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/diy/ - Do-It-Yourself

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1151071 No.1151071 [Reply] [Original] [archived.moe]


>I'm new to electronics, where do I get started?
There are several good books and YouTube channels that are commonly recommended for beginners and those wanting to learn more, many with advanced techniques. The best way to get involved in electronics is just to make stuff. Don't be afraid to get your hands dirty.

>What books are there?

Getting Started in Electronics Forrest Mims III
Make: Electronics Charles Platt
How to Diagnose and Fix Everything Electronic Michael Jay Greier

All New Electronics Self-Teaching Guide: Kybett, Boysen
Practical Electronics for Inventors: Paul Scherz and Simon Monk

The Art of Electronics by Paul Horowitz

>What YouTube channels are there?

>What websites feature electronics projects or ideas?

>Where do I get components and lab equipment from?

>What circuit sim software do you use?
This mostly comes down to personal preference. These are the most common ones though:
NI Multisim
iCircuit for Macs

>What software should I use to layout boards?
Circuit Wizard

>> No.1151072


Old thread reached bump limit

>> No.1151155


Might want to include Fritzing in the layout board software section. I don't use it much personally, but it is free and very user friendly.

>> No.1151209

Apparently it's at its character limit, hence the thread link coming afterwards.

You forgot the dash between "/ohm/" and "electronics general".

>> No.1151243

Looking to swap the inline remote on my headphones with an Android compatible donor from the dollar store or Amazon so I can use the inline volume controls.

>Why don't you just change the resistors, Anon?
It's not that simple anymore. Apple's standard now emits a short string of data (the sound you hear when you plug in a set of headphones) to verify an Apple certified device is being used from an IC on the little board.

>> No.1151359


>> No.1151398

>no aliexpress.com mentioned anywhere
That's where most of the hobbyist get their components and gear.

>> No.1151454
File: 1.41 MB, 2386x1090, Screen Shot 2017-03-27 at 5.38.04 PM.png [View same] [iqdb] [saucenao] [google] [report]

Hey this looks pretty good, what are the chances that the chips are complete garbage?

>> No.1151456

Never had any trouble with chips ordered from Aliexpress. Readymade soldered boards? Sure. Chips? No.

>> No.1151459

Considering they're nearly 100* the price each including shipping on Mouser I won't buy from them, but they are barely 7* the price at Jaycar for the ne556, what's the difference? Also their ne555 chip is more expensive than the ne556, for whatever reason.

>> No.1151467

Ancient design, easy to clone. Might be less reliable but at that price you're not expecting top-tier shit.

>> No.1151517

Made myself an arduino uno, any cool projects for a beginner?

>> No.1151581

Cool's subjective, think of something you would find useful and work your way from there. If what you want seems to complex, break it down into basics and work your way to the more complex parts.

>> No.1151599
File: 3.63 MB, 3120x4160, IMG_20170327_142258.jpg [View same] [iqdb] [saucenao] [google] [report]

I ordered some bucks and boosts, Chyna sent me this instead. It's a Xilinx 2C64A CPLD. I've never done anything by JTAG before, can someone give me a quick gestalt as to what I need to program this little guy? I think he's neat.

>> No.1151621
File: 191 KB, 511x495, 3e531158b9c5524298b961eaf377aeae.png [View same] [iqdb] [saucenao] [google] [report]

I have this step up doing 5v to 12v, the input current is of 0.12A i think, i want to easily regulate the ouput of the step up from 0 to 12v, do i have to just add a 100ohm potentiometer?

>> No.1151636

What's the cheapest source for ESPs/a cheaper alternative chip for IoT?

>> No.1151652

> no part number, specs, or even switching IC
It depends on the length of the string.

>> No.1151653

Sorry, https://pt.aliexpress.com/item/MT3608-2A-Max-DC-DC-Step-Up-Power-Module-Booster-Power-Module-For-Arduino/32611355118.html?shortkey=qqA7fEv2&addresstype=600

>> No.1151654

Two things, I don't read Portugese, although I do find it interesting that you guys use Tension for Voltage.
>o módulo do IN + e-depois de 2 ~ 24 v, NO ajuste do potenciômetro pode ajustar a tensão de saída, a tensão de saída é maior do que a tensão de entrada.
>questões Que Necessitam de Atenção:
>1. A tensão de entrada não deve exceder a tensão de entrada máxima.
>2. A corrente de saída de pico atual não é mais do que a TV da universidade.
If I understand that correctly, this will not do step down. Limiting your output as your rotate that potentiometer between ~5V to Whatever it can do.

>> No.1151655


I will be connecting that to a usb port, so it can turn 5v into 12v so i can then, connect a fan that i have, but i want to be able to control the rpm of the fan, without touching the step up.

>> No.1151662

So you want to adjust the voltage without touching the potentiometer? Yould desolder the one mounted on the board and run wires out to one in a better place.
Also keep in mind that not all fans will take nicely to simply lowering the voltage.

>> No.1151663
File: 7 KB, 582x502, highfrequencypwmfancontroller_1270299403.png [View same] [iqdb] [saucenao] [google] [report]

You can add a PWM fan controller after the module, or if you want it to be simple and don't mind little heat, a potentiometer and a transistor.

>> No.1151671

Yes, that's what i want to do.

But isn't that what happens with fans that only have 2 or even 3 pins?

Thanks mate, i struggling to understant the circuit tho, is that only for the PWM controller?

If the potentiometer and transistor solution gives more heat, i prefer the controller, i'm making this exactly for heat dissipation.

>> No.1151672

First you need to download Xilinx' ISE design software. (https://www.xilinx.com/support/download/index.html/content/xilinx/en/downloadNav/design-tools.html)
It's 14GB installed.

Then you need Xilinx' JTAG programmer. Which costs $250. But luckily you will find chinese copies on eBay for about a tenth of that.
(eg.: http://r.ebay.com/QBot7D)

And you will probably need to learn Verilog or VHDL. (Although schematic design is possible.)

>> No.1151676


I know Verilog and how to use ISE, I've just only ever programmed FPGAs on dev boards. the programmer was the missing link, thanks man.

>> No.1151691


which has more value in the industry, VHDL or Verilog? are they interchangeable?

>> No.1151701

Apparently depends on where you live. Verilog is said to be more popular in the US.
You can do mostly the same things with both languages.

>> No.1151706

I'm European and I learn VHDL because that's what companies supposedly use here. But Verilog has SystemVerilog which could be useful as well.

>> No.1151734

I figure you guys might know
In my last semester of EE and I really want to be an FPGA engineer/programmer but I've only had 2 classes that even touched it
What kind of board and shit should I get so I can at least practice more with it? Xilinax seems to be the one most companies around here use

>> No.1151744

Digilent sells some pretty nice Xilinx FPGA boards, both 7 series and older
They have student discounts, i think their cheapest artix7 board is like 60-70 bucks

>> No.1151750

Reposting because I was dumb and posted it in the old thread

>> No.1151755
File: 96 KB, 625x462, 1398511843728.jpg [View same] [iqdb] [saucenao] [google] [report]

I've been looking for a decent DMM (mostly hobby stuff. Low power microcontroller things and shit) and after scouring the internet I've kinda narrowed it down to 2 meters that fall in my price range of ~€100:
- Uni-T UT139C (€40)
- Brymen BM235 (€90)
The Uni-T is chink shit but seems relatively well built. Has a ton of features but isn't the safest meter around. Since I'm not working with high voltage I suspect I could get away with that.
The Brymen is of higher quality, more accurate, has quite a good feature set and is much safer due to actually good fuses. It's more than twice as expensive though.

Not sure which way to go here. Any recommendations between these two? Or maybe something else altogether?

>> No.1151765

you need a xilinx platform cable
the original is quite expensive, but you can get chinese knockoffs for ~30 bucks on ebay which work perfectly

>> No.1151766

I wouldn't touch uni-t with a barge pole
they just can't seem to be able to figure out how to make something that isn't pure shit

>> No.1151769

there is going to be a current on the input even if you have nothing on the output
the core losses account for that current draw

if you short the output, you will essentially kill the inductance of the core and there will be no EMF to stop the current on the primary from climbing sky-high
a fuse will certainly be blown, provided you picked the right one for the job

>> No.1151782

Thanks, that's what I thought. Should be a small amount of current with any decent transformer, right?

>> No.1151811
File: 5 KB, 259x194, download.jpg [View same] [iqdb] [saucenao] [google] [report]

I was checking one of these with a multimeter and I managed to degrade the voltage by .5 by using the amperes setting. Why does it still measure 3.2v when it is considered "dead"? Why did applying power with a multimeter make the voltage go down?

>> No.1151817

>amperes setting.
That's practically a dead short, and should only be used in series with a load

They're 3.7V "nominal', 4.2V fully charged
If the voltage goes too low, it damages the battery. Minimun Voltage varies depending on the battery.

>> No.1151835

>should only be used in series
But you still use it what it was made for, holding and distributing a charge. Why can the dead ones only be used in series?

>> No.1151840
File: 32 KB, 475x451, multimeter-series-measure-current.jpg [View same] [iqdb] [saucenao] [google] [report]


If you attempt to measure the AMPS as you've described on a good cell you'll quickly have another bad cell or a fire or a damaged meter or all three.

lipo: 4.2v = full charge ~3.2v=fully discharged
notice how the 3.7v is half way between the two?

>> No.1151849

Alright. I guess I'm also misunderstanding why they've labeled it with an amphour rating. They never did that on old batteries.

>> No.1151850

A battery's voltage depends on how fully charged it is. When a Li-ion gets below 3.2V, you need to charge it specially with a constant current supply, which isn't worth it considering the energy you get out of this stage. This is why Li-ion protection circuitry always prevents the cells from going below 3.2V. The circuitry also prevents the cell being charged above 4.2V, at which point the risk of explosion gets higher.

Car batteries also have 14.something as their max voltage, and 11.something as their miniumum, below which they're considered dead.

TL;DR: Don't over charge or over discharge batteries.

>> No.1151859

So an 18650 battery bank using dead cells, is just a way to store wattage before inverting and distributing?

>> No.1151890

>using dead cells
They're only considered DEAD if they won't take a charge.
If they're at their minimum allowed voltage, they're DISCHARGED and can be RECHARGED
If they can't be recharged, they're dead.

>> No.1151892

>They never did that on old batteries.
With lithium batteries it's important to not exceed the Ah rating times the multiplier.

Also: It's a selling point
Higher Ah rating costs more
Cheap lipo with high Ah rating are chinese lies to get you to buy their firestarters.

>> No.1151920

Get that Pink/Pynq whatever board

>> No.1151953

An "Ah" rating is just a roundabout way of labelling them with an energy stat. Current * time = charge, and charge * voltage = energy. You can multiply the Ah (Amps*hours) by the cell voltage and get the energy contained in Watt-hours, which is pretty annoying if you want to use SI units, but whatever. The conversions are Wh * 3600 = J, and Ah * 3600 = C. A standard 18650 energy capacity would be around 35kJ.

I just don't see why they don't give batteries a kJ rating instead of a mAH rating, it says a lot more when comparing Li-ions and LiFePO4s, not to mention in comparison to Ni-MHs and lead acids. An energy rating is almost always more useful than knowing how many coulombs of charge a cell can hold, and if you can just convert one to the other, why not just put the most useful stat on?

>Cheap lipo with high Ah rating are chinese lies to get you to buy their firestarters.
Yeah, in a bigclivedotcom video he takes apart a "100000mAh" USB battery bank and finds it to have two 1600mAh Lipos in it. I wouldn't trust the "too good deals", but at least they mass produce those Li-ion protection circuits so much they're economical to use in their own shitty products, so fire hazards aren't as prolific as they might have been five years ago.

>> No.1151955
File: 188 KB, 600x336, 1081965-01.jpg [View same] [iqdb] [saucenao] [google] [report]

I bought this on sale at my local electronics shop for ~400 canuck bux

UNI-T 2102; 100MHz, 1GS/s. Seemed too good to pass up.

Should I have just saved that money and invest in a better brand? How reliable is this chink shit? My μc is fried so I can't really run tests at the moment.

>> No.1151973

It's all about the Rigol Z nowadays

>> No.1151995

That's what I've been hearing.

But they're so expensive, especially if I wanted one with the same specs

>> No.1152018

>I just don't see why they don't give batteries a kJ rating instead of a mAH rating
Historical reasons are a large part of this. People tended to have X ampere loads, making amp-hour rating more useful. And as long as the discharge curve is relatively flat, like it was with lead-acid, NiCd and NiMH batteries, watt-hours didn't convey much more information.
What comes to watt-seconds, practical battery lives are usually measured in hours, sometimes in days or years.

