid question but the output is 6v because the dc 12v vcc source is turned into two 6v peak AC alternations at the output right?

i have a dc adapter i chopped of the wires of and now i use it to drive a car headlamp(i think) that uses 12v but still lights up at 3v. to turn it on i use a custom made switch i made that neccessarily has to be a spring... but of course a spring is also an inductor. will this do something funny to the ac-dc converter? i barely know what im doing halp.

>>2670318
You can achieve 50% if you use transformer on the output. This works because of impedance transformation.

>>2670342
>a spring is also an inductor.

in general that is true, but it will be an extremely pathetic inductor, and will have no noticeable effect on your invention. godspeed anon.

>>2670342
Watch out anon. If that car headlamp has a switching converter in it, it will draw approximately a constant power. So at low voltages it will draw MORE current.

new /mcg/ thread for those who aren't refreshing the catalogue for it:
>>2670671

Noob here - I need help, I was desoldering a micro usb from a board with a heatgun and I think I applied too much heat I think since I pulled what look like little copper leads off of the pcb board. I'm assuming these are necessary? If I just went fuck it and soldered on the new micro without those leads, will that hurt anything? This port is only used for charging.

>>2670686
Here is what the board looks like, probably need to clean it up a bit, huh?

>>2670686
It should be fine. For charging only outer most pins are used.

>>2670686
>will that hurt anything?

no.
you can see on the PCB the 2 pads that lifted arent connected to anything.

piano anon from >>2669138
issue: sometimes touch sensors detect much faster keystroke that they should
I disassembled it and I'm now cleaning rubber switches under the keyboard
I will use distilled water
it seems that rubbers aren't damaged just dirty so it should work perfectly after cleaning

I suppose it works like this
while depressing the key the switches are closed in order, from furthest one to closest.
measuring latency between signals from these switches allows to calculate exact parameters of keystroke.
simple, easy to repair design but I'm thinking if there could be a better way to do it with magnets suspended under the keys and then analyzing induction in coil underneath the key while avoiding induction from other key or eliminating it in calculations somewhat

LCD screen for large industrial machine is blank.
+5v and -22v rails are good, but the LC driving voltage (V0, ~+24v) is only +5v when powered on. Main board supplied with +5v and +12v from external PS, creates -22v on board, and +24v with pot between +5v and -22v rails.

Rather than find faulty component on main board, my thought is to cut trace for V0 at LCD and inject +24v from separate PS. Any reason this shouldn't work? In testing I'm seeing ~+10v at the logic pin VDD when disconnected from machine and +24v at V0.

Datasheet from LCD PS section attached.

>>2670686
Probably not enough heat
I don’t think the copper foil layer is “glued” to the surface, it seems like the roughness of the copper forms a bit of a tooth with the underlying epoxy/phenolic board.

Hello, I'm trying to get into electricity for the first time (sorry if it's not the right thread but there isn't one dedicated to electricity only in the catalog) but I'm a type of books I need at least a couple of the most basic level to help me in the first steps, i don't plan to do anything practical for now i just want to understand the basics about circuits and stuff.
>inb4
https://libgen.rs/
help me choose and i'll stay away from this board for a whiley

>>2670755
Pic related would be a good introduction to electricity.

>>2670755
Google navy et manual modules 1-20

>>2670782
>>2670764
Thanks a lot

If I were to approximate a homogeneous solid of copper of volume V as a mesh of 1D wires, then assume every wire as a resistance proportional to its length divided by the total length of the mesh multiplied by the resistance of a copper wire of same volume as the solid, then use the same mesh as a thermal model for FE simulation, could I get a good model of Joule Heating for any solid ?

>>2670729
Is that 5V measured from VDD or VSS? If it's VSS, it suggests that the pot is damaged or there's a fault inside the IC. Desolder the pot or try to measure its resistance in-situ, I'm guessing it's full of gunk or got worn down.

If you do use an external power supply, put a resistor in series with it in case something goes wrong.

>>2670904
I think it would work. I'd write it as the resistance-per-length of each wire is equal to the resistance-per-length of the solid, but multiplied by the number of wires in the cross-section. In the simple case of a constant cross-section, at least.

But I think you can do vector calculation instead, using the electric field form of ohm's law instead.

>>2670922
5v measured from VSS. I suspect the pot as well, but getting to it on main board will be a herculean task.

I sincerely appreciate your help.

im having trouble with a desoldering pump being ineffective and people are telling me to just use water. why are hobby communities like this

>>2670939
If the pot is dead, either the upper track is shorted or the lower track is open-circuit.
If the upper track is shorted, then connecting a 24V supply between VDD and V0 with a resistor will just leave it at 5V (VDD-V0 = 0V). If this is what you measure, you'll need to remove/destroy the potentiometer before it can work. If you don't use the resistor in series with the 24V PSU, you'll short the 24V PSU out, possibly burning the chip or the remains of the pot.
If the lower track is open-circuit, then you'd end up with a VDD-V0 < 24V. If this is what you measure, then you can leave the remnants of the potentiometer in place and it should work once you remove the series resistor.

>>2671003
>water
Huh? I don't understand.

Assuming you're working on THT parts, you can try hollow desoldering needles instead of a pump. They work decently well, though square pins in round holes can be a bit tight. Also the cheap chinese hollow needles have handles that melt too easily.

I'd try tearing down your desoldering pump fully to remove any solder dust or other gunk, and replacing any suspicious grease or oil. It could be a blockage in the airflow, or something preventing the mechanical action of the pump being as fast or as strong.

>>2671007
>I'd try tearing down your desoldering pump fully to remove any solder dust or other gunk,
I have. I'm working on mangling PS4 pads to have leads so I can connect a similarly mangled XBox pad's buttons to it so I can play it on PS4s at local game tournaments.

I think the pump is just a cheap too-big piece of shit for fine soldering. The nozzle is like 4mm wide and has walls 2-3mm thick. I've considered replacing it with a needle off a pump kit or something but don't have one lying around.


>>water
>Huh? I don't understand.
yeah same hence my question. niggas really out here

>>2671020
I bought a cheap desoldering iron that's just a soldering iron with a hollow tip connected to a manual solder sucker. It works surprisingly well. Didn't come with a grounded tip though, so I replaced the 2 pin plug with a 3-pin one, and slapped a 1MΩ resistor between the ground wire and the tip. Nice and ESD safe now I think. It came with two nozzles, one about 1.2mm wide and one maybe 0.9mm wide, which is the internal diameter of the tip's hole. The tips themselves are more like 2.5mm wide, so they wouldn't really be suitable for dense (e.g. 1mm) pitch headers. If you have THT HDMI or USB connectors I'm not sure what to use, I guess I'd maybe go for hot air considering those connectors are mostly metal anyhow.

I bought a cheap iron but it only has pencil tips. i know you're not supposed to file down tips because muh coatings but if i'm not using it very often does it really matter as long as i aggressively tin it?

>>2671051
What kind of iron is it?
Check aliexpress for other sorts of tips.
You can file a tip down, but it will expose bare copper which will get eaten away by solder pretty quick. And it requires some skill to use copper tip, because it has a tendency of oxidizing etc.

Could someone point me in the right direction?
I got my filthy hands on a FLIR uncooled vox microbolometer sensor that I would like to hook up and see how it works. The issue is I am retarded and don't know what to google to learn or understand the connections used on the sensor module.

Pic related, board A was connected to the sensor part B via the J4 connector on the top left. The only cable leading out was a white flexcable from nr 2 on bottom right. What is this connection called? I assume it carries both video and power as it was the only hooked up part? What is the three pin labeled 1 or J5 for? Power? Video? Cumslot?

>>2671053
it's some store branded likely rando chink oem thing but it's designed as a heater coil around long (like several inches) removable tips that are more or less just a long slug of plated copper. the tip is held in with a single screw that just presses it in and friction does it. it's not the kind of tip that threads into a hole or, god forbid, is the actual point of electrical contact in the iron. i imagine i could find some random piece of metal that's vaguely the right size but i got a pack of 5 extra tips with it so i dont mind destroying one since i wasnt even
confident the thing wouldn't either instantly burst into flame or simply not get hot at all as soon as i plugged it in. it does actually work though and 99% of my complaints about soldering have been answered by having an iron that actually just fucking works (and i am actually more mad now because over the years people gave me protips that would simply not work because 99% of irons are trash that dont work)

however, i'm doing stuff mostly with consumer electronics repair/mods so i feel a chisel tip would be easier to handle and slightly more versatile than the kinda dull pencil tip. also just being copper rods it probably wouldn't be too terrible to occasionally re-file and i'd be tinning it aggressively before and after use anyway

if i have spare lead and lots of flux lying around could i just dunk it in straight up blobs of molten lead or something? could i do something really ghetto like get an appropriately sized piece of copper tubing and jam a scalpel/craft chisel blade into the end? maybe cram some cheap clay or something in the tube for thermal mass?

>>2671247
I'd guess J5 is a microcontroller programming port, or a UART communication port. Something that isn't normally used aside from production and troubleshooting. That said, maybe it is used normally and carries power to the sensor, since that flex cable probably can't carry much current.

Any plans on what you'll connect the flex cable to?

>>2671007
Got it anon! Bad trace from -24v rail to pot. Pot is fine. Bodge wire and we're kickin ass. Thank you again for your help.

>>2671509
>>2671509
>>2671509
Can anyone help? I'll also need to be making a high pass filter and a band pass filter.

>>2671531
how many poles/db per octave? active or passive?

>>2671534
At least 12, active.

>>2671531
>Can anyone help?

google knows of 976 million web pages to help you.

holy SHIT
not even the Asuka drop did this
we are SO FUCKING BACK

>>2671540
I can’t find anything with variable cutoff.

This is what I’m attempting to replicate. I’m not an expect but it looks like a bunch of preconfigured passive filters that are swapped between with a switch? This is for audio btw, they would have to be subsequently amplified to avoid volume loss, right?

>>2671528
Cool shit.

>>2671531
>0Hz
Please elaborate. Frequency is a logarithmic scale, if you want to have a range of 1.5kHz to 6kHz, that's a max:min frequency ratio of 3, so you need to have impedances that change by a factor of 3. If you want to have a range of 0kHz to 4kHz, that's a ratio of infinity. There may be some strange filter topologies that approximate this, but you're best off specifying some sort of lower bound. For example, if it's for audio use, you don't really care about frequencies below 20Hz. Go 1Hz if you care about infrasound.
>variable
For variable cutoff, you're either looking at potentiometers or some sort of programmable gain amplifier circuit. Probably monolithic, but you can make your own using resistors and analogue switch ICs. Programmable gain is the way to go if you have more than 2 poles, have an extreme max:min frequency ratio, or want to use some other circuit to adjust the gain.
>inb4 vactrols
Yeah it's an option, but your max:min frequency ratio isn't brilliant.

You can also use operational transconductance amplifiers.

>>2671536
I assume you mean 12dB/octave = 40dB/decade = 2 poles? That's doable with a dual-gang potentiometer, though even with a logarithmic one you may find it's hard to adjust the cutoff.
I know you can make a variable frequency Butterworth sallen-key high-pass and low-pass, but for a band-pass the only topology that comes to mind is an IGMF, and I'm not sure if you need 2 or 3 variable resistances to make one of those work properly. Simulate those circuits I guess.
But you may still want to go for an array of analogue switches instead. You can even cascade them in a binary fashion, e.g. have 1kΩ, 2kΩ, 4kΩ, 8kΩ resistors, and by switching the analogue switches about you can make any combination 1k,2k,3k... up to 15k. I think it's actually easier using capacitors, since they add in parallel.

But selecting the right analogue switch IC isn't trivial. I recommend the DG4xx and DG6xx series.

>>2671549
From your thread, you're trying to use this in a synth. I would suggest looking at existing eurorack filter modules for examples of parts that can actually be obtained nowadays. https://kg.kg/cem3350-eurorack-filter/ for example or https://www.soundsemiconductor.com/ .

>>2671554
It's for a synthesizer, I'd be working with audio. This graph shows what I'm trying to replicate.

>>2671560
Interesting, I'll check these out.

I'm also going to need to make a chain of 8 "resonators" each tuned to a specific frequency. The idea is to be able to pass sawtooth waves through and shape the wave in various ways. Here is the circuit of one of these resonators. I don't really understand what it's doing and googling "audio resonator circuit" doesn't turn up much.

>>2671256
don't do any of this

just buy a new iron/tips

if you're doing electronics shit those tiny usb irons are perfectly adequate if you're careful

is there an easy way to solder stuff that has plastic in it (like headphone/serial/etc connectors) without fucking melting them?

>>2671582
>an easy way

no.
either you develop skills, or you buy parts made with old-school (non china) heat-resistant materials.

>>2671549
yes, that's why we usually use active filters instead of passive ones, to avoid the gain loss. If you're looking for a variable filter, it might be better to use a tunable filter instead of fixed ones that are swappables, unless those filters are used to tune specific frequencies of interest. Do you also need a 3rd order filter? depending on your application, you could use a simple 2nd order sallen key filter made of resistors and capacitors instead of inductors. This has the advantage of being an active filter too.

