/diy/ - Do It Yourself

Newfag here.

I don't want to get lung cancer. How important is it to use proper ventilation when soldering? Best I've got is the overhead fan on my stove, think that's enough?

Anyone knows how to drive ultrasonic transducers?

>>2767462
I use a normal fan and haven't died yet.

>>2767462
Who hurt you, Anon?

>>2767463

>>2767469

>>2767469
>>2767470
Can that be done with less parts and simpler?

>>2767462
Most of the smoke is the flux, and a lot of that is rosin which comes from pine trees.
Humans have lived around fire for millions of years which puts off worse stuff including burnt rosin.
If you’re worried about it, you should never go camping either.
> but i use synthetic flux
You’re on your own there…. I’d probably use a vent hood in that case. Most of my flux is in my flux-core solder and It’s 50 years old now.

>>2767462
You usually want something to specifically move air from right in front of your face. Like 10cm from the workpiece. A simple fan blowing/sucking the fumes is fine if you have good ventilation otherwise. If you're in a room without ventilation, that's when you want to strap a filter to your fan.
Well I just hold my breath in a room with a window open.

>>2767463
With a resonant circuit of some sort. A half-bridge with an appropriately sized inductor and capacitor and inverting feedback would be my attempt. Square waves aren't gonna be as efficient. A ZVS circuit might be fine if you can tune its resonance to equal that of your transducer. There might be ICs dedicated for the purpose of driving them in ultrasonic cleaners you can take a look at.

>>2767474
It's not pure rosin (which is pretty ok to solder with), it's rosin mildly activated (RMA). You've got artificial stuff in your flux just like the rest of us.

>>2767472
Yes. The IR2111 and dual FETs are the meat of it. The left side of the circuit generates and modulates the signal. Look up datasheets and example circuits.

>>2767472
I’m not an expert on driving transducers, but usually the seem to have an “ideal” freq. they want to resonate at which gets the best power transfer.
I think you can just drive them with an lm386 or something… they are basically a capacitative load.
If you try and drive them under or over their resonant frequency, you can do it, but there will be a lot of power loss on the output. Same with their impedance.
(That’s why they have a transformer in >>2767470)

>>2767468
You laugh, but this inductor has a stellar Q-factor.

>>2767482

>>2767470
Bwahaha… how old is that schematic. Audio transformers were most common in the tube era and early transistor era. You could walk into radio shack and get one for, like, $1-2. Now??? Better get some ferrites and give your kids a transformer winding job with their tweezer-like fingers in exchange for internet time or an apple watch that you were going to give them anyway.

>>2767470
Bwahaha… how old is that schematic. Audio transformers were most common in the tube era and early transistor era. You could walk into radio shack and get one for, like, $1-2. Now??? Better get some ferrites and give your kids a transformer winding job with their tweezer-like fingers in exchange for internet time or an apple watch that you were going to give them anyway.

>>2767491
>how old is that schematic
Soundlazer- it's not that old. There's an option for an inductor in case you can't source or wind one yourself.

anons, i am so hilariously retarded, i built a simple 555 circuit, soldered everything on a PCB, tested it: not working. after some troubleshooting i accidentally noticed that i grabbed an LM358 instead of 555. i don't even store 555s in the same box. I don't know why i grabbed it from that box and didn't even check it. the most hilarious part is i tested every pin on lm358 as if it was a 555 and was wondering why it didn't work.

>>2767509
Take note, class. This is what happens when you solder without a CPAP machine and 12 mRNA spike protein booster shots.

t12 or pinecil?
i need to solder small electronics
t12 is about $35 on ali and pinecil is $40 without psu (idk how much would one cost)

>>2767463
I drove one with an h-bridge (two SN754410 piggybacked).
I used a scope with current probe to dial in the PWM frequency until I hit the resonant frequency exactly (gives you a nice sine when it happens).

My diy ultrasonic cleaner project ended up as a failure though because I didn't know that the transducers need horns to properly transfer the waves to the bath.

>>2767525
Could you give me a circuit diagram?
>need horns to properly transfer the waves to the bath
You mean the nuts you solder onto the metal under the bath and then epoxy the transducers on to? There's a different kind of ultrasound machine not used in cleaning but used in laboratories that uses a ultrasound probe that can be put into any sort of liquid and will irradiate it.

>>2767531
I never made a nice PCB for it or anything.
It was a super simple setup, outputs directly on the transducer, PWM on one input, PWM+NOT on the other.

>>2767564
I'm a chemist, not an electronics guy. A simple sketch would speed this project up by a ton.

>>2767568
Look here >>2767469
TL072 is the audio pre-amp chip, TL494 is the PWM section, IR2111 is a half-bridge driver, and the IRF630MFPs are the power FETs (amplified output to the transducer array). You could just generate a 40kHz square or sine wave and feed it through a pot and into pin 2 of IR2111.

>>2767571
Right now, I can't produce the 40kHz signal. Can that be done straight with an arduino or should I also use the TL494 part of that circuit? What's the pre-amp part for? Just to increase the signal to the TL494 to some voltage it can use?

>>2767509
use sockets

How do anons clean old boards?

>>2767572
https://www.amazon.com/1HZ-150KHZ-Frequency-Adjustable-Module-Generator/dp/B0CFRJDCH3
You could use Arduino if you want. TL494 does the PWM of the FET driver. The pre-amp is the audio signal that is carried by the PWM frequency before the final amp stage. The schematic describes a sonic projector. Point the transducer array at an NPC skull and whisper bad things into their head.

>>2767568

>>2767472
https://www.youtube.com/watch?v=f8sRapa-swM

>>2767582
Compressed air and a dry brush. If it's still dirty, isopropyl alcohol and cotton swabs or toothbrush.

why are all my servos buzzing even the tiny ones? i drive them from a 555 as a quick test. adding a huge capacitor across the power rail didn't help. could it be due to jitter in the 555?
the period doesn't have to be 20ms exactly, right? the PWM pin doesn't draw any current, correct?

>>2767592
Is it wired on a breadboard? Check your connections.

>>2767593
no, soldered on a PCB.

