/diy/ - Do It Yourself

>>1656975
You should add Ben Eater to the YouTubers list. He has incredible videos on designing a computer and video card using only 74LS parts

I'm making a bluetooth speaker, partially to understand audio and electronics better but mostly for the fun of it.
I have a few issues though;
1. are tweeters really just a voice coil with an x-material dome over it? Pic related
2. I'm using a crossover to seperate highs and lows, but have 4 Ohm speakers and probably 4-6 Ohm tweeters, the amp supports 4-8 Ohm. So if I have the amp at 4-8 Ohm range, then the crossover going to two speakers at most likely both 4 Ohm, will that work properly?

That's the important ones
3. 50W per audio channel, 40W speaker and 30W tweeter, how will it share that power? Because I think 30W for a single tweeter is insane, especially when it'll take away from the barely existing oomph the speaker already has.
4.1 do li-ion 18650's really need to be balanced at the same voltage first? I'll be connecting them to a charge/balancing board anyway.
4.2 such a board wont produce too much heat charging at 1A/5V right? Though I might need a better charger as that'd take 12 hours for 4 3000mAh 18650's

Many thanks in advance. If this works out you'll probably see me again sometimes, as well as in woodworking.

>>1657117
1. yes. voice coil and a magnet
2. don't know enough to say but will probably be fine. if i'm not mistaken there will be a spot around the mid frequencies where both tweeter and sub aren't filtered out, where the impedance could be lower than you anticipate, *if* you're using a parallel passive crossover circuit.
3. depends on filters used and impedance of each driver and whether series or parallel
4 don't know

Audio is an excellent reason to get into electronics. That's what transistors were first developed for in fact.

New to /diy/, is electronics a field that pays well?
I absolutely love the idea of applying principles to efficiently solve problems, and am currently going to a university for a related degree. What kind of jobs usually pay well and relate to this; and are said jobs obtainable with a computer engineering degree?

>>1657343
Does that mean that pic >>1657117 only needs a magnet to be a functioning tweeter?
Thanks for the help fren.

>>1657348
Also interested, but EU based.

Help me Ω, you're my only hope

>>1656886

>>1657427
Ohm meter will tell you.

>>1656975
There has never been a naked chick anywhere near pic related.

That being said, somebody should make one for me and I will be the first to have a naked woman who is >4/10 in the same room as that craft project.

>>1657117
>>1657343
>4.1
Yeah, they should be close. I was looking into some of the balancing boards on Amazon and Ebay, and people were saying the balancing part won’t send much more to any of the individual cells and over a single charge cycle it might only make up 0.1V difference. So even if they’re the same exact cells but one is 4.0V and another is 3.4V when you go to charge them, you will probably end up with one overcharged and the other at like 3.9V. It will take a handful of cycles to get them balanced and you have a chance of fucking up the cells by under/over charging them.

>4.2
Read the reviews. I have these little USB charging boards for 18650s and those cunts get pretty hot. I put the IR thermometer on it and IIRC it was getting up to like 150F on one little part. Maybe you don’t need a heat sink, but leave some space between the hot part and anything that could cause problems.

>>1657453
>4.1
Then I'll take my time getting them all charged as similairly as I can to avoid trouble.

>4.2
I'll keep it in mind. Thanks fren.

>>1657453
>>1657449
>/ohm/ is an anonymous, non-smoking general.
Fuck off cunt.

>>1657117
I can help you out with the Impedance of the speakers/crossovers/amp, but I'll need more information.
What amp are you using, what speakers, what crossover? A lot of your questions are vague and without more info, there is no solid answer.

>>1657427
That sub/box combo you posted is two subs at 4 ohms each, with two desperate terminals to hook them up individually.
You can run each sub with their own amp at 4 ohms each, or wire them in parallel to get 2 ohms, so you can run them with a mono amp.

>>1657449
This is the stupidest, gayest flex that has ever been posted on 4chan.

>>1657532
I find that hard to believe

>>1657518
Well I don't have the amp or crossovers yet, but the amp is based on the TPA3116D2 chip and the crossovers will probably be these https://aliexpress.com/item/32754896681.html , though I might make them myself if that's better (cheaper?).
Which weeters I'm not sure about yet.
Speakers are LE10005-009A JVC 4Ohm coming from SP-THA85F satellite speakers saying it has 80W power handling capacity (2 speakers per satellite, so 40W per speaker I think) and an impedance of 6 Ohm (because they're in series, right?). Later on I'm going to do the measurements to get the right type and size enclosure.

So I need to convert 2 sources of 5V down to 3V and up to 12V. I bought 2 of pic related step-down DC-DC converters. The stepping down to 3V works fine, but I can't get it to step up to 12V. I thought I could maybe switch input and output to get it to step up instead. Am I just stupid and do I need a step up converter to get 5V to 12V instead? Or am I just not turning the potentiometer enough?

>>1657614
12>5

>>1657519
Hmm well since there's only one speaker wire coming out of it I should I assume it's wired in parallel? Also if they were completely separate wouldn't the wattage spec be different? Like it would say 350W x 2 or 1400W or something? I'll have a closer look at it this weekend, it's installed in such a way that I can't really get a proper look at the terminals, but only one speaker cable's attached and it certainly sounds like both speakers are hooked up

>>1657614
A buck converter doesn't have to be a boost converter. See pic related difference. Check what you're buying, anon.

Is there a switch that would save it's state even if the signal is turned off? Pic related what i'm thinking in a mechanical sense. The switch is loose and gets turned into whatever position the coil is under load.

>>1657712
bistable relay

>>1657732
Thanks!

look at this misleading shit on these honeywell pressure sensors. they say "0.15% accurate" but it's actually like 7% accurate without calibration based on the full scale span. am i supposed to own a pressure reference to calibrate it with? fuck these cunts

hello ohm
is stm32 ohm?

>>1657776
some say it's not, but nothing interesting ever gets posted here so i say go for it

>>1657777
your quads deserve some shit
mcu's are always torn between computer science/programming and using their peripherals/ electronics stuff around them
everything and nothing

Can someone give me an example of when I absolutely need an inductor and what would happen if I didn't use one? I know what they do, but I'm kind of confused about when I should actually use one.

>>1658101
Imagine you sell inductors..

>>1658101
About everything that's confronted with high power. It reduces wear quite a lot.

Say I have some standard 12V DC PC fans. What's the maximum safe voltage I can give them? Need to increase airflow.

>>1658135
Literally written on them or in specsheet. Usually 13.6~14.0. Nonetheless that's a dumb idea.

>>1658151
>spec sheet
I bought 6 fans for 10 bucks, I don't have a spec sheet

And YOU'RE a dumb idea

>>1658153

>>1658151
17 volts on avg. It won't give you more powah

Building a tube amp turret board and the schematic calls for a 50/50uf 500V capacitor. But I can't find one of these little shits in stock anywhere for the life of me. The cap is an axial dual so the "can" version would kind of throw everything off since I would have to mount it differently.

Any ideas? Maybe I could fine two 50uf 500v caps and connect them?

>>1658206
Do you even ebay?
I found it in seconds.

>>1658207
I typed in 50+50 500v on ebay for usa by the way.

>>1658206
I would have used two 50µF/500V caps.

>>1657776
>>1657777
just getting used to stm32. playing around with an old discovery eval board. push button on a gpio, rising edge triggers an interrupt, callback toggles two led and writes some shit to an usart.
should replace an arduino, which is just too limited for my little project I have in mind.

>>1658207
I checked ebay. Did you find the cap I posted or the "can" type with all three prongs on one end?

>>1658206
Is the 500v an absolute?

>>1658206
They're on back-order...

http://grangeramp.com/shop/index.php?main_page=product_info&products_id=541

If you can get by with 450 volt they seem to be available.
https://www.partsconnexion.com/mundorf-m-lytic-hv-450v-3-lead-dual-section-axial-electrolytic-capacitors.html

>>1656975
>claiming not to be a faggot
>t.OP
doubt

>>1656992
>one youtube series on a dead hipster meme
>deserves a link in the OP
doubt again

>>1657348
>>1657411
fuck off, we're full

>>1657776
as long as you're not using duino on it, I don't object

>>1658258
easily

>>1658206
two caps would be fine

>>1658153
>I have junk, what do?

>>1658101
boost converters aren't possible without them. also, tuned circuits in the VHF/UHF bands are really hard to do otherwise

>>1658349
>drunkposting

>>1658349
>duino on it
That would be heresy.
Only the HAL lib/driver, maybe FreeRTOS.

Is there a flow meter that measures up to 0.01L per minute accurately? I want to have semi-realtime predicted mileage on my bike and other options are exponentially harder (though way more reliable).

what exactly to EEs do all the time? Is it all circuits or also electrochemistry?

>>1658403

is the bike EFI or carbuerator? Most EFIs will have a data port and can tell you the flow rate of fuel and air lines if you dig in far enough.

>>1658403
i'm not seeing anything in a reasonable price range. googling for flowmeters gives industrial suppliers that will only quote.

>>1658410
Unironically getting thrown into management two years in. If you're asking because you actually wanna do stuff, get into a trade.

>>1658415
this. the moment you're given any responsibility in an engineering office is also the moment you stop getting to do any fun design work yourself.

>>1658379
I wish

>>1658403
>10mL/min
plenty of 'em, for a price. some of 'em even work on solvents like gasoline! did you check Grainger or McMaster-Carr or your local equivalent MRO supplier yet?

>>1658474
>grainger or mcmaster
>transducers of any sort

is there any flaws in the clone arduinos that original arduinos dont have?

is arduino possible to use in industry level or is it even close?

buying a clone and plugging it in my usb port to program, wont drop any viruses could it? just being safe..

>>1658491
>is arduino possible to use in industry level or is it even close?
Don't use an arduino in an industrial setting. Industrial designs have cases, better EMC design, i.e. are designed to operate in electrically harsh environments, and have harsh temperature tolerance.
Also the atmega328p will not fail-safe to the internal RC clock if the external crystal fails.

I think the arduino build environment itself is a baby-shit terrible platform for industry. I wouldn't trust avr-gcc with anything that could risk capital or lives.
That doesn't stop companies from making "industrial" arduinos though, google around there are a bunch. They are expensive.

>>1658499
What would be the first things to look into to make something "industrial" then, besides just full custom silicone?

>>1657692
>Only one wire
That's not shown in the picture, how do you know that?

>>1658514
Aside from PLCs you mean?
Also "silicon" is the metal, "silicone" is the polymer.

>>1657595
>amp is based on the TPA3116D2 chip
Good deal, it can put out good power
>crossovers
You can do much better quality, but those are dirt cheap. As far as the impedance, make sure your tweeters and subwoofers are the same impedance for good balance.
>Speakers are LE10005-009A JVC 4Ohm coming from SP-THA85F satellite speakers
This is interesting, because if those are 4 ohms, but two are together in the enclosure, you shouldn't get 6 ohms, unless there are other components in the speaker enclosure, like a filter of some sort. I would assume they handle 40 watts each if two can handle 80. Take a multimeter to them and read the actual impedance. They may be lower than 4 ohms.

>>1658517
Forgot to add:

Until you check to see how it is actually wired up, it is anyone's guess. Websites don't give accurate information all the time. The watt ratings could be a series, parallel, or individual handling rating - it doesn't specify.

>>1658482
well they're $115 at Digi-Key, so throw another roo on the barbie either way

>>1658499
>baby-shit terrible
excellent choice of words
>avr-gcc with anything that could risk capital or life
is it known to be that buggy with basic math or flow control?

>>1658491
maybe the arduino general would know best
>>>/diy/arduino

>>1658299
Thanks, bud. That'll work. Apparently the tolerances on these caps are wide as fuck so 47uf will be no issue. 450v shouldn't be a problem either.

>>1658522
>Aside from PLCs you mean?
Yeah
>Also "silicon" is the metal, "silicone" is the polymer.
I really don't care anymore. Whoever made that glorious one letter differentiation should be shot.