>>2671586
ok what skills prevent the plastic shrouds from melting

>>2671582
1. try to remove the plastic if possible (for example, if you're soldering something inside a headphone, try to remove it form the case).
2. If you cannot remove the plastic, try using a high quality soldering iron with temperature control, and a high quality lead solder (since they require lower temperature)
3. solder one joint at a time as fast as you can. Don't hold the soldering iron on there for more than a second and let it cool down for a bit before soldering the next joint.
4. Try tinning the pads before soldering the component, it might help with transfering heat to the pads instead of the connector.
5. Probably should have been first, but plan ahead. Make sure you got everything you need to do the job properly, to reduce fuck ups and the time to solder.

Usually solder connectors are not that easy to melt if you solder it properly and even if they do, as long as they are still functional it doesn't really matter if they are a bit fucked. If it's really an issue, try practicing a bit on junk boards before trying for real.

>>2671256
>it's some store branded likely rando chink oem thing but it's designed as a heater coil around long (like several inches) removable tips that are more or less just a long slug of plated copper. the tip is held in with a single screw that just presses it in and friction does it.
So just a simple tip that is basically copper wire with weird shape on the end. You can definitely buy these on aliexpress, or even make yourself out of copper wire of suitable thickness.
>however, i'm doing stuff mostly with consumer electronics repair/mods so i feel a chisel tip would be easier to handle and slightly more versatile than the kinda dull pencil tip.
I suggest you just to bend the tip into J hook shape, as with this you can solder THT and SMD pretty easy.
>if i have spare lead and lots of flux lying around could i just dunk it in straight up blobs of molten lead or something?
Lead doesn't stick to copper. You need tin in the alloy in order to tin the copper.

>>2671594
>what skills

- a good soldering iron + quality solder + eye-hand coordination will let you make a connection in 1/4 second.
- various methods of drawing heat away from the body of the connector, such as clamps or submerging in liquid.

>>2671590
>yes, that's why we usually use active filters instead of passive ones, to avoid the gain loss
Is there any reason you can't just pass the output of the passive filter through an amplifier?

>>2671596
shit. is there something i can just dunk it in to get it to temp safely if i'm worried about it multitask

also once a tip is oxidized bad is it salvageable at all? i'm already down one tip because i got up to get a coffee while it got hot and came back to a black tip. can i use metal polish or something on it if solder isn't sticking to it and flux is just burning away

>>2671601
That's actually what most of them do, it's pretty much an RC filter in series with an op amp buffer or op amp amplifier, but some topologies are a little bit more complex and give different performances or characteristics than a simple RC or LC network. If you want you can read up a little bit more about it on wikipedia
https://en.wikipedia.org/wiki/Active_filter

The sallen-key filter is a popular one, very simple to build and analyze, and it's a second order filter (pretty much two RC network in series), so pretty sharp roll off with the possibility to control the gain as well. You could replace the RC network in the filter with an LC network to get a 4th order filter if i'm not mistaken. You can also tune the Q-factor above 1/2 in that circuit, something that cannot be done with regular passive filters. I'd also stick with op amps instead of transistor amplifiers, just because it's easier to design for but if you want some fun and know the math and theory, you could design your own amplifiers using discrete components.

>>2671608
while waiting for a response i yolo'd and , while cold,
>hit it with a mild small steel wire brush (actually out of a dremel kit) to get the crud off until a dull shine
>used some brasso and a shitty shop towel to polish the tip (i just spun it in a glob of brasso and the
>brushed some liquid flux on and let it sit until dry (only a couple minutes)
>wrapped the tip in .5mm solder, straight up coiled around like a decorative wrap
>plugged it in and turned it on
>rotated it gently in hand and applied even more solder
>tip is actually fucking tinned now except for the very end where i guess i couldnt brush effectively
>turned it off with a big glob still on there

if any newfrens who keep getting memed on by cheap irons & are as frustrated as am this worked

i think tinning it keeps failing because it doesnt have enough heat to melt 1mm solder i have been using to tin it or do larger jobs but the .5ish stuff I have did fine so i guess i'll only buy .5mm or finer now ever again because all other solder is apparently a meme unless you're doing plumbing with a butane torch or some shit

>>2671567
Sorry to be a retard but the more I think about this the less sense I make of it. The original paper says:
>It will be seen that the fundamental, certain harmonics, or groups of harmonics can be eliminated by means of the resonator chain. This is equivalent to accentuating other harmonics or groups of harmonics.
So let's say you have a 440hz sawtooth wave. You pass it through a bandpass filter removing everything but frequencies in the range of 500-800hz. Now there's nothing left for the next filter to attenuate but that narrow frequency range.

Instead of removing everything but the range I want to emphasize, how can I emphasize just that range, but still leave the other frequencies intact? What if I want to emphasize both the ranges 500-800hz and 1800-3000hz?

>>2671582
a thin metal clamp at the base of the joint will act as a heatsink. they're called "heatsinks." use them.

>>2671624
>So let's say you have a 440hz sawtooth wave
Remember that a 440Hz sawtooth wave also has harmonics at other frequencies. If you pass it through a bandpass filter removing everything but 500-800, not only are you somewhat filtering the original fundamental frequency, but also all the harmonics. You'll get a very small attenuated sine wave around 440Hz assuming your filter is not too strong. If it's an ideal brick filter, then you'll get nothing since the sawtooth fundamental frequency and harmonics are all outside of the 500-800 range. But real filters are never ideal, so you'll still get some stuff outside the 500-800 Hz.
>Now there's nothing left for the next filter to attenuate but that narrow frequency range.
Well since you have a non-ideal filter, there will always be stuff to filter, although significantly attenuated. This is something that is done sometimes in real life, what you're doing is cascading filters together to either make a higher order filter (sharper roll off at 3db point) or to make bandpass/notch filters or a combination of those.

>Instead of removing everything but the range I want to emphasize
So just to make sure I understand you properly, you want to take the 500-800 range (assuming something is in that range, in your sawtooth example, there shouldn't be much in there unless it's a mixed audio signal with other stuff on top of it), and amplify it while keeping the rest of the signals, correct? In that case, what you want to do is take the original signal, filter the range of frequencies you want to amplify with a bandpass filter (so 500-800 are let THROUGH), then amplify those, then take the same original signal and ADD it to the above signal you just filtered from the original and amplified. You can easily add two signals with an op amp. If you need more help let me know, but hopefully this will point you in the right direction.

>>2671608
>shit. is there something i can just dunk it in to get it to temp safely if i'm worried about it multitask
wdym?
>also once a tip is oxidized bad is it salvageable at all?
Depends. They sell tip refresheners (basically strong flux with some solder), or you can just use plumbing flux with solder and brass wool. But thing is that if iron coating is gone, tip will get pitted really fast, especially these days with lead-free solders (hope you're using leaded though as it is less pain in the ass to use) and elevated temperatures.
I've a hakko 900 style soldering station, and I've a habit of setting temp to max (480C), and if I use unplated copper tip, it would disappear in about 1 hour of active soldering. Coated tips don't get dissolved that fast.
> i'm already down one tip because i got up to get a coffee while it got hot and came back to a black tip
That is flux residue. Before you leave iron, clean tip with paper towel (dry, don't use those wet pads cleaning sponges, because they leave limescale on tip) or brass wool.
You can probably clean it off with brass wool.
>if any newfrens who keep getting memed on by cheap irons & are as frustrated as am this worked
Idk, iron is iron, just a skill issue really. Other thing I've noticed is that beginners have a lot of problems with coated tips in general. Idk why. But I suggested them getting bare copper tips instead, and they had much less issues with it taking solder etc. mainly because in case of a major fuck up with a tip they can just sand it off and try again.

>>2671536
2-pole variable filters are very common in synths, why not just google "diy VCF schematic?"
Here's a random schematic I found that looks clean. From what I'm seeing, a lot of them use OTAs.

>>2671567
>resonator
It's basically a high-Q circuit, with a round-trip gain of slightly less than 1.

Do you want the modified frequencies to move along with the fundamental frequency? Or stay static? I always thought that if you add a filter in order to amplify the 6th harmonic of a 440Hz wave, you want it to accentuate that 6th harmonic when it's at 880Hz, not the 3rd harmonic as you'd get with a static filter.

Look into switched capacitors as variable impedances. As well as being usable for things like I describe in >>2671554, you can also run them on a PLL multiplied clock in order to make them follow the fundamental. PLLs are cool, nobody steal my edgy harmonic lock effects circuit that uses type-1 phase comparators for partial locking.

>>2671582
High temperature and being fast.
Low temperature makes you slower, thus you will hold iron for longer and since metals are heat conductors, they will transfer heat to the plastic and ruin your day. If temperature is high and you're fast, there is not enough time for heat to get conducted into the plastic and thus everything is fine.
It is kinda like stick welding, a lot of people get filtered out by welding thin metal just because they put current so low rod isnt melting fast enough which heats up the metal more and blows a hole eventually, while at higher current you can just lay metal faster and don't blow hole as most of heat is used to melt the rod, not heat the surrounding metal.

>>2671582
This: >>2671598, but also really good workholding setup. You should be free to jam the iron in and out and feed a bit of solder in as you do so, and for that both parts of the work need to be held solidly in place. An alternative to feeding in solder is to have a small-ish and relatively fresh blob of solder on your tip and give the workpiece a dose of flux before soldering. This frees up one hand for holding one side in place (especially wires) and probably allows for an even faster joint than when feeding in solder. If both sides are already sufficiently tinned and fluxed you may not need the blob on the tip, though it does make for excellent thermal contact.

>>2671631
>Do you want the modified frequencies to move along with the fundamental frequency? Or stay static? I always thought that if you add a filter in order to amplify the 6th harmonic of a 440Hz wave, you want it to accentuate that 6th harmonic when it's at 880Hz, not the 3rd harmonic as you'd get with a static filter.
Ideally yes but I have no idea how to do this... I'm not sure if the original synthesizer did this or not.

Here's a detailed description of the resonator chain.

>>2671636
If you have access to the control voltage used to generate the sawtooth, this is trivial to do with any VCF.

>>2671638
>If you have access to the control voltage used to generate the sawtooth
I don't think I do, I was planning on using a C64 SID chip.

anyone knows of a simple tunable RC oscillator circuit with the following specs:
1. NO ICs, only discrete transistors (nmos or npn/pnp, no pmos or jfet or unipolar)
2. only 1 capacitor
3. no inductors
4. preferably adjustable with a resistor trimmer instead of a capacitor trimmer, but fine if not
5. preferably an adjustable duty cycle trimmer, but once again fine if not.
1-3 is critical for my application, 4-5 not so much.

>>2671643
>1. NO ICs, only discrete transistors (nmos or npn/pnp, no pmos or jfet or unipolar)
>2. only 1 capacitor
>3. no inductors
>4. preferably adjustable with a resistor trimmer instead of a capacitor trimmer, but fine if not
ramp generator. idk about #5 but maybe look for a tranny schmitt trigger, that's how most synths do it (saw -> schmitt -> PWM)

>>2671638
Oh yeah you'd just add the control voltage of the oscillator to some offset before sending it into the VCF. I guess logarithmic control voltages (e.g. 1V per octave) ensure that your offset remains the same, harmonically speaking.

Logarithmic control voltages have always seemed complex to produce, but they seem quite useful now that I look at it. How do you properly tune such a logarithmic converter? I hear using a BJT is better than using a diode.

>>2671644
cheers.

>>2671647
idk, some old dutch site explained it but I lost the link and it's probably dead now due to linkrot. It's probably a common circuit

Here's what I remember. R2 and R4 are multiturn variable resistors and need to be fine tuned. IIRC R4 controls the steepness of the log/exp curve, and R2 controls the net offset.
You also need to figure out a ~4 component TEMPCO resistor network to substitute R2 and R3, to offset the +3300ppm/C temperature variation of Vbe.
Thermal coupling isn't too hard, just sandwich the tempco between the BJTs and cook some shrinkwrap around them.

How to hook up a capacitor to a simple constant current source to charge it linearly?
I'm messing around in falstad but I can't figure it out...

How do they manage to power a buzzer which needs atleast 40mA with a coincell?

>>2671940

>>2671941
>old thread died only three (3) days after new thread was made

Latest cable abomination:

>>2671953
Is there at least a USB hub chip in the cable?

>>2671953
tune in tokyo

>>2671950
i hate the antichrist

>>>/vg/442616538
Artificial Academy 2 General /aa2g/ #1289
Butt Stacking Edition

Welcome, this general is for the discussion of ILLUSION's Artificial Academy 2.

COPY ERROR MESSAGES WITH CTRL+C, PASTE THEM WITH CTRL+V INTO GOOGLE TRANSLATE. JUST CLICK THE WINDOW AND PRESS CTRL + C, IT WORKS.