>>2767568
since you're a chemist, i'm assuming it's an ultrasonic bath? this isn't really a beginner friendly project. i've had this project on the back burner for a while. most transducers are driven hardest at fairly high voltage, like 200V. so you need to create a 200V square wave and drive it at ~40khz with a reasonably well matched impedance... and then track that ~40khz to the resonance of the transducer which will vary with the load (temperature, how much fluid is in the tub, geometry of the objects in the tub, etc.)

chinkshitter ultrasonic baths generally use royer oscillators which are complicated and prone to blowing the fuck up. i wouldn't want to DIY one.

this guy has some videos >>2767589 that outline a valid approach. you use a DDS (direct digital synthesis) IC to generate a ~40khz square wave. you then monitor current or voltage/current phase of the transducer and create a software control loop that steps up or down the 40khz wave's frequency to reach resonance.

you might be thinking, "why not do this entirely with the arduino since it can generate PWM." this isn't possible because the PWM resolution on an arduino is terrible at 40khz. you can look it up because im too lazy to do so, but it's nowhere near the 0.1hz steps that a cheap DDS IC will allow.

the other approach is to do it all analog with something like a CD4046 IC. see this project https://github.com/leacog/PLL-ultrasonic-driver for an example. it has an arduino in it but it's basically for show (displaying current and frequency.)

>>2767595
Is your battery fully charged, or are you using an external PSU? Also, digital servos making noise is kinda normal. Try a battery that's run down a bit just to see if it quiets down. You could try cleaning the positional track in the servo for good measure.

>>2767602
i power the board from a 5v phone charger. the biggest servo i measured draws about 300mA while repositioning/twitching so the charger should be able to source that much current easily. i have several brand new micro servos and they all buzz/twitch like crazy, worse than the bigger ones.

>>2767582
I literally spray it with the garden hose if it’s really gross, and scrub it with dishsoap and a soft brush or a paintbrush to get into tight areas.

If you’re paranoid, soak it in distilled water for a bit afterward.

If you are a psyco/autist dip in in an bath of 99% 2-propanol for a minute.

Then let dry. Leave it in a warm spot by the hearth.

>>2767604
If you have another PSU, or even better a battery, swap it out. Phone chargers are pretty much all noisy and not suitable for certain things. The only other advice I have is to keep the wires as short as possible to your PCB.

>>2767592
Maybe the frequency is too low?

>>2767599
Not him but I’ve got a couple of transducers from ultrasonic antifouling kits that I plan to bolt under a sink for ultrasonic dish washing. PLLs are incredibly based, I’ll check out that link since I’ve got dozens of 4046s.
He might also be making an ultrasonic emulsifier, which could be useful for making sauces.

>>2767610
I tried a 9V battery with 7805 and a micro servo behaves the same. I also checked the waveform on the scope, and I noticed that as soon as I connect the servo, the PWM level drops from 5v to 4v and the rise time jumps up from 3us to 20us. Yet VCC doesn't droop and remains at 5v, only the PWM signal drops. 4v is within the normal range of these servos so it is not an issue but I am still curious why that happens. Maybe it has something to do with the circuit. Maybe the output transistor doesn't open fully or something.

>>2767654
Read the 555 datasheet, it cannot output up to its positive rail. I’d look for the internal schematic of such a servo, if I recall they’re all pretty standardised. Should give you an idea of what kind of frequency response the servo has. Maybe you just need to change the PWM frequency, or maybe change some passives inside the servo, or maybe add more inertia to the output.

>>2767660
Regarding the voltage drop. Yes 555 pin3 goes up to like VCC-1V but I feed it to an output BJT. I think the value of the collector resistor is too high. Once the servo starts drawing a little current, about 1v is dropped on the resistor. Again, it may not be a bad thing, so that the servo is not driven with the full 5v. And yes, I will play with the PWM frequency. Honestly I don't know what to expect. Maybe a bit of vibration is normal. But I thought once the servo position has changed and it "settles" it should be quiet and draw very little current. Not buzzing and vibrating.

just got an old Power Designs Model 2005 power supply that apparently has an internal oven for reference voltages. the oven switches on and off as long as the power supply is plugged into an outlet, so would it be bad to leave it plugged in when not in use (like for months at a time)?

>>2767689
For precision power supplies, keeping the voltage reference at a constant temperature is the point. You only need to care about that if you actually need the precision and have other equipment for calibrating the power supply. The manual should have detailed instructions.

rollin for something neat

>got a blu-ray player from a thrift store
>accepts disks, spins, but no picture or sound
>take the top shell off to make sure nothing out of the ordinary is happening, bugs, debris, etc
>everything looks fine, just seems to be faulty hardware
>google model number and issue
>video describing my exact issue almost to the letter
>have small experience with this kind of thing via fixing my gamecube and ps2 long ago, decide to dismantle it and clean the laser
>put it back together
>now it doesn't even accept disks, just takes them and spits them right back out, no longer spinning either
worth it to repair? or should I just toss it? was only $5 and I bought it for the experience but it didn't even come with a remote so I dunno man. I like tinkering with tech but this is my first project where I'm going in completely blind on all fronts and I have a PS3 to play blu-rays so there's no need to continue. But I give up on a lot of stuff I try so I was looking at this as a "finally break something open and see it through to the end" kind of thing. But now the weekend is over and I'm not sure I want to come home and fuck with it after work every day.

>>2767259
>>2767260
According to Tesla in a 1932 New York Times article:
>It is sufficient to charge the body to a pressure of 1,000,000 volts, which could be borne without discomfort, and all the particles of dust and foreign matter adhering to the body are instantly thrown off and the body cleaned without any danger to the patient. I have performed these experiments very often and always felt a highly beneficial reaction.

Although in this (https://timesmachine.nytimes.com/timesmachine/1894/09/30/106875357.pdf)) interview from 1894 (around the "An Explanation of Electrostatic Force" part) he said it was 3MV instead, but it's where I got the 1MHz figure from.