Rechargeable batteries have had amp-hour ratings as long as I can remember. Dunno why they aren't usually stated for primary batteries (unless you bother to check the actual datasheet).

>> No.1152019

Supposedly you can hack the upgrades.

But anyway what you got looks similar to my DS1102E but with a larger screen. They're probably based on the same basic design. No frills, no problems. UI is a little awkward though.

>> No.1152023

is it possible to drive a jfet switch circuit with only a single dc volt source? i.e. the input voltage and the gate "pinch" voltage are one and the same?

>> No.1152024

Hack them? In what sense, giving it a bigger bandwidth or sample rate? I've heard about this too but I never really looked into it. Are you telling me I could go with a cheapo $200 model and hack it to function like a +$1000 model? If this is the case, I will probably go ahead and purchase a rigol and try return the uni-t.

DS1102E was the model I was actually intending to purchase at first but bitched out because it would have cost me +600CAD as opposed to saving myself $200 and going with the uni-t. The uni-t seems to work fine (from a quick test I did with my malfunctioning spare μc), just wondering if the whole "chink shit" meme really holds any weight.

>> No.1152039

UNI-T is easily enough of a name brand to avoid the "disappearing seller" thing that happens when you ask for a refund, which is one of the main problems with chink-shit these days. I don't think there's much that can leave you sorely disappointed when it comes to buying standard bench top oscilloscopes, and most people will never use most of the features of a full top-line scope anyways. You at least got it on a warranty, right? If you find that you can neither return it nor sell it for a small loss when you need a better feature, tough luck.

I'm on the lookout for a soviet dumpster-scope like everyone else on /diy/ has, mainly because the nearly complete lack of digital components renders upgrading it simply a matter of replacing individual components with better ones. Also analogue electronics and tubes are pretty aesthetic.

>> No.1152054
File: 365 KB, 1632x916, WP_20170328_11_59_42_Pro.jpg [View same] [iqdb] [saucenao] [google] [report]

I bought an old suitcase and turned it into a boombox. I'm considering buying a 5000mAh 6S LiPo battery from hobbyking, but I need a practical and easy way to charge it once it's inside the suitcase.

I've thought about buying this BMS:


The same site also sells this charger:


Isn't that charger basically just a transformer? If so, could I also use it to power the amplifier directly when I have access to a power socket?

Also, It doesn't seem to be a CC/CV charger, which to my knowledge means I should charge the battery slowly to reach full capacity. I read somewhere that 0.18 C (In this case 0.9 A) is slow enough, but how would I limit the current to that? Can I just put in a resistor with R = 25.2v / 0.9A and appropriate power rating?

>> No.1152067

The charger shouldn't have any trouble in powering the speakers directly when plugged into the wall, but I'd run a test on them to make sure neither the charger nor the battery get too warm. That sort of battery should have temperature protection built in, but I'd run the test regardless. A good idea is to wire an IEC socket in to the side of the case, and install the voltage converter within the case if there's room, then any old yobbo with an IEC cable (anyone with a desktop) can just plug it in.

Now what you're chasing to do is probably safer than most of what /ohm/ would do instead, which is buy some 18650 cells, wire them in series, attach them to a charging circuit, and include some voltage converters if the charging circuit doesn't. Probably add a USB charging socket too, so you can keep your phone battery high when you're pumping tunes from it. You could still do this with the correct circuit, but it probably wouldn't come in it's own little enclosure. We'd also buy all the components from AliExpress and risk a house fire, but the end result is much more customisable.

Constant current chargers are only needed if you discharge the Li-ions too much, which shouldn't happen assuming you've got the correct protection chip, which is probably built in to the battery regardless. I'm not knowledgeable on the slow charging you're talking about, but it sounds like it's referring to a method of getting the constant current required for over-discharged cells. Assuming you've got all the recommended bells and whistles for your Li-ion battery, you shouldn't need anything like a dropper resistor, all that should be handled by the charging and protection circuitry.

Also might I ask what sort of amplifier you've stowed in there?

>> No.1152074

>cheapo $200 model and hack it to function like a +$1000 model?
It isn't THAT magical, but yes, slight HW changes or software updates can turn several Rigol's scopes to much better / more expensive instruments.
This isn't unique to Rigol, but the other scope makers are doing much better job at keeping their SW update stuff secret.

>> No.1152075

I'm not too worried about returning the UNI-T, I bought it from an electronics hobby shop, so they would probably take it back and just resell it in their own store.

I have just looked into the scope hacking for the Rigol. From what I've found, it just seems common to hack the DS1052E into a DS1102E, which seems redundant given that my UNI-T still ends up being cheaper if I were to go that route. It would make more sense to buy a rigol if i could hack it into a very high end model from a relatively cheaper price point.

Ultimately, I just want to know if I didn't "skimp out" on any functionality/reliability/ease of use by buying the cheaper brand.

>> No.1152076

Well then I ask, is there a list of models and their subsequent potential upgrades they can receive via hacking? I might be willing to pay a bit extra if that means ending up with a +$1000 scope. Though, at the end of the day, 100MHz 1GS/s is probably as much as I need at this stage.

>> No.1152083
File: 48 KB, 560x403, FWOK87YHWLD1KNQ.LARGE.jpg [View same] [iqdb] [saucenao] [google] [report]


I read about the slow charging thing here: http://www.powerstream.com/li.htm

"When the charge rate during the constant current phase is low, the charger process will spend less time during the constant voltage tail. If you charge below about 0.18 C, the cell is virtually full when the 4.2 volts is reached. This can be used as an alternative charge algorithm. Just charge below 0.18C constant current and terminate the charge when the voltage reaches 4.2 volts per cell."

As for the amp, I have this one: https://hifimediy.com/T3-mono

I also put together a preamp of sorts, a piece of stripboard with an active Baxandall tone control circuit and a high pass filter to filter out deep bass

>> No.1152096

That is an alternative charging algorithm, and while perfectly valid, it sounds like your charger does not do this. Charging with a larger CV tail is probably faster overall in comparison to charging 400kJ at a measly 0.9A. This is only an estimate, but this would take the battery a little over 5 hours.

While I'm not sure if a constant voltage supply would necessarily be faster, since it's what all the power drill chargers do I'd bet it's at least an easier option even if it isn't as fast. Combining the two and having an actively regulated current/voltage supply would be ideal and faster than the other methods, but it probably requires quite some circuitry, if not a microcontroller.

CC chargers also have to have a different output depending on how large each cell is, and how many of any cells are in parallel. CV chargers however have to have a different output depending only on how many cells are in series, and therefore can charge any number of cells in series as long as they aren't below the 3.2V threshold.

I'm not sure how "to-scale" that diagram of the charge capacity % barely increasing by 40 in the CV range is, nor how applicable to other charge schemes, but since CC chargers aren't terribly common for low-end electronics, I think we can assume discharging a Li-ion to 3.2V does make use of most of its energy.

>> No.1152097

>any number of cells in series
meant to say
>any number of cells in parallel

>> No.1152105

>Also, It doesn't seem to be a CC/CV charger,
It is CV at 25.2v
It is Current Limited to 2A
The BMS takes care of managing the charge curve.

>> No.1152182

Just get the cheapest one then (380ish USD), and hack it for the 50MHz->100MHz upgrade. You can also unlock deeper memory (24M!!!), various trigger modes and various decoding protocols.

>> No.1152276

Anyone know anything about the seeedstudio mini soldering iron? Looking to replace my current one which is just not very good at all.

>> No.1152279

Whoops I should really specify it's the ts100 model. Looks real fancy, I just don't know if it lasts. A friend got one, and seemed really nice.

>> No.1152311


Oh, alright. I thought the 2A meant that's just the highest current the charger can give before it gets fried.

>> No.1152326

>highest current the charger can give before it gets fried.
If you attempt to get more than 2A out of it the 25.2v will start dropping to keep it at or under 2A.
When you set up the BMS set it to not draw more than 1.9-2.0A
If you want to charge faster than that get a higher amperage power supply @ 25.2v and adjust the BMS to suit.

>> No.1152332
File: 55 KB, 565x414, iMAX V6AC.jpg [View same] [iqdb] [saucenao] [google] [report]

>I'm considering buying a 5000mAh 6S LiPo battery from hobbyking, but I need a practical and easy way to charge it once it's inside the suitcase.

Just get one of these https://hobbyking.com/en_us/imax-b6ac-v2-professional-balance-charger-discharger.html

Hobbyking is out of stock at the moment but there are other sources.

No need for BMS because this item does the charging and has cell balancing built it.

It's primarily for AC use but can charge the 6S pack from a 12v - 18v dc source, like an auto battery.
Cigar lighter adapter and you have portable charging.

I've had two of them. The first one was DC only but I used it so much at home I decided to get the AC version. I got rid of the DC only since the AC will do AC or DC.

If you look on eBay you can find one for the price of the BMS and you won't have to worry about whether the power brick you want is suitable or not.

>> No.1152343

I'm getting back into electronics (studied EE for 2 years before deciding I'd rather do CS, but recently my interest in electronics rekindled).
Been ordering all kinds of shit from aliexpress.
What are some jelly bean components that are useful to stock up on? Already got some kits for 1/4W resistors, ceramic and electrolytic caps, diodes (regular, zener and schottky) and transistors. Also a couple of mosfets.
Any other components that are useful to have a supply of? (or even specific part numbers)

>> No.1152345

the BMS I'm thinking of buying does not seem to have any way to set the current limit, how would I do it? would a resistor work?

>> No.1152374

>lm358, ne5532, tl072 opamps
>lm393 comparator
>lm317, also lm7805/7812 for less breadboard components
>cd4xxx multiplexers and inverters plus whatever else
>LEDs, trimpots, 10-turn pots, relays, pushbuttons, dip switches, photodiodes, varactors
>axial inductors
>4-10uH 3A toroidal coils
all of these can be had in packs of 10-100 for $1-2. i also got 10 8dip attinys for $10 on an auction, you might get the same mileage. i'd strongly recommend getting 5+ of the shitty ch340 arduino nanos for about $2 each.

>> No.1152379

>the BMS I'm thinking of buying does not seem to have any way to set the current limit, how would I do it? would a resistor work?

Forget the BMS and get the iMAX I posted here >>1152332

It's programmable for each battery type.

Whatever you used it for last, it will be ready for that when you plug in in again.

>> No.1152406
File: 1.77 MB, 1167x793, hardwire.png [View same] [iqdb] [saucenao] [google] [report]

How much of a fire risk does the 12v cigarette lighter socket in a car pose?

I bought a dashcam for my car, and it came with a hardwire kit. Pic related
If this were to fail, could it cause a fire?

It is connected to my 12v lighter socket, power only connects when switch it on.

Also what would happen if the 12v wires for the socket somehow came loose and shorted each other. That would blow the fuse and not cause a fire right?

Im a little worried about having such a cheap power supply

>> No.1152407

I should say all the "hardwire" kit does is takes 12v and pushes out 5v USB

>> No.1152427

Running off AC mains I might be worried, but if it's only doing 12V then it should be fine.

>> No.1152451

I want to use the output of SN74HC132N Schmitt trigger NAND gate to drive a passive peak detect, and feed that into another input of the same chip. The only thing I'm worried about is that the output voltage specs on page 5 of the datasheet
list output currents that are the negative of what I'd expect, i.e. they test with negative output currents for high outputs and vice versa. Why's that? It is actually capable of sourcing 20mA on high outputs, right?

>> No.1152501
File: 3 KB, 325x302, TTL NAND.png [View same] [iqdb] [saucenao] [google] [report]

Under 9.2.2
>2.Recommend output Conditions:
>Load currents should not exceed 25 mA per output and 50 mA total for the part.

I think with TTL, floating output is considered "high". To actually make a positive voltage, you need a pull-up resistor.

Not sure if this applies to 74HC.
Slap a 1K resistor between output and ground and see if it drops ~5V with a "high" output

>> No.1152540
File: 614 KB, 2432x1631, FullSizeRender.jpg [View same] [iqdb] [saucenao] [google] [report]

Just bought a can of sardines because I heard they make good electronics housings, what do they taste like?

>> No.1152556

Your lighter socket is probably fused.

>> No.1152559

This too.