>Downloads:
/aa2g/ Pre-Installed Game, AA2Mini: https://tsukiyo.me/AAA/AA2MiniPPX.xml
AAUnlimited updates: https://github.com/aa2g/AA2Unlimited/releases

>Information:
AA2Mini Install Guide:
https://docs.google.com/document/d/e/2PACX-1vS8Ap6CrmSNXRsKG9jsIMqHYuHM3Cfs5qE5nX6iIgfzLlcWnmiwzmOrp27ytEMX03lFNRR7U5UXJalA/pub
General FAQ:
https://web.archive.org/web/20200216045726/https://pastebin.com/bhrA6iGx
AAU Guide and Resources (Modules, Tans, Props, Poses, and More):
https://docs.google.com/spreadsheets/d/17qb1X0oOdMKU4OIDp8AfFdLtl5y_4jeOOQfPQ2F-PKQ/edit#gid=0

>Character Cards [Database], now with a list of every NonOC in the megas:
https://docs.google.com/spreadsheets/d/1niC6g-Xd2a2yaY98NBFdAXnURi4ly2-lKty69rkQbJ0/edit#gid=2085826690
https://db.bepis.moe/aa2/

>Mods & More:
Mods for AAU/AA2Mini (ppx format, the mediafire has everything):
https://www.mediafire.com/folder/vwrmdohus4vhh/Mods
/aa2g/ Modding Reference Guide (Slot lists for Hair/Clothes/Faces, List Guides, and More):
https://docs.google.com/spreadsheets/d/1gwmoVpKuSuF0PtEPLEB17eK_dexPaKU106ShZEpBLhg/edit#gid=1751233129
Booru: https://aau.booru.org

>HELP! I have a Nvidia card and my game crashes on startup!
Try the dgVoodoo option in the new win10fix settings.
Alternative: Update your AAU and see if it happens again. If so, disable win10fix, enable wined3d and software vertex processing.
>HELP! Required Windows 11 update broke things!
winkey+R -> ms-settings:developers -> Terminal=Windows Console Host

Previous Thread:
>>441051309

>>2671963
No. It's just two electrically-seperate USB A-to-A cables made with a single length of CAT6 cut from a patch cable with a broken end. Couldn't find any 4-core wire lying about, and hey the thing already has twisted pairs. It's to run from a USB hub to the back side of some wallplate USB sockets, pic related. It's the USBs on the left, the right USBs are just power outputs. The BNC feedthrough is for connecting to my oscilloscope's blanking input. The other two USBs from the USB hub will go to USB-to-RS232 converter boards, which will feed the two DB9 plugs you can see at the bottom of the box. One of these will likely always be connected to my oscilloscope via a custom null-modem.

So once I make the PCBs for the USB-to-RS232 converters I'll need to make some more custom USB cables, though this time seperate cables that will be A to B instead.

I want to make a light-up target. The concept is simple; behind the paper target is are two sheets of aluminum foil separated by another sheet of paper. They act as a capacitor, and when the bullet passes through it gets shorted, causing a light to switch on until you switch it back off.

I don't know electronics well enough to make it myself, but I figure it'd be a pretty simple circuit.

>>2672064
>two sheets of aluminum foil

very bad idea.
what you want instead is a piezo or microphone detector to pick up the very very high volume sound of a bullet crack.
so, a sound detecting piece, followed by a sound amplifier, then a comparator to create a digital signal when sound surpasses a certain volume.
you can get used (thrift store) shock detectors in drum controllers for video game systems, toy drum kits, and baby movement monitors.

>>2672071
That sounds needlessly complicated and terribly impractical.

>>2672064
If you can mechanically seperate the sections of the target, then a piezo disc might work to detect impact on those sections. But I think the alfoil method could be better, and also cheaper for when you inevitably hit a sensor directly. You could easily have different sections with only a few mm between them (throw that alfoil on a laser cutter idk) to light up differently depending if you hit the bulls eye or some other section.

The key part will be getting the alfoil setup so it triggers reliably, but doesn't give false triggers. I think you'll need to have some sort of insulator (e.g. MDF, craft foam) between the two alfoil layers to prevent them touching normally, but regardless once a bullet goes through there's the possibility that you'll end up with a scrap of alfoil from the front layer remaining and producing contact with the rear layer. The only thoughts that come to mind would be to measure the resistance between the two alfoil sheets and trigger the "target hit" indicator whenever it goes down significantly. Not too hard, with a cheap microcontroller like an arduino, though I imagine you'll need a 4-wire sensing setup. You could also just blast 12V across the sheets after each reset to burn/melt away any scraps. But that will make the selection of the insulating material a little tougher. Rockwool?

The latch circuit, assuming you don't have a microcontroller to do it with, can just be any old SR latch. You could use an NE555 IC for this. Which also adds the option of using it to add an automatic timed reset (e.g. "target hit" indicator only comes on for 5 seconds).

>>2672064
it won't work, targets that have light-up bits don't use a real circuit, it's just a type of material full of quarts or something that when it's struck/chipped will spark or glow. electronic scoring systems use either the system in my shitpost below (basically a pair of antennas)

what you're describing is a capacitive touch system that would require a complex controller board, always need constant calibration when Literally Anything happens, and probably not work as well after having holes put through it and patched up

again if you need a glowy target i would use a physical system like maybe a backlight from the inner sides of the backside of the target (so light will pour out of the hole) or maybe there is some kind of paint that will glow when struck the same way some blocks of materials do (usually exotic but cheap crystals)

you could even go full hick and use some kind of impact low explosive

>>2672071
this is also very dumb, chronometers for bullets are baiscally a pair of antennas that detects a change in magnetic flux when a bullet goes through it
chronos will time the changes between two antennas about a foot apart, modern electronic targets that use that basically work like first-gen capacitive touchscreens except using those antennas around a big square to triangulate where a bullet passed nearby instead of two plates touching
or some targets just use an optical system because it's "easier" electronics wise even if it's just trading that for a coding challenge

>>2671978
why not wire directly to the wallplate/use a screw terminal block so you can replace the cable more easily

>>2672098
>low explosive
I think he should just cover his target with nitrogen tri-iodide

>chronos
Oh yeah, wonder how easy they are to diy? I figure they're hard to make because they'd have to be pretty sensitive. Triangulation would be even harder, you'd need to have a way of determining distance from the bullet to some reference other than signal strength, because that varies on bullet size and composition. Unless you just use 4 seperate capacitive sensors, and use the relative signal strength of two on each dimension to figure out distance.

>why not wire directly to the wallplate
The only wallplate inserts I could get cheaply (staff discount) just have a female USB A socket on the front and back sides.
>use a screw terminal block
Eh, more bulky and less robust. Either way I've just got a conventional USB hub zip-tied to the back of the plywood, and I don't really want to rip it open and solder wires to it.
What I've done is more modular, and if I need to seperate the cables I can just slice off the outer insulation.

I did kinda want to wire data pins to the back of the USB + power wallplate, or wire a seperate PSU up to my USB power lines, but that sounds kinda dodgy without a USB opto-isolator.

>>2672064
There's some literature describing something similar, aluminum foil adhered to both sides wax paper. Such a setup was used back in the day for measuring bullet velocity with two such sensors spaced a known distance apart and the signals fed into an oscilloscope. I recall some mention of similar systems used in ballistic laboratories in the 40s and 50s. You could probably rely on a decently sized capacitor charged to a couple hundred volts to clear any short formed between the two sides after a bullet passes and not risk igniting the paper.

>>2672101
>Oh yeah, wonder how easy they are to diy?
I've heard they're easy to repair but generally not reasonable to make yourself because yeah, they have to be incredibly sensitive and use high end chips and exotic materials

>>2672108
That would work but be basically disposable if not outright one-use, no?

>throw a couple hundred volt cap in there
I think the foil/paper object is there to be the capacitor, and you measure the capacitance/impedance of that and how it changes when you put a fuckin' hole in it.

>>2672111
>>2672108
Considering cameras are so good now, I'm surprised a normal-ass entry-level camera and a meterstick aren't used in ballistics labs now rather than chronos.

modern ballistic chronos are more for testing guns at home with a setup you can throw in a toolbox when you're done.

>>2672113
I'm repurposeiaaaaang a broken monitor into a light. It's the kind of monitor that uses a single LED strip for backlighting.

I can not for the life of me figure out the polarity of the connector to the light strip. It has SIX wires (blue, white, 4 black) and none of them in any combination get me continuity. I know my multimeter works, I get resistance across the chassis.
also I know it's not the strip itself because the monitor DOES light up with the backlight when it was plugged in fully assembled. I'm spooked to give it power directly to brute force it because aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaadfsfdsfd

I must have had a stroke or something, what retarded thing am i doing wrong? It's just a damn light strip surely there's just a DC in and ground line SOMEWHERE aaaaa

>>2670704
They used to do it that way (with the inductors) in old analog synthesizers, though velocity sensitivity wasn't all that common in them
They didn't have to worry about isolating the keys' inductances from eachother because they were monophonic

What do I do with this PoS?
It is a compressor relay from the mini-split. It keeps on welding shut.
Is it worth to disassemble it and try cleaning contacts with paper, or it is just better to find Omron or smth better than Sanyou whatever relay. If yes, how on earth do i find replacement from other manufacturer?

>>2672169
There's also an enable pin and backlight dimmer pin.

>>2672180
Replace it with a 280V SSR, and check your start/run capacitor.

>>2672169
Post a clear, well-lit pic of the backlight connector on the PCB. I want to see traces.

>>2672180
>If yes, how on earth do i find replacement from other manufacturer?
google

How do I fix bad horizontal linearity on a crt monitor that has no controls for it and no visibly damaged capacitors? Do I have to replace every single capacitor on the board because that sounds like hell.

>>2672169
>It has SIX wires (blue, white, 4 black)

i also have one with 6 wires.
applying 48Vdc across the two reds and two blacks lights it up.
the other two are not needed.

>none of them in any combination get me continuity

your DMM puts out maybe 2V to test continuity.
you need way more voltage than that to make it thru a series of LEDs.

if you kept the monitor's PCB, plug it in, turn it on, and take voltage measurements.

>>2672248

now with uncensored nude photos.

>kicad plans to release a major version every year
well then fucking make it so it imports all the libraries from the previous ones
anyone who designed more than a shitty blinky led pcb has a shitton of custom libraries and models which they then have to fucking reimport into every new major version and it's a major pain in the ass

I need to do stereo->mono conversion on an input audio signal, but I also want to have a coupling capacitor to block and DC. With regards to the summing resistors and the summing amplifier, where should the capacitor go? If I place it after the amp there's a possibility DC could distort the audio signal, but something tells me putting it between the summing resistors and the amplifier wouldn't be wise

>>2671766
coin cell can easily do up to 100ma

what does the yellow part do

>>2672329
As you have it drawn it's perfectly fine. Depending on your amplifier and what comes after it you should also add capacitor on the output as amplifier will produce non-zero offset error. If you have amplification in the next stage it will amplify that offset error.

>>2672341
Protects the battery from being overcharged or overdischarged.

>>2672344
so hooking it to tp4056 is basically putting on two condoms?

>>2672329
>stereo->mono conversion

dont fall for the Op-Amp cartel tricks.
no silicon, no batteries: all you need is two resistors.
caps, which are probably superfluous, can either go one per input, or one on output.

>>2672356
>putting on two condoms?

i can imagine a situation where having two protection circuits in series could end badly.
but dont wanna talk about coz there's an infinitesimal chance i might be wrong (for the first time ever).

>>2672169
Monitor LEDs are awful. You should replace the strip with better LEDs.

>>2672217
I did aliexpress. Because Omron was 8 dolla, and that one was 1 dolla. But from a different manufacturer, because this PoS was sticking since day 1.

I beheaded the relay, and probably 1/2 of contacts are missing and there is a burnmark on plastic, and i know compressor doesnt draw more than 5A. Cleaned them with sandpaper and now i have AC again
>>2672206
SSR would produce 4-10W of heat. Thats too much.
As for start/run capacitor im pretty sure it is fine. Compressor starts easily
I should have bought an inverter AC...

>>2672180
Looks identical to this one:
https://www.jaycar.co.nz/20a-12v-spst-pcb-mount-relay/p/SY4029
If that helps at all.

>>2672235
It has to be caps within the horizontal ramp generator. TV schematics should be pretty similar, so look for a schematic online even if it's not from your TV. It should be possible to roughly trace the circuit regardless.

>>2672252
Ok, are any of the pins on other side of the connector (of the main pcb) connected together?

>>2672284
I think if you use apt-get or homebrew or whatever to cause it to update, it keeps all your files in place. At least it works for minor versions, not sure about major versions.
Is there a way of importing symbols and footprints just by opening a project? Because they still show up in an old project.

>>2672341
It's polyimide tape covering a protection circuit. This is usually a DW01 plus a MOSFET pair like the FS8205A, these handle overvoltage protection, undervoltage protection, and overcurrent protection. But they're pretty shit at doing so, the undervoltage protection threshold is like 2.5V which is frankly useless. They will also not linearly regulate current at all, they'll just turn on and off. So if you connect 5V to one directly, no it won't charge properly. A circuit like a TP4056 is required. Some TP4056 boards come with these ICs already (you can tell because they have two more ICs on them), but in that case nothing bad will happen from running two protection circuits together.