>>1658590
https://en.wikipedia.org/wiki/Derating

>>1658514
>What would be the first things to look into to make something "industrial" then, besides just full custom silicone?
If you're rolling your own...read "electromagnetic compatibility engineering" as your bible which explains way more than I can put in a post.
Select components that work in the widest temperature ranges and are ESD tolerant. Select a controller intended for industrial or automotive applications, with fault-tolerant features. Being able to operate if the external clock fails is one such feature.
Write fault-tolerant software that does frequent memory checks and stack checks and use triple-redundant, majority rule variables for the most critical outputs or control variables. Obviously use a watchdog.
Use an esd tester and blast your shit with broadband RF.
Or instead of rolling your own...
Use a PLC, or industrial PC with a realtime OS, or industrial microcontroller board.

>>1658560
>is it known to be that buggy with basic math or flow control?
Flow control, like if statements with comparisons. I've encountered serious flaws in object code when compiling with any optimizations enabled.
>well don't enable optimizations then
Yes, once I turned off optimizations it worked as written, but that still didn't leave me with a lot of confidence in the compiler.
Who knows, maybe that bug was discovered by somebody else and has since been fixed.

>>1658607
>>1658560
thanks anon.

ok arduino is just a toy so is there any industrial level stuff BUT easy to program it to read sensors, and use if statements and such without getting a headache in C++/C/ASM?

I doubt there is.

>>1658596
https://en.wikipedia.org/wiki/Ketone

>>1658668
what do you need industrial strength for then? is there a particular goal you're interested in? who are you looking to please?

>>1658672
well i like high quality in whatever i am doing. i dont have a use for industrial use but it would be nice to have.

>>1658673
probably want to stick to the maker's own dev boards, then. TI and ST have pretty economical ones for their own processors.
>nice to have
disappoint

>>1658668
C isn't hard. tarduino platform is just C++ with a shitty standard library and some wall padding.

>>1658517
>>1658530
Hi anon, I managed to remove the cover and have a look at the ear of the sub enclosure. There are indeed two sets of terminals, one for each driver so yes, 2 x 4Ω is quite accurate and it's up to the owner (i.e. me) if I want to wire each separately (with a 1ch amp this is the same as parallel), or in series. The previous owner had it wired parallel to the old amp and I just did the same.

That brings up new questions though. It's my understanding that the amp will put out more watts (800W RMS) into 2Ω (parallel), but also potentially draw a lot more power which isn't ideal for a stock electrical system. Right now it sounds great and I have the amp sensitivity turned way down because it's just so fucking loud. In terms of both sound quality and efficiency, knowing that I'm running the amp super low, am I better off keeping it parallel or going to 8Ω and wiring in series? I am an audio guy but not car audio so I want to keep the battery and alternator as healthy as possible and that part's new to me. Diagram related. The amp is capable of outputting the RMS powers labelled below the amps

>>1658708
8Ω = peace of mind.

>>1658717
Hmm maybe, could you elaborate a bit for me though?

>>1658718
meets all your requirements
no accidental overloading
all components in their soa

>>1658708
Don't you want stereo audio, assuming that's a stereo amp? Pretty sure the middle one will not only give you better audio quality, but be nicer on the amplifier too. The middle one is driving 800W split into 400W per channel, while the left one (which I assume was working beforehand) was driving the full 800W from a single channel. If the left one already worked without overheating, then the middle one will certainly be fine, as the load will be spread across twice the number of output circuits. Even more so if it has output transistors, not sure if subwoofers are used with class-Ds or not.

Quick question:

I'm trying to figure out how much power my house's circuit breakers can handle before tripping.

The only useful info written on them is that the ones labeled for lower-power purposes are 'C10', the highest power ones C20, and some C16's in between. Live in 'Straya.

Any pointers? Already took a google and didn't find anything obvious.

>>1658748
the numbers are the rated current. you can multiply that by 230V to get the rated power. the letter is basically how fast the breaker will trip, since they don't automatically trip the second you go over the rated current. C means it'll instantaneously trip at 5-10x the rated current. it'll trip more slowly at lower overcurrents.

https://en.wikipedia.org/wiki/Circuit_breaker#Standard_current_ratings

>>1658750
Thank you very kindly for the information and the link! So, just to make sure my napkin math is correct, a C10 breaker will handle only upto 2,300W, and then then beyond that it will eventually trip?

Could you please explain why they're designed that way i.e. why they allow current over the rated for a period of time? Assuming thermals are the concern rather than something else, I would imagine that the level of heat would quickly mirror the amount of power - i.e say 3,000W were put through the C10 breaker, would everything reach steady-state temperature very quickly and sit there, overheating, for a relatively long time waiting for the breaker to eventually intervene?

For context, I'm trying to figure out why my house's overhead light breakers are going off seemingly randomly. The only thing that would be drawing a lot of power would be that on top of usual standby type power, we do run, worst case, about ~8kw worth of electric heaters (three separate bedrooms upstairs, one down - It's a sharehouse). I realise that's a lot of power now, enough to trip even the biggest breaker easily, but the breaker marked for appliance power has only tripped a handful of times, whereas the overhead light breaker trips 10x a week. Flipping it back soon after it's gone off means it just trips a few minutes later... Could our appliance power trip our overhead lighting breaker? Thank you kindly again for your time!

PS: Not to disrespect your no doubt greater knowledge on these matters, but I was under the impression that Australian power was 240v rather than 230v?

>>1658758
i'm american so i just googled "australian voltage", but it looks like it is in fact 230v. we have a similar misconception here where people think our mains is 110v instead of 120v. in reality the voltage can vary, so you might measure 240v or 220v from your outlet at a given time of day.

breakers are designed not to trip instantaneously because devices tend to draw a current surge when starting up. motors need a large kick to start their shaft spinning, and electronics all contain capacitors (tiny batteries) that act like short circuits for a moment until they're charged. it's also generally not that important that a breaker trips quickly at 11A in a 10A circuit because in reality wires can handle a fair bit more current than they're intended for. they'll heat more but not catastrophically so, and they'll reach a steady state temperature like you said.

i'm an EE, not a sparky, but if the 10A breaker for your lighting circuit is tripping and not the 20A main breaker then it's not caused by your appliances. it might be faulty wiring. call an electrician.

>>1658758
Not him, but voltage varies between 220 to maybe as high as 250, even within the same country. Where I live (NZ) it's apparently supposed to be 230 but when I measure it it's usually closer to 240. Bigclive showed that once his voltage was as high as 249 or so. Anyhow it's <5% difference so it shouldn't matter to the breaker itself.

Now assuming you don't have a bunch of incandescent lamps, the problem could be a wiring fault (perhaps water ingress), which wouldn't be good news if it's somewhere inaccessible.
You could also try swapping the breaker around for another C10, in case it's the breaker that's working incorrectly, but I doubt it.

Where can I buy leaded solder in EU?

I've been using Cardas' meme audiophile solder because I can by it from GB ebay seller but it's expensive as fuck. 10 € for 5 meters.

Specifically I am looking for 62 Sn / 36 PG / 2 Ag / 0,5 mm for SMD work.

>>1658777
>62 Sn / 36 PG / 2 Ag
Aliexpress *might* have that blend, not sure if I'd trust it though. Does Digikey or Farnell or that lot not have it?

>>1658773
>call an electrician.
That's exactly what I'm trying to justify to our landlord. He's responsible for this sort of thing, but he's too cheap to do anything about it. One of my housemates sabotaged us by suggesting to the landlord it could be our heaters, but that doesn't make sense to me if they're on different breakers to the overhead lights, which is what trips all the time (the appliance power has gone out a few times as well, but 10x rarer).

>>1658774
Yeah, I've heard that the voltage does vary, but I thought it was nominally 240v. That's what all my equipment states, but eh. As you said not a big deal.

I highly doubt the lighting power draw is higher than the breaker is rated. When it tripped earlier this evening for example, there was significantly less than the usual amount of lights on, and none at all during the day.

I'm thinking there's something along the lines of water or other damage, but I would've thought that if it were water ingress due to rain, it would get very bad very soon after it started raining, and stay bad for a solid while. But if it's water related, it isn't correlated enough to rainy days enough to notice it.

I'd replace it myself happily, but between the effort+cost and the high rent I'm paying to make this the landlord's responsibility, he can just fucking pay for an electrician to do that, as he's already agreed to in the contract. I only need the verbal ammunition to make it happen =/

>>1658777
https://youtu.be/AT4vESXV0wA

>>1658783
>my housemates sabotaged us by suggesting to the landlord it could be our heaters
there's always that one retard. regardless of what the cause is, the breaker's tripping and it's probably illegal in aus for you to service the fault so he'll have to call an electrician eventually.

>>1658785
Yeah, cheers.

One last question - There's 4 breakers on the right of a testing switch (the ones on the left are group labeled as 'main power' e.g. oven, ac etc). One is the lighting, two are just 'power' (wall sockets I'm assuming), but the forth is labeled "TAS TIC" (or TAS TIL perhaps).

Any idea of what the acronym means?

>>1658411
Carburator, nothing else, it's simple an old.

>>1658413
>>1658474
Oh well..

Other idea, would measuring the deltaGas and putting that up to a tachometer (along with temp- and humidity-meter for somewhat higher accuracy) turn into something useful, you guys think?
Because if I get enough data I should be able to get a rough idea of how much gas I'm using at what rpm (also taking throttle in account). Though I think this isn't really /ohm/ related that much, other than: what else could I need to make this work (temp- humidity- and tachometer, lambda probe maybe, something to measure throttle, servo maybe).

>>1658708
>That anon from earlier
What amp model do you have? Is it 1 channel or a 2 channel? I'm didn't see anywhere what amp you are using.
Assuming you are using a 1 channel amp, I would wire the subs in parallel and run them at 2 ohms, assuming the amp is rated for 2 ohms. 800 watts is the end rating that it CAN get to, so as long as you keep the gain/sensitivity down, you won't be hitting those high power demands.
Wiring in series to get 8 ohms works too, but higher impedance requires more voltage from the amp to get the desired wattage. This is useful for higher frequencies, such as your speakers in your doors that handle vocals.

>>1658853
Just spitballing complicated ideas for the fun of it:
Use a graduated cylinder that drains into the carburetor. Optically measure the gas level in the graduated cylinder. When cylinder level is low, open a valve to quickly refill the cylinder from the gas tank, close the valve when it approaches full level.
Flow measurements won't be valid during this brief fill period but so what.

>>1658911
i thought of that too but i wonder what the resulting variable fuel pressure would do to the throttle response. i have a motorcycle and i have no idea. i guess you could also replace the fuel pump with a constant displacement pump, but good luck finding one with the same specs and fuel compatibility

>>1658911
I don't think I fully understand, use the graduated cilinder because it's easier to see usage from, instead of having a closed gastank with nothing to eyeball from? But then I don't think I can get an accurate idea of gas usage, especially if wanting not to die trying to read the cylinder.

>>1658966
>fuel pressure
I'm not sure either, but afaik carburators are pretty easy in that regard, because as long as there is enough gasoline in the float-bowl the jets will pull the correct amount regardless. So unless the engine uses liters per kilometer instead of the inverted, it should be fine.

>>1658966
Caburetors in motorcycles are gravity fed and regulate with the float.
>>1658974
>But then I don't think I can get an accurate idea of gas usage, especially if wanting not to die trying to read the cylinder.
Fren, this is /ohm/, do it electronically. I'm not suggesting you read cylinders or switch valves manually.

>>1658788
>There's 4 breakers on the right of a testing switch

all your questions can be answered if you do a 10-minute survey of your house. switch off each breaker one by one, and go around to see what went off. write it down. scotch-tape it to the inside of the breaker box. no more wandering, no more silly speculation about what's what.

my guess is the breaker is just old and senile. if you are able to cut off the main power to the box, you can switch the wires going out of 2 breakers (of the same size). if the problem remains at the same breaker, then the problem is the breaker.
otherwise, something is genuinely taking too much current. since you dont have a clamp-meter, you have to go around and switch things off by trial and error, then wait. (if you were really courageous, you might disconnect the wire at the breaker, while it's live, to see how big a spark you get - this is a poor man's current meter.)

>>1659004
Right, lmao, I suppose a float would be most reliable and then attach that to a rotary encoder with a spring perhaps? This way set values of the encoder can trigger things like the valve to refill, etc, will see what else when I need it. Then get the valve to reset the measurements when it's opened for easier data analysis and prediction later on with smaller chance of error as well.