>> No.1152567

The sign just indicates the output current direction. When the output is high, the current is measured between the output and ground. When low, between the output and VCC.
And yes, it is nominally capable of sourcing 20mA, but that's a heavy load. You can expect significant output voltage drop. Consider using a buffer.

Floating inputs register as high on bipolar TTL. This does not apply to HC132, which is a CMOS chip. And normal gates, like '132, have totem pole outputs. You don't need to pull their outputs up.

>> No.1152613

Hey /ohm/
guy from months ago who was talking about using discrete logic here again. Not important if you dont remember
I'm considering using arduino and adcs to measure voltage/current to higher precisions. am i capitulating senselessly? y/n

>> No.1152639

I've got no idea what capitulation is, but hey I'm designing an LCR meter with an arduino and an ADC too. I'm hoping to use a 1-2ch 24b ADC, two reference resistors, and a voltage regulator. 2ch if I'm doing 4-wire sensing, which I might still.

Using discrete logic in place of an ADC would be a right pain in the arse, but at least you wouldn't need to convert the relative voltage through the ADC into a resistance, which I'm pretty sure only a µC can do for me. When it comes to measuring voltage that should be pretty easy with voltage dividers, but measuring voltage across a shunt might require some division. If your shunt resistor is a negative power of 2 like 1/128Ω, then you can just feed it into a shift register and shove it 7 spots to the right. Or left, not sure which one. There might be ways of current measuring that don't require a shunt, but I'm not sure how they work. I guess you'll have a BCD encoder and a 7-seg encoder, but you're looking at quite a lot of gates total. I suppose you'll have multiple ranges (different shunts / voltage divider arrays) and some sort of auto-ranging capability? It shouldn't be too tough to do auto ranging discretely either, just run a lead off the shift-register output into a logic-level relay that switches the voltage dividers. I'm not sure if normal logic level relays can handle high current, so you might want to have a 12V rail so you can use a high-current car relay.

I guess you could go for a few high-quantity purchases of universal gates, but soldering all the SMDs will be a pain in the arse.
Doesn't look too bad, but it is all SMD and even then you'll be taking up quite some space. I wish you luck, but if you're not up for a many-month project, half of which is mapping it out in spice, you'll switch to the dark side.

>> No.1152658

caving in basically
some other anon praised me for going discrete logic circuits route, and i do wanna do that still.. but the impetus was initially wanting to make my own thing for reading voltages
Discrete logic was more the logic chip ICs instead of a ready-built thing (such as an adc)

It's for my power supply project. my power supply might possibly have more adc bits than my actual DMM (i forget its specifications)

I too have looked at getting a 24bit adc and making a precision volt meter of some sort

as for current measuring, wouldn't i just feed that through a differential amplifier, then feed that voltage to the input? or would it be btter to voltage divide across the resistor and feed the two divded voltages ino the ADC?
I still don't really get (or can find much literature on, though i didn't search THAT hard) on things pertaining to op amp non linearity, which is appraently something i need to consider when using them to do measurements? With the diff. amp. -> adc issue, i wouldn't know how to tell if its calibrated properly or not, since a lot of my old resistors are kinda on the lower side of their specifications now.

In fact, that's a problem with makin ga high precision volt meter with a 24 bit adc too... how do i know if 1.000000 volts is REALLY 1.000000 volts etc? i dont have a dmm that has that amount of precision and accuracy, but how would that DMM know how much 1 volt is lol

>> No.1152707

And there goes my money. Kinda wary of getting some of the more (normally) expensive and/or sensitive components from aliexpress though, as I'm fairly sure 99% of anything sold on there is counterfeit. Best case it just werks, but I've seen cases where people got like ICs with just a slab of copper in it. Or MOSFETs that were barely connected to the heatsink and simply blew up under normal usage.
Is there really no cheaper reliable source than digikey/mouser/etc?

>> No.1152708

meant to reply to >>1152374, my retardation gets in the way sometimes

>> No.1152771

>use wall wart to power breadboard via chink breadboard power supply (uses ams1117)
>takes 7-12V
>wall wart says it outputs 12V
>breadboard power supply fails
>measure wall wart
>it's over 17V
guess that also explains why the lm7805 on my arduino was running hot as fuck as well

fuck, I really need to make myself a good and stable power supply.

>> No.1152772
File: 1.84 MB, 695x693, motorcontrol.png [View same] [iqdb] [saucenao] [google] [report]

Pic related, what kind of booster stage should I use to provide enough base current to drive the transistor array? Can I use a P-channel MOSFET for this task? Is this how IGBTs work (FET drive stage + BJT power switch)?

Going one step further: What kind of circuit would I need to be able to control the amount of base drive current going to the transistor array with microcontroller GPIO pins? I was thinking that combined with a current sensor, the microcontroller could select a suitable base current depending on the motor load. The amount of torque produced by the motor is proportional to the current consumption.

>> No.1152787
File: 58 KB, 900x838, 57.jpg [View same] [iqdb] [saucenao] [google] [report]

Are those zero force insertion sockets any good? I would like to use them in a relatively high frequency circuit (~60 MHz).

>> No.1152799

Are there any other anti-oxidant compounds like Noalox or Deoxit or OX-gard that is more common in third world countries?

Can't find them in my country.

>> No.1152818
File: 174 KB, 1467x1100, 71Oh14p4xdL._SL1500_.jpg [View same] [iqdb] [saucenao] [google] [report]

I got a kit of pin headers, including ones in pic related. How do I trim these ones down to 9 long instead of 40 long?

>> No.1152825

cut it at the tenth pin and grind the rough end to match the factory finish on the other end
you lose one pin position for each cut
dremel with a thin abrasive cutting wheel works great

>> No.1152826

Never mind, I got it. Scored all around with a box cutter then snapped it with my hands

>> No.1152830

I've got no idea how current measuring is done without a shunt, the use of a differential amplifier is probably a much better way of doing it. But check a multimeter schematic if you want to know what the real guys use.

Just for information, a 4,000 count DMM has a resolution of 12 bits, while a 60,000 count DMM has a resolution of 16 bits. A 24b ADC would theoretically give 16,000,000 count, which I've decided to use for whatever reason.

I wrote a little python code to compare the actual (resistance) value to the measured (resistance) value rounded down to the 24 bits, and then both rounded to the 4 digits I'll want to display. Since the device will be most accurate when the resistor being measured is close in value to that of the series reference resistor, I set the code to find the first incorrect measured resistance value on either side of the reference resistor's value, and like this I get a range of about */5000 being accurate on either side of the reference resistor value. Using two reference resistors, a relay, and some clever software, I'll get a resistance range from 10mΩ to 1.25GΩ. I should run some tests to see if decreasing the ADC bit count will decrease this by much. I definitely recommend writing a little code if you're up to the task.

Now an ADC works with an input on either side of a potential, such as the one on the other side of your voltage dividers, and has a high-accuracy reference voltage fed into the side by a voltage reference IC. The output is a binary fraction of the measured voltage divided by the reference voltage. In this manner a 11111111 on an 8 bit ADC will refer to the full 1V/V, a 00000001 will refer to a 0.00392 V/V (1/((2^8)-1)). The key to an accurate ADC reading of voltage will be having a highly accurate voltage reference. They also can't make much current so I wouldn't even think about using one to power your array of gates or an Arduino.

>> No.1152831

Guys I'm looking for a thread / story about guy that got 3 phase power supply that was really big and heavy. I can't find it anywhere. The name of that PSU was "Fuk" or something like that

>> No.1152832

Just get a desktop PSU out of a dumpster along with a soviet scope like everyone else.

>> No.1152852

Actually, after running the numbers a little, I've found that measuring resistance without a reference resistor for every order of magnitude requires a far higher accuracy ADC than a voltmeter does. Though this might be because I'm searching for 4 digits of accuracy from the low and high values, say to get 10.00mΩ and 1.250GΩ instead of just 0010mΩ and 01.25GΩ like on a multimeter. I'm interested to see which way you'll choose.

I'm also planning on displaying the results on nixies if I can get my hand on a good set, just for the challenge.

>> No.1152860

Actually, I do need a scope yeah.
I see some cheap-ish analog ones on auction sites near me, but those are massive and I really don't have any room for that. I'd love to get a Rigol DS1054Z which would fit neatly on my desk but that's way too much money for me to invest at this point. I'm only just starting out.

>> No.1152879

I didn't think the analogue scopes are usually that much bigger than the digital ones, just usually 3 times deeper if it's a fairly new one like a fairly recent Hitachi. The newer ones a re compatible in features to lower-end modern digital scopes. Though there was that one on TradeMe that was half my weight. As far as I know you're looking out for 2 channel, and anywhere in the 20MHz+ range. That's just to account for the logic frequency of an Arduino. The really old scopes are usually pretty lacking in features, but I imagine they'd be pretty fun to disassemble.

>> No.1152902

>"Fuk" or something like that

FUG but I'm not sure if you can find it by that.

>> No.1152915

This it?
I'd appreciate your gratitude, but I think I'd appreciate saying LRN 2 GOGLE more.
Git gud.

>> No.1152918

Thanks a lot

>> No.1152925
File: 1.19 MB, 1920x1080, 1437530791576.jpg [View same] [iqdb] [saucenao] [google] [report]

Noob question:

I bought a Digital LED strip, well a few of them, 5V and 12V ratings.

Adafruit's LED strip uberguide is telling me it's good practice to put a 1000uF capacitor between the power terminals.

I don't have a 1000uF capacitor, and I know I don't need one but I have 1uF 50V, or a 220uF 16V.

So 2 part question: 1. I want to know why 1000uF is suggested, what would be the effect of only putting a 220uF? 2. should I put the 220uF? the 1uF? or just go without?

( I have 4x of the 220, but I also have 4 strips)

>> No.1152936
File: 2.97 MB, 480x270, output_QQzhUp.gif [View same] [iqdb] [saucenao] [google] [report]


So they tell you it's best practice to do that just in case of over voltages. This rarely happens if you have a decent regulated power supply.

Also, I don't like that they suggest such a large cap because it takes such a longer time to react to voltage fluctuations. The 220 uF caps should be fine. The 1uF probably wouldn't be able to do much damping in the event of over voltage.

>> No.1152938

What the fuck that's massive. A 47µF should be more than enough. The resin to have one is to limit the current across the LEDs initially, giving them a crude soft-start feature by shorting the battery temporarily. You can do the capacitor time-constant maths, but what sort of current are you expecting to pull from each LED strip?

>> No.1152941


Make sure you have EMF protection on that thing, senpai.

An RC snubber or a diode would be useful. You don't want that huge back-EMF kick from when your control turns it off.

>> No.1152942

Tayda electronics is reliable but not really that much cheaper.

>> No.1153072

A shunt is just a low value resistor. You put a differential amplifier across that resisor (shunt), read the voltage across, it and that voltage is the current (after increasing the gain so that it gives you the units you want.
That would defeat the purpose of using the nice ADC though I suppose.
with a current source whose output you can verify, you can measure the voltage across a resistor and then its voltage will give you the resistance

>> No.1153075

I know what a shunt is. Reading the voltage is done with an ADC, how else would you do it? At some point you have to convert the analogue voltage reading into a digital value as displayed in the 7-seg, unless you just want to plug your multimeter into it, which is pretty ghetto. Analogue voltage dials aren't nearly as precise as I'd get with 4 digits unless they have some sort of Vernier scale, which is far slower to read and probably nonexistent.

Using a current source to measure very high (MΩ+) resistances is also not an easy task, and I'm not confident enough with practical current source circuits to prototype one without blowing an IC or two. The dividers/amplifiers needed would also incur their own error. A voltage source makes it harder to read low resistance values, but I'm not measuring shunts over here.

>> No.1153082
File: 30 KB, 350x350, image.jpg [View same] [iqdb] [saucenao] [google] [report]

Theoretical question, if a house had 3 prong grounded wiring (U.S.) but that wiring was aluminum, how would that interact with wifi? Have an issue where the lights dim when the modem is under any kind of load, but I also can't help but feel something at the base of my skull with the 5ghz blasting, tell me if im crazy but could stranded wires like this be causing this?

>> No.1153084

On the other hand it has been fun to see the routers beacon rate reflected in the lights.

>> No.1153118
File: 33 KB, 635x300, 2017-03-30_02-42-29-570983133.png [View same] [iqdb] [saucenao] [google] [report]

>want to buy a gyroscope for $1.33 something from CHINA
>get this
What did they mean by this?