I have a Z523 Logitech speaker set.

The right speaker has started 'cutting out' — I'll turn the knob past the little notch at the beginning to get the power on, but if I move any past that whatsoever, the orange power indicator LED turns off, and the speaker makes a tiny squeaking noise and turns off as well. It's powered through a VGA-style (not sure what else to call it) cable leading to the subwoofer. The subwoofer continues making audio, but the right speaker does not, so I'm assuming it's the right speaker to blame. I've got the whole right speaker disassembled, PCB out, and I'm considering maybe the problem exists entirely within the volume petentiometer? However it's pretty compact and I don't see any way to actually inspect inside it. I have a few options:

>1) Order a new potentiometer for this (not great, because it seems highly customized for some reason)
>2) Get some de-ox-it spray and try to cram it in there with a big blast
>3) Go to /ohm/ and post this in case one of you have any other suggestions

Please help. I only have minimal skills when it comes to diagnosing circuitry problems like this. And I can't just buy another set of these since every pair on eBay is from another country and the shipping would be more than the price of the actual product.

>>2672417
Deoxit is a good idea, but your problem is most likely in the power supply section. Look for bulging caps and discolored areas, and feel for hot components.

>>2672417
>I'm assuming it's the right speaker to blame

highly unlikely.
speakers are good old boys.
they dont go bad, unless drugs are involved.
a more likely candidate is the STA540 power amplifier chip.
power amps are *born* bad.
likely, at some input level it starts to oscillate the right channel, which causes it to draw a lot of power, thus dimming the power LED.
if you disconnect the right speaker (even if you have to open it and cut one wire) the problem will likely remain, meaning the speaker itself is alright.

>>2672417
I can't really understand why turning the volume dial up past the switch knob would cause it to turn off, unless there's some sort of mechanical obstruction that blocks the switching element. If the pot has an external switch I can't see that being possible, even an internal switch is just a plastic cam that shouldn't change the switch after it gets past its actuation point. The contacts shouldn't even move after the actuation.

But the volume potentiometer itself shouldn't easily influence the power status. Does this issue happen even without music playing? I can maybe see it as a power supply issue, where when the amplifier tries to put out more power than the PSU can handle it browns-out, which could explain the squeak. Things to look for would be dodgy PSU caps, also any series components (e.g. pass regulator ICs or transistors, inductors or resistors making low pass power rail filters, also capacitance multipliers).
It may also be that the bias current is proportional to the volume setting (would be strange but would kinda do something) in which case maybe the Vbe multiplier is being set to the wrong offset by the potentiometer, going so high that the high bias current causes the PSU to shut down, or just blocking the signal. But that's a shot in the dark.

I'd figure out the wiring of the pot+switch assembly and recreate it. Replace the switch with a dead-short, replace the pot with fixed resistors, if you set the volume to max it should be as simple as no resistors at all, again a dead-short for each channel.
The connector is a DB9, they're reasonably common so you might be able to buy one to solder stuff onto instead of monkeying around inside the pot+switch assembly. You can also just buy an RS232 / serial cable and cut an end off. You'll still need to reverse engineer the cable though.

Also:
https://www.youtube.com/watch?v=q49-NIMyJIk
https://www.youtube.com/watch?v=FkkTYqi4ZF8
https://www.navegantpelmon.org/logitech-z506-repair

>>2672457
Oh that's a reverse engineering. I'd have split up the blocks more, that wire spaghetti (especially with that mock ground rail) gets in the way of seeing the bigger picture.

No obvious signs of fuckery, though Q3 + Q2 is a strange circuit for pulling the standby pin low. Absurdly complicated active filters though.

I found this schematic of the pot assembly, but the pinout of the 9-pin connector looks a little dodgy, needs a bit of refinement I suspect. Especially since it has 10 pins...
I also expected the 3.5mm socket to be switched from those RCA pins, idk. If you chuck this page:
https://www.elektroda.pl/rtvforum/topic2169015.html
through google translate maybe it will explain itself, it looks like the same speaker and they do mention a DB9.

>>2672470
i forgor

what kind of chip is that and why couldn't you just bypass it? it is not a phone, it is a fucking welder, no rocket science.

>>2672503
It would be trivial to bypass. Only if it has a backup battery and can transmit wirelessly will they know exactly when you remove the thing, which I doubt it it may be the case. But even if it doesn't, the CCP monitor your power usage. So if they see spikes of 1-5kW as you weld that coincide with the microchip turning on and transmitting, and then the spikes continue but the microchip stops transmitting, you've got reasonably suspicion of tampering. Even if it doesn't transmit but goes for periodic inspection, they can compare the recorded data then. Even if you make your own welder, they might just be inspecting all power spikes under the guise of green energy enforcement or whatever. Though there's nothing stopping you from running a welder off a generator, or using a battery powered welder (e.g. 4 car batteries connected in series).

I don't understand the specific benefit of knowing when people are welding, or controlling when they can weld, but it's more data for the CCP surveillance state either way, so it's hardly valueless.

i just realised these dual-gang pots aren't broken on one wiper, rather they have two coaxial shafts with one wiper for each
don't have any knobs for them though, i'll probably try 3d printing them

>>2672503
>what kind of chip is that and why couldn't you just bypass it?
ID and govt. registration. Like with guns in most of the countries. You know, first they take your guns, then you need to register toilet paper, and get executed if you use hand instead of paper.

But if seriously, welder is just a glorified SMPS. And it would be just a simple lock-out like in medical equipment with lasers and such. Maybe even laser welders have some sort of access control, because it is technically more dangerous than normal stick welder that would just give you a shock. In worst case you just replace whatever IC drives the IGBTs with different one, that doesn't have smarts in it.
>>2672510
>I don't understand the specific benefit of knowing when people are welding, or controlling when they can weld, but it's more data for the CCP surveillance state either way, so it's hardly valueless.
Ppl can make guns with welder, obviously. Jews fear the welder.
There is a bright side to this, no more indian 5-minute lifehacks where they just turn metal stock into scrap metal, as they wont pass mental fitness test

>>2672510
it is twitter so it could also be a joke or a political bait because it really looks the dude is just repairing his welder.

>>2672526
>no more indian 5-minute lifehacks where they just turn metal stock into scrap metal
Nah they don't buy new welders anyhow. They either use car batteries, oxyacetylene cylinders, or some rugged welder from before the 90s that's withstood the test of time.

>>2672560
Oh yeah that's what I was thinking. I think it's pretty unlikely that this shabby guy being filmed jamming his ancient soldering iron into an old welder is performing some dystopian work for the CCP. I could believe that the headline was applying to new welders or welders in official service right now, but they're not going to send around goons to every damn rice farmer who needs to re-weld his tractor's cracked cast iron flywheel each day.

>>2672562
this one needs a chip too

>>2672565
When you look at this, does it make you feel like you're trapped in a nightmare on an alien planet full of incomprehensible creatures corrupted by demons?

Or is it just me?

>>2672571
No, not this one. There's plenty of things happening today that make me feel the way you described. Compared to all that madness this picture is quite benign, just poverty.

>>2672576
It gives off a circus vibe. Darkness. Suffering. A fruitless struggle to evolve. Monkes with typewriters.

>>2672565
Like... You're welder. Why didn't you weld the core of the welder so it doesnt vibrate?
>>2672562
> oxyacetylene cylinders
If anything, you'd need loicense for those much sooner than some shitty inverter.

>>2671631
From what I gather from >>2671636 the left part of the circuit amplifies the signal from the passive high and low pass filters and the actual resonator begins from component 201 on. Apparently all resistor values are "given merely by way of example"; do you know how I could calculate those and the capacitor and inductor values so each resonator unit can resonate at the given frequencies (2637, 1760, 1174.6, etc.)?

are cheap handheld oscilloscopes good enough for car stuff?

How to buy electric motors if you are a hobbyist? For example I'm building non-conventional electric vehicle, I know how much torque it needs, I know how much RPM it needs and I know it has to be cheap since I see 1800W BLDCs on aliexpress for $25, while mine should be just 500W.

But where do I buy mine? Non of those BLDCs specify their torque. Non of those specify their RPM (yea yea, no load KV rating lol).

>>2672664
Do it analytically by figuring out the transfer function of the circuit. Then the Q factor, and resonant frequency should drop out of those equations.

>>2672673
Don’t put it on the spark plugs.

>>2672682
> 500 W
You mean kW don’t you? Minimum is probably around 100 kW motor.

>>2672722
No, I mean exactly 500W. Why are you having a problem with it? The scooter wheels go as low as 250W.

Please don't distract from my main point.

>>2670315
>SOLDERING IS EASY!
holly fuck i hate you faggots so much
been wasting the whole morning tryin to desolder some capacitors from a mobo and they wont budge.
tried without flux or wick, didnt work.
>just buy some flux and wick faggot, its easy!
buy flux and wick, no difference, just more noxious gasses to breathe in.
>just dont breathe those in faggot, EASY!
2 different mobos, motherfucking solder doesnt get into the wick, no matter how much flux i use, temp, tips. what a waste of time.
>AND MONEY, FAGGOT, EASY!
gonna try a couple monitors next, after i fail with those, i give up.

>>2672732
It's your fault for thinking soldering == desoldering. You're having problems because motherboards aren't exactly easiest things to deal with. There are multiple layers of solid copper inside that eat up any heat you apply. Your best chance is to destroy old cap and remove leads one by one by heating and then using pliers to pull out leads when they start to move. Solder wick won't do anything useful here. You actually need to apply more solder for better heat transfer. Wick is just for cleaning things up. Use your brain for one second and start thinking about how heat moves from your iron to the lead and where bottlenecks occur.

>>2672682
Ready-made hub motors I'm not sure about. If you're doing a chain drive you can get any old RC hobby BLDC, the aliexpress specials have Kv and sometimes torque specifications. You can also convert any outrunner BLDC to being a wheel hub motor, but it does mean some amount of fabrication.

>>2672732
Soldering is easy. Desoldering though isn't. I bought one of pic related, it works great for the price. It's a 929DV, whatever that means. You can also try hollow desoldering needles.
But honestly for 2-pin components you can just melt one joint, tilt the cap away from that side, then melt the other and tilt in the other direction, repeat ad infinitum.

In your case you've got a heavy ground plane, so if the leads aren't budging AT ALL when you tug on the cap, chances are you just aren't getting enough heat into the joint to melt the solder all the way through the plated through hole. You'll want to be using an iron at least 30-40W or so, ideally use a temperature controlled iron at least 50W. In a pinch a ~70W non-temp-controlled iron might power through the joint, but I'd be wary on using one of those with a delicate PCB.


As the other guy alludes to, adding extra solder to your tip is a great way of decreasing the thermal resistance between your soldering tip and the joint. Adding flux is a way for that blob of solder to stay nice and metallic and not go all crusty, in the event your desoldering operation takes more than a 15s. It's also advisable to make as much surface area of your tip as possible be in close proximity of the joint. In the case of a conical tip, this means putting the tip on its side, naturally the blob of molten solder would sit between the tip's side and the joint. It may take a while of doing this for the solder to melt all the way though, so keep lightly tugging on the cap and it will move more once done. Don't pull too hard or you might delaminate a copper pad if the joint hasn't melted all the way through.

>>2672738
>Your best chance is to destroy old cap and remove leads one by one by heating and then using pliers to pull out leads when they start to move.
done that, the leads get stuck inside the mobo and wont budge.
>Use your brain for one second
too much of a hassle, not even the solder from a tv board gets removed by the wick, im just there holding the iron and breathing all that nice stuff. this is for pros with pro tools. im done.

picrel i wasnt able to remove even one bit of solder after applying heat for 1 min. at 450 C, wick wont do shit and the flux just vaporizes.

>>2672741
As I said. You need to add more fresh solder to the joint you're trying to desolder. Preferably leaded 60/40 to lower the melting point. After you remove component then you can use wick to clean things up. And even with wick you need to ensure good heat transfer. A tiny bit of solder on your iron will help you "start" the wick because heat will flow properly. You can't do anything useful poking around with a dry tip.

>>2672740
thanks anon.
>929DV, whatever that means.
have you tried that tool with mobos? will it work 100%?
if it gets the job done i might just buy one.

>>2672743
>have you tried that tool with mobos?
No, I only tested it on single-sided boards. Tomorrow I'll measure the power consumption and give it a shot on some solid FR4. If it melts it easily and is at least 50W I'll give it the pass. But even then, if you don't have the technique to melt solder using a temp controlled iron on a mobo, I doubt you'd be able to get it working with an open-loop iron like this is. Unless you've got one of those shitty 10W "temperature controlled" soldering stations that actually just have an open-loop TRIAC dimmer inside them.

>>2672740
thanks for the tip, its a struggle tho.

>>2672750
doesnt get shittier than what i bought
claims to be 60w

>>2672753
You literally bought pic related.

How can I improve my prospects in an electronics career?