>If it's water you're worried about then make one of those multi-stage filtration stages or aquaponics or whatever to recycle it. Saying "it sounded cool" would be a far better justification of this project than "electricity is cheaper than water" or "don't like showering".
Water, buying soap, shampoo, towels, washcloths, cleaning the shower, washing the towels and washcloths. All of those things can fuck off.

>>2767320
>Still gonna kill you, but at least you're clean afterwards.
No thanks.

>>2767731
Yeah he also said he could cause an earthquake with his meme tower and that the future of long range power transfer was wireless. It may be beneficial in some ways, but it still won't be a replacement for showering.

>>2767726
Save the laser diode for funtimes later

>>2767745
>Yeah he also said he could cause an earthquake with his meme tower
I'm pretty sure you're mixing up two different inventions. He patented his earthquake machine and it's a really simple, small device, not the tower.

>and that the future of long range power transfer was wireless.
He did figure out how to transmit electricity through the Earth pretty efficiently over long distances, but he wanted to transmit it through the air and failed.

>It may be beneficial in some ways, but it still won't be a replacement for showering.
Not for normies, sure, but for me. And maybe other weirdos like me.

>>2767704
Rolling

>>2767726
Desolder and resolder everything as practice idk

Another year, another dead HDMI monitor.
Pic related. I've fixed a handful of these over the years; always dead caps, always look visibly blown with peaked tops.
This one has no visibly blown caps, so not sure where to start.
Do I need to desolder the caps to test? I have a cap tester.
Also noting those power diodes, board underneath looks crisp but I've never seen them blow b/f.

>>2767944
Oh, and symptoms of dead monitor: Won't turn on / no power light. Thus why I'm looking at the power supply vs. the control board.

>>2767944
>>2767946
Dead backlights.
>CAUTION: HIGH VOLTAGE
They're CCFLs. If you're going to bother with it, convert to LEDs.

>>2767948
lol can you even replace the CCFL back on these panels? I always assumed they were sealed together with adhesive or something.
Tested supply... it's generating 5V and 15V. Didn't test the 800V backlight output but figure if that was dead, the monitor would turn on with no picture. This is acting more like the control board's dead.

>>2767948
>>2767963
So can you actually replace the backlights on these things with pic related?
I had no idea that was even a thing.

>>2767963
>can you even replace the CCFL back on these panels?
If you can find working CCFL tubes, yes. On small to medium size monitors they're tucked into a metal (reflector) channel around the edges of the screen.
>the monitor would turn on with no picture
So the backlight is on and stays on? or it turns on, flashes, and turns off?
>>2767971
I don't know if they work straight off the HV. Guessing you disable the output transformers (remove or lift the low-side supply pins) and connect the LED driver to the 12V on the low side of the transformer. Then find the on/off and brightness (PWM) pins and wire them to the LED driver.

>>2767979
>12V on the low side of the transformer
15V, sorry.

>>2767963
>figure if that was dead, the monitor would turn on with no picture.
Shine a flashlight at the screen and power it on. Can you see a logo or "no signal" message? If not, press the menu button and look again. At least you'll know whether the mainboard is working or not.

>>2767944
post a pic of the flip side

>>2767988
>>2767979
Backlights are not powering on.
The monitor is refusing to light the "Power" light up. Power light is off, stays off.
Power Supply has 15V and 5V at the output to the control board.
>>2767989
Here you go.

>>2767963
>can you even replace the CCFL back on these panels?

- the odds of you being able to remove the old lamps and to replace with LEDs without breaking something critical is around 1%
- LEDs get hot and need to be thermally coupled to some substantial piece of metal. CCFLs dont need that so it may not be present
- LEDs will typically need a 48V (or more) supply that's current limited; that adds cost and complexity

so the real fix is this: visit a local thrift store or three.
before the recent inflation hit, you could get 24-inch ones at $10 and 27-inches at $15.
the ones that incorporate both TV and monitor usually have a shittier display.

>>2767998
>LEDs get hot
>LEDs will typically need a 48V (or more)
There are drop-in 12V LED strips specifically made for this purpose. We're talking small monitors, not big TVs.

>>2767997
There's one 8-pin IC (high-freq switcher) in the middle that looks to be in the hottest area of the board. That might be toast.

>>2767998
I’ve saved lots of the.
I’ve replaced some ccfls, but then the other one usually fails after a few months, so the lifetimes are strangely consistent.
I’d replace with LED equivalents, and just put a dimmer knob on the back to adjust the brightness… it’s better than their fuckheadary menu system.

>>2767998
>the odds of you being able to remove the old lamps and to replace with LEDs without breaking something critical is around 1%
OK, that's what I thought. I've fixed a few of these displays before when it's just caps or burned wiring. Appears this is beyond my skills or tools. into the trash it goes.
I've got a new panel on order; I can get new Dell 24" for $100 delivered same day.

>>2767491
I miss radioshack like you wouldn't believe. There was one just a quarter mile from me, but it closed down just as I was getting into electronics.

The idea that I could just walk up the street and buy a fistful of components sounds like such far-off fantasy now.

>>2768036
>The idea that I could just walk up the street and buy a fistful of components sounds like such far-off fantasy now.

I did that. Now I buy tons more for way less and it shows up at my door two days later. And the new stuff is 100x more interesting than the resistors and op-amps I bought at RS. It was nice at the time, but I hardly want to go back.

>>2768041
Do you mean that you wouldn't patronize a local business if they stocked the same stuff as Digikey, Mouser, LCSC, etc? I grew up close to a Micro Center and lament the fact that I have to drive 600 miles to browse there now.

>>2768036
>it closed down just as I was getting into electronics
You didn't miss much. The ablity to source components and information using the internet is leaps and bounds better.
Pros:
> Mimms books
> They sometimes had stuff you could use
> Toys and robots were cool; I loved their catalogs as a kid
Cons:
> parts were relatively expensive compared to now, or buying mail order back then
> store employees were clueless about components
> most finished devices they sold were meh
> electronic tools mostly sucked
I got really frustrated w/ RS as a kid, and gave up on electronics. I just recently got back into it, and stuff is so much easier and cheaper now it's actually fun to do.
t. xoomer.

>>2768043
>if they stocked the same stuff as Digikey, Mouser, LCSC, etc?