>> No.1153121

I'd start by checking the lamps and possible dimmers first.

Ebay trying to cover their ass bit too actively against the US government faggotry?

>> No.1153126

Eh I found one for a couple of pennies higher and got that based in the US.

>> No.1153171
File: 2.08 MB, 1920x1080, Test.webm [View same] [iqdb] [saucenao] [google] [report]

Webm related

The fuck is going on with my μc? Beginning of webm is when I'm probing without grounding. Then I ground the probe, autoset, then I get this mess of a waveform. The μc is pulsing my Leds just fine, yet the oscilloscope doesn't seem to like what's going on at all. Changing the horizontal scale does nothing as well.

Is my μc fucked? (Just fyi, I have already programmed it to pulse on some arbitrary frequency)

>> No.1153183

Curious question:

Do any of you anons repair or salvage electronics for petty cash on the side?

>> No.1153184

Normal batteries are still lead acid or alkaline. The batteries have significantly higher internal resistance, you would get like .5 volts if you tried to draw a few amps, vs Li-Ion which can discharge a crapton. It makes their energy delivered vary substantially across their lifetime. An example would be speakers: they draw a lot of power, so if you tried to estimate battery life at x wattage, you'd find it highly non-linear. There's a reason NiMH would advertise "lasts longer in digital devices". It's because it's true.

>> No.1153185

Are you on DC or AC coupling? Any filters?

>> No.1153190

You DO understand how a transformer + rectifier +cap works right? If you really cared you'd have grabbed a linear regulator (like the lm317)

>> No.1153200
File: 316 KB, 1000x933, Square Wave Outputs.jpg [View same] [iqdb] [saucenao] [google] [report]

DC coupling it seems. Haven't touched the settings, just bought the scope like 2 weeks ago.

I think I may have found the problem though.... I put 1K pullup resistors from the output pins to VCC and now I'm getting proper square waves (pic related). I forgot that the P0 ports (that I'm using as outputs) of the 8051 are open drains.

>> No.1153244

why would EAR apply to you importing something from china

>> No.1153320

>but that wiring was aluminum, how would that interact with wifi?

It wouldn't

Aluminum wiring need special consideration when installing.
The difference in metals causes galvanic corrosion where the aluminum wire is attached to another device.
One way is to use anti-oxidizing grease on the connection.
You probably have a corroded connection at an outlet or switch or breaker.

>> No.1153328

Just got my pack of 5 L293D chips in the mail, time to have fun with motors

>> No.1153355

They don't want to let you make ICBMs.

>> No.1153594

What FPGA board should I get for like 100 USD or less? I was thinking the Pynq (65 with student discount) but I'm not sure. I can just hook up shit to its pins right? Like more switches and 7 segment displays and stuff? Still new to this stuff so I'm trying to pick a board that'll last me a while

>> No.1153612

Make your own. If you use some relatively small FPGA and don't need super high speed peripherals, it isn't even difficult.

>> No.1153627

Pynq is a good value but it's oriented toward the Zynq stuff more than traditional FPGA (which may be the way of the future anyhow).

Good learning experience but some prior electronics knowledge advised.

>> No.1153688

I have the EP2C5T or something like that. Basically the cheapest FPGA breakout board. Its from Altera so you can get it from eBay along with the programmer for 15-20USD or so. No peripherals except for 3 LEDs and one pushbutton, but you can hook up your own.

>> No.1153735
File: 59 KB, 1152x616, Sound-generator-using-555.jpg [View same] [iqdb] [saucenao] [google] [report]

So hey /ohm/, sorry for coming across as a total noob here (which I am.) I'm trying to build a simple contact synth, basically a skin resistance pitch control, similar to this : https://www.youtube.com/watch?v=leVtU_o-rRw
I've breadboarded mine with a 555 IC (basically like in the pic but with skin probes rather than a photoresistor) but with skin resistance between 0.5 and 1.5M the output frequency is much too low. Is there any way to bring the voltage back up after going through the probes so the chip outputs nice audible frequencies, or must I can the whole thing ?
Sorry if personal army, etc.

>> No.1153736

C1 and R2 also affect the frequency. Try a smaller capacitor.

>> No.1153743

Thanks anon. I'd already messed with everything but C1 apparently. I put a 2.7n, the smallest I have, and it's working pretty okay. Thanks !

>> No.1153751

I'm working on an arduino based guitar pedal, but that's what insterests me. I plan on making a spectrum analyzer too. To you want to make something practical and useful? Artistic and creative? Definitely go through the sites tutorial projects to get a grasp of the coding if you're not already familiar with it.

>> No.1153919

What are some cool projects you guys have done with arduinos/microcontrollers?
Trying to decide on something useful I could make but I'm not sure what. Was thinking maybe an automatic lock system for my front door?

>> No.1153974

If you're just a hobbyist the low end Zynq, Coolerrunner, Artix, Spartan, Cyclones will be just fine for whatever you're doing.
If you're looking to make it a job someday you need to touch something 7 series or up.

>> No.1153982

What do the 7 and up series offer the others don't?

>> No.1153996

Heck yeah, I'm waiting on some 298s

>> No.1153997

If using a capacitor, what is the approximate range of voltages useable in that capacitor? I.E. if I had a 16V cap, would it operate with 9V?

>> No.1154003

the rule for electrolytics varies but it's generally at least 20% over the maximum voltage it'll see including transients. if there's transients and you're too lazy to calculate them then 50%. with shitty ceramics 50% will prevent the capacitance from degrading excessively due to dc bias.

>> No.1154004

So I could use 16V electrolytic caps with 9V DC and not see any issues? I'm trying to build a simple amp, so would using a lower voltage cause any issues with the sound?

>> No.1154013

i'm not sure whether higher voltage capacitors tend to have higher or lower esr (series resistance). lower is better, and you should be using good low esr caps anyway for audio.

barring that, there won't be any difference between the two.

>> No.1154162

Depends how precise you want it I suppose

>> No.1154171

I guess, but accuracy matters a whole bunch too.

Does anyone have any recommended methods for measuring inductance and capacitance with an Arduino? I could make a driven LCR circuit off the µC's clock and vary the frequency, but I'm wondering if I could detect this with an inductor/capacitor with high ESR/EPR. I could also pump them full of energy and read the time constant, which might be better. I'll have each L / C circuit seperate from one another, with a relay or two to switch between them.

It would be really nice if I could find their inductance/capacitance and their ESR/ EPR, but that might be too much to ask. I'm assuming that capacitors have a fairly low series resistance and a very high parallel resistance that explains their DC current and discharge leakage current. While I know that an inductor has a series resistance, preferably a low one, I'm not sure if it should have a parallel resistance, because the only time it would be significant would be when the frequency across the inductor is very high, and before that point the stray capacitance will kick in. Measuring the inductance and capacitance of capacitors and inductors (non-respectively) might also be useful, but I can't see myself building anything at that frequency yet, unless FM frequencies count.

>> No.1154245

Worse than Altoids

>> No.1154287

Is it ok to cover welding with hot glue? Just to protect.

>> No.1154291

you won't get ESL and parasitic capacitance measurements off an arduino. you need a fine NCO (pref DDS) to hunt for resonance at least. altium has an impedance measurement handbook that can give you more ideas but i think that's the easiest. you can measure the ESR of an inductor with dc the same way you'd measure milliohms anywhere else: with a largeish current source. you need enough supporting circuitry that it definitely doesn't qualify as an arduino project though. moreso for capacitor ESR.

i read an article about trying to measure the insulation (parallel) resistance of capacitors and the answer was that you as a hobbyist simply can't do it. there's too many conflating factors. the only time i've seen a parallel resistance considered for an inductor is when it's used as a rough representation of steinmetz losses.

>> No.1154302

I bought this step up: https://www.aliexpress.com/item/MT3608-DC-DC-Adjustable-Boost-Module-2A-Boost-Plate-2A-Step-Up-Module-with-MICRO-USB/32611355118.html

Connected the fan's red and black wires to it, then the red and black from the usb, the fan spins but i can't change the speed with the potentiometer.

>> No.1154308

i just checked and it steps up to 9v, but moving the potentiometer doesnt do a thing.

>> No.1154309

The voltage rating of a capacitor refers to the maximum voltage the capacitor can handle before frying. Using a lower voltage won't affect the capacitor's performance in any meaningful way.

>> No.1154466

Thanks! Now since this project is an LCR meter I can just check the ESR of the inductor with the resistance function, after giving it a little time.

Now I assume that a capacitor discharges over time because I'm pretty sure my multimeter's resistance function checking the value every few seconds isn't the only thing contributing to the cause, but I could be wrong. Since the very highest resistance range on the meter doesn't pick up the value (and since other studies show it to be in the 300GΩ+ range) I don't think I should bother myself with the self discharge/parallel resistance.

Measuring capacitor series resistance remains something I want to do, and the only way I can think of to do this is to extrapolate it from the voltage across the reference resistor once the varying frequency has put the circuit in resonance. Of course, this would need to be calibrated with known values, but that's just another software task. I guess I could also check the ESR of an inductor with this method, though whether it would be more accurate than a DC measurement is unlikely.

As far as I see it the way to figure out the inductance/capacitance of an impedance operator is to start iterating through increasing values of frequency across an LCR circuit and record the AC voltage across the reference resistor at each frequency division, and when that voltage starts going back down again the µC focuses on the area where resonance happens and finds the precise value. This doesn't feel like a trivial task, but it should be fine as long as my ADC's maximum frequency is high enough.

The potentiometer looks like a many turn model, maybe 25 turns. It's possible you aren't turning it enough to get a meaningful change, how far can you turn it before it stops?

>> No.1154476

It just burned.

>> No.1154508

Also I can't use the output clock of the µC as the frequency? I figured as much, but that is what a few tutorials I saw did. I just hope the NCO can output high enough frequencies, otherwise I'll have to incorporate auto-ranging with multiple capacitor/inductor values. I might have to do that anyway to avoid getting stray capacitance or inductance messing up my values.

To get a (slightly stupid) range of 0.1pF/H - 100F/H between 100Hz and 500kHz, measuring inducance is actually pretty easy (with the help of a supercap or two). But if I want to measure a capacitance below 1nF then I'll need to use an inductor with a value higher than 1mF, or the frequency will be in the mid-high MHz. That's with the L,C, and R in series, so I'll run the numbers to see if putting them in parallel makes a difference.

Oops, there goes 50c and a month of shipping.

>> No.1154514

I think that i'll buy an external fan controller, i read that the step up could damage the motherboard.

>> No.1154520

When it comes to installing anything into your computer, I simply wouldn't trust anything from AliExpress.

>> No.1154528

It's just connect via usb.

>> No.1154535
File: 119 KB, 324x351, 1268306392231.jpg [View same] [iqdb] [saucenao] [google] [report]

Maybe you guys can help me out?

I have a small battery powered device that the charging port stopped working. I never used it away from a USB port so I figured I would just power it from USB directly.

It had a 3.7V 400MaH battery, so I took that out and put this in its place. http://www.ebay.com/itm/272461399550

Now the thing turns on then immediately turns back off. So I'm thinking it needs a little more MaH then that converter provides. So should I toss in a capacitor or some shit?

>> No.1154538

do you have a scope? the load your circuit is putting on the shitty buck converter may be destabilizing it and triggering some ovp or uvlo. if that's the case a small electrolytic capacitor on the output could help. or it could destabilize it more. if you don't have a scope you can't check that, the only thing you can do is make sure the nominal voltage under load is ~4.0-3.4v.

more details would help too.

>> No.1154549


Picked this up from my library. Good for a read-through or just reference?

>> No.1154554

360 No scope.

>> No.1154559

>I figured I would just power it from USB directly.

USB 2.0 port has a maximum drain of 500ma

Your buck converter:
>efficiency is 75-90%

If your device draws more than 375ma and the converter is operating at 75% the USB port will limit the current into the converter to save itself.

Try to determine the current required to operate the device.
Also check for start-up surge current of the device.

>> No.1154562

>anno domini 2E3+2^4+1
>not using a 2.1A socket

>> No.1154580
File: 24 KB, 800x469, arst.png [View same] [iqdb] [saucenao] [google] [report]

hi /diy/, /g/ mech keyboard addict here. Going to wire up my third keyboard next week, and wanted to know if it were possible to solder a component at a distance, using a wire or something. Would it introduce too much latency to the signal the switch sends to the board? Any tips on doing that?
Adding a diagram for clarity

>> No.1154584

That'd be more of a worry from the mechanical side than the electrical.