> Spent 4 years in college studying electronics engineering
> Didn't finish as I had to suddenly move to europe.
> Had to start over and get a job, only work in tourism/restoration for 2 years until I got into a school which had a degree in Electronics Maintenance (I believe it was like say, trade school? It was only 2 years).
> Intership was in a small company, designing a PCB for a main product but mostly it was repair work and documentation.
> Got a job right after with a well-known guy in the arcade/emulation community, had to work on emulating a handheld from scratch, even though I barely had any knowledge in programming. Thought it was a mentorship role considering my lack of inexperience (previously communicated and accepted).
> Got fired after a month after being unable to meet the expectations.
> Got hired by the same company I did the intership for my school. Finished the PCB I did back then, and designed another one. Both products are being sold and even installed in lot of places.
> Mostly do IT work now, repairing these devices, documentation. Little electronics work after.
> Even got a raise.
> Learned a bit of bash scripting, python, raspberry pi usage, some postman and so on.

I am comfortable in the company I am now but I want to keep improving my chances in the electronic side of things. I only have the trade school degree but I don't think this will suffice to get into a better position in the future without an engineering degree. There are some schools that also do specialization courses for people that finish trade school but I would have to see how I can even fit it into my schedule.

Are just doing personal projects the way to go?

>>2672768
>I had to suddenly move to europe.
Where are you from? Be honest.

>>2672771
South america

>>2672773
Start building a portfolio of personal projects. It doesn't matter if it's simple shit. Just have something to show prospective employers so they know you aren't starting out at square 1. Don't copy things that have been done to death like electronic business cards. It's just annoying.

Half the battle is being a likeable character. Don't be a spastic. Keep reading, building and testing. You already have marketable skills, now you need to make employers want you. Market yourself.

>>2672779
>Market yourself.
Follow people in the industry on social cancer media and network with them. Create a linkedin profile, farcebook, jewtube, etc. and spread your e-AIDS far and wide. Tell the HR department that you're transitioning or something. Instant hire. lmao

my mainboard stopped working. like it is completely dead. I have the theory that the fuse maybe burnt. is pic related the fuse? there is no pass measurable. if it is the fuse, why is there no values printed on it? what shall 101 even mean? how can I find a replacement to order?

>>2672785
Looks like a fuse to me. You said there's no voltage reading when you probe the fuse, so it's bad. Now you need to find the short that's causing the fuse to blow. Good luck.

>>2672789
but how can I find a fuse replacement? 101 does not say much..

>>2672792
Where does the trace lead to after the fuse? This is why schematics are handy- no guesswork.

>>2672792
Unplug the board and do a continuity test on the fuse. If it beeps it's good.

I'm trying to figure out how to power a 12v device for only a minute or a few minutes (does not need timing precision) using only mechanical means (no programming).

What is the simplest way using the least number of parts and the least power? (*hint; think natural mechanical limitations of devices)

>>2672820
use a mechanical watch with a seconds pointer. NOT a contact when it hits the 12.

>>2672820
> 12v generator
> egg timer
> mechanical switch hooked to timer
idk

>>2672820
Container of water with hole + float switch.

>>2672753
>cheap no brand chinkshit with ALL TEH FEATURES

How do you store your SMD resistors and capacitors? Do you cut the tape into flat strips or store it as a single roll? Or do you extract them from the tape and store them in a box per value?

>>2672732
>motherboard
Motherboards are usually multi-layer and pretty high thermal mass, so desoldering can get tricky, especially if your soldering equipment is trash.
>tried without flux or wick, didnt work.
What kind of iron do you have? if it is blue chinkshit mains iron - bin it, since even fixed temp 30W iron would be better.

Also, those look like capacitors, why would you even need a wick or solder sucker, if you can just heat leads alternatively and pull it out slowly on side you melt solder.

Soldering is easy... If you know how to solder lol. So get some practice boards and just get used to the behavior of the iron, solder etc.

>>2672820
I got a dial timer that i salvaged from a toaster oven i found in the trash.

The primitive technology method is to have two dishes of water on a metal rod with a fulcrum in the middle. When the dish is full enough from water dripping into it from the other dish, it the balance will cause the dish to fall making contact.

any idea what the TP is?

>>2672924
test point

>>2672931
fuck, obviously, can't believe i didn't realize that

>>2672934
Everybody takes a shit in their brain once in a while, Anon. No big deal.

>>2672889
Depends.
If I have a whole reel, I don’t touch it. Who got time for that.
If they’re static sensitive, mosfets, I don’t touch them and leave them in the tape.
If I already have a bin and there’s only a few I take them out and put them with the rest.

It’s the same theory with using donor boards. You never bother to remove all the components because it’s work you may bever need to do… just leave them on the boards (if you have space) until you need them. Goes for parts salvage boards, too.

I'm planing to build a single ended stereo tube amp. I for one prefer closed metal cabinets with gray painting.
but this time I want to build a open cabinet amp.
the style I want to use is like pic related: tubes in one row, magnetics in the back. I want it to be wider than deeper.
I made a photo set of four possible lineups of the power and driver stages. at this point I don't want to talk about technical merits and drawbacks. at this point it's all about the looks.
the post with the possible tube combinations will follow.

I'm not sure if I'm going to use a rectifier tube

>>2672958
the possible line-ups
what looks the best? also I won't put the smaler tubes between the bigger ones.

>>2672959
If you want to be fancy you could incorporate golden ratio or some other math to adjust the spacing. Or since you have space background on your wall, arrange tubes in a constellation, there is no reason for everything to be on a straight line. Or you can adhere to Dieter Rams principles of industrial design.

>>2672971
>Or since you have space background on your wall
sorry I think you got me wrong. what I did there in my lab is only a conceptual "study". spaces will be optimized. also my electronics workbench is not the place where the final amp will be used. due to the dimensions of my TV lowboard I got only the option to go wide and not to go deep.
still I thank you for your time to respond to my request :)

>>2672939
But I mean imagine you need 100 different values of SMD resistors, 100pcs per tape, all curled up and stuffed in an ESD bag per value. That's 100 bags. If you store them as is without unpacking them, that's a huge box that takes up a lot of space, and you'd have to look through 100 bags to find the right value.

>>2672980
"SMD sample book"

>>2672982
That's awesome. But a lot of work. Love the idea.

>>2672971
>>2672976
I'm sorry I got you wrong!
that's a great idea to position the stuff in nicer constillations and to couple it with my interest for space. but:
>there is no reason for everything to be on a straight line
there is a manufacturing and noise immunity reason to actually do it in a straight line.
manufacturing: I want to use solder terminal boards. the best method is to use the mounting studs from the tube sockets.
the noise immunity stuff: I want to keep input tubes and wiring as far away from the mains transformer and choke as possible. cris crossing lines are suboptimal, also as introducing parasitic Ls and Cs

>>2672983
They're already filled when you buy them.

>>2672985
>300 330 360 390
What E-value step is that? I'd rather have fewer values and combine them.

Any tips/recommendations to build a nixie clock?

>>2672988
nm it is 5% E24 but it is unlikely i'd ever need all of these values

>>2672768
you did some actual design work previously so you pretty much have your foot in the door
as the other anon said work on some own projects and just apply for design jobs

What kind of inductors are used in RF circuits? Mostly air core coils, or MnZn or NiZn toroidal ferrite cores or even SMD inductors? I have a bunch of inductors like this used in SMPS circuits, on the order of 1-100uHs but I don't know their specs. What happens if they are used at higher frequencies, say 10-100MHz?

>>2672900
>What kind of iron do you have? if it is blue chinkshit mains iron - bin it, since even fixed temp 30W iron would be better.
>Also, those look like capacitors, why would you even need a wick or solder sucker, if you can just heat leads alternatively and pull it out slowly on side you melt solder.
ive managed to do that, but the solder that remains blocks the hole. i can remove it with the solder wick but it takes forever. how expensive is the soldering iron that i need?
>Soldering is easy... If you know how to solder lol. So get some practice boards and just get used to the behavior of the iron, solder etc.
ive recapped 2 monitors and now they work, i only have the motherboards left, but they seem more work than what im willing to do and spending more money now, idk, it seems like a waste since once i recapped those mobos it might be years util i need to use the tools again...

>>2673030
> inductors “used at” higher frequencies
A fundamental use for them is a RF tank circuit that resonates with a capacitor at a certain frequency.
There’s usually (at least one) tuneable inductor in there.
So maybe “used at” isn’t quite right to describe what’s going on.
Of course, there is other uses, such as filters.

>>2673030
high permeability (and thus high impedence, see voltage divider) inductors are used for voltage transformers and chokes
low permeability are used for resonant tank circuits

Do you think i can desolder and resolder this with just an iron and a hot air gun? how hard can it be?

>>2672998
Yeah, that's true. But they were pretty modular so it's not like the PCB is doing something amazing (both of them had some design flaws that couldn't be fixed due to time constraints and pressure) and there was some parts already established from previous versions, so I feel lacking in PCB design knowledge to convincingly say I know how to design, mostly electrical stuff and the advanced stuff

What's a cheapo quick way to tac weld lithium batteries? I bought an ego lawnmower secondhand and it dies quickly. I already opened it and have stuff ready to swap but I need a good way to re-attach the nickel strips. Should I just solder it?

>>2673085
>cheapo quick way to tac weld lithium batteries?

there's a million youtube videos on the topic of making one using a microwave oven transformer.
but they all go overboard with timers and complex swing clamps, and shit.
all you really need is to clamp some sharp points of #14 solid wire to the end of the secondary, and push it against the nickel for a quarter second.

>>2673072
Just send out applications and if you get an interview don't downplay what you have designed

>>2672753
Those irons may or may not just have an open-loop TRIAC power control in them. I have a similar one that definitely has analogue temperature control, but I've heard otherwise for some of those. The analogue temperature control isn't very linear anyhow, you're better off going for one of those irons with a small digital display on it and 2 or 3 buttons.

>>2672820
>only mechanical means (no programming)
Does a 555 timer count as no programming?

>>2672989
Pick your tubes first and base the design around that. See if you can get symbol tubes that will be useful, I've definitely seen some with symbols like "Hz" and "A", not sure if you can get "AM" and "PM" though. Blue underglow looks like shit. Upside-down 2s for 5s looks cool. Socketed tubes will be better for testing and hot-swapping, but not all tubes have solid pins rather than wires. If you add a GPS receiver you can synchronise the time perfectly without an internet connection.

For your circuit design, choose whether you make seperate driver boards for each tube (modular) or put all the tubes on one board. Not sure what driver IC to use, also not sure what software to use. I see a lot of them using STM32s, so if you pick one of them you can likely just throw existing firmware on it.

>>2673060
The thermal pad on the underside will make it tough, I'd not want to desolder it unless I could avoid it. A reflow plate would be fine though, if the reverse side was clear.

>>2673085
If you’re careful, I’ve heard of people just soldering them without any issue. Others people swear by it.
You probably want to do it quickly, so you might want to use a solder gun, or high wattage iron.
You might want to wrap the rest of the battery in a damp cloth to make sure the cell doesn’t overheat.
I’ve had a bit of a problem getting the solder to stick using this method, but it coukd be because if a cold joint. Ymmv.

>>2673118
> GPS receiver = get time
eff that, just use WWV or CHU signals.
make it a separate module though with a common interface just in case.

>>2673108
>The construction is kept very simple
microwave transformer
arduino
hand made electrodes

I made one with a car battery
motor cycle solenoid
copper nails sharpened
push buttton

>>2670318
use a multimeter

>>2673118
>The thermal pad
there is no thermal pad, this is the footprint

>>2673336
Ok that looks ok. Just be sure to put some foil tape atop the IC to shield it from your hot air.

I may want to have two 3-phase H bridges in parallel, I'm wondering how to place the transistors close to each other. For a given phase that I'll call [A], is it better to have a pair of [A]'s half-bridges where each low-side FET is closest to its corresponding high-side FET? Or is it better to have both of [A]'s low-side FETs right next to each other? I know it would be ideal to have all four of [A]'s transistors as close together as possible, but my geometry means one compromise or another needs to be made. Pic related. I'm thinking it's the one on the left.

My issue is that TO-220 FETs can only handle so much current, hence the need for 2 sets of them. Any SMT package is harder to sink current from, and larger THT packages will be harder to fit. My PCB and its components will be fitting in a 32mm wide enclosure, and TO-220s are 10mm wide. I might maybe be able to squeeze two in sideways, but the pins are going to be bent at a sheer angle since the pads themselves are 15mm long. I guess I can trim the pads. The whole PCB will be pressed with its FETs against a big heat sink.

They'll be driven from the same gate drive output (though on seperate totem-pole current amplifiers), and will be identical parts, maybe even hand-matched if I need to.

>>2673368
MOSFETS have a positive tempco, unlike BJTs, so there is less of an issue, but you can still put maybe 0.5 Ω resistors to sum their outputs if you’re worried about it.

>>2673371
>0.5 Ω
That's 10 times the resistance of each motor winding when stalled, I think the PCB traces will do just fine.