Yes, if a store within walking distance stocked 17.2 million components I would go there and drool and come home with $500 worth of stuff I'd probably never use. The fact is, the internet has changed how I shop. Maybe not you, but no way do I drive 30 minutes any more to get something that will be at my door in 2-3 days.

>>2768041
> interesting
Yes, interesting. As in this re-badged fake chinese shit is really interesting.
> how was your blind date last night?
> let’s just say it was interesting and leave it at that.

just completed this prototype of a distance sensor for a client of mine. It measures distances using a Tof sensor and sends it through a BT module to a phone

>>2768069
yes, I'm aware that everything you buy on the internet is fake, but thanks for the heads-up.

>>2768073
made the PCB on my rickety and modified 3018 cnc. I can't recommend it, I nearly missed my deadline because the Z axis leadscrew kept screwing itself out of the bearing. (that's why I had to add all of the lead on top of the stepper motor)

>>2768073
made the PCB on my rickety and modified 3018 cnc. I can't recommend it, I nearly missed my deadline because the Z axis leadscrew kept screwing itself out of the bearing. (that's why I had to add all of the lead on top of the stepper motor)

if anyone is on the fence about buying one of these, do it. way easier than separate soldering iron + solder sucker.

>>2768078
Can you use it in regular soldering mode with another tip?

Where do I find a good oscilloscope for under $50?

Has anyone here charged a lithium battery very manually?
I have only ever done it properly with a cvcc

I currently have a camera with a discharged battery, and a 5v 1a wall charger for a phone.
My plan is to wire the charger to the battery and plug it in, the battery will draw as much current as the charger can give and then sag the voltage to match. I'm hoping I can simply monitor the voltage and stop it when it reaches 4.2

Just how fucked am I rn because it's just gonna be like this, I shouldn't exceed the c rating with 1a

>>2768168
Do you have any other device with a single built-in 3.7V lithium cell and charge circuit? Borrow it to charge your battery and then order 9000 TP4056 modules for 7 cents total.

>>2768172
I thought about it but I don't
Im literally packed to go on a trip and now I either figure out how to charge it or I have to stop at work in the morning where I have tons of equipment to use.
I basically thought my main camera was at home and it isn't, I don't know where it is, and my backup camera is discharged.

>>2768176
I strongly advise against doing what you want to do. It's unsafe and lithium fires are difficult to extinguish + toxic smoke. RIP in advance, Anon.

>>2768078
They aren't grounded though. I replaced my one's cable for a 3-pin one, and added a 1MΩ resistor between the ground wire to the tip. Now it's ESD safe, and probably human safe too, so long as that resistor isn't so large it prevents my RCD tripping.

>>2768107
You can kinda solder with it even with the normal tip, but it's a large and cumbersome iron to do general purpose soldering with. Not regulated either.

>>2768168
That power supply's I/V curve won't just be a square with nice 1A constant-current limiting. Some of those chargers will droop in voltage as you load them more, but that's usually AFTER they hit the 1A limit. Worst case scenario you'll need your battery to get down to 3.2V or even 2.5V, at that point I bet the charger would be outputting substantially more current than it's nominal value. Assuming it was even outputting linearly at all, chances are it instead just enters a fault mode and strobes the output.
TL;DR get something to limit current (like a 2-10Ω resistor), a 4-4.2V zener diode across the cell would be a good idea too

How springy is nickle strips? I want to make some battery contacts for some weird batteries and while conventional contacts might work, they seem weirdly expensive. I was thinking just get the thickest nickel strip (0.3mm) and bend that into shape, but I've never messed around with nickle strips so I don't know how it takes bending and flexing.

Nothing too outlandish voltage or amp wise.

>>2768206
Get them of some broken device, or a device you converted to run on AC mains.
Or, go to the dollar tree and get some LED widget with 2 or 3 batteries, throw away widget and keep spring contacts.
At any given time I have several devices lying around I can immediately steal contacts and springs from.

anyone have experience with getting american appliances to work on european outlets? i'm a private chef who's moving to europe and i can't live with leaving behind 10-15k in cooking appliances at home, or selling them at a 50% loss.

i know absolutely nothing about electronics, but from the preliminary googling i've done; i'll need a step down converter for the voltage, and some type of power supply or battery to provide 60hz power from the 50hz outlets for anything that uses a motor.

the motors on my appliances are all single phase induction. i've read some people arguing about whether the speed of single phase induction motors are actually reliant on hz, with some saying that it's only a problem with different types of electric motors.

anyways, i'm just trying to figure out the cheapest way to go about this without setting a clients house on fire, or having them freak out when they see a bunch of aligator cliped wires sticking out of a computers PSU plugged into their wall

>>2768206
Not very. It's definitely more resistant to work hardening than steel or copper, but it's pretty floppy. You'd be better off buying some spring steel, or scavenging a spool of it out of a vacuum cleaner's cable retraction mechanism. Aliexpress or alibaba probably sells battery contacts by the hundred if you know where to look. If not you can always just buy battery holders for dirt cheap and scavenge the contacts from there.

>>2768218
>provide 60hz power from the 50hz outlets
The 50/60Hz difference probably isn't too big of a deal for most stuff. Only appliances with clocks it really matters for, everything else will run somewhat slower, probably doesn't matter. Fixing the frequency would require a VFD, which is expensive, but some VFDs can output an effective voltage of 120V. The price of such a VFD might be comparable to an isolation transformer, idk, but you will want it in a box. A VFD would also give you more control over you motors speeds, if you so desire.

>i've read some people arguing about whether the speed of single phase induction motors are actually reliant on hz
It makes a difference, but not a 20% difference. For an induction motor with very little load, the difference will be close to 20%, but for an induction motor under a decent load the speed difference is probably 10% or under. Start/run cap probably won't need changing.

Another thing that's definitely worth looking into, is whether the appliances were designed to be converted to different voltages. If the US/rest of world appliances come from the same factory, they may well have just used motors with double ups of their windings. Put them in series for 240V, put them in parallel for 120V. Usually this manifests as a panel on the motor itself with wire lugs that can be shuffled about, but if you're particularly keen there may be work to be done in the motor itself. Buying a replacement motor (especially 2nd hand) may be cheaper than a voltage conversion transformer in some cases.