>>1658777
>leaded
y tho
try ali, you can find eutectic SnPb all over. maybe not with the silver alloyed in, but that's kind of a meme anyway

>>1659066
>y tho
Apparently that common cheap no-clean flux doesn't work well with the RoHS stuff. Even Louis Rossman uses leaded solder for his computer repairs.

Max232 anon again, got a shitty arduino code in there trying to receive the data. The 8 year old SD card library is giving me issues so I'm ignoring it for now.
Even with my circuit not having any bouncing (which was causing the ±9V rails to collapse during testing), I can only assume that I'm trying to toggle the CTS line too fast because those rails are still collapsing. I guess I might have to homebrew a solution. For receiving that's easy; two resistors + inverting the bits on the software side. Not sure about transmission though. But before that, I'll try significantly larger output caps on the rails. And before that, food.

I'm in the beginning phases of building an analog synthesizer from scratch (you know, because I like torturing myself, don't you?)
I need a CV keyboard to control the oscillators (the things that play the notes)
CV usually uses a standard of 1volt:1octave, so each note will have a fixed distance from another in relation to their voltages, exactly 1/12th of a volt apart.

my question is whether this (honestly crudely drawn) keyboard would work, with some expansion.

the general idea is that the top rail acts as a voltage divider between, say, 6 volts and ground
the resistor on the far left (likely some resistors and a potentiometer for tuning) would have a high enough value that the lowest voltage you could get from the leftmost switch is 4 volts, and each switch would increase that voltage by 1/12th of a volt (for 24 keys), up to 6v on the far right

I understand this would mean that more than one key cannot be pressed at a time (it would only pass the higher voltage, right?), and that's fine as it can only generate one discrete waveform at a time.

I've rambled on enough, so my final question is just "will this (theoretically) work with fixed key resistors and a tunable ground resistor?" (and a fixed input voltage)

feel free to ask for clarification if needed, as it's midnight and I am on the verge of passing out, so it might be totally incoherent

>>1659133
R2R ladder?

>>1659134
what? I have no idea what that is, but it sounds like 'resistor ladder'

while I'm not *new* to electronics (I can follow traces on boards and figure out what they're for on simpler stuff), I am new to analog stuff.
also a crucial point is that when no keys are pressed (all switches open) CV_OUT sits at 0 volts (or whatever might be on the other end of its cable)

>>1659134
>>1659137
should've googled it first, but yeah it's exactly a resistor ladder, made into a human input device.
my question now is "can this be tuned with the potentiometer at the end to change the distance between key voltages" ( I think it can) and "if you press 2 keys at once, will it be different than pressing just the lower-resisting one" (I think not, path of least resistance and everything)

if I'm right, you helped me fix my own problem with 11 characters, so you deserve a cookie... or something.

I'm going to bed now, so hopefully I can go order some resistors in the morning (i miss radioshack)

>>1659103
ah, cool. happy shopping
https://www.aliexpress.com/wholesale?catId=0&SearchText=0.5mm+63%2F37&switch_new_app=y

>>1659134
hi newfren
you'll want to put a fixed current source at the top end of the resistor stack. otherwise you're changing the voltage between keys, not sure if you really want chromatic effects, maybe could be fun
if you use 100 ohm 0.5% resistors, a current of 833µA would be quite convenient
also see /ohm/ RULE 4

>>1659103
ah, cool. happy shopping
https://www.aliexpress.com/wholesale?catId=0&SearchText=0.5mm+63%2F37

>>1659133
hi newfren
you'll want to put a fixed current source at the top end of the resistor stack. otherwise, when you vary that resistance at the bottom, you're changing the current flowing through the whole string, thus changing the voltage between keys. not sure if you really want chromatic effects, maybe could be fun
if you use 100 ohm 0.5% resistors, a current of 833µA would be quite convenient
also see /ohm/ RULE 4

>>1659142
With an R2R ladder, the point of having resistors in series with each switch is that you can differentiate between which of multiple switches on at the same time; none of them are a direct short to the output. Hence it will be different than pressing just the lower-resisting one. The most common arrangement is to use it as a parallel DAC of sorts, with the side with the lowest resistor being the most significant bit. Arguably you could tune the resistor sizes to not only give you proper octave tuning (2^1/14 or whatever) but also make it such that multiple buttons at the same time would give a correct sounding mix. The math might be a pain. Having a synth where only one button can be pressed at once is a bit shit, after all. Hence why I'm going the 74HC165 + microcontroller route with mine. I'd consider having an individual oscillator per key, which could make for a fun PCB design.

As for tuning with a potentiometer, not unless you first buffer the signal with something like an op-amp. If constant-current then a tunable current source would work fine.

this place is slow enough that a tripcode really isn't needed

Not very /diy/ but is life good for an EE with micro/nanoelectronics major?

Has anyone here ordered 18650 cells from chinks on ali and wasn't actually scammed?
Chinks sell them for super cheap but like 90% of those offers are a scam so i need some tried and true store to order from

>>1659217
Last I remember there was something along the lines of a /g/csg 18650 infographic about what cells to watch out for, and it's probably still fairly relevant. Maybe someone here or there will post it for you.

>>1659217
>implying the other 10% are real
tried and true stores will probably be local, as junk isn't worth shipping by the book. maybe the local vaporizer store? if they're fake it's not you who gets chinked

>>1659224
Chinks selling cells with legitimate brands on them are usually pretty good, so long as they don't say "6000mAh" on them.

Is this man jesus?
https://www.youtube.com/watch?v=eHHGQq2YyRk&feature=youtu.be

>>1659126
>bouncing
>But before that, I'll try significantly larger output caps on the rails.
please say you're not putting big capacitors on any of the rs232 signal lines...

>>1659280
signals are either 5VDC or 0VDC so bypassing with big caps on signal lines is only logical

I am attempting to power up my ts100 by pumping 5V into this fucker and pumping 12V 1.5A out
https://www.aliexpress.com/item/32813707358.html?spm=a2g0s.9042311.0.0.27424c4dfMOYgN
But every every time i try to turn the iron heating on it resets.
It should handle up to 2.5A output current and i only need 1.5A output, so i don't understand what the problem is.
The power supply for the booster is my bench supply 5V so that is definitely beefy enough

>>1659303
Why do you think it resets?

>>1659309
well the ts100 has a computer in it and you press a button to start the heating process, but when i try that after a fraction of a second it resets as if i power cycled it

>>1659310
>as if i power cycled it
That could be a hint. Have a multimeter or even a scope?

>>1659310
>after a fraction of a second
A fraction of a second after what? Maybe double click has a meaning.

my crt tv gradually does picrel on bright backgrounds
can't find anything like this, only pajeets degaussing tubes, help

>>1659326
Looks like automatic degaussing fails. It normally does it at switch-on, you can clearly hear it. The critical part is some NTC resistor or so in series with the large degaussing coil I think.

>>1659342
No it must be a PTC resistor.

>>1659326
>crt
a time traveler eh?

>>1659321
after you turn the heating on
what do you mean a double click?
i know how to use the thing, i use it all the time without the boost converter and it works fine

>>1659312
i measured the voltage and it is at 13V on the output just as i set it, but the boos converter must be chink shit or something that can't handle the current.. that is my only explanation

>>1659342
when image displayed isn't very bright/white it just fades back
also when the patches are onset, after quick channel change to blank input it looks exactly like picrel
temperature?
>>1659348
Phillips PW9551, I like its image

Any of you fellas have experience making gifts??
I just remembered my dad's b-day is coming up. He's been dealing with cancer the past couple years and I'm not sure he'll be around next bday so I want to make something nice, but ever since he got diagnosed he's slowly stopped his hobbies cept for constantly watching crime shows lol

any advice? I'm thinking maybe something al la jim williams (pic related), but a thermometer seems kinda lame

>>1659372
nixie tube clocks are always a great gift (in the realm of cool electronics)

I'm guessing the reason for the capacitors on the output is to short any AC leakage current to ground?

>>1659405
On the AC input, high frequency noise flows through the low impedance path of the capacitors to the earth ground. This avoids the electrical noise being transmitted back down the AC input and causing problems with other equipment in the form of EMI (Electro-Magnetic Interference). On the DC output, the capacitors have the same function, this time avoiding high frequency noise appearing on the output of the power supply and causing problems with the load. Note in some cases there may be only one output to ground capacitor.

https://blog.uk.tdk-lambda.com/uk/2015/06/16/grounding-open-frame-power-supplies/

>>1659352
>can't handle the current
Imagine you start the heating process and your iron generates a short current spike that exceeds what the converter (plus 5V source) can supply and it resets itself. If that is the case a large capacitor could bridge the short negative voltage transient that the iron cannot handle. Btw: Even a toy scope is better than no scope.

>>1659405
output is rectified so it looks like the standard output filtering/smoothing capacitor usage

>>1659412
No, reservoir capacitors are not shown.

>>1659426
Sure is what those two capacitors look like on the right side of the pic, on V+ and V-

You guys seem like you know the answer to this, but how do I gain employable PLC programmer skill? I don't want a bunch of shit and not have demonstrable skills any good resources?

>>1659431
I don't think pure PLC programming skills would land you a job, you would also need general electronics/electrical experience.

>>1659429
if you ignore the circuit

>>1656975
>anonymous non-smoking general

TIL that solder doesn't stick to titanium, so a pair of curved titanium tweezers made my first attempt at SMD soldering pretty easy!

>>1659491
Really, how?

>>1659502

>>1659500

Doesn't stick to steel or aluminum, either.

>>1659513
What are the legs of components actually made from? I guess I just assumed it was steel, but I guess not?

>>1659515
plated copper

>>1659515
mostly tin plated whatever

>>1659280
No, on the rails created by the MAX232's internal voltage converters. It didn't help, but it looks like I can send a valid signal to the oscope with just TTL, so I'll ditch the MAX232 and use resistors and a diode as my receiving circuit.

>>1659387
perhaps the connotations of giving a clock to someone with limited time aren't entirely positive

>>1659585
it's at least useful

>>1658788

Aussie Sparky here

TASTIC is a heat lamp, it would have been wired separately and it's the heat lamp, fan, light combo that would be in your bathroom.

Regarding your light circuit tripping, I would say it's a faulty breaker, if it was water or ingress tripping the circuit it should be protected by an RCD (Safety switch) that would trip before the circuit breaker, the circuit breaker just protects the fixed wiring for excessive current draw or short circuit protection. Should be a very straight forward job swapping over a breaker that an electrician could do in 10 minutes, probably would need to do an insulation resistance test to see if there is any breakdown in the cable to cause it to short out, but my best guess is that the breaker has just had it and has a faulty mechanism.

Technically Aus is 240V +/- 5% from supply, but most theory states 230V

>>1659588
Assuming he doesn't already have a clock of some kind. The man with two watches is never sure what the time is, you know?

A farnsworth fusor operating in star mode could make a nice ornament, if you first test for UV, but perhaps purely non-functional ornaments aren't what he wants to go for.

>>1659582

>>1659607
>try println(asciichar); first:
R

P

U

;

P

U

;

>try print(asciichar); instead:
RPU;PU;
I just can't win

>>1659636
Oh what the beans is happening now?

>>1659387
yes of course, that would definitely be a good one. but unfortunately not feasible in less than a week, and way too much for a broke ass student. and lol >>1659585.
>>1659602
I've never heard of that but certainly looks intriguing.. An ornament of the sort would definitely work. I think anything utilizing HV can't miss. I'll look into it

>>1659687
well, bday is within a week, but will have at least 2 weeks before I see him, I should say.

>>1659673
Aw yeah, got this shit off my oscilloscope via RS232 to an SD card. Scaling the graph should be easy, the volts/div data is plainly written in the HPGL after all.

>>1658777
Silver will just make it brittle. If it's marketed as audiophile grade, you should avoid it like the plague.
Buy regular eutectic 63/37 with a good flux (very important). Only purchase reputable solder brands like Kester, Aim, MGchemicals, Multicore, etc. It's not really expensive and it makes a world of difference compared to the shit chinks will sell you on aliexpress.

Help me to not kill myself doing something stupid.