Also the tempco is only positive when the FETs are fully on, it's negative for some of the switching region. But I don't think I'm in danger of frying the FETs solely from 2x switching losses. Especially since the high currents will happen at low motor speeds, where I can lower the PWM frequency (one of the many features of the based TMC4671).

what do we think frens?
only 14 burgers

>>2673435
That ain't gonna cut it for a motherboard. Look for a ceramic preheater with around 500W output.

>>2671630
Don't build that. It sucks. If you want something smooth (think playable sinewave self-oscillation) go for a CoolAudio VCF chip. If you want the Moog sound, look for the Moritz 4-pole diode ladder filter design.

>>2671766
1. push-pull, using two outputs
2. play sounds which are near the resonant frequency of the driver
3. use a speaker with a high impedance; an old-fashioned 100 Ohm speaker as used in a transistor radio will give you a lot of volume on 5v

>>2673435
Useless crap.
Borrow your mom’s iron, and just invert it.
You should already be using it to transfer your laser toner pcb layout to un-etched copper fr4.

>>2673569
>You should already be using it to transfer your laser toner pcb layout to un-etched copper fr4.
i hope thats a joke
bugmen will make 5 4layer pcbs for $2
making a single pcb at home will cost you more than that

>>2673571
>he fell for $2 meme
Now add shipping + taxes + imports and 叫你生孩子沒屁股眼 it's actually $20.

well this makes no fucking sense
minimum via annual ring is .15mm and if we do the big boy math
0.5 ring - 0.3 hole = 0.2mm annual ring
so why the fuck is kikead complaining?

>>2673579
>and if we do the big boy math
You're not enough of a big boy to do such advanced math. You're subtracting 2 diameters and expecting to get a width value, when in reality you get another diameter. Ring width is (0.5 - 0.3)/2.

>>2673368
>>2673371
I read the datasheet on that thing, they’re one step away from letting me hook a wyse terminal up to it directly and issuing ATDT commands to change register values.

I think it should be the first layout because of nonspecific thoughts about switching (I think the H and L are supposed to be close to each other for complicated reasons like a twisted-pair/balanced line), heat distribution and matching, and potential failure modes (like you said, stall conditions)

Are those little dots all around the GPU some SMD resistors ?
I think I killed a GPU.
How things went bad ? the GPU Fans were doing huge rattle sound. Bought new fans, installed them.
I put thermal paste for CPU on the chip, started the comp, and I had some sort of stripes in pink.
VGA mode is working, but as soon as I request GPU informations with nvidia-smi, even on console, those stripes run on the screen.
I "naturally" - speaking of the way thermal paste can blur a surface - found thermal paste on those ultra tiny smd components. Cleaned everything carefully, but it remains the same after tries with some 1mm special conductivity pads.

trying to reverse engineer drum core inductors as I plan to build some custom ones down the line

using some formulas I found online and some stupid questions
>is u initial same as ur
>are my guesses for Aeff and leff even in same direction

I suspect I need to dig deeper into gapped core calculations and just calculate without gap, as overall it looks like current formula is more suitable for rod ferrite rather than multi-layered drum core inductor

>>2673571
No, I already have a lifetime supply of ferric chloride, also used to re-electroplate my soldering iron tips, and an original lexmark laser printer with blacks so dark and thick it’s practically like the ceresist dry transfer.

>>2673593
>SMD resistors
capacitors

>>2673593
Those are decoupling capacitors.

>>2673594
I assume you’re copying a class D amplifier.
Wouldn’t it be easier to do an in-circuit (your own test circuit) characterization?
I think you’ll have to do that eventually anyway, so I’d just start with that since you have no idea what kind of ferrite it is and you may never be able to get ahold of it anyway.

>>2673596
>>2673597
ok then RIP that GPU I bet, I will try to test them with ESR but doubt of any good issue.

I want to generate ELF electromagnetic waves with electronics. Is this possible? I've tried doing some research online and I saw some people saying a regular antenna would have to be EXTREMELY large to make ELF waves, but then another person said you could manually rotate a magnet or charge at the frequency you want? It seems like I could just make a normal AC generator and just have it make the magnet or coil rotate at the low frequency, right? Are there generators that can do this already that are small, lightweight and hopefully cheap? I want to be able to adjust the frequency.

>>2673631
It might still work, Anon.

>>2673634
I feel having not the necessary expertise.
At boot I have the logo of my motherboard and the pink stripes in background. Linux boot is going well, in VGA mode, and as soon as I launch X or request as said earlier nvidia-smi to get infos I got a "no gpu found" and those pink patterns. Nvidia drivers are loaded, those same drivers I use with another card, which is working.

>>2673635
Did you reball an old chip or install new?

>>2673633
I doubt that rotating a magnet would produce any significant ELF waves. Conservation of energy still holds and if you want to transmit 1W of ELF RF power then you need to expend as much (even more) power when you rotate the magnet. At low frequencies this magnet would need to be massive. This technology is only really viable for military with enough land and resources.

>>2673637
well it's the old and unique chip, the one that got thermal paste on its smd capacitors.
It's bitter feeling to lose 300 bucks like this

>>2673640
If you put a gun to my head I'd guess that some of the balls aren't touching the BGA anus pads. Could also be balls touching, which is very gay.

>>2673638
Damn. Is this still the case if I only needed the electromagnetic wave to provide around +/- 0.5V?

>>2673118
>Pick your tubes first and base the design around that
Where should I buy them? I can only find links for sets and kits. The rest is Aliexpress stuff, which I am not entirely sure they are reliable or if they will even get here in one piece

>>2673646
When talking about EM radiation it's always better to talk about power. There is a big difference in 0.5V on 1MOhm resistor vs 0.1Ohm resistor. US military ELF transmitter consumes 2.6MW to transmit 8W of RF power. This ELF thing is really impractical and only used because it can penetrate water so they can communicate with submarines. Why do you even need to operate in ELF range?

>>2673435
Looks neat, assuming it has proper temperature control. 65W is enough for small PCBs.

>>2673593
Did you use electrically conductive thermal paste? The silver-looking stuff?

>>2673633
It is possible, and while you could try to use a capacitive antenna, I think a magnetic one would be far easier. A big loop antenna. But they're not very efficient at low frequencies.

Maybe you can send the signal back down your power outlet and into the power distribution wires? Depends on the frequency whether the distribution transformers will let it in.

>>2673648
old stock from tubes-store.com or ebay

>>2673658
>Did you use electrically conductive thermal paste? The silver-looking stuff?
I had Noctua, no idea if it's conductive :5
Maybe testing it with meter

>>2673661
"NT-H1 provides top performance right from the start and doesn't require a longer "burn-in" time. If you happen to make a mess, that's no problem at all: NT-H1 is not electrically conductive and fully compatible with all materials commonly used in PC environments."

>>2670315
>>2670315
It is worth these mobile like multimeters or not?
It seems fragile and does not show the same response as the dial ones. But the numbers are big enough and bright. It seems a clear advantage to dark environment or if you need glasses to do anything.

>>2673771
Seems to me that there should be an iphone or ipad meter by now that uses bluetooth and has an even better “dark mode” display.

>>2673783
Yeah, thanks for the clarification.

>>2673771
I know the Aneng Q1 is considered to be worse than the more traditional AN8009, but I’m not sure how much of that is due to the wacky new UI. At the very least, if they use digitally controlled transistors it will be more electrically delicate and will result in worse SNR than a rotary switch. Mechanical relays would probably be fine, but there’s quiescent current to worry about.

>>2673792
I’d rather have a selection of dataloggers for measuring different things. A voltage one and a current one, with different ranges. High current ones would just be clamps.

>>2673807
It uses a latching relay like the Q1.

>>2673811
I was gonna ask if that was 10A rated, but now I look the better doesn’t have a current range at all. No thanks. I’d maybe get it if it was a clamp meter.

is a job in controls engineering for a full service automotive engineering firm worth it or should I look to other opportunities? Is this a high stress job? What is the day to day like anons? I'm thinking of switching into this. the pay seems good at 35/hr starting with no travel only to some local plants

>>2673658
I'm >>2673633
Neat, thanks.
What would sending it to the power distribution wires do? I don't know the right term to Google to look up what it does.

>>2673579
this has to be b8. you cant actually be this retarded

>>2673601
building somewhat specialised buck-boost converter

Currently just trying to get deeper understanding of drum core inductor design by going through books but mostly it's more standar E, RM etc cores or toroid cores

>>2673865
>What would sending it to the power distribution wires do?
The idea is to use the distribution wires as an antenna. I was looking into this for receiving ELF (especially schumann resonance) but theoretically it would be just as effective to use it for transmitting. That said, transmission lines are really lossy for low frequencies. They've got a bunch of loads connected across them, so the vast majority of your power would end up dumped into them instead of being radiated. It's only worth doing if the benefits from having a larger antenna supersede these downsides.

>>2673881
I think you're better off either:
>buying some of these cores to characterise yourself via oscope
or
>deriving the correct magnetics to use from first principles instead of by reverse engineering
For this latter one I'd just use superior toroidals anyhow.

>>2673648
I got all mine from ebay. Usually sets of a few tubes but you can find individual ones for sale. Keep an eye out for deals, certain popular tubes (notably IN-18) have a tendency to be overpriced. Smaller and less popular tubes can be surprisingly cheap if you look around.
They basically all look good, so the type doesn't really matter as long as it's big enough for your liking. I found this site to be a decent reference for how they look size wise: http://www.jb-electronics.de/html/elektronik/nixies/n_sammlung_komplett.htm?lang=en

>>2673882
> toroids
From what I know about magnetics, except in cases where you need, say, high frequency air cores, it’s impossible to beat a toroid except they cost too much to make because they have to wire through the hole.
Other inductor types just trade off other qualities, sometimes literally Q factor, for being cheap to produce.

I just have a bunch of ferrite beads and wind my own chokes and transformers in most cases since I’m just a hobbyist and not churning out thousands of these things.

>>2673882
Neat, thanks. For my project I'm looking for something ideally small, but the concept of the power lines acting as an antenna is neat.

Dat fucking Swoog always gives me DAT only reciepe when I bring him a gold coin.

>>2673917
It's pretty common to make a twin-T active notch filter to filter out mains frequency noise, I wonder what you'd hear if you connected one directly into the wall?

>>2673648
>>2673658
Here's a spreadsheet of nixies I made over 6 years ago, but updated just now. Most prices have gone up by a factor of 2 since back then, which is kinda shocking but I have more than 2 times the disposable income since then so I may well buy some once I come up with a good project that isn't a clock. All these beautiful under-utilised tubes displaying Ωand V and such, I should make a desktop multimeter, though I can't justify that without it being at least 6 digit with dual displays, so I need to get better at instrumentation circuit design.

Not sure if the IN-1 or IN-4 is better matched with the IN-7 series. Their matrix VFD, electroluminescent display segments, and decatron tubes are also pretty appealing.

>>2670315
roll

>>2673899
>>2673933
>>2673658
I appreciate the recommendations and that chart is pretty nice. Still don't know if I'll do it as I am unaware on what the skill level for making such a thing is but I was trying to think on something to build and it just came to me. Still it's good to know what kind of available resources I can have at hand.

>>2670315

found a non-shit version of op's pic in some Yuropean fag's interesting web site.

>>2674122
all that for what, a microphone preamp?

>>2674171
>for what

156W mono earphone amplifier, for owners of very inefficient earphones.
this guy (Plamen Todorov) is legit for real.
even specifies you should use oxygen-free input cables.

>>2674193
...right.

>>2674122
Is there a name for the T15+T20 differential amplifier circuit? Seems like the guy was too autistic about symmetry to use a long-tailed pair like everyone else. The T13,T16,T17,T34 circuit is also really strange and I'd like to understand it. I'm guessing it's a differential to single-ended converter of some sort, though with that 100Ω trimmer in there I'm doubting if there's really differential signalling going on at all. Maybe the double-sided circuitry just has common-mode signalling for biasing purposes, but it feels kinda overkill compared to having single-ended signalling with a Vbe multiplier before the power stage.

>>2674227
It looks like a weird way to eliminate crossover distortion. Probably hasn't seem a Vbe multiplier before, or has some weird reason for not using one

>>2674265
Yeah it's definitely looking like some sort of anti crossover distortion circuit, looking at T10 and T41 in particular. I was under the impression that a Vbe multiplier was already as good as you get from a tempco perspective, but maybe they're thermally infeasible if you need hundreds of milliamps if not multiple amps as your base current. Personally I'd side-step that by having a 3-stage darlington/sziklai output instead of the common 2-stage, but maybe that has its own downsides.

RP1 is for crossover distortion / bias current, RP2 is for adjusting the DC bias feedback loop, but RP3 is a mystery. It looks like some sort of DC bias control since it's between two nodes that should move with constant voltage offset between them, but its output has a series capacitor. I can only see it being useful if the signal at T21's emitter is a different shape to the signal at T35's emitter, which would suggest it's not very linear despite all the complex stages. I don't get it. Maybe RP3 is somehow to remove startup pop?