>>2768225
i've read a VFD will send out high voltage pulses that will fry the shit out of anything the power passes through before reaching the motor

>>2768229
Yeah, all it will be doing is switching rectified mains with sufficient duty-cycle to make the RMS voltage as seen by the motor look like a 120V sine wave, there's still a bunch of ~340V spikes in there as far as I understand. VFDs are the sort of thing you put on the motor itself, and possibly some control electronics if you've specifically ensured it can handle the spikes. It would be a more involved process to convert the low-power stuff to run on 240V directly by swapping out low-power PSUs, and using the VFD specifically for the motor. That said, some simple kitchen equipment just has relays and switches, which would probably handle it just fine. If you don't need the frequency control, then the only advantage of a VFD over an isolation transformer will be its weight and size. I'd guess they'd be about half the size and a tenth the weight. Isolation transformers for hundreds of watts are beefy. Probably not too big of an issue if you're just keeping the stuff in one kitchen, but if you're moving it from client to client, it's definitely something to consider.

why do high end soldering irons like jbc use transformers instead of smps? the fuck is the point?

>>2767459
What's the market like for EE majors?

>>2768314
Getting replaced by AI in 3 years.

>>2768327
artificially intelligence (indians) have been around for decades. 2 more weeks, i suppose.

>>2768314
start learning people skills

>>2768340
>Start learning how to kiss ass, lie, cheat, and steal.
No thanks.

>>2768342
start learning how to beg for food and shelter then lmao

>>2768311
Old design. Why change it?
Soldering iron stations need a weighted base for stability anyway. Why have multiple parts?
You can use unrectified AC for the element? Why bother with a high current rectified source?

>>2768343
I'll just fly to Mexico, change my name to Ramone and walk across the Arizona border with my hand out. Then I get everything for GRATIS!
Easier than convincing HR that I'm a worthless retarded nigger, perfect for a worthless job in their worthless corporation. What do you think of my job hunting strategy?

>>2768314
All engineering does is look up and apply stuff that the material science guys and physics guys wrote down in tables.

>>2768347
>material science guys and physics guys
Most of whom are not capable of engineering without further education and training. You're comparing apples to oranges. It's similar to comparing the work of a brain surgeon to a dentist.

>>2768347
All material science does is write down stuff in tables that the instruments, engineers built, put out.

>>2768350
correct. except for the retarded dentist part. what was your point?

>>2768353
How could you possibly miss the point?
>All engineering does is eat scraps from physics departments.
Physics is more about doing drugs and brainstorming with soi fags about what-ifs.

>>2768354
>Physics is more about doing drugs
It has to be sad to be in physics these days, compared to way back when there were things to be discovered, real concepts and facts that changed the world. Now you have to pretend to believe horseshit like "do we live in a simulation", and "is time travel possible" to get some recognition. Whereas engineers still do what they have always done, which is make cool shit.

>>2768355
Exactly, Anon. Physics = grifting academic bullshit, engineering = as real as it gets. It should be obvious to anyone with a functioning brain by now.

>>2768179
>>2768180
>TL;DR get something to limit current

We are good, I ended up just finding the charger
Of course this charger has external leads for charging random cells too like half my shit kek

>>2768206
>How springy is nickle strips?

have you considered pogo pins instead?
specifically the round-headed ones.

>>2768218
>i can't live with leaving behind 10-15k in cooking appliances

easy: add up all the wattages of the appliances, add 0.01% headroom.
call a yorupean electrician and ask for a quote on such a transformer and x number of 120V outlets.
my guess is around 400,000 US pennies.

>>2768351
> no, wait… engineers made something! I swear it.
We build most of our own stuff.
A better analogy is that the scientists are the actual doctors, and engineers are chiropractors that insist their friends and relatives call them “doctors” and belong to a little self-help support group that tries to emulate freemasonry and scientology. Engineering is basically a grift that goes where the money is. Civil engineering in montreal canada is practically organized crime and threatened people on the front page of their website… but they were just more organized than most.
Sure, there were a few engineers that did some noteworthy stuff over time, but not recently.
Modern EE is hilarious, they know absolutely nothing and will not be replaced by AI, they will be replaced with nothing. I remember we got this one guy that was a “software engineer” … he couldn’t write any software, he just ran around and said shit like we violated the law of demeter and we needed at least 7 levels of object inheritance. It was then I realized the whole discipline had basically imploded. Most engineers know their actual worth which explains why most of them—not all—have this intolerable and insufferable arrogance to them.

>>2768389
>We build most of our own stuff.
post pics
>Engineering is basically a grift that goes where the money is
muh "peer-reviewed" LK-99
>Civil engineering in montreal canada
Nobody cares.
>“software engineer”
lol
lmao

I was recommended the AiXun T3A. How swindled was I?

I was recommended the AiXun T3A. How swindled was I?

>>2768399
If you're going to spend $120, get a Hakko FX-888D and order direct from Hakko. Amazon will send you a used station in a beat up box for the same price.

>>2768363
>Bent piece of metal, 20 pieces for 10 bucks
>100 two piece copper tubes with a nested spring, also 10 bucks

Thanks for the suggestion.

>>2768408
>100 ... 10 bucks

you need precision manufacturing, and quality materials.
if you go for the cheapest option, you're buying a boat load of problems.

>>2768354
so it's dumb elitist shit? go to school kid, the adults are talking

>>2768311
Transformers are much less complicated, and intrinsically more reliable. Same reason they're still used for alarm control panels. Uptime matters in companies, but it's less of a big deal for hobbyists. If your soldering station dies, use your old iron to repair it, that's a good experience for a hobbyist. A more portable station is also pretty handy.

>>2768399
If you need the power output of 200W, it's worth it. Like for soldering big lug terminals, big cup or turret terminals, XT60/XT90 connectors, SMT power packages, that sort of thing. If not, a T12 station will probably be similar in reliability and build quality for a third the price. You don't need 200W for simple through-hole soldering or low-power SMT packages.