>> No.1154586

>simply can't do it
challenge accepted I suppose

>> No.1154587

the switches are going to be secured to the curved plate above, which won't move relatively to the PCB. But maybe you're right, - I could have some additional support under the plate. It would be quite a complication, though

>> No.1154588

If this is the typical Cherry-type switch then I think you want to use flexible (stranded) wire from the switch to the board for strain relief. But if this is a full size keyboard assembling it is going to be a nightmare.

>> No.1154599

it is a cherry-type switch, yes. The keyboard is just like this, - https://github.com/adereth/dactyl-keyboard the point is that I already have all the materials to make an ergodox, so the idea is to use the ergodox electronics with a fancy curved case.

>> No.1154609

Hmm, personally I'd say trying to reuse the PCBs is more trouble than it's worth. But if you have more time than money the equation might be different for you.

>> No.1154616

Why am I too dumb to make my stepper rotate? It just seems to wiggle back and forth

>> No.1154620

you're either triggering it too fast or your steps are off. i just wrote some stepper driving code last week. example is unidirectional but you can derive what you need from it if you know C at all.

>uint8_t coil4 = 0b11000001;
>uint8_t coil3 = 0b01110000;
>uint8_t coil2 = 0b00011100;
>uint8_t coil1 = 0b00000111;

>coil4 = coil4 >> 1 | coil4 << 7;
>coil3 = coil3 >> 1 | coil3 << 7;
>coil2 = coil2 >> 1 | coil2 << 7;
>coil1 = coil1 >> 1 | coil1 << 7;

>PORTx |= (coil4 & 1) << PORTxn;
>PORTx |= (coil3 & 1) << PORTxn;
>PORTx |= (coil2 & 1) << PORTxn;
>PORTx |= (coil1 & 1) << PORTxn;

>> No.1154630

I have tried multiple delay times, and unless I'm off by orders of magnitude, it should be fine. My code is something like:
Repeated for the 4 steps given by the motor datasheet, with the colors as #defines for the hex of each gpio pin signal to the L293D chip.
I need to try to test if each wire to the motor is in fact going high and low, I should be able to do that with my meter

>> No.1154632

be sure you ohmed them out right too and the supply wire(s) are actually the colors they're supposed to be

>> No.1154635

I double checked i have the phases matched, and red on atx psu is 5V, should I try orange for 3.3V?

>> No.1154637

steppers will spin fine overvoltage. undervoltage should give you a worrisome buzz but no movement.

if your meter has hz and duty ranges that's an easy way to validate your driver signal. if the stepper is explicitly going one step and then back it's definitely not a supply issue. seems to me like you have some wires backwards but you checked that.

>> No.1154642

I'm not sure if it's actually going forward then back. The rated step size is 1.8° so I'm not sure if I'd be able to see that. I just hear and can feel some thudding at the frequency I'm stepping through my loop

>> No.1154643

>I need to try to test if each wire to the motor is in fact going high and low, I should be able to do that with my meter
Across each coil put a resistor in series with a couple LED's in parallel facing the opposite way.
You can see not only the steps, but how fast they're going

>> No.1154645
File: 16 KB, 1053x80, 1490485686346.png [View same] [iqdb] [saucenao] [google] [report]

sounds like undervoltage or inadequate drive current. the l293d has a darlington output so it might be dropping too much voltage and as a result not allowing enough current to flow in the coils. if you have a uln200x sitting around try that. otherwise i think you'll need a higher supply voltage.

>> No.1154649

I do have a couple ulns and udns, but those don't really work for bipolar (4 wire) steppers, correct? You might be onto something with the undercurrent, the motor datasheet says rated current is 2A and rated resistance is 1.4 ohms (per phase).
I'm going to try the LED thing, as measuring voltage across a phase was inconclusive

>> No.1154653

oh no, they don't work for bipolars. if i'm not wrong though you're significantly overdriving your chip. with a 5v supply you should be getting (5V-1.4V-1.2V)/1.4 ohms=1.71A across the coils.

if the 293d can actually pass that current without falling out of saturation then i'd expect it to be fried since the datasheet specifies a 1.2A 100us maximum. i don't think it's fried though, i think it's just self limiting at a lower current. you might be able to get away with paralleling multiple drivers.

>> No.1154661

It's not fried since it does keep working.
Anyway, the LED test lead me to find out that I'm having the really fucking annoying problem again where about half the gpio pins on this mcu don't work

>> No.1154662

What is the safe/normal operating temps for these 100W power resistors from china... would 80W be pushing it, i would be using high quality cpu thermal paste for them and probably 40mm fans in a metal enclosure.


>> No.1154669

This might help.

>> No.1154707
File: 7 KB, 774x120, ISP.png [View same] [iqdb] [saucenao] [google] [report]

Where can I read up on ISP?
I seem to be only able to send 32 Bytes when I send more or less the readback only gives me zeros. Thats why I had to fill my code up with 0s for it to work, but in the future I want to write programs bigger than 32 Bytes so I need to figure out how to send more.

>> No.1154709

It's anyone's guess how much the Chinese lie about the ratings, but generally speaking, running power resistors at 80% of their maximum rating means that they get very, very hot. Often the maximum ambient temperature is also quite limited.
That said, sufficient cooling allows you to run a resistor at 100% rating, at least at room temperature. (Assuming you weren't scammed.)

>> No.1154711

I'm not an expert or anything, but how did you figure out that you needed exactly 32 Bytes? Trial and error? Or is it a spec somewhere? My best bet is that having each written packet be a preset size so to cut down on unnecessary formatting, so I guess you'll have to send multiple packets, but I've never touched a microcontroller in my life so it's entirely a guess based off low-level digital logic knowledge.

>> No.1154714

Those things are meant to be used with a heatsink as per the awfully general datasheet I posted, and have two power ratings depending on whether they have heat sinking or not. If in doubt just wire two lots of two in parallel, but it's a bodge to rule them all. If in doubt, a little forced convection will do wonders.

>> No.1154715

Since you apparantly mean AVRs, see the datasheet.
It is typical that the program memory is divided into small pages.

>> No.1154734
File: 105 KB, 956x627, pages.png [View same] [iqdb] [saucenao] [google] [report]

I pretty much copypasted from https://www.quaxio.com/programming_an_at89s4051_with_an_arduino/
So thats where the 32 Bytes came from.

Actually not AVR but 8051. Does pic related have something to do with this?

>> No.1154738
File: 101 KB, 912x694, What I needed.png [View same] [iqdb] [saucenao] [google] [report]

I think I found what I needed. This makes sense now I didn't know that the pages >>1154715
mentioned were a thing so thanks for that.

>> No.1154987

Like the virtex-7, kintex-7, artix-7 and zynq-7000? And is it because they're newer and use Vivado instead of ISE?

>> No.1155003

Vivado is one thing. More transceivers, more logic, more DSP, more IO, less power consumption, smaller transistor size.
Intel PSG hasn't gotten their shit together yet. They're having problems at the moment but at some point they might be a real threat. Microsemi is getting back into the programmable business it seems

>> No.1155009

Alright neat.
Looking at job postings around me for FPGA engineers and some have working with a Zynq board listed for preferred experience.
Do you have any recommendations on what I should get? There's the Pynq for 65, Zybo Zynq-7000 for 125 or maybe something else?
Thanks anon

>> No.1155176

Can't you just take out the IC and just have a constant voltage on where it's output was

>> No.1155215

>A 24b ADC would theoretically give 16,000,000 count
Wish it were that simple.

>> No.1155235

>hourlong video
Ah fuck, RIP my assignment.

>> No.1155238
File: 192 KB, 1000x1001, nuvitron-vintage-nixie-tube-clock-expensive-gadgets-in12-in-12.png [View same] [iqdb] [saucenao] [google] [report]

hey /ohm/, newfag here
Come this summer, I'm finishing uni, and I'm going to have some free time on my hand. I'm absolutely new to anything electronic, and I'm already collecting books listed in the OP. I have a few questions though.
My ultimate goal is to make a nixie tube alarm clock, I even found blueprints for them, now since I know nothing about thing like this, what do you guys think, how much time would it take to get to that level, where I can actually make the thing? Any advice on nixie tube projects? Pic releated, I don't know yet if I want steel housing or wood housing, I have a thing for wood panels desu
Also, what are some good newfag projects?
Sorry for sounding like a fag

>> No.1155243

The simplest at least somewhat /diy/ option would be to buy a kit. You'd need to learn to solder, but that's pretty much it.

>> No.1155244

I've thought about kits, I haven't completly disregarded them, but if I'm making something like this, I want to learn how to do it from scratch, knowing these skills might be actually useful, and I always wanted to learn, my father knew electronics from his time being drafted (ex-commie block here), and I always felt sorry that my generation didn't get this education.

Then again, buying a kit would be a good first time project to teach me soldering, no?

>> No.1155246
File: 359 KB, 1000x562, img.jpg [View same] [iqdb] [saucenao] [google] [report]

so basically you want to put a meme in a box and make it look like a commercial product?
building a clock are we?

dude just buy this its too hard for a first time electronics project then stick it in a box. unless you have a supply of free nixie tubes and driving circuitry, you might save 20 bux building it yourself https://www.aliexpress.com/item/Glow-tube-clock-clock-SZ1-SZ8-QS30-nixie-10-anniversary-edition/32781650525.html

>> No.1155247

>how much time would it take to get to that level
Well it's good that you're not hoping to immediately be able to just make one of these, they're a fair task for even a seasoned novice such as myself. Now depending on how much of a shitlord you are your circuit will be different, and it's likely you will kick a different circuit as you figure out what you enjoy in electronics. But I'm assuming you'll be using some integrated circuits and not a magnetic pendulum, a hall effect sensor, and a bunch of cascading-marble clock-divisors. Hey there's an idea. Full shitlord is using someone else's code on an Arduino, btw.

So you'll need to learn some basic digital logic, basic power supply stuff, and basic semiconductors just so you don't fry your parts:

•For logic you should get some logic gates and fuck about with them to make an electronic combination lock or something, bonus points for Karnaugh maps.

•Power supplies are a bit of a pain to mess around with since it's hard for someone without a half-decent bench-top power supply to get low voltage alternating current. For this reason buying a few 555/556 timers is highly recommended, you can use them to make a high frequency square wave source with which you can mess about with transformers. Alternatively, if you're feeling brave you could fuck about with microwave/neon-sign transformers until you learn a lesson about alternating current power supplies or electrical safety. Try making some sort of AC-DC power supply or two, a step-up and a step-down would be cool.

•For semiconductors you might want to make a darlington pair touch-lamp, or an LDR triggered LED or something simple. It doesn't matter that much, just introduce you to some concepts that might be applicable to power supplies and amplification, maybe tubes too.

Once you feel confident with a fist full of transistors, ICs, and lead poisoning, you should try your hand at an LED/LCD clock or two, they're the perfect mockup for a nixie clock.

>> No.1155258

I don't how much time you'd need, as it depends on your motivation, the available learning material and even your idea of what it means to start from scratch. What I can say is that at least nixie clock isn't conceptually horribly complicated and that the internets are full of schematics you can use as a basis (even if you don't understand how every little thing works).

I recommend you to learn to solder before touching a kit. It's not fun when you accidentally ruin the pcb or when the thing doesn't work due to shitty soldering.

Guitar pedals are quite popular beginner projects.
Bleep bloop tier musical instruments too.
Another popular beginner project is an adjustable power supply.
/diy/ actually has a 100-long list of project ideas, but I don't have it.

>> No.1155259

I don't really wanna buy a completed one, takes out the enjoyment. Also, it looks expensive, which reminds me, just buying the components, how cheaper would it be? Because if the parts themselves are expensive (I can see that with nixie tubes), I might reconsider buying a complete one then.

I literally understood nothing of what you just said, but the schematics I'm planning to use are in this: https://pastebin.com/u4pEYSYZ
I chose this because the guy who made it is hungarian too, and he documented his process.

Beep-boop instruments sound fun, I'll look into them

>> No.1155261

A glow bug (valve radio) would probably be a good fit for a wooden cabinet. Varnished cherry wood is most excellent.

Just make sure there is adequate ventilation and no risk of overheating.