I like his use of capacitance multipliers. I don't like him just using a 10µF series capacitor on the input.

has anyone tried QSPICE yet? it is being touted as a next gen LTSpice. I tried downloading it but gmail complains about a suspicious link and the installer wants to be elevated for "your own good".

>>2674293
>windows only
>windows 10+ of all things
into the trash it goes

>>2674296
isn't LTSpice windows only as well? also would anyone use anything other than windows?

>>2674293
Spice was originally a command line tool, ltspice is mostly just a front end to it for zoomers and millennials that only type with two thumbs.

>>2674305
works flawlessly with wine
>why would anyone use anything other than windows?
windows has been dogshit since W10, why would you use it for anything besides work requirements and gayming?

if i laid out all my tht ics end to end, they'd be over 8m long

man it's pretty annoying that jlc can only PNP one side of the pcb since both sides of my pcb are densely populated so it won't be saving me that much work

>>2674293
It doesn't work with wine so no. There is already ngspice, ltspice, qucs, xyce... The real issue with spice is finding/making realistic models.

the fuck? jlc charges extra for color now?
greedy bastars
last time a year ago i ordered 4 layer pcb they didn't charge anything extra for other colors.
Now the cheap option is only the ugly ass green

I mean it's not a huge deal the pcb will be enclosed in a case so it's not visible but it still annoys me i have to use the ugly ass green color

>>2674404
well they can't put multiple boards of different colours on the same panel
be nice if you could crowdsource enough PCBs of the same specs and order an entire panel from JLC or whoever. not only colour, but copper and fr4 thicknesses as well.

>>2674408
i used jlc for years for dozens of orders and never used the ugly green and never got charged extra for it
so if they did it for years, why start charging now?
it really annoys me because i'm not stupid enough to throw out money on different color on a part that will be hidden in a case but at the same time it pisses me off i have to look at ugly green when soldering
also for some reason the SMT coupon only works for green pcbs now and it's extra$20 bucks to do smt on non green pcbs and there is zero excuse for that

>>2674409
Pretty sure they charged extra for other colours like 3 years ago when I was looking at making a yellow board. But some colours are charged differently to others.
Or maybe it was just a longer processing delay. Idk it was 3 years ago.

>>2674413
nope, for years the colors were free
i ordered $2 5xpcb of various colors many many times
even now you can still do that for 2 layer pcbs, but they now charge extra for 4 layer pcb colors and smt
so i have two options, live with the hideous green or redesign the pcb to be 2 layers, which would be MAYBE doable but huge pain in the ass since i can't make the pcb any better and it would be dumb to clutter up my design just for color change

>>2674415
apply the solder mask yourself anon

fucking bugmen ruined my entire day FUCK
i hope they drown in those fucking floods

I bought these custom cable mods to pretty up my new pc but the back side panel of my case wont close because the 24pin cable mod is too short to tuck under the PSU shroud and the width between the panel and the mobo panel is too short. Would it be safe to lengthen them with solder butt connectors with another 24 pin cable I have? (theyre not as nice and I only bought them because they were on a great sale I had the same length problem with them also it seems they may be smaller gauge wire though it could just be the sleeves)

Idk why they dont just make the cables 50cm because ive tested them in multiple cases and have never used them because this exact problem.

>>2674420
These are the butt connectors that are basically just solder centered inside a heat shrink non slip wrap plus black heat shrink to tidy it up

>>2674417
NO
fuck this
i won't let the abominable insectoids win!
i will retrace the whole fucking pcb down to 2 layers if i have to, i am getting that fucking custom color without paying a single fucking extra cent more, i don't care if it will take me a whole extra day i'm doing this, i didn't spend fucking years getting masters in EE to be bamboozled by some god damn chink

>>2674425
>https://www.youtube.com/watch?v=a2YRMixW9u8
>4 layer PCB with black solder mask. How much?
>four dorra extra for the mask
>*smashes stack of PCBs with a baseball bat*
>NOOO
>2 layer PCB with black solder mask and SMT assembly
>fifteen dorra
>*smashes a shelf full of SMD parts*
>NOOO, take it, just take it, we give coupon for 20 dorra, no smash our things
>*submits order and leaves*
>滾你媽的蛋

>>2674433
good job i spit soda on my keyboard

>>2674361
never heard of qucs but i like the name

>>2674433
what a racist POS. that's why it is called a CONVENIENCE store. if you want cheaper prices go to walmart. seriously, i wonder if movies like that are even possible in 2023. a scene like that would cause massive protests and the movie would be canceled.

>>2674433
lmao

>>2674425
Nigga, ever made PCB yourself? Be happy you can get PCB made for $5 at all on professional equipment with professional quality.
>but i want lgbt colored soldermark
Guess what, electrons dont care about color.

what le fug?!
same shipping option, left is for 15 empty pcbs
right is for 10 same pcbs, but populated by components
are you telling me those smd caps and resistors are so fucking heavy they need to charge extra $8? Thats it. I'm fucking done.
No PNP, i will just solder that shit manually.

If my device is
1)purely digital (no incidental radiators like motors)
2)isn't an intentional radiator (no Wi-Fi, bluetooth, etc.)
3)Has a clock speed below 1.7 MHz
4)Is battery operated
does that mean I get to skip EMC compliance testing?
Like, if I wanted to sell some little doo-dad that uses a photoresistor and a transistor to light up an LED, I shouldn't have to pay $10,000 to get it approved for sale, right? There has to be some kind of approval process right? Can I self-certify RoHS compliance?

>>2674528
>purely digital
pay up boy

>>2674318
>windows has been dogshit since W10
I think you meant since Windows 8. I will never forget that awful "start menu".

>>2674554
3.11>95>98SE>NT>XP>7>10 LTSC

Just made a shitty vertical one take after staring at a monster can and a piece of wire on my desk

>>2674554
>Windows 8 ... awful "start menu"

sure, but it's fixable.
you can install Classic Shell, which lets you nuke both the phone-like interface and the Metro Apps.
so you get more functionality than Win7 with only a small slow-down, while avoiding the obnoxious and rapey Win10.

>>2674532
"Inherently benign equipment" ??

>>2674609
Nice.

I don't know why I ever listened to the solder sucker FUD this thing's fucking awesome
I'm never going back to solder wick after this

>>2674781
Wick is still good for cleaning pads, but solder suckers are pretty rad. I wish the Hakko vacuum desoldering gun wasn't so fucking expensive.

>>2674809
Buy one of these: >>2672740
They’re functional and cheap.

>>2674781
>>2674814
The Engineer sucker is really good.
The silicone tube allows you to press it right on your iron and the joint and give you a good vacuum seal.

>>2674848
Looks good, but not as good as a seal of molten solder. Probably more expensive than the desoldering sucker iron too.

>>2674781
Depends what you're doing. It is good to have both. Also you can get stainless desoldering needles and toothpicks.

>>2674781
I've always just used a can of compresses air and heat up the solder so it mealting and then blast it the shit away with the airs.
Doesn't work well in the middle of the board though but cleaning out through hole is easy

Redpill me on peltiers
Some say it's bad to turn them on and off repeatedly. Is that true? And if it is, does that mean that PWM is out of the question?

>>2674848
any sucker that doesn't apply heat is useless piece of trash
chinks sell electric suckers for like $3 just get that one

>>2674942
Don't buy these pieces of trash.
Had one which melted its insulation and the tip become live.

>>2674934
I've never heard anything about it being bad to PWM them, but I guess it's not impossible. What I do know is that peltier devices have a maximum power point, and feeding more current than you have to actually makes the cooling power worse because of the extra added heat. So I'd want to use an open-loop buck converter at the minimum, but preferably a MPPT algorithm on an MCU that reads hot- and cold-side thermistors to ensure that it gets the most out of your watts.

>>2674848
This one is nice and doesn't feel like cheap shit, but don't forget to clean it.

is it a good idea to bypass the console of my old treadmill that keeps throwing E6 error codes(loose wire) with a dial that goes straight to the motor?
any sort of pre made ac to dc board that would allow for this so i dont burn anything down?

>>2670315
I need a soldering machine for electronics circuits and electronics components. I usually work with soldering paste. I ask to /adv/ and they send me there. Can u help me for that one ?
Thanks.

>>2675039
Reflow plate, reflow oven, hot air, infrared. Use the internet Dewey decimal system to research what is available and then build it yourself with junk.

Generally speaking, how should i decrease or increase voltage across a circuit? Often i have a part of a circuit that needs 5V while other needs 12V/24V.

>>2675109
How much current does each need?
Is it battery powered, or is it going to be plugged into a wall?

>>2675109
You could take a wall adapter with a sufficiently high voltage for both 5V and 12V for instance and smooth out the output with a big capacitor and then use voltage regulation to clamp the voltage to both 5V and 12V. That's the general idea at least. Don't fry yourself with the capacitor. Or use two DC power supplies.

This image looks like it has additional caps for noise reduction.

>>2675145
>>2675146
it's after the power supply, so no filtering needed, in this case i have a dc 12.5V supply that i need to convert to 5V and then to 24V to feed a dual 80W audio amp.

To bring down voltage, i've seen people using zener diodes or some kind of thevenin equivalent, but i've never seen that with other voltages other than 5V. Then i have no idea how to increase voltage, i believe it would be using a coil of some sort.

>>2675149
There's some called a "boost converter" you can use to increase a DC voltage at the cost of current. That's as much as I know. I haven't really bothered to understand how one works. My knowledge extends to udemy classes and like chapter 1 of The Art of Electronics.

>>2675149
You'd be better off using a 24V PSU and bucking that down to 5V. More efficient (less heat).

>>2675155
I've used those, but they take space and feels cheap to have it hang around in a circuit.

>>2675158
I don't have that option as this is part of a broader system. But how would you buck down from 24V to 5V? Just a regulator?

>>2675164
A CC/CV buck converter that can output enough current for the 5V circuit, split off of the 24V rail. The 24V just goes straight to the amp.

>>2675167
I have 12.5V at the start, not 24V.

>>2675175
Then you need a boost converter that can output 150W @ 24V (and a power supply that can handle it) if you want to listen to the amp at full volume.

>>2675109
>how should i decrease or increase voltage across a circuit?

getting 5 out of 12 is easy.
read https://www.thegeekpub.com/243087/voltage-regulator-tutorial/

getting 24 out of 12 at 5A is anything but trivial.
easiest is to add a second power supply of 12V @ 5A in series.
see pic.

anyone have experience with the Power Integrations TOP line of highly integrated switching ICs? are they generally reliable or are they a meme? i want to make a 120W flyback (12V/10A) to power an inductive load (brushless DC motor.) these TOP ICs seem pretty cool... if they actually work.

>>2675201
>getting 5 out of 12 is easy.

in fact so easy, you probably already have a few spares.

>>2675149
>24V to feed a dual 80W audio amp
You'd be best off with a linear 24V power supply. Switching supplies (and by extension switching DC-to-DC converters) are generally a bad idea for audio purposes since they're electrically noisy. You could still get decent results from a 24V switching power supply if you have some good ripple rejection afterwards though, think LC filters and/or capacitance multipliers. Assuming you can get away with just a single +24V rail, chances are an amplifier wants ±24V which is easier to get from a transformer-based PSU.

As the other guys say, it will be much easier to get a DC to DC converter (still beware of noise) to step down to 12V or 5V for lower power stuff, than to get a converter to step up. It's best practice to design your mains power supply or battery system to be at the voltage of your most power-hungry load, within reason.

>>2675206
>integrated switch
Just use a TL494 with external FETs. With them you can make a push-pull converter that doesn't need a flyback transformer (and the air-gap it requires) which makes transformer selection or creation significantly easier. Use the pullup from this blog as a pull-down:
>https://www.circuitden.com/blog/11

>>2675290
>TL494 with external FETs
space is a major concern, not sure i'll have enough room for something like that.

>>2675290
>>2675441
sorry, didn't mean to discount the rest of what you wrote either. flybacks seem like a pain in the ass due to the air gap requirement, but they lend themselves to tons of integrated solutions with good application notes and reference designs -- which is good for a noob like me. i've never studied two forward designs although i have heard their transformers can be smaller and more compact.... so maybe this is worth investigating. thanks.

>>2675441
Actually the integrated MOSFET's 1Ω RDS_ON isn't bad for 240V. If you're on 120V it's worse, but not awful. Still worse than what you'd get from an external FET, even a small PowerPAK-SO8.
What's the stall current going to be for that BLDC? I imagine it will be a lot higher than 10A. Or will it be fine to drive it with an ESC that restricts current to 10A?

Also FYI there are versions of the TL494 (TL598) that have push-pull outputs for driving FETs directly, though they're more expensive and still don't have the fancy soft-start and such features you'd expect from a more modern chip like you selected. So I'd definitely look into push-pull off-line switching ICs. Maxim, TI, and I think OnSemi or Microchip have decent selector tools on their website for switching controllers and converters, see if one of them tickles your fancy.
If you need to shrink down your magnetics, look into more esoteric magnetic core materials.

You can always use a lower-power supply with a lead-acid battery to buffer the power.