Recently moved into an old house with mostly 10A circuits, and that just doesn't deliver enough watts for the induction stove top I want to use. (3800w)
Best solution would be to upgrade a 10A circuit to a 16A, but that's sadly not an option. I do however have a 20A circuit available that I can wire it to, I just need some tips on how to do it safely.
I've heard I shouldn't use more than 75% of the watts the induction plate is designed for as the safety wouldn't work as intended, is there a way I can wire it up and still use the maximum wattage?
The induction plate is designed to work best on 16A as it would almost consume the entire circuit.

>>1659777
>tfw replied to trips with the exact same trips

>>1658777
to answer your question, you can buy good solder from component distributors like Mouser, Digikey, Farnell, TME, Bürklin, Arrow, RS Components. Avoid vendors of arduino faggotry like Adafruit and Sparkfun, they are not above selling you rebranded crap.

>>1659780
You're barking up the wrong tree here. Start your own thread.

>>1659780
See rule 0

Time for some ghetto soldering

I'm trying to repair a headphone and can't get the solder to wet the incredibly thin and enamel coated copper wire. I've tried soldering through it, burning it off, scraping it off with a knife and sandpaper, none of those work. Is there another way? Would acetone dissolve the lacquer?

>>1659925
have you tried flux?

>>1659932
Yes, no matter how much I throw at it, can't get t solder to wet the copper, at all.

Wanted to build a temperature sensor/adjusting circuit.

Catch is, it's meant to regular temperature in a cloche system. Had some leftover materials I was gonna toss together and I'm a lazy bastard by heart so this was meant to keep it a sealed system and to prevent heat damage during heat waves.

It's supposed to be portable and low voltage. I imagine the thermistor circuit isn't a problem, neither would the motor meant to open the ventilation cover. The issue will be the fan. What exactly can you pull on a low voltage circuit that's fan related that won't drain the battery down in a few hours?

>>1659941
If it is copper it can be done, but is it?

This question might come as odd, but what's the fringe-est thing EE are working nowadays? maybe it's something related to biology but I don't know where to get myself informed about whatever is the vanguard on the field, which I know is massive, nowadays.

t. CS in the making but interested in other fields as well.

>>1659951
It is. One is copper with clear lacquer, one is copper with green lacquer (looks like copper after hitting it with flame/knife edge/sandpaper). That's why I'm so surprised. I could see having problems with aluminum wire but this is just copper with some awful coating

>>1659965
I know that type of wire. I succeeded by scraping off anything with a cutter blade and then tinning the bare copper at low (!) temperature (< 250°C) using standard 60/40 type solder wire with no additional flux.

>>1659970
One of my problems was that the incredibly thin wire tended to break when doing that (or hitting it with sandpaper). I did it again now and stopped after a handful of strokes with much of the coating remaining. Threw a shit ton of flux on it and got about 3 places over an half inch strand where it wet the copper. Looks like shit and is brittle but it seems (and sounds, after testing it) like I have a good connection now. Just need to jerry rig something to stabilize it now because it looks like it'll break if you cough at it.

What is wrong with this circuit? It works in falstad, but the physical thing doesn't. It's supposed to make a motor spin one way when it receives a high level in one input, spin the other way when it receives a high level in another input, and stop when it receives a signal in a third input. This is just a dual flip flop / or gate.

>>1659947
Strange question. Just chose the right fan and the right battery, use PWM if you want to regulate it.

>>1659987
>trying to drive a high-current load with low-current outputs
did you check the datasheets of the real parts to see if they could drive a hundreds-of-milliamps load like a motor?
>doesn't work
that's a /g/-tier complaint

>>1660112
The motor driver circuit is elsewhere, did you think I was trying to drive it from the outputs of a logic gate?

>>1660119
some people have and do
now that I know where you're coming from, I see literally nothing wrong with this circuit, given clean square-wave inputs and a well-bypassed Vcc of 3.3-5V, except for possible setup/hold violations. put a very small RC lag on the output of the '32 and see if it helps

>>1660119
if you don't explain you are not retarded then you can't get mad when someone assumes you are.

did you power the flipflop ic?

what measurements have you taken to validate your results vs expected outcome?

Any good repository for electronics books? Looking specifically for Electronic Measurement Systems: Theory & Practice, if you happen to have it.

>>1660136
Yes it's powered. I've used the same flip flop IC in a different circuit and it works like it's intended.

>what measurements have you taken to validate your results vs expected outcome?
It just does not do what it's expected to do. It will change states when I plug a sensor (a board with a ttp223, capacitive touch sensor, which works fine on its own) in either slot while the board is powered, but not when the sensor itself is triggered. The stop input will reset both flip flops like it should, but that's about it.

>>1659976
What flux are you using? Rosin jelly flux is great for covering shit up and I've seldom had any problems with it.

>>1660176
use an oscilloscope

>>1660159
libgen is pretty good, doesn't have that one tho

>>1660176
so everything works but the clock, correct?
you didn't state your Vcc. ordinarily this doesn't matter but it could matter with mixed HCT and HC due to the former's asymmetric logic thresholds. if it's not a plain old setup time violation, maybe it's that

>>1660226
rosin jelly flux (by LACO, if that matters). Tried it with the no clean stuff from a syringe but that didn't work at all.
It's kind of ridiculous how much of the jelly version I had to throw at the problem to get even the abysmal results from the picture.

>>1660260
I might have had that issue once before with some very fine stranded copper from a pair of earphones that the cat got to. Increasing the heat eventually got solder to stick, but it didn't get me good results; there were areas that were permanently unsolderable thanks to some sort of residue left on the wires.
I'd strip a new section, clean it with acetone for a while, then immediately dip it into rosin before soldering at a low temperature (~220C). Perhaps an acid washing step to actively strip any oxides could help too.

>>1660260
>the no-clean flux from a syringe
makes sense, no-clean fluxes are on the less active side
>acid-washing
HCl would have made the flux more active and pre-cleaned some of the oxides and weird organic shit from the wires

>>1660228
>so everything works but the clock, correct?
I think nothing really works. The flip flop is getting a clock signal from god only knows where.

VCC is 6V. Like I said, the component itself works perfectly in a different circuit.

>>1660304
>6V
you're operating the device outside of recommended conditions and claiming not to be retarded?

I made a color sensor from an Atmega328, a RGB Led and a photodiode. It's for sorting objects in a conveyor belt. While it works well enough to measure red, green and blue levels and from that obtain the hue of the object with a simple algorithm, it seems like the voltage difference between different light levels is quite small by using the photodiode like I am currently doing. What kind of opamp circuit can I use to turn the small difference (4.27 to 4.5v) into a bigger difference so that I can have a bigger resolution and less influence of noise? This is for sorting the objects by hue and I can't use a camera or a sensor like TCS3200 (I mean, I could, but the sensor chip alone costs more than the arduino I pulled the MCU from)

>>1660307
high impedance is a must

>>1660306
I say 6v because it's 4 AA batteries, but since they're NiMH it's closer to 4-4.8v. Also:
>the component itself works perfectly in a different circuit.

>>1660307
So you flash red, then green, then blue, and measure the amplitude of each reflection with the photodiode? You could arguably skip all that and use a second RGB LED as the receiving photodiode and just shine a white light on the conveyor constantly. Might need some tuning as I think the red LED would pick up green and blue light also, but that's easy enough to do.
Arguably, pulsing the LED with AC might be better in order to get an absolute amplitude, since you could filter out the DC component which would contain noise due to ambient lighting.

Now a simple non-inverting amplifier circuit would work fine. Since op-amps work better closer to the negative rail than to the positive if I recall correctly, you'd want to swap the LED and resistor around in your circuit. Then you could get away with using 0V as your op-amp's ground rail, which I think would work fine. Pic related, set the ratio of one resistor to the other to be a factor of 5, which would give a gain of 6.

>>1660307
I used this to try to calibrate a DLP 3D printer long ago. if I remember correctly, Vo=-Id*Rfb
$0.03 LM358s are a bit howyadoin for precision work like this. spend at least $0.06 on a quality op amp with high input impedance and a common-mode voltage range slightly beyond the rails. MCP600x is my go-to for this sort of thing and they're cheap. be sure the op amp you choose has a CM voltage range including the rail you're working against

>>1660309
>in a different circuit
with a different power supply?
>clock signal from god knows where
so it is in fact getting a clock signal? have you tried injecting your own in place of the 1G32?

>>1660312
>So you flash red, then green, then blue, and measure the amplitude of each reflection with the photodiode?
Yes
>You could arguably skip all that and use a second RGB LED as the receiving photodiode and just shine a white light on the conveyor constantly. Might need some tuning as I think the red LED would pick up green and blue light also, but that's easy enough to do.
The wonders of quantum mumbojumbo. I can try this instead of the photodiode, but aren't they much less sensitive than photodiodes? I'd need the opamp circuit still.

>>1660316
>aren't they much less sensitive than photodiodes
They are, so if you already have some non-optical noise in your signal you might be in for a bad time. JFET op-amps may be a good idea. By increasing the size of the biasing resistor on the LED you'll get a higher signal but also more noise, so some experimentation might be needed in order to get the highest signal to noise ratio before amplification. The amplification stage can have any amplitude really, so even if you're down by 50dB as a result of improving your SNR it shouldn't matter.
Also I realised that judging with voltage gain isn't the best way to go about this, as I believe they act more like current sources. Hence something more like >>1660314 might be better.

>>1660318
unlike common bipolar op amps, some JFET op amps, in particular the TL07x, have a CM input range including the upper rail but recommend inputs stay ~3-4V inside the lower one. (the TL06x and TL08x datasheets recommend that inputs stay 4V inside either rail, so pretty much only good for audio work)
also JFET op amps that work at single 5V are uncommon, at best

>>1660321
Oh it's that bad, eh? Good thing I never bought any JFET op-amp ICs, since I almost exclusively work with 5V single rail.

>>1659925
My technique for that is to have a large blob of solder on the tip, set temperature to at least 350°, and then keep pushing the wire in and out of the blob.
After a while the insulation is completely melted off and solder will start to stick, even without flux.

>>1660360
not if any residue remains, which it can with the wrong sort of insulation

Brother lets keep 4+4chan ALIVE.

#CONQUER4chan

>>1660361
This style of wire is designed to burn off like that.
You're supposed to stick them in a solder bath for a while to tin them.

What I'm doing is essentially the same idea but doesn't need an actual solder bath.

>>1660362
can you shove off

Thoughts on a diy power supply? I wanna buy one from ali, to get started with this electronics thing.

>>1660393
Do you have any computer power supplies lying about? Also an old laptop power brick you aren't using could also be fairly handy with one or two of those <36V CC/CV buck modules. Personally I just use 5V USB for 90% of my projects, but what you want to do may require something more than that.

>>1660398
>computer power supplies
THIS
Or just buy a cheap one. They put out great power and are simple to use. Google ATX bench power supply.

>>1659280
>>1659748
Me again, gonna put a 1mF cap on the RS232 signal line. After a diode, such that I can feed the unused input through a 7805 to power my circuit without needing an external power source.
Pic related, 22mA is typical output short circuit current, which should hopefully be more than enough even when writing to the micro-SD. My USB tester is showing no current at all (<5mA) when writing to the SD, and I think I trust it.

how can I keep my cables organized? I have my power supply cables running through the top surface of the desk which clutters the work surface and looks messy as fuck. any ideas or suggestions for canle management?

How would one go about recharging a lead acid battery with a bench power supply?
I assume directly hooking it up and setting it to 13V is a bad idea

>>1660398
Not really, also I was just asking because I thought It'd be nice/fun to "build" a power supply for my future uses. I will consider what you said though.

Is there any way to refurbish a 6v thermal flasher that's stuck on? I have an old motorcycle and my choices are shelling out $50 for an NOS flasher or buying a generic one, making a spade to bullet adapter wire and praying it works.

>>1660415
>How would one go about recharging a lead acid battery with a bench power supply?

a bench power supply with adjustable current limiting is the best way to charge a whole bunch of diff chemistry batteries, including lead acid.

if you have no current limiting, you dont exist. use high-power resistors or light bulbs in series, and put a timer on your supply so it shuts off after a number of hours. time determined experimentally.

>>1660424

this also applies to you. a computer power supply which can supply 100 amps before it detects a short and shuts down is an insane thing to have on a bench where you're gonna be making mistakes all the time. without current limiting, you're gonna be so traumatized by the smoke and explosions, you'll become permanently afraid of electronics.