>> No.1155265

Ok short points to take note of:
>make a normal clock first so you don't fry your tubes and get familiar with the components
>learn how integrated circuits work, especially the ones you're using, start with some simple 555-timer circuits
>learn how to solder cleanly
>learn how not to electrocute yourself with alternating current power supplies
>learn how transistors work
>don't use a shitty plastic project box for your clock, use wood or metal, or even vinyl wrap over MDF, get creative
>upside-down "2"s instead of "5"s look cool
>you WILL waste money

>> No.1155274

That's just a humble intro into a wonderful world of ADCs!

>> No.1155280

aliexpress has them for about 12-15$ each. so for a 4 nixie display its about 60$ just for the tubes. compare that to a 4 digit 7segment display for about 2$. wondering why nobody uses nixie tubes anymore?
the tube driver, hv5630 is 10$
the pic is 5-10$, you will also need a pickit for another 10$
you will also need a circuit board of some kind, a temperature controlled soldering iron $50, miscellaneous interfacing circuitry resistors caps etc budget 10$

...he appears to be using a 555 as a real time clock. the pic he's using has a built in quartz crystal clock which would be far more accurate.

>> No.1155286
File: 167 KB, 915x798, ZD-931.png [View same] [iqdb] [saucenao] [google] [report]


I have the opportunity to snatch one of these soldering stations for 60.- EUR from the local hobby shop. Is it a good deal? I mean, I'm not familiar with this brand and the known brands like Weller etc. are out of my price tolerance for the time being.

>> No.1155386

How can you tell if a microcontroller has locked firmware?

Is their anything in the JTAG spec about disabling JTAG on a finished board?

>> No.1155389

Read lock bits, see if they're set. Or try to read out the software. If it's garbage or zeroes, assume locked device.

>> No.1155446
File: 56 KB, 1176x876, bjt driver.png [View same] [iqdb] [saucenao] [google] [report]

I found this interesting schematic in a patent document. It is a circuit for driving the base of a power bipolar transistor "T1". The basic idea is to produce a variable base drive current for the power BJT which is just enough to keep the device in saturation. In this way the necessary base drive current could be minimized.

I've been trying to model this circuit in LT Spice, but so far haven't gotten any meaningful results. The patent claim does not feature any component values at all, even voltages/currents are not specified at all. Is there any way to find a starting point with the component values?

>> No.1155466

I have one of these. Not using it a lot because of lack of opportunity, but does its jobs as expected.

>> No.1155476

T2-T5 form two pretty standard current sources, one for turning the transistor on and another for turning it off. Dimension upper for maximum required base current and the lower for whatever turn-off current you want.
Then the actual anti-saturation circuit has T6-T7 pair for disabling it when it is not needed. R8 sets the saturation test current. It shouldn't be that critical, some milliamps should be ok. Dimension R7 accordingly. Then R9 sets the saturation voltage limit. Dimension R9/R10 so that VR drops when the wanted saturation voltage (present across R9) is reached. Dimension R10/R11 so that the anti-sat circuit is capable of turning T2/T4 current source off.

>> No.1155486

What cheap soldering iron should I get?
I had one laying around and tried using it but I'm pretty sure I botched my shit up, the tips too big and retarded

>> No.1155523

No I'm pretty sure he has an external oscillator too, a 4.096MHz. Not sure what the 555's doing, maybe dividing the signal without a metric fuck-ton of T-flip-flops. And you shouldn't be using a µC anyway, I'm pretty sure a dedicated clock IC is a far better way to go.

>> No.1155557
File: 3.54 MB, 1954x2436, chips.jpg [View same] [iqdb] [saucenao] [google] [report]

Found these in an old box. They certainly look very interesting. Could they still be useful?

>> No.1155586
File: 149 KB, 1406x853, NixieBoard.png [View same] [iqdb] [saucenao] [google] [report]


How much experience with electrical engineering do you have? Computer engineering? CAD (eagle, fritzing, etc)? Depending on these things will determine how much time it will take you.

>> No.1155604

Technically they could be.
Just look up specs on each one and see what they are meant to be.

The ones with windows are probably EPROM chips of some time, ErasableProgrammableReadOnlyMemory. The ERASING option was done by baking the chip under a UV light through the little window. In use the window would often by covered by a sticker.

Whatever all those chips do it is likely they do it slower, hotter or simply in an outdated fashion but you never know what you will find out.

>> No.1155621

Zed is a good midlevel card. if you could get something working with an FMC like an ADC/DAC, RF, or video peripheral you would be a shoe in
DMA is important too

>> No.1155641

as generic as it is, id recommending reading electronics for dummies. it was so helpful to me in building my own synthesizer.

>> No.1155647

I have few white led srips connected to meanwell hlg-240h-24b power supply.
It's a 240w 24v psu with 1-10v and pwm dimming.
How could i make it compatible with Apple HomeKit, Alexa and other fancy "home automation" apps?

>> No.1155650

pirate EAGLE. you'll need to learn how to install libraries to get the components you want (like most programs)

chonelectronics is a cheap place to buy bulks of electronics. they got all sorts of stuff.

>> No.1155773

Now I'm not sure how those home automation apps work, but you'll need at least a microcontroller (Arduino) with some way of connecting to the home automation server, probably a wifi board. You'll probably be dumping the entire PWM circuit except for the power transistor, which you'll hook up to a PWM output(s) of the Arduino, maybe with a BJT in between to get enough voltage to the switching FET's gate. Most DC PWM circuits are pretty similar, so you shouldn't have trouble tracing it and finding what parts you want to keep.

You'll have to look up how to connect a microcontroller to a home automation network, but many people have done so before and it should thus be well documented.

>> No.1155776

And looking at your datasheet it shows the power supply has inputs that can be used as PWM inputs anyway, but you'll have to switch these up to 10V, and it's only 100Hz-3kHz, so you might hear a buzz. I'm not sure what in the way of inductive losses using an ultrasonic PWM frequency would get you though.

>> No.1155789

555 is just a part of a memetastic nixie power supply.
Microcontroller is a rather handy way to build a clock, allows more customization and is likely to be cheaper than some antiquated clock IC.

>> No.1155818

I'm having a hard damn time in design.

We're assigned to design a BJT common collector for my lab, but I have no clue where to start since the professor never goes step by step how to do this thing.

I tried applying some resistors against the formulas given and the gain, but never got it to work.

Any hints?

Thank you!

>> No.1155844
File: 40 KB, 882x586, sanwa-TA55-KIT.jpg [View same] [iqdb] [saucenao] [google] [report]

The joy of assembling/soldering a functional analog!

>> No.1155850


Put your audio frequency AC signal without DC offset on the base of some small signal NPN BJT with a 1K base resistor, put a 1K resistor between the emitter and -5V, connect the collector to +5V.

A common collector amplifier with 1K output impedance.

>> No.1155866

>antiquated clock IC
I just figured that digital clocks are made in such volume that an IC with an oscillator input and a multiplexed 7-segment output would be cheaper than buying a microcontroller.

The MCP7940M has an alarm, any time division you can think of, digital frequency calibration, 64B SRAM, and all at 1µA standby current. 46c each and I'd say it's a fair shot better value than the average microcontroller, not to mention one less manufacturing process, programming, to go through.

In comparison, an ATMEGA16 will run you $3.22 at the least, and the only advantage would be programming some sort of additional daylight-saving function.

Looks cool, have a link?

>> No.1155876

Of course, since I imagine an ATMEGA16 is overkill for a clock, you could try an ATTINY for 24c, but whether 1kB is enough for the code is semi-marginal. A simple code will fit, but if you're storing timezone and daylight saving data for another 20 years, it might not fit.

Either way it is a marginal cost difference for any clock with production cost over $5 a piece.

>> No.1155935

I buy shit from Aliexpress. My AVRs work fine. Other stuff too. Order your search by "number of orders" then choose components/stores with lot of 5 star reviews.

>> No.1155940

So, I'm currently trying to assemble some radio stuff with an nRF24L01+, controlled by an Arduino Pro Mini.
My problem: My Arduino is a 5V version. I'm trying to power the entire assembly with a 9V battery, using the Arduino's 5V output to power the RF module.
For those who don't know, the nRF module is 5V tolerant on the input pins, but only when the VCC voltage is between 2.8 and 3.3 Volts.

I have an LM317 voltage regulator, but that one cannot make the small drop from 5V to 3V.
I looked for voltage dividers but those are apparently not suitable for my purpose.
I found another type of voltage regulator, but that one has a minimum current much higher than the radio module's power draw. I need something that works with 100mA and less current.
I read about buck converters, but those apparently use coils and interfere with wireless signals. And the module I'm using is already known for being finicky as hell.

I just looked up the AMS1117, but that one only exists as an SMD version. I've seen a version where the SMD is soldered onto a PCB to make it through-hole, but that would require me to use Ebay or Aliexpress, so I'll keep that option for later.

So, before I invest too much effort into this shit, does anyone have a good idea on how I could best do this? Any options that I missed? Would a diode do the job?

>> No.1155961

That's an RTC. It won't drive any nixies or even LEDs in itself. It is meant to be used with a microcontroller.

What comes to the actual all-in-one clock ICs, they generally have 7-segment outputs for direct display drive. That's not exactly convenient for nixie clocks. Some have BCD outputs, but those chips seem to be rather rare.

>only advantage would be programming some sort of additional daylight-saving function
Or elapsed time timer or egg clock or multiple alarms or support for GPS or whatever.

>> No.1155976

I thought Horowitz and Hill was the standard text.

>> No.1156005
File: 2 KB, 274x167, linear-regulator-series-circuit-01.gif [View same] [iqdb] [saucenao] [google] [report]

How about using a simple zener + transistor regulator?

>> No.1156047
File: 307 KB, 1013x619, peace-at-last.jpg [View same] [iqdb] [saucenao] [google] [report]

pls respond

>> No.1156051

Your question is stupid. I seriously doubt any single brand is available in all the world's shithole countries.

>> No.1156068

I'm looking for relatively cheap oscilloscope, up to $250. Analogue or digital I don't care. Used or not, I don't care. At least dual channel - this is something I care for.

Which brands to avoid? Which brands to pick?

Also - I can get old(but also very cheap) communist oscilloscopes in my hands, the thing is - I'm not sure if they're worth the tiny amount of money they're sold for.

>> No.1156073

>My problem: My Arduino is a 5V version. I'm trying to power the entire assembly with a 9V battery, using the Arduino's 5V output to power the RF module.
Let me think.

You can make one of your digital outputs to have pull-up resistor engaged, so it'll be ~3.3V when low, now the problem is that it won't be able to get much power out of it.

>> No.1156107

>I just looked up the AMS1117, but that one only exists as an SMD version.
1117 type voltage regulator came in TO220 package too.
Or you can use L4931 in TO92 package.

>> No.1156139

I assumed the outputs were made to go into another dedicated IC that handles I/O and converts into 7seg/BCD/ etc. format, if only because you can do all the functions of a RTC with a µC.

>> No.1156142
File: 35 KB, 267x249, 31786.jpg [View same] [iqdb] [saucenao] [google] [report]

Is there a way to tell which side of this transformer is the primary without using any measuring instruments? One side has "GD" written on it and also has a dot.

>> No.1156174

This brings back memories, extending the range of your analog meter by calculating and using power resistors.
Have to measure more than 10A? Sure i'll whip out my cheap ass modified analog meter.
Nice clock ahmed.

>> No.1156205
File: 2.32 MB, 3264x2448, 20170404_165835.jpg [View same] [iqdb] [saucenao] [google] [report]

its probably fine.
charge it slowly with constant current to full voltage 4.2

I've been getting into rescuing cells from laptop batteries.
so far i've only tossed away one, due to damage form my overly enthusiastic disassembly, not bad cell.

capacity might be lowered over the years, but they work fine for my projects.

>> No.1156206
File: 1.84 MB, 3264x2448, 20170404_170135.jpg [View same] [iqdb] [saucenao] [google] [report]

putting them in a cheapo powerbank.

>> No.1156212
File: 2.07 MB, 3264x2448, 20170404_170412.jpg [View same] [iqdb] [saucenao] [google] [report]

4chin needs to let me post pics in the proper orientation.

>> No.1156215

not even multimeter?

>> No.1156217

The logic required to handle the I2C interface would be more complex than the rest of the IC.
Also, no need to assume anything, since clock ICs exist. The only one with BCD outputs I'm aware of is NS's MM5309 and the related chips. It went out of production ages ago, but NOS chips are still available. Price varies from $10 to $lots.
Some equally antiquated chips are still in production, like LM8560. The Chinamen sell them quite cheaply (under $2) on Ebay, but since it has 7 segment duplex outputs, it is rather cumbersome and expensive to use in this case.
There are also some newer designs, but I haven't seen them sold in small quantities.