>>2675450
>What's the stall current going to be for that BLDC? I imagine it will be a lot higher than 10A. Or will it be fine to drive it with an ESC that restricts current to 10A?

the motor will be magnetically coupled so the stall current should be pretty reasonable. honestly 100W is probably considerably more than what i'll need, and i'm making the ESC myself so it will have overcurrent protection.

>>2670315
Is the BeagleBone ecosystem pretty much dead? Someone suggested I build a drone with one since it claims to run ArduPilot and have all the sensors already integrated on the board, and I looked for tutorials, and they all seem to end with "we gave up because we couldn't find any documentation anywhere to get it working."

Does anyone know where I can find a female barrel connector jack sized 4.0mm x 1.35mm? I've looked at Mouser, Digikey, and even Amazon, and none of them have these. They have 1.7mm ID, but not 1.35mm.

Note, I'm talking about the female jack, the one that the round male connector penetrates.

This is a standard jack size on ASUS laptops.

>>2675526
https://www.newark.com/wurth-elektronik/694103107102/dc-power-jack-r-a-1-35mm-5a-18v/dp/99AH1279?st=barrel+jack

>>2675206
I used a chip from power integration for an off-line flyback converter. If you can find a suitable transformer, go for it, otherwise you should go for some IC with an external FET and your own transformer, but the circuit becomes a bit more complex (but at least you get more control over output power)

Where can I buy capacitors that are capable of handling very large currents in a resonant circuit? I've tried several different options so far, but they were all unable to handle the heat they generate. I've had no luck finding anything in the several hundred nanofarad to single digit microfarad range that's physically large enough to take this kind of power.

Is there a certain type of capacitor that I should be looking for? Or is my best option to buy a few smaller ones and drown them in oil?

>>2675686
change your magnetics so it's higher voltage and lower current

>>2670315
If I wire 2 amp chips in parallel, will the output be changed in any way? Like, one chip exactly on top of the other, each pin of one chip connected directly to the corresponding pin of the other chip.
The idea would be for them to share load, but I don't want any extra amplification.

Photograph unfamiliar.

>>2675709
Any small differences between them could lead to one amplifier sinking the current sourced by the other amplifier. But if you use balancing resistors it should be fine, think something on the order of 1Ω. It might also be possible to use negative feedback. But check the datasheet, it may specifically say you can do this.

One guy did this with 555 timers for more output current, pic related.

>>2670315
why does the elec challenges say to avoid arduino?

>>2675739
>say to avoid arduino?

with arduino, no brain required.
just copy/paste.

>>2675739
Because a lot of those challenges can be completed without Arduino, and are trivialised by it. The point is to challenge yourself with something. On the other hand, using a simple project with a microcontroller that ISN'T an Arduino is a challenge for people who haven't moved from the Arduino IDE.

>>2675738
I see. Thanks.

What is this type of DC-AC converter called? The transistors are briefly turned on when SENSE is at the lowest point.

I'm building a 9VDC to 5kHz ~200VAC converter for a resistive load (human penis), and that's what I came up on a breadboard. As I see it, the LC resonance "traps" the current to LC and keeps the shitty battery out of the loop. Is that what they call a resonant flyback? I tried reading about resonant flybacks, but they mostly talk about resonance reducing stress on the transistors so I'm not sure if that is it.

>>2675752
I'd call it an RF class-C amplifier.
A flyback converter specifically stops current suddenly for a voltage spike on the output as the magnetic field collapses, so I wouldn't call it a flyback topology. Though resonance does reduce the stress on transistors if implemented properly, it usually means deliberately only switching off the transistor when the current through it is zero, thus reducing switching losses. This requires that the current will go to 0 naturally after leaving the transistor on, which will happen with a series LC circuit but not your parallel LC circuit.

>>2675739
Cause the point of the challenge isn't to build the thing, it's to deepen your understanding of electronics, and you can do that only when you're actively meddling with every single resistor and diode in your circuit, which is not possible when dealing with microcontrollers.

Arduino is like the microwave food of the electronics world. It accomplishes its goals awesomely, it's super easy to use, and for its price, it provides incredible precision and repeatability. It's great for when the end product is the only thing that matters.
But if you want to actually learn how to actually cook, you have to start with raw material, piece by piece, otherwise you won't even be aware of all the intricacies, let alone understand them or learn how to tweak them.
If you eat microwave pizza all day, you won't know how to cook meat to perfection or how to use spices. All you know is how to use the microwave. In the same way, if you use arduino all the time, you won't understand why the circuit does what it does, or how to tweak it to make it better. All you'll know is to connect some modules together, copy/paste a program and press a button.

>>2675739
Arduino is basically a toy version of a microcontroller. Just skip it and get right to programmable chips if that's the kind of thing you want to do.

>>2675755
That makes sense. Thank you.

>>2675762
brainlet take

mechanical timer ideas;

>>2673118
>>2672923
>>2672868
>>2672866
>>2672820

I just wanted to say thank you fellas. I am interested in all of these.

>>2675762
bigbrain take

>>2675528
Won't work, sad panda. The OD of the jack is 3.9mm, and it's designed to take a 3.5mm OD plug. ASUS plug is 4mm OD.

It's the only receptacle with a 1.35mm pin, so there's nothing else that will work. Thanks, though.

>>2675866
Another option is changing the barrel jack to a USB-C jack with a USB-C trigger board. You could also use a standard jack and wire it in, but then you have to secure it.

>>2675528
>>2675869
Yeah, but I don't want to have to chop up the power brick since it works with my laptop.

I've decided I'm overthinking this. I am a tool user, not some pleb who has to buy parts from electronics shops. I'm just going to make my own barrel jack female receptacle. And it's going to have hookers and blackjack too.

>>2675872
Good luck, Anon. I hope every hand is an ace and a face.

Whatis this formatting I see everywhere?:
\(R_E + R_{SW}\)

>>2675901
Probably tex/latex.

>>2675906
Is there a userscript I should be running to make it render properly? Google is no help.

>>2675918
try cloudflare, mathjax, the site itself etc.

EE hour. if V=LdI / dt and solving for L=VtN/I essentially L~V/I, so it is equivalent to the Ohm's law for resistance, even though L is reactance/impedance. But it still sort of obeys the Ohms law R=V/I.

>>2675999
With complex impedance Z=f*L*2*pi*j, it will obey Ohm's law 100%. Same with all passive components and amps in linear region.

>>2675918
Where do you want to render it, on this board or in a generic HTML page? /sci/ can render Latex.

>>2670315
What are some good servos to use for a robot arm that needs to be able to rotate very quickly, accurately, while picking up 15 lb objects.

Preferably with 1/10th of a degree precision, at least, and able to rotate through full 360 degree ROM in less than half a second.

Preferably with some common power supply. Just plugging it into a normal outlet is an option too.

>>2676254
>picking up 15 lb objects
At what radius (arm length)? If it's a foot, then that's 15 foot pounds or 20Nm.
>able to rotate through full 360 degree ROM in less than half a second
2 oscillations per second, or 4π radians per second.
If you want both of these specs at the same time (exerting a constant 20Nm of torque while moving 4π radians per second) that's 4π x 20 = 251W of power. God I love SI. In practice you won't be fighting gravity or extreme friction all the time, so you can probably lower that to 100W or maybe even 50W without it taking too long to accelerate up to speed, so long as your stall torque is actually enough to surpass gravity. Do the kinematic equations yourself if you want to get an idea of what it will look like with X mass and Y torque.

Anyhow, I'd look for ~100W servos, steppers, or other motors that can have an absolute encoder connected to. The actual torque isn't that big of an issue, because you can use gear or sprocket ratios to convert the speed up or down (likely down) to get the right torque. Ballpark size will be half a fist, maybe a whole fist. Stepper motors are generally larger for their power rating, but are capable of low speeds, often without needing a gear ratio.

You will need a seperate power supply and a dedicated motor driver for basically anything over 5W.

If your arm length is greater by a factor of 2.5 (i.e. 2.5 feet) then multiply all those power ratings by 2.5.

what's this motif called and what's it used for? some sort of capacitor multiplier?

I bought this CRT hoping to use it as a monitor (for vintage games) but I didn't check and it doesn't seem to take any audio/video input (see 2nd pic, I don't know what those symbols mean)
Can I do anything about it?

>>2676312
Here's the second pic (forgot to post the collage)

>>2676311
Not a capacitive multiplier. More like a snubber for switching transients.

>>2676313
At least one of those is an external antenna input, though I'm unfamiliar with the type of plug. See if you can find a manual for that. I suspect you'll need to get an external RF modulator to use that TV as is, though you'd get a better picture quality if you instead open the thing up to add a direct video input, maybe plus seperate sync signals, or even RGB inputs if that's a colour TV.

>>2676326
I found this picture of the exact same product but by a different brand so I'm suspecting that they both just rebranded a Chinese CRT and I can't manage to find the original chinese one. But yes assuming that everything else is the same the two symbols should mean what's on this pic. The only different thing is that the model in the pic also has audio and video inputs, could it be that mine has that too but for whatever reason they chose to cover it?
I'm a bit scared to open it because of the high voltage warnings all around it, and even if I do open it I don't know what I should look for

>>2676329
yeah, you probably shouldn't open it then.
tough luck, at least now you have a cool dust collector.

>>2676326
switching transients? then why have I only seen it in small signal RF amplifiers?

>>2676313
The inverted peace sign is the antenna input. What interface is your signal source (RF, composite video, S-video, etc)?

>>2676313
In the US you have to tune the TV to channel 2 or 3 (VHF) to see the picture. It might be different if you're in another zone. idk

>>2676369
Yeah thanks, I also figured that the other one is just the headphones jack.

I want to send the audio/video from my computer to the crt, so the signal can be in whatever format I want it to be when I buy the adapters, I think the easiest way is to buy an rf modulator as the other anon said, even though I watched a YouTube video where he makes it look extremely easy to convert it to take composite signal (https://youtu.be/OzcwI_kVRug, this is basically my same model)

>>2676377
It would be better to add a composite input, Anon. Much, much better. RF looks like ass. It bleeds like crazy.

>>2676379
I want to try that, how can I be sure that the capacitors won't shock me and everything else is safe? Anything else I should know before attempting this? I'm also going to buy a soldering gun since I don't own one

>>2676388
All you have to do is discharge the flyback anode and large caps. Unplug the TV. Get a screwdriver with a non-conductive handle, strip a couple inches off the end of a wire, and wrap it around the screwdriver shaft. Strip the other end and solder an alligator clip.

Clip the end of the wire to the metal chassis of the TV. Then gently slide the tip of the screwdriver under the anode cap. To discharge the caps, touch the positive lead with the screwdriver. Pro tip: Discharge the flyback anode twice.

>>2676394
and use a long screwdriver, not a little pocket screwdriver. The flyback is throwing out like 15kV, and 10kV arcs at around half an inch (12.7mm) at sea level.

>>2676284
Thank you. If anyone can recommend a specific brand to look at or where to shop for these, let me know.

>>2676411
>>2676284
am I being trolled? are there seriously steppers available to plebs that can lift that much weight?

>>2676436
I don't know, you tell me. I don't even know how steppers work or stay in place once power is cut (if they can).

I thought all the gear shit on servos was just for knowing the position and/or modifying force for output, but the actual drive is just some shit with magnets on it - motor creates current and turns it. That would assume it flops down once power is cut. But again, I don't know shit, going to go google.

>>2676439
>stay in place once power is cut
They do not, not by themselves at least. You can get brakes that disengage when power is applied if you don't want things to fall.

>>2676329
If you're lucky the composite RCA socket will be there on the PCB but unpopulated. One hand behind your back.

>>2676366
>then why have I only seen it in small signal RF amplifiers?
Ah yeah then I've got no clue. It might be to reduce the high frequency gain, but you're usually better off with a base-to-collector capacitor.

>>2676436
Ah yeah I didn't do any research at all when making that post. Looks like you're out by a factor of 10-30 on the amount of torque common steppers can put out. So you'd still need gear reduction regardless.

>>2676439
If you feed them through a worm drive they stay in place when power is cut. Otherwise, no.

>>2676366
>why have I only seen it in small signal RF amplifiers?

my guess is you're looking at RF oscillators, not amplifiers.
the C-E cap is absolutely necessary for the oscillator to oscillate.

let's say I want to make a variable load for a solar panel maximum power point tracker. How would I actually implement that, robustly? What's the big kid professional way of doing it?
I can use a digipot but then it itself becomes a limiting factor in the power. They also have discrete resistance steps.
I can use a MOSFET, which I believe acts as a voltage controlled resistor. They have a continuous resistance range, but they're not linear. This can be worked around by baking a compensating term into the control rule afaik.

>>2676658
>make a variable load

go to youtube.
type the thing you want.
you have now learned how to fish.

personally, i like things country simple, so i just wire some light-bulbs in parallel.

>>2676671
sweaty pie that is not the kind of variable load I'm talking about

>>2676674
>not the kind

ah cool, so it's more of a bukkake kind of load.