Got inconsistent results with a multimeter while measuring resistance.

After some mild scraping on the contact points the results were more within what I expected.

Could it have been some oxidation on either the terminal screws or leads?

>>1660585
What prevents you from finding that out?

>>1660596
Everything is in order now, just wondered how common bad probe leads or screw terminals are.

>>1660328
TL0xx were op amps for a different time, when analog computation and phono amps were king, and you didn't usually take them with you (the audio-technica sound burger notwithstanding)

>>1660363
can confirm, a good hot iron with a large tip and a big blob of solder on it is a convenient, low-volume substitute for a solder pot when small work is involved

>>1660411
>>>/diy/qtdttot/
or
>>>/o/

>>1660393
mains power is not a good choice for a first electronics project. >>1660398 is probably the correct answer

>>1660600
oxidation is simply a fact of life

>>1658777
>>1659066
Burger here. 60/40 tin/lead master race. Have pounds of the stuff. That unleaded crap causes so many headaches. Always cracking, lots of failures on anything that thermal cycles significantly, or sees vibration. Keeps my job going tho, especially reapairing car instrument clusters, usually SMT resistors are missing, replaces them and clean unleaded crap away, put new ones on with sweet delicious leaded. Read somewhere recently that a plane fell out of the sky due to all the flight computers failing (no backups left to fail over) and it was all due to unleaded solder joints failing. You can have my leaded solder when you pry it from my cold, dead soldering iron.

>>1660614
>not 63/37
smuganimugirl.jpg

>>1660466
I thought connectors were 4mm bullets but but the different contours are making me doubt their compatibility.
What do you guys think?

>>1660622
>benis egz dee
it's fine, anon

I was messing with RLC circuits and noticed that in this setup when I tweak the L value, the voltage across it peaks at some point. So I came up a with a cool problem that I haven't seen in text books. Given this setup of RLC in series with fixed values for R=100R and C=10uF, find an expression for L to maximize voltage across it. I mean, clearly we want to lower Xl to lower the total Z and therefore increase current but we also want to keep Xl high enough to maximize the voltage drop across it. Can /ohm/ solve this? If Vin = 110V, what should be the value of L and what's the Vlmax across it? Or if you are too lazy to do the math, what's the general approach?

>>1660127
>put a very small RC lag on the output of the '32 and see if it helps
This fucking did it

Actually I didn't put the RC on the output of the 32, I added a RC circuit like this and now it works flawlessly

Man, who would have thought that "muh add random capz and resistors" is actually necessary in certain cases!

Thanks for the idea, buddy. /diy/ is the best board.

My garage door opener starter sputtering today. I tried everything physical to no effect before I took the mainboard out and saw pic related.

Now I can't identify this resistor. It's burnt, so everything looks like slightly different shades of orange/brown. How can I identify this resistor to replace it? It's larger than the rest, the body is 14mm tall. You can see the proper resistor colors on other ones in the background.

Also what is the soot circled in the upper left? It didn't come from the blown resistor but I don't see anything else blown out. Is it from that transformer?

>>1660664
that's one way to exploit the difference between logic thresholds of HC and HCT to meet the 15nsec setup time requirement

>>1660665
without reverse-engineering most of the rest of the board, it's not possible to deduce the value. you could try to find a similar copy of the same model and read it directly. or, if you're especially devil-may-care today, measure what's left and (if not open) assume that heat caused the resistance to increase by roughly 10-20% and that's why you're not getting enough current for stable operation
or try chemical analysis of the remaining strip material, lel
>soot
just wipe it off with an alcohol-moistened paper towel

>>1660665
dings in the varnish that keeps the transformer core together. harmless

>>1660665
>Also what is the soot circled in the upper left?

that's a weld.

as for the resistor, assuming it's open and you have a ohmmeter, there's a trick where you can find the resistance of a broken resistor by measuring the 2 halves and adding them. finding the right spot to measure is the hard part.
anyway, the idea is you break the resistance in half and see if one of those halves has continuity. if so, measure ''ohmage'' and double the value. otherwise, there's a small chance google can find the schematic for you.

>>1660684
Shoot. Well it looks like that 12 cent part just became a new $250 garage door opener.

>>1660697
Ok thanks. Should I plug it back in and check it by poking with a roofing nail? Sparks = it's working right?

>>1660698
>that's a weld.
No, under the transformer on the PCB. It's black with soot, it wipes off with my finger.

It's an opener from 1993, there's zip online. No replacement boards, no schematics, nada.

Thanks for trying dudes, I'm flipped.

>>1660543
>up to 100A
>not making smoke and explosions
Not sure what kind of thyratrons you're working on, but for most of us a 100mA or 1A current limiting would make more sense.

>>1660665
Reverse engineering the circuit is the only way I can think of to figure out the replacement resistor value. But if you happen to have a big wire-wound rheostat lying about you could sub it in. That top band looks black, and the bottom one is probably brown, which is a problem because black doesn't make sense as a tolerance (nor as a first digit). Pic related could arguably help, but it's a 4-band resistor so I doubt it.

I don't suppose there's a service manual for that, is there?

>>1660697
He's circling the dirt underneath the transformer.

>>1660704
I believe it's upside down with brown being the 4th band, on the "top", when I first looked at it I thought it was red orange orange brown which would be 23Kohm with a 1% tolerance, but because those two middle bands are dissimilar colors AND dissimilar from what I think is the red (#1) band, I can't be sure.

There is a detailed install manual with several wiring diagrams, but it doesn't have an internal schematic, only wiring diagrams for power cable, sensors and opener buttons.

>>1660708
In that case, all I can suggest is to trace out the circuit around that resistor and figure out what it's in series with and hence what sort of current should be going through it. With a single-sided board like that it should be pretty easy, if you can get god photos of it.
I can guess is that it may be a fuseable resistor, especially since it's right next to a MOV or two (or are those Y suppression capacitors?), but I'm unsure what "stuttering" means and it probably doesn't indicate the whole thing going open-circuit. Still, there aren't any other high-current components nearby and it won't be a resistive dropper for a power supply of some sort so I can't guess anything else.

>>1660663
It's just resonance, it's determined by frequency and has no bearing on the actual voltage other than the output amplitude. Try using complex impedances to make a transfer function, the answer should be pretty obvious. Or just run an ac analysis in spice.

>>1660699
>$250
$250 might be worth a few minutes of tracing
one low-effort high-return assumption is that it's part of a shunt regulator in the fashion of Pic related. the shunt diode is a more or less constant-voltage device. the resistor value is selected to get that diode to dissipate some amount of power up to its rating when rectified mains voltage is applied. so, you find its shunt diode on the board, guess or determine its power rating by its package and/or markings, guess or determine its voltage by markings and/or by injecting current-limited dc into it until constant voltage is achieved, calculate the shunt current by I=P/E, derate by subtracting 30%, and calculate the resistance value by good old R=E/I. it's a good idea to go a couple or three notches higher on the resistance and probably go to the next higher power rating for the resistor, if it can be made to fit
>$0.12
for that price, you could buy an entire assortment, and determine the correct resistance empirically (starting from high resistance) until it works or until the foil lifts off the board

>>1660704
>>1660708
by convention, the tolerance band is separated from the value bands by a wider space. on 1/4W and 1/8W 1% resistors the difference is nearly invisible but here it is obvious. also note the metal deposit in the center, not present on other bands. therefore you're looking at a band that was silver or gold before baking
as for the value, most dyes darken toward brown when heated enough. 25 years at 80°C is probably enough

>>1660717
varistors would not be called out as C on the silk

>>1660717
>It's just resonance,
I thought so too, but resonance just means xC=xL so they cancel out and Z is the lowest and the current is at maximum. But that doesn't mean I*xL is at maximum, right?
>Try using complex impedances
Yes that's what I did but the answer is not that obvious because you'd have to do one more step and optimize the transfer function to maximize I*xL. If you set xL=xC then keep increasing L from the resonance point, the current will go down but the voltage drop across L will keep increasing until you reach the maximum I*xL. BTW the answer is pretty close to the resonance point so I was wondering if it is possible to further change RLC values to move Vlmax further from the resonance point. The red graph is I(xL) and the blue one is VL(xL). The dot is the resonance point for the given values.

>>1660741
Ah I think I got it: it has to do with the Q factor. Increasing R will decrease Q and will make the resonance curve more flat further separating the resonance point and VLmax.

>>1660723
>varistors would not be called out as C on the silk
Oh shoulda noticed that. Still makes you wonder.
>$250 might be worth a few minutes of tracing
Exactly my thoughts.
>shunt regulator
I don't think so, the transformer in the back has what's probably a rectifier bridge at the output of it, so any low-voltage supply they have will likely just be generated via the transformer. I imagine those larger diodes near the power-resistor and caps are just freewheel diodes for the relays. He could read the diode part numbers and deduce whether they're zeners or not with relative ease. Now that I think of it, those caps are probably noise suppression for the relays too. Makes you wonder what all those smaller diodes are for, if not some sort of noise suppression for that pin header. But whether my guess of a fuseable resistor holds any water at all relies on whether they'd use a 2W power package, which perhaps isn't as likely as I was thinking.

>>1660665
pic of underside

>>1660723
>>1660782
I'm pretty much resigned to buying a new opener, the only multimeter I have a some chink free one from a Harbor Freight coupon and honestly I'm way out of my element, even if you worked up a step by step it would be like reading phonetics without understanding. Electricity is magic.

But if you want to have a look for fun here's both sides.

>>1660782
>>1660784
Oh and looking at that pic I see there's another blown resistor, behind the right end of that black patch wire. It's sizzled and the back side of the board is discolored there too.

>>1660784
Done some simple tracing, the power resistor is across pin 1 and pin 8 of J1 (where the top pin is pin 1). It's in parallel with R72 if it were installed. J1 pin 1 also connects to relay K3's upper-right pin, the right pin of diode D6, and to the positive pin of the large electrolytic in the top-left and to the output of the bridge rectifier, (and to a bunch of other stuff) so it's safe to say that J1-1 is the low-voltage power rail. I can only assume it's a 24V rail, considering the voltage of the relays. J1 pin 8 is also connected to one of those little ceramic capacitors to a rail (all the other caps are also tied to this rail) which leads nowhere except that big hole surrounded by solder, so I assume it's the chassis ground.
No mysteries here, can you show what's on the other end of J1's (ribbon?) cable?

>>1660798
Oh and the other dead resistor leads to +24V and to the upper pin of J2.
And the diode is across the coil of the relay, and the blue capacitor is across the contacts of the relay.

The other anon may be correct that it's a shunt from a zener supply, if there happens to be a zener on the other end of the jumper. Shunting a plausible 50mA to ground through such a resistor on a 24V rail would cause it to waste 1.2W of power, potentially justifying its rating if that is the case. But why they didn't use another winding on the transformer doesn't make too much sense to me.

>>1660798
>can you show what's on the other end of J1's (ribbon?) cable?
My car's in the way and the ladder is put away but here's the diagram. That cable is for all the inputs, switches and sensors.

The problem the opener had was it would randomly stop or reverse as if one of the stop sensors is being tripped. It started happening once every activation or so with the door getting partially open, but got worse and worse until now, it stops within 1 second of the button being pushed.

I don't think there's any significant hardware at the other end of any of those J1 wires, just low voltage switches and sensors. I have no idea what J2's "Sensor Board" is, it's attached to the gear train next to the motor's capacitor. Maybe it's to sense unwanted movement, RPMs or torque.

J3, the big white wire bank, goes to the motor.

>>1660806
Ok I'm lost. I can't fathom why you'd have a power resistor heading to limit switches or to that section on the left. What are those 3 squares with circles in them supposed to be? Those limit switch symbols are also alien to me, as is why the down limit switch has two wires on that one end. I can identify what looks like pullup resistors on the PCB, which would make sense for use with the limit switches, but there are both power resistors and normal 1/4W resistors in the same section of the PCB, and none of them have the same values.