>> No.1156221

Primary and secondary reflect the intended use, not the actual construction.
That said, primary tends to be the innermost winding and if your transformer is made for random offline switcher, the primary usually has thinner wire.

>> No.1156224

We're not using any audio signals or anything though, it's a sinusoidal function generator with basic components. Class name is Electronics 1.

I spoke with the lab instructor he told me that it's not as easy as step by step solutions and that it's kind of a creative side in Engineering.

I guess I'll mess around with it in PSPICE and see how the current is flowing, but I mean, what you suggested makes sense since it's starting with something and moving up to testing the gains, but I don't know.

I guess starting now, classes wouldn't have hand holding anymore ;_;

>> No.1156228

Are there any companies that have discounts for students for functions generators and oscilloscopes?

>> No.1156235
File: 68 KB, 702x672, 1489602872383.jpg [View same] [iqdb] [saucenao] [google] [report]

Just bought a Pynq. Hope I didn't just waste 85 dollars

>> No.1156298

Is it ok to use a darlington transistor in place of a bipolar?

>> No.1156312
File: 128 KB, 1652x628, discount.jpg [View same] [iqdb] [saucenao] [google] [report]

Rigol and Fluke has em. I'm sure there are some other companies that offer discounts as well.

Pic related.

>> No.1156314
File: 8 KB, 197x256, drooling.jpg [View same] [iqdb] [saucenao] [google] [report]


>> No.1156487

Thanks folks.

I think I'll go for the Z-diode approach.
Time to wait for a China shipment.

>> No.1156498
File: 1.68 MB, 300x168, 1466763109273.gif [View same] [iqdb] [saucenao] [google] [report]

Want to build my own power bank, trying to figure this out. Please help.

Would it be more efficient to step up 3.7v to 5v, or to step down 7.4v to 5v?

Would making my own dc-dc voltage converter be more efficient than a cheap Chinese one?

Pic unrelated and provided purely for your attention and entertainment.

>> No.1156499
File: 96 KB, 1115x705, a.png [View same] [iqdb] [saucenao] [google] [report]

Depends. Are you ok with higher saturation voltage, higher base-emitter voltage, lower speed and the integrated B-E resistors?
Pretty often those aren't problems, but sometimes they are.

Just a reminder: low voltage zeners are trash and require quite a lot of current to operate properly. Pic related.

>> No.1156500

Also how can I limit the output current?

>> No.1156501

Step down is likely to be more efficient, since the currents are smaller.

>> No.1156502

>Just a reminder: low voltage zeners are trash and require quite a lot of current to operate properly. Pic related.
Well, fuck.
I ordered 2V Zeners.

>> No.1156506

Thanks, I hadn't thought of that.

>> No.1156511

>receive stack of ICs wrapped in plastic from aliexpress
>or stuck in regular foam
>or casually thrown into a plasic bag
>surprised when they miraculously still work
Every time.
99% percent of chinks has never heard of ESD apparently

>> No.1156521

When your merchandise comes from trash cans or is desoldered from junk, things like ESD protection start to sound bit silly.

>> No.1156540

>Depends. Are you ok with higher saturation voltage, higher base-emitter voltage, lower speed and the integrated B-E resistors?

Probably. Thanks, man.

>> No.1156573

Doing a project on an Altera DE2 FPGA board
Is there a way for me to hook up an arduino to the GPIO pins on it and communicate wirelessly with that arduino?
Like on the transmitting Arduino I have some sensors and shit and I transmit that data to the other Arduino which would output the bits to the GPIO pins. Can I do that?

>> No.1156574
File: 29 KB, 971x717, Uload, Ib, Ic.png [View same] [iqdb] [saucenao] [google] [report]

Thanks a lot for your advice.

After some tweaking, I eventually managed to get this kind of base vs. collector current response.

>> No.1156579
File: 87 KB, 1266x840, sch.png [View same] [iqdb] [saucenao] [google] [report]

Here's the schematic that I used for that simulation: >>1156574

One problem is that the minimum value for T1 base current is about 0,4 A, even when no collector current flows (0 A).

>> No.1156590

What is your problem here? The wireless communication or hooking up the Arduino?

>> No.1156591

I was just wondering if hooking that up and doing it was possible. I don't have the components on hand so I can't test it. I have the two arduinos communicating over RF though fine.

>> No.1156667

Hey you look like you know what you're doing, could you briefly explain the syntax in the".tran" line? I've just been copying it from circuit file to circuit file after seeing it on a yt tutorial, and feel like a scrublord.

>> No.1156668


I didn't say audio signal, I said audio frequency signal ... ie. no more than 10s of kHz.

>> No.1156670


Most ICs are actually not very ESD sensitive.

If you got 2n7001s or other old types of MOSFETs like that you can throw them in the trash though.

>> No.1156687

Same thing mate, assuming you're lower than 20kHz.

>> No.1156785

I made a circuit that takes an audio signal in through a 3.5mm female connector, runs the left and right channels through a CD74HC4053E analog switch, and out to another 3.5mm connector. When I tried to use it, though, I only got noise out of the other end, which was hooked up to an audio amplifier. I also tried running the channels of one connector directly into the other and got no signal to the amp. Any idea what's going on? I know the amp is fine, since I plugged it straight into the music source afterwards and got music out just fine. I also know the switch isn't broken, since I used it earlier to switch power to an LED.

I'll be checking it out tomorrow with an oscilloscope and multimeter, but I'd appreciate suggestions until then.

>> No.1156786

.tran is transient simulation. The numbers are various specifications.
Check the help file in LTSpice.

>> No.1156807

What would you guys recommend to get component wise when starting out?
I've got a couple arduino unos, more resistors and LEDs than I'll ever need and some servos already. Almost nothing besides that though.

>> No.1156846


>> No.1156851

14.4 for my AGM battery

I've never seen any that have anything that protects it though, if you charge over that at trickle current then you risk leaking the seal

>> No.1156897

I assumed the lower current sink is for the main transistor turn-off but when I took a second look, apparently it is turned on only when the main transistor is on. In that case it would be there to sink the extra base current away.
You can also try a smaller R10 or drop the base driver's supply voltage a bit (diode in series?) so that the anti-sat part can drive it fully off easier.
Or just change the driver logic otherwise. The circuit looks like a product of evolution and tinkering in any case.

Well, and of course you could read the patent text, which probably explains at least a little what the numbered blocks are meant to do and how.

>> No.1156900

>plays with FPGAs
>Arduino is a problem
Maybe I misunderstood something, but first you decide what kind of messages you want to send and then select some suitable signalling method for conveying the required amount of data between your FPGA and Arduino. For example, if you just want to send two fixed format messages, you could use two FPGA pins to request Arduino to transmit them. In that case the Arduino software would poll the pins and when they're active, send one of the preconfigured messages. You can handle the reception (or status checking) in a similar manner, via couple of IO pins.
If you want something fancier, you could implement (for example) a slave SPI port in the FPGA end and possibly add couple of notification lines, like "FPGA wants to send". Then the Arduino software would read/write messages via the SPI, either by bit-banging or via hardware SPI.
Of course, at some point the Arduino just becomes a pointless hindrance and it makes more sense to connect your radio directly to the FPGA pins.

>> No.1156916
File: 874 KB, 3280x1176, ammeter.png [View same] [iqdb] [saucenao] [google] [report]

So im building this power supply and im trying to make sense out of the volt and ampmeter i bought that didnt come with a wiring diagram except some paint drawn images on ebay. Im having trouble implementing this meter in my setup. I hooked the meter up according to "wiring diagram 1" but the meter shows essentially double the current of what is actually pulling (tested with my DMM) So i started playing about with the adjustment pot which only changed it by 5% ish (no where near enough). Gave up and hook it up accordingly to diagram 1 (basically just cut off the negative that goes directly from the 12v supply to the meter. And the fucking thing works accuratley even under 4volts which is stated to be the lowest possible for only 1 PSU. So im not even understand where my meter is getting the power from at this moment but all readings are verified and accurate. Can someone help me understand what the hell is going on. Im a beginner as you can probably tell and i just want to wrap this up in a box and use as my stationary supply but im affraid of doing it now thinking something is going to catch fire.

>> No.1156920

>tfw BJT and MOSFET test in around 8 hours.

Any tips before I go in? I have the idea how to solve the common transistor amplifiers now and have a basic understanding of design as well! (I'm >>1155818)

From DC, find the variables, then go to AC and find the gain and input and output resistance/impedance.

I sure hope I do good!

>inb4 professor sees my post and adds something crazy

>> No.1156922

I just put this sick bastard together, but it sounds like merzbow taking a fat shit. There was barely a bypass, barely. The led instantly burned out and when it plugs in there's just noise and louder noise.
When I unplug it I can't hear my guitar. How do I diagnose this problem? I tried reversing polarity on the jacks and just got the same problem but with no bypass at all. My soldering job was good too. I'm real disappointed. I spent the last 6 hours working on this

>> No.1156949

would it be viable to sandwich a peltier cooler between a cpu and the heatsink? (In this case a liquid all-in-one cooler)

I've seen peltier cooled computers that have elaborate dual liquid loop systems with the peltier somewhere in the middle, but my method sounds a lot simpler.
I would fill the area around the CPU socket with putty obviously to stop condensation, and hook the peltier up to a molex connector.

>> No.1156983

Are you trying to permanently run sub zero or what?

>> No.1157056

What do you guys use to hold components, wires, etc? I only have a little 30~project kit and they don't come with resealable bags for the 20 or so resistors, 15 breadboard wires, switches, etc.

>> No.1157057
File: 286 KB, 1500x931, 91g5f71h5CL._SL1500_[1].jpg [View same] [iqdb] [saucenao] [google] [report]

I use this thing:

Apparently not available on amazon.com, but it's quite useful. Can even be wall-mounted.

I also have another smaller thing for the small parts that I have low amounts of, like voltage regulators.

>> No.1157059

wall mounted would be super helpful, I'm already out of room in my tiny bedroom. thanks for the tip

>> No.1157090

A quick question:
I have an audio system with an AUX input via audio jack. If I plug in my smart phone it's a bit too quiet (thanks to fucking EU headset norm). So I built an amplifier and it works quite nice. But I'm a bit concerned about the voltage: The amplifier has a maximal range of 15V. I curb the volume via a pot between amplifier and input. Is it possible to destroy the sound system by high voltage even if the music volume is only moderate?

>> No.1157091


will this actually handle 12amps? I plan on actively cooling it

I'll need about 40 amps total so I'll get 4 of them

>> No.1157150

Which is the better use of $100 for someone with relatively little electronics equipment?

>Hakko FX888D soldering station
Would replace standard wall-plug iron

>Fluke 115 multimeter
Would replace $20 meter, would also be closer to $150 than $100

>Lots of ICs and passives
Maybe having components is worth more than tools?

>> No.1157190

I remember one connector company had this really trendy webpage and advertised how great their sample program was

What was their name?

>> No.1157201

Provided its wattage is high enough to be more effective than the forced convection alone, sure. But I'd ensure it's not pulling your CPU too cold with a PWM supply linked to a thermostat. Heck, if you design it right, you could use a temperature-varying resistor (along with a constant one in series) as the PWM control pot, maybe with a trimmer as well to adjust. Though maybe PWM isn't terribly necessary compared to more primitive power-control methods. Follow your dreams anon, overclock your COD machine!

Also this would be a great kit to sell to "hardcore gamers" for 10x the material price. Tell them the programmable RGB LEDs make it run faster.

>> No.1157233

What do you use the most and what do you think you need the most?

>> No.1157253

I know you can get custom PCBs made, but are there any services that will make you a wiring harness? I've got a project in mind for my truck installing later-model doors with power everything but I want to get a harness made that plugs into the existing pigtails. I can get kits to replace the connectors on those to fit exactly but I'd rather not do up the entire harness myself.

>> No.1157304

What's a good tool for crimping jumper wires?
I only got simple crimping pliers and I haven't been able to make a good solid connection with them.

>> No.1157356
File: 743 KB, 300x236, 1428474284409.gif [View same] [iqdb] [saucenao] [google] [report]

>want to set up electronics lab
>mention some of the stuff I'm looking to acquire, including a scope, when visiting parents
>next day dad messages me he got me a free scope through one of his ex-colleagues
>it's a Philips PM3350A
how'd I do?