An Aoyue or Yihua station with a standard AC transformer is probably going to be more reliable but heavier, bonus points for getting one that takes cartridge tips. I think Aixun make transformer-based 200W T245 stations too, but they are more expensive again.

An actual brand name like Hakko or JBC is going to be more expensive than a chinese brand name, and for not much benefit, but if the better QC is valuable to you then go for it.

>>2768403
A third the output power too.

>>2768433
>A third the output power too.
On the rare occasion that 70W won't cut it, pre-heating the board with hot air solves the problem. If Anon is gonna be making stained glass windows or soldering heavy metal all the time then he should go high-power.

>>2768428
>so it's dumb elitist shit?
Yeah, that's what I said.
>go to school kid
Never again.
>the adults are talking
reddit speak

This is from a MOSFET. It says max threshold voltage is 4V and in the previous page it says absolute maximum is 20V.
What happens if I give it 5V?

>>2768445
At 5V it always triggers.

>>2768433
Not the person you're replying to, but any thoughts on this Weller 60W? It's in stock near me and I'd like to get it today if it would work for soldering a power connection to an amp without any real issues. Appreciate any thoughts on it.
>https://www.homedepot.com/p/Weller-60-Watt-120-Volt-Corded-Soldering-Iron-Kit-with-LED-Halo-Ring-WLIRK6012A/315743463#overlay

>>2768445
Threshold Vgs means the voltage at which it will be capable of conducting.
There's a minimum and maximum listed because the manufacturing isn't perfect so that voltage can vary from one transistor to another.
TL;DR anything above 4V will always make any MOSFET of that type to conduct.
Absolute maximum Vgs means the max votage you can give at the gate before the MOSFET blows up.

>>2768445
>What happens if I give it 5V?
Higher Vgs = more Vds.

>>2768393
> I’m an EE and you’ve definitely struck a nerve.
Solar freakin’ roadways!

>>2768456
Post more politically motivated EE hacks who are filling their pockets with tax dollars and producing nothing. While you're at it, post pics of the stuff you built.

>>2768393
> I demand that you call me Doctor!
I thought you drove trains.

>>2768465
>I demand that you call me Doctor!
Who do you think you are? DOCTOR Jill Biden?

I'm trying to amplify an arduino PWM signal using a mosfet.
I'm trying to control the speed of a small DC motor (R1 in the pic) but it isn't small enough to be driven by the arduino itself, it needs more power. So I'm trying to feed it with a 12V power supply but modulate that using a mosfet triggered by the arduino PWM signal. Pic related is my circuit.
It doesn't work because mosfet stays on instead of opening the circuit when the signal is low. I think it has to do with its capacitance. How do I fix it? I've tried putting a resistor in series with the gate and the ground so the mosfet could discharge through it but that didn't work.

>>2768477
Put a pulldown resistor from gate to source. The higher the value, the longer it takes to discharge

>>2768477
this is isolated, but same idea

>>2768477
https://docs.arduino.cc/learn/electronics/transistor-motor-control/

>>2768484
>>2768486
>pulldown resistor
That means just a normal transistor, right?
I think the lowest I have is 470 ohms. Arduino can produce either 490 Hz or 980 Hz signal, is that enough for either of these and if not, how low does it have to be? Also in general, would higher frequency mean the resistor needs to be of a lower resistance?

>>2768488
>normal transistor
No. It's a resistor between the gate and source of the transistor. 470Ohms will do. All it does is discharge the gate capacitance in the transistor junction when power is off, which switches the FET off.

>>2768488
you might also want to use a gate resistor but they're usually about 10-20ohms but its not super important (put it after the pulldown resistor so you dont get a voltage divider), what mosfet is it specifically and whats the current your motor is using?

>>2768494
>what mosfet is it specifically
IRFP260
>whats the current your motor is using?
0.22A, 12V. It's a cooler some old computer power supply I'm using for testing. In the future I might use something bigger.

has anyone used these before ? how hot can they get ? just want to try and build some heating mat with a 12v source, as long as I know this is just a regular resistor right ? nothing fancy

>>2768508
oh fuck here is the image

>>2768493
>>2768494
Still doesn't work.
Mosfet isn't triggered and motor doesn't turn on.

>>2768514
pics or it didn't happen

>>2768445
5V will be enough to drive the FET into saturation at over 250µA, probably over 100mA too, but check the Vgs/Ids graph to see if it will be linear for your maximum current draw.

>>2768448
Eh, I'd go for something temperature controlled if you plan on doing more soldering, but it should be fine for ~14 gauge wires or thinner. It should handle wires up to 10 gauge but be kinda slow.

>>2768508
>>2768510
Does it have a datasheet?

>>2768514
Do you have a freewheel diode? Is the 0V rail of your arduino connected to the 0V rail of the 12V power supply? If you answered no for either of these, correct it. If it still doesn't work, you may have damaged the motor. Your schematic should look something like this >>2768487, you can ignore S1 and the 10k resistor.

>>2768530
>Do you have a freewheel diode?
Nope.
>Is the 0V rail of your arduino connected to the 0V rail of the 12V power supply?
Also no.
Will try to copy that schematic.

>>2768530
it looks like its either 33ohm/m or 17ohm/m and can do 25 or 40W/m
I found this video https://www.youtube.com/watch?v=EulACmPGfzY I will buy some and play with it, its only 1 usd per meter, cool stuff

>>2768537
It may well change its resistance as a function of temperature. If the resistance goes up with temperature as I imagine it will, then it's sorta self-regulating with a constant voltage supply.
The only problem I'd have with it is it may be a pain to terminate wires onto. Not sure if the strands will break if crimped conventionally, you certainly can't solder to it. I'd definitely want to put a ferrule on it before putting it in a screw terminal too.

>>2768533
>>2768530
Any ground pin on the arduino will do, right? The schematic doesn't show which and I'm not totally sure they're all the same...

>>2768556
Yeah they're all connected together

>>2768562
Still doesn't work.

>>2768565
ded fet? replace the fet after the diode is properly in there

>>2768566
Just checked it, it's fine.