>>1660784
that's fun
it looks like R69 is part of the power for the "photocell" transmitter and receiver. there's a tap that runs to a quad op-amp or comparator under the radio board so the controller can tell that the photo-beam is connected and that it is not signalling something in the way. so we know the value is probably defined. if the photo-beam sensor is a 4-20mA current loop, as is conventional in industrial control, then a probable resistor value is 1200 ohms, brown-red-red

>>1660814
>three squares
screw terminal block

>>1660828
>screw terminal block
To what? I can't tell if the "pushbutton, common, photocell" are referring to that terminal block, but if they are there's a lack of any button on the diagram. But it's definitely possible that the dead power resistor is current-limiting for an IR LED, in which case you just have to look at the IR LED and see what package it is. The package will tell you what heat dissipation it can handle and you can sub the resistor with whatever suits the purpose. Of course the LED could also be dead, which is something you'd want to check.

>>1660784
>>1660828
which is confirmed by the remains of the damaged coating
1200 ohms, 1W (may as well get a 2W), ±5%
https://www.digikey.com/product-detail/en/stackpole-electronics-inc/RSF2JT1K20/RSF2JT1K20CT-ND/2021801

>>1660831
yeah, it's a shitty drawing
>inb4 meme arrows
guess you're just supposed to know that the other side of the button goes to the common terminal
>current limiting for an IR LED
but what of the receiver? Pic related is more likely. big red dots are the screw terminals (not in order), red dotted line is the enclosure boundary of the drive unit (right = outside of box)

>>1660833
Does that circuit work as a sensor? I assumed there was some missing information there since they didn't just connect the two sensors together at the transmitter-receiver part of the diagram. It's certainly odd if they are paralleling the two.

Also I missed a part of the circuit, the end of the power resistor goes all the way around the edge of the PCB into the are underneath the daughter-board, probably through another resistor and into two pins of a DIP14 IC. So it is likely being measured as an analog value, probably by an analogue IC judging by the amount of passives around that part of the board, probably to be sent into the main chip.
Also that IR LED is probably being driven at something closer to 50mA, not 5mA. At least that's what I'd have done.

holy shit, fucking local jews are selling high quality multimeter probes here for $40 and i found nearly identical ones on ali for $1.8, this is crazy!
I can't believe the local jew keeps getting away with it

>>1660814
>What are those 3 squares with circles in them supposed to be?
Those are wire terminals, to bridge the internal circuit to the external wires run through the walls to the push button and light sensors.

>>1660828
>>1660833
>brown-red-red
If that's brown then the even darker 4th paint line is black and that doesn't make sense? Black isn't listed under tolerance.

>>1660839
>since they didn't just connect the two sensors together
The two sensors are connected together in parallel at the "squares with circles" wire terminals.

>>1657614
kek, you need a boost converter for that
or a buck boost converter

>>1660839
absolutely. currents in parallel add. as long as the phototransistor in question can sink that much current, easy. the IR LED's current can be allowed to rise and fall a bit in opposition to the receiver signal. keep in mind there are lenses, enclosures, and maybe blinders on both sides
>likely being measured as an analog value
the pinout of the DIP14 is consistent with the LM339 quad comparator. I see a window comparator arrangement on pins 1-2,4-7 of the chip, a data detector of some sort on 8-9,14 of the chip, and I lost interest in what the 4th comparator was doing
>50mA
first, the numerical currents are just for illustration. actual values will vary and require a look under the radio daughterboard (cute mounting scheme)
second, y tho. what desirable comes of it? wiring might need to be made thicker or more complicated, risk of light spilling or bouncing around an interfering object, risk of a short throwing a spark causing fire or explosion, you'd have to triple the power rating of that resistor. there are probably more reasons that don't come to mind immediately

>>1660853
I think the center of the band being a bit sparkly suggests there was once glitter in it, suggesting 5% or 10%. I think it would be unlikely for a mass-production device like this to use a 1% power resistor lightly, especially since it would imply that the receiver and transmitter are of similar precision. it would also imply the resistor has five bands. 10% doesn't seem compatible with a current monitoring circuit
but if it is in fact 1%,
https://www.digikey.com/product-detail/en/vishay-bc-components/MBE04140C1201FC100/BC4524CT-ND/7351954
is only 50 cents more

>>1660855
>lm339
I was thinking that it looked familiar, with the power pins slightly offset from the middle on either side.
>y tho
Well A: higher signal:noise ratio assuming it isn't fully blinded from the outside (e.g. as in your pic)
and B: because how else did a >1W power resistor overheat? I guess it could have been thermal shock from too many heating/cooling cycles, but they used a >1W for a reason.
My low estimate is 20mA, since it's IR and those only drop 1V or so it could be as high as 50mA without burning through it. Either way the wire thickness won't be terribly important, for example: 32AWG (0.16mm) wire is rated at 180mA at +60°C.
>spark or fire
It's 50mA, not 5A.

If we can agree that yes the dead resistor is being used to limit current to the IR LED, then the actual value will be semi-critical when it comes to hitting that comparator threshold.

So listing possible colours that line up with 10% standard values:
>10
>12
>15
>18
>22
>27
>33
>39
>47
>56
>68
>82

12 is the only pair that looks earthy enough and with the right contrast. 1.2k would give about 20mA.

>cut open chink dupont cable
>it's copper inside
i think i just got reverse chinked

>>1660704
So i just set the constant current to say 3A, and then let it run until i detect the battery at say 14V?
That seems wrong, i know lead acids are supposed to have like several charging cycles

>>1660882
wrong reply friend
You'd probably be fine if you set the current to 500mA and "trickle" charged it up to 14V. Not like a car alternator is going to charge with any sort of fancy charging cycle.
Anyhow, googling for "lead acid charging curve" should do the trick.

It's a different matter entirely if you want to recover a properly dead lead acid however.

>>1660885
Well it's an expensive deep cycling agm battery so i don't want to fuck it up.
And i also don't want to melt my also expensive bench power supply

>>1660861
>blinded
it wouldn't be. lenses and apertures exclude most off-axis light. if they were especially clever they might have even modulated the LED and received and demodulated on the receiver side, to pass some sort of signal even when blinded. we are speculating blindly as to the level of technology in the actual transmitter and receiver, the simplified sketch is just "one way they could have done it"
>because how else did a >1W power resistor overheat
it looks like a 1W component to me. I only suggested 2W so he could leave this thing to his grandchildren
>heating/cooling cycles
would happen on average a little more than twice or thrice a day, if due to operation. you also get one per day from weather absolutely free, maybe a lot more if winds are variable and cold and the garage is ventilated on only two sides
also, carbon resistors generally increase in value as they age, and faster at elevated temperatures, per Arrhenius' Law. the effect is slight but present
>If we can agree
it's being used to limit current into the wire, transmitter, and receiver, in toto. any current limiting particular to the transmitter is located inside the transmitter (maybe another 1.2k resistor?), which there would certainly be, otherwise the receiver would have very little headroom to pull current and thereby vary the sense resistor voltage

>>1660886
>I've got an expensive thing, how do I nigger rig it
wew
lead-acid chargers are $20 on spamazon, which might be closer to your level of risk tolerance

>>1660887
He said 17mm long, aren't 1Ws usually shorter than that?
>another 1.2k resistor
It's plausible I suppose. If there were two in series, perhaps it's possible that something shorting the second one (water ingress) caused the first one to die.

While we're here, does that R underneath the end of the black bodge wire look dead, or just a bit dirty? It's part of a completely different circuit, so if so it will likely be from a different issue.

>>1660886
Don't worry, you will smell it.

>>1660888
he said 14mm, in >>1660665 ... which, according to this Stackpole datasheet, is 1mm shorter than their 2W. if the source voltage is in fact 24V and not 24*sqrt(2) volts, it is not possible for a 1.2k resistor to dissipate more than 1/2W. also the door would have been unable to close in case of a short in the light-beam circuit (the window comparator tests for that)... unless the window comp is faulty too
>resistor under the bodge
it doesn't look dead yet, but it has seen better days. if anon is going to place an order anyway, he may as well add on a 1.8k 1/4W

>>1660891
>this stackpole datasheet

several days ago, some anon was trying to use optoisolators to transfer serial data across an isolation barrier. I got bored this weekend and decided to measure, not least because one of my projects in progress requires to transfer serial data across an isolation barrier. a TLP521 was set up on the UART pins of an Allwinner H2+ dev board, looping transmitted data back to received data, using 3.3V CMOS logic levels. best data transfer speeds were obtained with a 2k dropper resistor and 10k pull-up resistor. at 57.6k ASCII data was successfully received with no error. at 115.2k no data was received. framing errors were not checked
according to the datasheets, the TLP521 is only a little faster than the jellybean PC817, which I do not have in stock atm. I might test them later

>>1660891
It's got a filter cap on it, so I'm guessing 24VDC is correct. It could be as high as 40V per pic
https://omronfs.omron.com/en_US/ecb/products/pdf/en-g5le.pdf
and the filter cap did look like a 50V model, but I doubt they were running it hot.
It could be a 680Ω? Blue-grey-brown would roughly have those darkness transitions, assuming a blue could get toasted into that much of a warm tone. Guy should buy one and put it in the oven to check.

>>1660899
neat

I want to pick up sound from many microphones at once and get the output via USB. Is any book in the OP in particular good for learning how to do this?

>>1660858
>10% doesn't seem compatible with a current monitoring circuit

that's a silly thing to say given that the distance between transmitter and receiver is unknown, and could easily vary by 100%.

>>1660909

for the price of a book, you can get a ready-made professional product that takes zero time to build.

>>1660909

for the price of a book, you can get a ready-made professional product that takes zero time to build.

>>1660909
First look into USB class compliance.
https://www.usb.org/documents
https://www.usb.org/sites/default/files/audio10.pdf
USB is a pretty complicated standard that needs a fair bit of thought put into how you define your device, as all the data going to and from it will need to be interpreted by your computer, preferably without having to write drivers for it. I imagine there are standardised drivers for mono and stereo microphones, but you'd need to find out if it's possible to have more than two channels without resorting to some sort of analog multiplexing (such as mixing a channel up by 40kHz) or driver writing. Looking at the document it looks like the "bNrChannels" value that describes the number of audio channels is written 0x00 you could arguably get it up to 0xFF, or 255. There also seems to be position values for use for describing surround-sound, which is interesting.

A fairly easy method is via V-USB (possibly USnooBie too), which I believe is best put on something like an ATMega32U4 or possibly an STM32. Naturally you'll need to choose a microcontroller that can handle the number of ADC channels you want to use.

>>1660917
>his books cost 44GBP
Jesus.
If he knows what he's doing he could easily pull this off for a quarter of the price (probably with inferior sound quality). But that's a big if.

>>1660917
and this board is called /diy/, you fucking retard.
I need to build it because I need it highly customized and tweakable.

>>1660923
it will be a big time sink though
what's it for?

>>1660922
>>>1660917 (You)
>>his books cost 44GBP

there are a bazillion price points, number and types of inputs, external or internal, USB/transformer/battery power sources, etc.

fixating on one random variable could be a sign of autism. pls visit a professional for an evaluation: you dont wanna be the last to know what everyone else knows.

>>1660922
thank you so much. this is exactly the kind of info I need.

>>1660924
science (for real).

>>1660923
>I need to build it because I need it highly customized and tweakable.

then the answer is no, none of the books tell you how to make a USB gadget.

>>1660927
double-spacing is a sign that you're not from around here.
pls visit a professional for euthanasia, or do it yourself.

>>1660930
then you're free to not reply if you don't have any other helpful resource suggestions.

>>1660931
Making your correspondence look good is now a bad thing?
Sure thing kiddo.

>>1660933
>Making your correspondence look good

a lot of girls are on their period this morning.

i checked Amazon for fun, and AoE 3rd ed is fucking $97 new in hardcover, and $86 in ebook format. that's way more than 44 UK pesos.

a lot of girls are on their period this morning.

i checked Amazon for fun, and AoE 3rd ed is fucking $97 new in hardcover, and $86 in ebook format. that's way more than 44 UK pesos.

>>1660941
I don't see why people mention the price of books?
it took me <30 s to get free download links for all Eds

If you have say a 4V zener diode and pump 10V into it, will the zener start dropping only any voltage above its limit or all voltage?

So if there is going 10V into my load, and i add the zener before the load between the +10v rail and ground, will my load be getting 6V, or 0V?