>> No.1157357

I do a lot of scrapping old electronics to make/repair other stuff. I would say the new soldering iron, but I know how important a good multimeter is

>> No.1157392

What's your pops do?

>> No.1157394

He's retired now, but he worked at some electronics manufacturer. He didn't really have a technical job but he obviously had connections with people that did. He's more into cars but knew a little about electronics. Used to bring home some scrapped stuff occasionally for me to play with, which greatly contributed to my interest in electronics.
And that's enough blogging for today.

>> No.1157400

Are those DIY oscilloscopes worth the like 30 bucks? Or are they pretty much just a toy?

>> No.1157403

If $100 is the price of a decent used scope... No, they're not 30% as good.

>> No.1157407


>I'll need about 40 amps total so I'll get 4 of them

They aren't current limited at 10 amps, so even if putting them in parallel didn't completely screw up the control loop they wouldn't share current evenly. The ones set to the highest output voltage will go to 14A and burn themselves out.

>> No.1157412


Do you need super high reliability in your tools? Are you stupid enough to probe European mains voltage or higher on the current setting? If no to either, then Hakko and Fluke don't really make sense for you.

Get a Bakon 950D, a soldering iron stand and a UNI-T 61E and you'll have some money left over for components.

>> No.1157469

so will you answer my question if it'll handle 12amps really or is it a chinese meme?

Your other post makes no sense, I'm giving them all 12 volts and they're running different things, by themselves, I'm not bridging them together... nor did I ask for your input. I just asked if they can handle 12 amps, because when I run each of them at 10 amps I want to be sure they'll last.. not your stupid fucking 14amp meme

>> No.1157485
File: 97 KB, 789x676, 81ybUAJz1OL._SL1500_.jpg [View same] [iqdb] [saucenao] [google] [report]

my car stereo is over 30 years old but its a mid 80s digital style that makes the interior of the car so its not going anywhere. i want to use a cheap drok amp to drive the speakers, however i run into the problem where of course all 4 speakers are independent to the built in amp but the drok amp only has a left and right channel. i dont want to tie the front and rear speakers together when i tap into them, so how would i go about making it so the drok amp uses all 4 speakers without tying them together so that theyre still independently wired?

>> No.1157535
File: 2.07 MB, 2560x1600, untitled.jpg [View same] [iqdb] [saucenao] [google] [report]

First time soldering in over a decade. Seems alright, not? Maybe a little too much solder on some pins.

>> No.1157539

Oh to clarify, I just soldered on the headers.

>> No.1157549


What's the impedance of the speakers?

What's wrong with the old amp? Can't you splice your phone output into it instead of the radio?

>> No.1157555

A0 is fucked, reflow a little more solder on it.
right hand 4 have a little too much. can't see the back.
in the end if it works it works.
not sure i believe your claim of being out of practice. i went 6 or 7 years straight into supervising a lab teaching it. like riding a bike you never forget!

>> No.1157588

150w rms 4 ohm
i probably could but i still want everything to work as it did before, just with a more or less direct line to the speakers. i currently have an antenna interrupt modulator (vs a cigarette plug transmitter) installed that you run your antenna wire into that plugs into the antenna in of your radio and hijacks one of the low frequency channels, and its still pretty garbage despite being directly hooked to the antenna.

>> No.1157648

>i want to use a cheap drok amp to drive the speakers,
>how would i go about making it so the drok amp uses all 4 speakers without tying them together

silly cat, get two drok amps

>> No.1157662
File: 13 KB, 757x212, lpc810pins.png [View same] [iqdb] [saucenao] [google] [report]


What is the simplest way to display a value with hardware using a chip with not much IO (NXP lpc810)?

I only want to display like 8 bits of data.


> want to buy an oscilloscope that is so old it has a floppy drive
> want to buy some broken medical equipment for the hell of it

...every thyme.

and I'm american too

>> No.1157668

That would be about $80 plus RCA splitters plus needing to mount 2 volume knobs plus either two 36v 10 amp power supplies or one 36v 20 amp power supply which at that point I'm better off getting a high quality regular amp and rewiring the whole car

>> No.1157669


If the radio and the old amplifier are really separate devices like in your picture it should be possible to splice in your new signal, although it might need a pre-amp if the voltage levels out of the phone are too low.


If you do use two DROK amps, add two high current 4PDT switches to switch the speakers between the old amp and the new ones.

>> No.1157674


i2c I/O expander, but it kinda defeats the point of using that micro in the first place.

>> No.1157685


But I thought the point of a micro was to blink leds

>> No.1157700

you can display 12 bits with 4 ios using charlieplexing leds


>> No.1157757
File: 188 KB, 950x950, Untitled-1.jpg [View same] [iqdb] [saucenao] [google] [report]

>too much money...

Then use two 4P-DT 12v relays.
The relays are wired to allow the original system to connect to the speakers in the original manner (four separate) when the relays are NOT energized.
The relays are connected to the new amp power so they pull up when the amp is on.
This disconnects the speakers from the original amp and connects them to the new amp.
When connected to the new amp the LF and LR are both on the left channel and the RF and RR are both on the right channel.

Your drawing was simplistic in that all speakers have two wires, not one.
If one connection at each speaker is actually grounded and the new amp will allow grounding of one side of the output, you can just use one relay or one 4P-DT toggle switch.
If one connection at each speaker is grounded and your new amp will not allow grounding of one side of the output you can't use that amp.
(Having one side of the speaker grounded is no longer common but is not unheard of)

>> No.1157787

brilliant, why didnt i think of that. even better i have a spare toggle switch near my arm rest that would be even better to toggle the relays and its already pretty fucked so i wouldnt be too torn up about drilling it and putting the volume knob there after removing and putting wires on it. i left out both wires because yes it is not a body grounded audio system so i felt it redundant, plus it made it easier to shit out in paint, all speakers return directly to the amp (i replaced all 4 speakers so i know for sure).

>> No.1157792

Does amplified audio not usually use common ground pins? Or is that an automotive thing? Because I can't see why having all the speaker and amp grounds connected could cause any audio issues, assuming you don't make a ground loop or get any interference from battery voltage fluctuations.

>> No.1157800

Many amps use an active device on each speaker connection.
The devices are wired to output out-of-phase signals.

>> No.1157895
File: 15 KB, 425x425, 41oCaDFKOGL._SX425_.jpg [View same] [iqdb] [saucenao] [google] [report]

Would this work?
The ratchet makes it better than what I have.

>> No.1157946

Is that a higher torque version of a standard one? I don't think that makes a difference unless you're dealing with really tough/thick wire. For normal stranded copper you should be fine with a non-torque-transforming model, as long as it has the right crimping-bits/bit-slots.

>> No.1157950
File: 141 KB, 1000x1000, HTB1ImbQKFXXXXbCXpXXq6xXFXXXk.jpg [View same] [iqdb] [saucenao] [google] [report]

The one I currently have is like pic related.
And I constantly get loose joints with it.

>> No.1158007
File: 32 KB, 493x383, ncs2211.jpg [View same] [iqdb] [saucenao] [google] [report]


>> No.1158010


>> No.1158046

Use a buzzer and present values using morse code.

This used to be a feature available in old version of Linux for the cases when the kernel locked up tight and you really, really wanted to know what had hit the fan.

>> No.1158295
File: 8 KB, 377x296, amp5.gif [View same] [iqdb] [saucenao] [google] [report]

Hi /diy/ after lurking for a while I decided to build my first circuit. It's just going to be a common emitter to boost the output of my 5MHz radio before going into the power amp on the antenna. Nothing fancy, just for learning. After I did the calculations and built the circuit on a breadboard I found out it has a gain of just below 1, with the gain increasing up to 8 (what I designed for) when I attached a signal generator and dialed down the frequency (it increases linearly).

Is this a problem with the breadboard or is this not a good circuit for voltage amplifying a radio signal? I heard I was supposed to choose resistor values that create half the supply voltage over the CE Junction, but I don't know what this means so I chose Rc/Re = 8 with 12/(RC+RE) = 5mA which is half the rated collector current for forward biasing. Am I supposed to bias the base to something in particular? I set it so that the signal doesn't fall below 1v during its cycle as I heard transistors have a 0.7v loss from B to E so you have to have more than this amount at the base. Sorry if this is something simple, I am new to electronics and have no college courses in it.

>> No.1158393

Automotive amplifiers are usually bridge amplifiers: two amplifiers, one inverted one non-inverted, with the load connected between the two. So neither terminal is ground.

That way, the output voltage can swing between -12V and +12V rather than 0V and +12V. This is pretty much required to get decent output power with a 12V supply.

>> No.1158429

What are some cool sensors I could implement onto a new project?
I'd like to use something more than just an IR or Ultrasound sensor

>> No.1158461

> pressing the reset button on my USB board shorts VCC to ground

>> No.1158516

The "0-12" vs "-12 - +12" reasoning doesn't make sense. To get "0-12" requires a 12V potential difference, which the battery has, but the battery cannot supply a 24V potential difference required for the "-12 - +12".

I see that using an amp without a voltage divider (or equivalent) at all would cause only half of the waveform to pass through the amplifier, essentially acting as a half-wave rectifier, which probably isn't that good for the speaker.

Using a voltage divider to power an amp, with the audio ground being halfway between the 12V and 0V, gives the audio signal a maximum peak voltage of ±6V on either side of the virtual ground. Unless you use something to step up the voltage this is unchangeable. I see how the waveforms from two amps could provide more current than just one, but not voltage.

Makes you wonder why car batteries don't have a "centre tap" lug to get a +6V ground from, only for use with audio. You could drain from individual sides of the battery if you had some sort of cell balancing circuitry, but at automotive battery currents that would be pretty expensive.

>> No.1158547

Try parallel plates that you constantly measure the capacitance of to determine the air humidity, along with a digital thermometer for reference.

>> No.1158552
File: 59 KB, 1050x1041, combined.png [View same] [iqdb] [saucenao] [google] [report]

hello I know basically nothing about electronics but I'm learning a little.

would this image be "ok" for either circuit? Is there a reason why #2 shouldn't be done?

and let's say I want the LEDs in parallel and only want to use one resistor, how big would I need it to be? just add them and round up to the nearest resistor size?

>> No.1158582

>let's say I want the LEDs in parallel and only want to use one resistor,

Yes, either will be fine as long as the LEDs are similar.

>> No.1158599

Both are fine. Check that:
> "(LED forward current) > ((LED forward voltage) - 9) / 120
is true, otherwise you'll need a greater resistor. 120Ω feels a little low for a red LED, because it puts the current in the range of 50-65mA.

>> No.1158698

bump limit reached

new thread here >>1158696

>> No.1158735
File: 12 KB, 791x359, 27MHz_4W_PA.gif [View same] [iqdb] [saucenao] [google] [report]

Your circuit has pretty high output impedance (roughly Rc) and that together with various capacitances forms a low-pass filter, killing your gain at higher frequencies. Since the output is not matched, your cable can be a significant capacitive load, too.

Typical solutions are tuned output, much smaller resistors and using other circuit topologies not having the same problems. Pic related is a 27MHz amplifier using the first option.

You dimension the base voltage divider so that the base voltage is emitter voltage + 0.7V in idle. The current through the divider is usually set to 5 to 10 times the idle base current (so that the base current won't upset the divider too much).

He's right, though. You can think it this way: your battery with a center 6V tap (and speaker connected to it) would allow +/-6V across the speaker (12V-6V vs. 0V-6V). Using two amplifiers, each having an output voltage range of 0-12V would allow +/-12V across the speaker (12V-0V vs 0V-12V).

>> No.1158750

With a bridge configuration, you can have +12V on output A with 0V on output B (thus A-B=+12V), or 0V on output A and +12V on output B (thus A-B=-12V), or anywhere in between. Thus the difference A-B can vary between +12V and -12V, a range of 24V.

Whereas if B is held at a fixed voltage (whether 0V, 12V, 6V or whatever), the difference A-B can only vary over a 12V range..If B is 0V, then the range is 0V..+12V. If B is 6V, the range is -6V..+6V. Etc.

Automotive (and portable) amplifiers invariably use a bridge configuration for this reason. Doubling the voltage gives you four times the power for the same impedance. Or allows you to have four times the impedance for the same power.

It's not an issue for mains-powered amplifiers because it's straightforward to create a balanced (-ve/0/+ve) DC supply at several tens of volts (the limiting factor is usually safety regulations; which require additional precautions above 50V).

>> No.1158989


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