>>2768569
Did you place a series resistor between arduino io and the gate?

>>2768571
No. This is the schematic as it is right now, the only thing that's not in there is a single potentiometer I'm using as an input to control the PWM signal.

>>2768575
Should still turn on and off. Put an LED+resistor on the PWM pin to see if it's actually going on and off. Not using a resistor on the gate could possibly damage that output pin of the arduino, though I doubt it.

>>2768579
I'll try that tomorrow, it's late here and I'm exhausted. Good night folks and thanks for the help.

I've made a mistake and put the output enables the wrong way. Do you think I could leave pin 5 floating, cut the trace of 6 and connect it to vdd?

>>2767459
Do I buy 20 SiC MOSFETs and couple AED capacitors, or should I try making a device at much lower power levels first (think 400V 300uF and couple normal MOSFETs) ?
Also, what would be the best way to get high voltage of one 18650?

>>2767521
Pinecil if youre in us, you can use a barrel jack adapter and any laptop psu you have lying around

Anyone might could tell me what this little board does on this lipo battery i ripped out of a thing?

>>2768722
protection board (overcharge, overdischarge, short circuit)

>>2768671
>I could leave pin 5 floating

an open TTL input is equivalent to a HIGH input, but you need a LOW, so that's no good.
but you've using an HC part which is actually CMOS, so it really depends on the design of the chip.
they could've made it so it emulates the TTL part it's mimicking.
but if they didnt, then leaving a floating CMOS input is a recipe for disaster.
so, in every possible case, you gotta ground that pin.

>>2768675
What kind of device?
>what would be the best way to get high voltage of one 18650?
For a high power conversion I'd want to go resonant or quasi-resonant. If voltage regulation isn't a big deal then a traditional ZVS driver should be capable of hundreds of watts if you pick the right transistors, more still if you add dedicated gate drive circuits. A ZVS circuit also has the benefit that the 3.2V minimum of the cell gets multiplied naturally for the gate drive voltage, I'd still want a zener but you should have no trouble getting 10V gate voltages.

Of course, you probably can't pull hundreds of watts out of an 18650. If it's just a low power high voltage converter, I'd maybe make a push-pull transformer driver with a TL494, but a ZVS is still an option.

>>2768722
Common lipo protection board with a DW01 and FS8205. Look up a schematic for how that's wired if you're curious. They protect against undervoltage, overvoltage, and overcurrent, though you can't rely on them for current regulation while charging.

>>2768579
The PWM signal works fine, I tested it with osciloscope today. I also moved some stuff about and probed all over and it seems the problem isn't the circuit, but the breadboard connections and possibly my electric fan causing some weird interference on the potentiometer input to the arduino. Or maybe that's just noise. Also if I lay if the pot on the table it stops working but I think that's due to shitty jumper cable connections.
Either way, it works without a resistor series with PWM signal, without the pulldown resistor and without the free wheeling diode. Now I'm questioning whether I really need all of those if I can skip on them. The pulldown specially, because it seems like that would be absolutely needed and yet it isn't.

>>2768815
The amp in my car works occasionally. It was completely fine until one day when it was extra humid and rainy it just stopped. My car diagnostics screen shows No Connection for the amp when it does not work. When the amp does work, it will usually be on an extra cold morning, or occasionally if I brake hard or hit a big bump it'll come on. When it's on its great, zero issues. No sound distortion, no weak sound, it works amazing until I turn my car off, then it's hit or miss if it'll work when I turn it back on the next time.

This made me think it might be a power connection issue, maybe an old broken solder connection since the car is a 2004? But I pulled the amp out of my car and as far as I can tell the solder looks fine on the power connections, but I'm not an electrical engineer and have limited experience so I could be way off base. I'm also not noticing any failed capacitors based off of examples I can find online, but again my experience in this realm is limited so I could be missing something.
>pic related, will post the other side in next post
Any ideas, just based off of looking at the board? This is a common enough issue that there are ebay repair services for this specific type of amp, so I was hoping there would be something kind of obvious that I could solder myself to fix.

>just buy a new one
The car has a weird speaker setup, when people replace amps they have to replace the rest of the speakers due to the speaker channels I think. I'm on a budget and bought a solder gun and some solder to try and fix it on my own to save some money and learn some more about electronics. New stock amp is over $1k, a refurb is around $500, and the repair service is around $400. I've searched junkyard cars and they don't have them, and the single one I did find since this started happening was dead as well.

>>2768929
Maybe a failing relay.

>>2768929
I know these pictures are probably useless for diagnosing, but just giving an idea of what I'm working with. I also have a multimeter if that can help, I tried diagnosing the capacitors but I'm not really sure what to look for. I'm mainly frustrated that it sounds great whenever it decides to work so I don't want to spend $400+ if it's something that can be fixed without too much difficulty.

I forgot to mention in the previous post, the fuse for the amp is also used for other accessories that don't have issues, so I don't think its that. And finally here's a link to the one obscure video I've found of someone repairing one of these or an extremely similar version, I posted it in one of these threads months ago just to gather some info. The guy doesn't explain what he's doing to repair the amp and it isn't great quality so I can't really learn much from the video unfortunately.
>https://www.youtube.com/watch?v=BuzPSBdWfxQ

>>2768927
>problem was dodgy wiring
breadboard moment
>Now I'm questioning whether I really need all of those if I can skip on them
Not using a freewheel diode means your voltage spikes will be going through the FET instead. Use one if you don't want to prematurely kill your FET.
The series resistor is good practice, usually MCU pins aren't specified for capacitive loads so you're best off playing it safe and limiting the instantaneous current output to the 20mA or whatever the pins are rated at. It won't interfere with the action of the power FET either way.
The pull-down resistor isn't necessary while the arduino is operational since the arduino outputs are push-pull, it's only for when power is off, but even then the internal diodes of the arduino will shunt any voltage out of the FET gate and into the power rails where it will get eaten by the MCU itself, so it's not particularly necessary.

>>2768929
As the other anon says, a relay is a good guess. Find the relay that turns it on and swap it for another non-critical relay and see if that makes a difference.