>>1660951

the graph tells the tale. it starts to conduct hard at around 4V and drops 4V, so you get 6V out, assuming you're pulling enough current.

>>1660965
This makes no sense.
Many circuit use it for overvoltage protection, but if you have IC that takes 10V and use 11V zener to protect it, then if you get say 15V voltage spike the zener drops 11V from it and it works fine, but if you get a 30V spike then zener drops still just 11V and your 10V IC gets fried with 19V

>>1660951
>will my load be getting 6V, or 0V?
Neither, it will be getting 10V because the 4V Z-diode has left memeland.

>>1660951
If you "pump" (whatever that means) 10V into your 4V zener you will fry it. If you have a constant voltage supply and do exactly as you described, you will have a fried zener and your load will see 10V. not 0V, not 6V.

But if your normal operating voltage is less than 4V and there are *brief* voltage spikes above 4, the zener will clamp the spikes above about 4V by shunting current to ground, and your load will see 4V during those brief spikes.

AoE is a meme.

>>1660967
The zener is installed across the voltage input.

The voltage across a zener diode is never more than its rating, at its rated maximum current. So, if you try to push a voltage over 11 V into your 11 V zener, the voltage will max out at about 11 V, until either the power supply or the zener dies.

How often does this need to be repeated.

>>1660928
>science (for real)
Good luck then! But I'd certainly consider using something like a raspberry pi with an external ADC or two such that you can read it solely with the GPIO pins, no need for jumping through the USB hoop at all.

>>1660951
use a resistor in series with it like a normal person

>>1656975
>ohm sweet ohm edition
open volts & short amps
halp what do

>>1661219
thevenin bro
maybe millman's theorem

>>1661219
Thevenin or that there loop method where you add the current loops, don't remember its real name.

>>1661220
>thevenin
thanks, got stuck with that
>millman's theorem
never heard, looked it up
have only one source though

>>1661234
>you add the current loops
Norton? That seems to be behind the Millman thing.

>>1661237
I mean solving for currents in the individual loops in pic related and then using those to solve whatever it is you're looking for. I think it would be the easiest method here

>>1661236
If nothing works then T to PI..

>>1661239
Oh, you mean KCL?

>>1661242
T to PI magic, aka Star-Delta. Could reduce the entire circuit to almost nothing. Failed with KCL, need to work on that. Thanks to all.

>>1660922
>V-USB
>audio
and you don't know off the top of your head why this won't work?

>>1660909
where are you starting from, electronics-wise? like most sciences, electronics begins with basic laws and ideal components, and elaborates them into real components and more complex networks

>>1660943
some people actually like reading and navigating wood

>>1661300
I only briefly looked at the V-USB documentation, is it too low-speed?

>>1656975
what is the best multi-meter for 50 bucks and below?

>>1661314
Aneng AN8009

>>1660923
Nah, you don't need it more customized and tweakable than a professionally made product.

>>1661316
while it work well in integrated things, or is the more general one for house wiring.

>>1661312
it's *only* low-speed. bulk and (pertinently) isochronous transfers are not available to a low-speed device

>>1661338
Then how about an MCU with USB built in? Not sure which ones he'd be looking at, but they surely won't be $60.

>>1661239
Superposition

>>1661364
correct, bluepills are almost free

>>1661337
house wiring isn't really what this general's for, but the AN8009 is built to take the abuse and will serve nicely as a mains test/measurement tool. see the safety labels below the input jacks, see http://www.ni.com/product-documentation/5019/en/

>>1661368
Yes it has true RMS with CATII at 1000V so it's fine for mains use. It also has a mV and mA (and µA) mode so it's also suitable for small-signal use. Not to mention the thermocouple, AC frequency, and non-contact sensing modes. 9999 count is also pretty nice.

Apologies if this is the wrong thread to ask in, but I need some help with electronics maintenance. This might be a brainlet thing to ask, but searching for answers online gave contradictory and unclear information.

My backward-compatible Playstation 3 can play Blu-ray discs but is no longer able to successfully read DVDs and PS1 and PS2 discs. I've wanted to open it up and clean the lens but I'm not sure what methods are best for doing so. There are reports of cleaning discs that use small brushes, but I've heard this can just stir dust around and cause further damage. I have 99% isopropyl alcohol and q-tips, but I don't know if that could strip away any layering or if 99% isopropyl alcohol will be too powerful. I plan on opening the console and dusting it out as well, so should I even bother cleaning the lens, or should I first test the console after using canned air?

My Nintendo Wii has been having similar issues. In June it began struggling with loading screens, couldn't load background music, and then began failing to properly read discs in general. I want to open and clean it, but I don't know if the Wii's lens can be damaged by substances that pose no threat to other consoles. Should I just use the isopropyl alcohol and the q-tips, or is there a specific cleaner/cleaning disc that is recommended?

Thanks.

Hi all, noob here
I’m trying to get precision air temperature control for an incubator. I would like to use ac phase angle control/dimmer circuit, but most off the shelf modules are limited to 250W. I was wondering if I could simply buy a zero crossing module alone, and then activate a 40A solid state relay instead of a triac?

>>1661398
You could carefully open them up, find the lens, cover with Kim wipe/lens paper, and then use compressed air to dust everywhere. and then clean the lens with the lens paper

>>1661399
PID controller? A simple dimmer will just change duty-cycle and hence change the average power, not have any feedback system. For incubation you almost certainly want the feedback that comes with a PID controller, though you can make your own (analog or digital). An SSR or TRIAC works depending on the circuit you have behind them, and a PID controller will often have provisions to use either.
A simple bimetallic strip adjustable thermal switch may also be sufficient.

What heater are you to use?

>>1661406
Yep, this would be part of a pid controller, I’m using an esp8266. Can you elaborate on how interchangeable SSRs and triacs are? Should I be able to trigger the SSR on and off between zero crossings?
I’m using a 1500W ceramic radiator with fan ripped out of a space heater.

>>1661409
>Can you elaborate on how interchangeable SSRs and triacs are
I was more alluding to how proper PID controllers (the ones with a power supply, display, built in thermocouple reading hardware, programming buttons, etc.) have seperate output pins for triacs and SSRs.
If you're programming your own ESP, you should be able to just PWM the output of the SSR without worrying about zero-crossing at all. Provided the SSR's datasheet says it's fine for the kind of switching frequency you'd use. The SSRs have an opto-isolated input so shouldn't care even if your ESP is floating up on one half of the mains cycle.
>1500W
Pretty beefy. That at ~230VAC?

What do y'all think about a circuit like this? Seems nifty, found it on pinterest, some unique content on there for sure.

>>1661415
>you should be able to just PWM the output of the SSR without worrying about zero-crossing at all
Huh, I figured that the response would be not be well behaved due to aliasing or something like that.(also, you mean pwm the input right)
Its 1500W in the us, 120v

>>1661416
Show pinout of ignition coil, is the HV output a positive or negative? Also holy shit that looks awful

>>1661422
oh yeah, pwm the input of the ssr, from the output of the esp

What is the simplest form of radiocontrol someone could implement using only passive components and a PCB antenna?

>>1661409
>Can you elaborate on how interchangeable SSRs and triacs are
SSR's are triac circuits encased in something

>>1661409
not at all. SSRs isolate, triacs don't. SSRs for ac output are usually designed to turn on and off only at zero voltage i.e. no more than 2x line frequency, triacs can turn on at almost any phase angle but only turn off at zero voltage. SSRs are somewhat protected circuit modules, triacs are unprotected monolithic silicon devices
it's a bad idea to even try to phase-angle a motor much larger than 1/2HP. back emf from the motor will kill your switch
would a simple PID on-off control cause too much process ripple? this sounds like a work project where you're looking for a working system with minimal effort, not a fanciful romp through new technologies or a class assignment

>>1661427
https://en.wikipedia.org/wiki/Crystal_radio

>>1661416
looks like an excellent circuit for attracting pissed-off hams and/or the radio regulatory authorities in your jurisdiction

>>1661425
The positive lead of the primary and secondary are the same, which I believe is standard for any 12v ignition coil.
>>1661432
It shouldn't generate significantly more interference than the normal operation of a standard vehicle, the 20+KV reverse biased diode before the aerial indicates that this circuit is not a RF transmitter.

Here's a similar circuit, with additional information regarding matching the capacitive reactance with the inductive reactance for presumably optimal current gain.

>>1661404
I appreciate your reply. Is this along the lines of what you're referring to?

https://www.amazon.com/Kim-Wipe-34-155-Case-60/dp/B00NB58GA2

What locals stores might have them in stock? Is there a particular brand that will be helpful if I don't use a Kim wipe? Thanks again.

>>1661436
>a diode
all free energy fags need to read this
https://en.wikipedia.org/wiki/Parasitic_element_%28electrical_networks%29

>>1661430
>crystal radio
Not very specific, but yes a simple diode detector is the simplest method. But for the modulation in the first place, an SA602 is going to be easier than any hand-wound transformer/inductor-based mixer, and if you're going to be using one of those it wouldn't be a stretch to use another for demodulation too.
I recommend using an emitter-coupled oscillator to generate your RF, since it's not as finnicky as single-transistor or multi-capacitor topologies, and is still really low on part-count.

>>1661443
Not to mention those things have a 50V forward voltage. I'm not too sure what the diode is supposed to be doing. Also:
>shumann resonances
Pretty sure those are way worse than AM or FM broadcasts as far as radiant intensity goes, but it's an interesting circuit nonetheless. I may build one since I happen to have a pack of those 20kV diodes and a HV flash-globe autotransformer in my parts' bin, a varicap too. My transistor tester is fucked though, so I'd have to figure out some way of testing the frequency of the tank circuit with my scope. Pretty sure I have a 74HC14 lying about I could use.

>>1661443
Energy harvesting is still a worthwhile endeavour, for things where batteries won't last and solar power is impractical. Not that I think it could charge a 12V deep cycle faster than its self-discharge.

>>1661443
Thanks for the EE101 info, captain obvious... Cool self rendering as well.

It's commonly asserted that aerial based circuits simply leech ambient RF from nearby transmitters or couple with HT overheads. Yet, if you were to calculate the average power density of the air and compared it to the output of some of these circuit configurations, you'd see the discrepancy in output power cannot be accounted for with hasty explanations of "stealing power," noting that experimenters have reported being over 200 miles from the nearest transmission lines and are able to power lights and charge batteries from air to ground potential.

>>1661444
>using only passive components and a PCB antenna?
>SA602
/ohm/ RULE 4, not that I should have answered an obvious underage poster to begin with
>50V forward voltage
look up the reverse capacitance and reverse leakage. they may be significant

>>1661447
The thing I find weird is that it's tuned to schumann resonance but the potential itself is a DC thing. Naturally you can't pull DC power out of a plate inserted in the middle of a capacitor (it just pulls the potentials of the plates your load is connected between together) so you need to actually get this power from somewhere in the form of AC, but it's still unusual. There's not a straightforward description of what's happening as far as I can imagine in terms of E&M. Help me papa maxwell.

>>1661449
>only passive
But you can't transmit anything with only passive components lest you use some god-awful spark-gap transmitter.
>RULE 4
He wasn't name/tripfagging, and he wasn't smoking either.

>>1661430
> not at all. SSRs isolate, triacs don't. SSRs for ac output are usually designed to turn on and off only at zero voltage i.e. no more than 2x line frequency
thanks anon, I had a difficult time with this topic online

> it's a bad idea to even try to phase-angle a motor much larger than 1/2HP. back emf from the motor will kill your switch
would a simple PID on-off control cause too much process ripple? this sounds like a work project where you're looking for a working system with minimal effort, not a fanciful romp through new technologies or a class assignment
thanks for the warning, but I'm not intending to use anything fancier than a relay on the fan, the load is literally a resistor. I did try pid on-off control with an SSR, but it causes my lights to flicker, my apartment is old.

> this sounds like a work project where you're looking for a working system with minimal effort, not a fanciful romp through new technologies or a class assignment
lmao lay off me, I just want to grow koji lol

>>1661430
> not at all. SSRs isolate, triacs don't. SSRs for ac output are usually designed to turn on and off only at zero voltage i.e. no more than 2x line frequency
thanks anon, I had a difficult time with this topic online

> it's a bad idea to even try to phase-angle a motor much larger than 1/2HP. back emf from the motor will kill your switch
would a simple PID on-off control cause too much process ripple?
thanks for the warning, but I'm not intending to use anything fancier than a relay on the fan, the load is literally a resistor. I did try pid on-off control with an SSR, but it causes my lights to flicker, my apartment is old.

> this sounds like a work project where you're looking for a working system with minimal effort, not a fanciful romp through new technologies or a class assignment
lmao lay off me, I just want to grow koji lol

>>1661430
> not at all. SSRs isolate, triacs don't. SSRs for ac output are usually designed to turn on and off only at zero voltage i.e. no more than 2x line frequency
thanks anon, I had a difficult time with this topic online

> it's a bad idea to even try to phase-angle a motor much larger than 1/2HP. back emf from the motor will kill your switch
> would a simple PID on-off control cause too much process ripple?
thanks for the warning, but I'm not intending to use anything fancier than a relay on the fan, the load is literally a resistor. I did try pid on-off control with an SSR, but it causes my lights to flicker, my apartment is old.

> this sounds like a work project where you're looking for a working system with minimal effort, not a fanciful romp through new technologies or a class assignment
lmao lay off me, I just want to grow koji lol

I have a very simple constant current source with lm317 like this.
The resistor (I = 1.25 / R) determines how much current is being pushed through the load and i would like to be able to change that resistor digitally somehow.
The resistance range i need is between 1 ohm - 100 ohm
Now, there is a bunch of digital resistor chips with serial interface or i2c, but they are all useless because they can only handle current in the range of milliamps, and i need to output currents up to 1.25A. How can i solve this?
(no buck converters etc, it has to be lm317)

>>1661463
So far the only thing i could think of is something dumb like getting a 2W multiturn pot and rotating it with a small stepper motor

>>1661463
A shunt resistor (0.01Ω) in order to monitor the current, that voltage feeding into an op-amp circuit along with a voltage divider of some kind. Probably will want two op-amps, one to amplify and buffer the shunt reading, the other to provide feedback to the transistor you'll be using to drive the current into the load.

>>1661479
>transistor you'll be using to drive the current into the load.
would that also work with fets?

>>1661460
not laying on you fren
ohh, you're PIDing the heater, not the fan. ok. in that case the thermal mass of the heater won't necessitate a high PWM frequency. maybe something like 1sec is enough
don't forget to snub the contacts of your relay

>>1661463
if you're willing to allow for a significant minimum operating current, you could place a digipot across R (chosen for minimum I) and connect the wiper to the adjust terminal. you would probably want to put a resistor on the 317 side of the digipot to limit maximum current too. be sure to confirm that the milliamps the 317 puts through its adjust pin are less than the milliamps the digipot can handle. also, reminder to consider isolation and the permissible voltage range on the resistor inputs, and also "wiper" resistance, and to use the lowest end-to-end resistance you can find
if you weren't married to that 317 I'd suggest you try a modern LED driver IC made for lighting. they are basically constant current sources in the form of a switching converter and can push amps no problem. many have a dimming input which can accept analog or PWM inputs (or both at the same time by varying your PWM voltage), and at least some will convert PWM to analog internally instead of just gating the current source on and off. semiconductor companies like Brightpower and MPS have a broad selection of LED driver chips for almost every need

>>1661480
MOSFETs can be noisy in their linear region, but sure

>>1661463
>>1661481
Pic related, top R is 1.25/Imin and rated for max power, bottom pot is as small as possible but at least 500 ohms, red R is Rpot*(1+(Imin/Imax)), I think. if accuracy and linearity are a particular concern, it wouldn't hurt to add a voltage follower, indicated in red

>>1661481
>connect the wiper to the adjust terminal
>>1661482
>R..rated for max power
100Ω 125V 156W

You can only increase the current set by Rs that way.

>>1661463
why not just pwm the output with a low-pass filter afterwards, and measure the current with your adc if you're already using an mcu?

>>1656975
I have experience with electronics but ZERO experience with audio shit. Now I need to make a guitar fx pedal and I have no idea what to do.
Is it viable making a chorus & delay effect using pt2399, analog switches and PIC autism to make parallel /serial connections with user input? How good are those ICs? I was thinking about using the PICs as digital delay lines but mine are 8 bit and have shit ram

I made a PCB game-controller for my smartphone. It works fine but I used those cheap mechanical buttons everywhere on aliexpress and they are noisy as hell.

I've seen PCBs from xbox controllers and the like and it's just a silicon membrane and some weird footprint on the PCB. Does anyone know a name for those things? The thing on the PCBs? Looks greyish, like carbon or something.

Or does anyone have experience with pic related? Are they quiet? Still, I only find it really small (4x4mm), I'd like them like my 12mm mechanical ones.

>>1661437
Any product for cleaning lenses should be fine

>>1661603
Also where the fuck I can read about chorus effect coeficients and delay times? Guitar forums are 100% cancer

You guys are probably the best bet for this question.
I'm looking at buying a laser diode to do some light cutting, in particular thick card.
What would be the recommended power for a nice clean cut with minimal soot?
Obviously more power would be best but if I don't need to spend the money on a 5W module I won't.

>>1661504
Rshunt's VALUE should be chosen according to Imin, but Rshunt will still be called upon to dissipate Imax^2*Rshunt at max current. exercise that prefrontal cortex won't you

>>1661463
this anon is right, you know >>1661506
and this is also why you design systems rather than just smashing two bricks together and painting yourself into a corner

>>1661603
>how good are those ICs?
PT2399? meh, could be good enough for what you want to do
PIC? shit on a biscuit

>>1661604
dome switches are about as quiet as the other buttons on your phone. in general, the lower the actuation force, the quieter the button

>>1661615
>coefficients
lel
start around 2msec and adjust from there until it sounds right

>>1661705
that's a thermal question, not electrical
>>>/sci/
or
>>>/diy/qtddtot
or
any of the hundreds of frickin' laser beams videos on youtube

>>1661604
I bought some of these a month ago:
https://www.aliexpress.com/item/32724698079.html
Note that the ones that came have 2 pins, not 4. They're probably not too good to be used without any sort of keycap, since they have a tendency to push over to one side, and they have a fairly small surface area on the top that isn't ideal for fingers.

>>1661851
shit like this makes LCSC, cluttered mess that it is, look like Digi-Key

>>1656975
is there anything better than omron switches for mouses ? I want the cheapest yet best switch for mouse switch replacment

>>1661884
Omron is a well-respected name in basic switches (including mouse switches) since decades. I wouldn't use anything else to refurbish a mouse I intend to use
>cheapest yet best
is this even your own mouse?

>>1661904
Yes, Moron is the best brand worship for shills and mouses.

Uhm, these 7805s have a quiescent current of 5mA on average, and I want something significantly lower than that considering the current being used by my circuit is less than 5mA. Is there any way I can use a MOSFET or diode or something to get better performance from a 7805? Could a zener regulator ever be better in this regard?

>>1661936
>Is there any way I can use a MOSFET or diode or something to get better performance from a 7805
almost certainly not with what you have on hand
>Could a zener regulator ever be better in this regard
not by enough to matter
Pic related is just one example of the thousands of low-Iq regulators from dozens of manufacturers, with many options as to input and output voltage ranges, precision, and cost. the example is $0.38/1 from digi-key, you should be able to find similar suitable regulators for 10 cents each in lots of 10 on alibay

>>1661936
>>1661980

>>1661980
>almost certainly not with what you have on hand
right, that's what I feared
I'll give it a test run and see if it can handle it I guess. I have both a 7805 and a 78L05, for whatever that matters.

>>1661986
for purposes of trying something, anything, you could put ye olde common-collector amp on a zener run at 1mA (or wherever the I-V curve flattens out enough, adjust by way of the series resistor). but if you're looking for an order of magnitude reduction in Iq, I think you'll be disappoint

Something like a PSU design using a cheap transformer. Yes all the filter caps are going to be 1mF. Yes those are ±325V rails giving a total of 650VDC across them. Yes it is a lot of banana plugs. The reason why the plug and socket look the wrong way around is because they're IEC C13/C14 standard.

>>1661936
Just get an LM4121

>>1662026
Wait there's no point on tying the two secondaries together as a ±18V supply if I can just get that by double-rectifying the 9V pin. So I might be able to get ±36V from this then, which is an interesting thought.

>>1661605
Is there a specific lens-cleaning product that has worked well for you? Since these lenses read discs (and the PS3 one reads two different kinds of discs), I want to be sure that nothing can be stripped away.

what is the difference between schottky diodes and nazi diodes? they seem to do exactly the same thing

>>1662063
>nazi
huh?

Schottky diodes have a significantly lower forward voltage so are preferred where you want to minimise heat produced. Now if you ask me why we don't use them instead of diodes always I can only guess it's a cost thing.

>>1662069
>huh?
germanium diodes

>>1662072
Oh. Germanium diodes are much more susceptible to thermal runaway than diodes made with silicon due to the statistical behaviour of the germanium itself near room temp. Technically you could make a germanium schottky diode (the schottky junction is a metal-semiconductor junction as opposed to the standard P-N semiconductor-semiconductor junction) with an even lower forward voltage. I think I saw a paper linked here a year or two ago about making schottky diodes from all sorts of different semiconductors and showing that some had forward voltages as low as 0.1V.
Of course, if the forward voltage matters that much to you you'd be better off using an all-enclosed self-powering MOSFET ideal diode, since they use a fully-ohmic junction. Pretty sure Texas Instruments have some designed for high-current solar arrays.
Though perhaps at really high currents it becomes worth using normal diodes again for the same reason IGBTs are used in place of FETs. You know, before you get to the point of using rectifier tubes or thyratrons respectively.

>>1662076
I see, i will stick with schottkys then since they have lower drop plus i need to switch them super fast and chinks sell them dirt cheap just like everything else

>>1662072
Compared to P-N diodes, Schottky diodes have faster recovery time but a higher reverse leakage current.

A germanium diode would be preferred where you're rectifying a low-voltage, low-current signal (e.g. the classic crystal radio design), but they're far less useful since the invention of the transistor.

>>1662076
>>1662086
Not him, but I also have a question. How do you select an optimal diode? Is it only based on maximum W you need just like with resistors? (No switching needed)

>>1662092
sounds like you're interested in the maximum average forward current and peak forward current ratings, which you will find in the datasheet, usually on page 1
and of course you use the cheapest available one that'll do the job

>>1662092

choose 1N4007 for power, 1N4148 (aka 1N914) for audio. that covers 99.5% of all non-switching applications.

>>1662097
>audio
You mean for effects pedals and such? I can't see where you'd use diodes for simply amplifying or transmitting an audio signal. Also why wouldn't you use a schottky for power? They have twice the maximum current for the same package size. Not sure what kind you want for ring diode mixers or temperature sense diodes.

>>1662100
>where you'd use diodes
cancerous fuzzfags, for example
>schottky
maximum peak reverse voltage is much lower. the young mage needs to see what happens when the smoke fizzles out of their workings, and look for a solution
>ring diode mixers
1N4148
>temperature sense diodes
2N3904

>>1662100
>I can't see where you'd use diodes for ... audio

diodes are used in over 1 billion different audio gadgets.

>why wouldn't you use a schottky for power?

because you have a parts drawer full of nearly-free 1N4007's that'll do the job.

>>1662107
Oh that's right, using diodes with op-amps means there's so little current going through them that their forward voltage is negligible. Makes me wonder about a transistor-based rectifier circuit that will work at radio frequencies.

>>1662109

>>1662115
>passing DC through your headphones
I shiggy diggy

>>1662116
How much and why not?

Yay! My new multibaby is here

>>1662126
Wow the probes that came with it are absolute shit, i hope the premium golden ones i ordered for $1.5 will be better

>>1662126
Replacement fuses included? Now 6x30 instead of 3.6x10.
Still dancing numbers until it settles on a value?

hey /ohm/, what is your goto for Chinese flux? looking for smth universal but no bga

I have a 1994 Minitel on which the display doesn't work. Andy idea of how can I troubleshoot this?
I didn't fount any dead capacitor or fuse

>>1662375
Special mention to the '94 consumer electronics assembly

>>1662379
bug fix