I'd pull the amp out and sit it somewhere while it's still plugged in, turn the car on, and see if you get the fault. Probe the voltages on the solder joints of the connectors. If voltages aren't different between fault/no-fault, then it may well be a problem on the amp board itself.

>>2768938
Guess I'll be keeping the diode and the resistors then. How do I size them up? I've said previously that the lowest I had lying around are 470 ohms, would that be enough for both? Should I increase them if I change the load from 12V to, say, 24 or 36? Also those are 5W resistors, I don't think I need them that huge, right?

>>2768942
I'd use 250-1k for the gate resistor, and at least 10 times that large for the pull-down, 100k would be pretty normal.

>>2768929
The torx look corroded, so its likely a connection issue on those plugs, however they do look gold plated. What is that white shit around the plugs? Salt residue? That’s nfg.

Odd there is no silicone around the caps and the little connector there…. Especially for a vehicle. Must be their first attempt at making something, they should probably go back to the laboratory.

Also not varnished, but the rest of the board looks OK.

I am in component sourcing hell. Stuck in a cycle of picking a well stocked component, putting it in the design, and then some fucker buys nearly all entire stock and I have to change design again.

Does anyone have any experience with Cleqee's higher bandwidth probes? I am looking to buy new probes for my Tek TDS 680C, but can't justify the cost of new Tektronix probes since they would cost more than I paid for the scope. I am looking at the Cleqee P6500 probe in specific.

Can you connect a smaller (not in pitch, i mean the same pitch but with less lines) ffc ribbin cable to fpc?

Like say i have the pic related that is for 50p ffc cables. Can I insert a cable with say only 18 pins? Would it hold to it? I think it should work as long as i align to the edge but i am not sure

>>2769228
If the pitch is the same, then I don't see why not. If you have a 50p cable, cut a piece of flat plastic to the same width and affix it to the 18p cable to keep it aligned with the connector contacts.

>>2769163
What parts are you having trouble with stock? For me it was current sense amplifiers, BMS ICs, and also some gate driver ICs. Had RP2040s go out of stock a few times, but they came back again within a week.

Anyone know anything about this ebike battery. it says 72v 48ah... the bike computer and charger says its at 100% but the bike only works with the charger in... also i measure only 3.1 volts with the multimeter from the charger port of the battery... apparently its been sitting for 6 months or more without charge.

i dont know what my next step is going to be as it wont charge with the standard charger. apparently you can use a slower charger and then perhaps it will work? i have another one that is 36v 4a output(vs 84v 5.5a of the chinese one). can i perhaps try with that one and have better success or do i risk damaging the cells.

if you know anything about how the cells are arranged or what the cells even are all info is accepted with gratitude.

>>2769290
CZZLP32

>>2769291
sorry wrong pic

>>2769290
>what the cells even are
A shit ton of li-ion cells. Probably 18650s or the beefier 21700/30700. Doesn't really matter for the purpose of charging, nominal voltage is still 3.7V

>if you know anything about how the cells are arranged
Hard to tell
If you divide the pack voltage by the nominal voltage you get the amount of cells in series. Or at least should. Chinese marketing is slimy so they often use the maximum voltage (4.2V) per cell to calculate pack voltage, because bigger number equals better product.
72/3.7=19.45
So 3.7 is not what they used.
If you divide by 4 instead you get 18, which would make sense since 19S BMS boards are harder to find and probably more expensive.
So it's probably an 18S pack. How many cells are in parallel is basically guesswork, it all depends on exactly what cells they used.

>>2769026
Well fuck me. I was so focused on the solder connections I didn't even realize. Thank you, now I have something to actually try before looking towards a professional repair service.

Any idea on how I would find replacement screws? It's a T10 socket, but not sure how I would find the right width/length of the screws since I haven't dealt with this before.

>white shit around the plugs
I can wipe it away pretty easily, it doesn't feel grainy, I think it's just dust. The amp is right near the vent that blows air in the footwell. If it was from salt or water I think I would've seen more damage than just the corroded power connection screws, so I'm hoping it is just dust.
>no silicone
The entire back of the board is covered in some sort of electronics epoxy/resin apparently from what I can find and based on how it looks, so that might be why there's no silicone?
>first attempt at making something
Well, it would seem that way based on the way these fucking amps constantly fail for everyone who has them and there's no viable fucking replacement. Thanks for that Lexus. Let's just make the high end audio option impossible to replace without spending absurd amounts of money.
>Rest of the board looks OK
Thanks, I thought so and it's nice to have some confirmation of that. Besides the corroded screws the board looked pretty good from what I could tell, which is part of why this shit is so frustrating to diagnose. I was really hoping for something obvious like a bad solder but seeing a good looking board and still having problems was making me lose my mind.
>pic related
Here's a better pic of the corroded screws for reference if you can suggest anywhere to source replacements, or if there's a good way of getting the corrosion off of them if they would still be usable, I'm open to any suggestions.

>>2769302
WD-40 and a wire brush should clean them up. An ultrasonic bath would do it too. When you reinstall them, use dielectric grease on exposed surfaces and between the PCB and bolt. You don't need much at all- just a thin coating.

>>2769290
Sounds like a case of a dead battery to me. The charger can provide enough power to get it up to 100%, but the self discharge rate is too high to stay there for long. It could be one or two cells are dead, causing other cells to be overcharged, which would explain why they would self-discharge real quickly. Is there a balancing BMS or otherwise a balancing charger? Can you measure the voltage across individual cells? Measuring the voltage after the BMS isn't that reliable because of the low-voltage cutoff, but it works if you're measuring while it's charging. But ideally you want to measure the cell voltages before the BMS, while it isn't charging. Maybe while charging at 100% too.

If the anon is correct that it's a an 18S pack, then the termination voltage should be 75.6V or thereabouts. If it's all balanced that's 4.2V per cell, much higher and you significantly speed up cell degradation. The minimum voltage per cell before significant permanent damage is about 2.5V.

>>2769026
>>2769307
Thank you anon, your help is appreciated.

I just pulled the amp back out of it's case and unscrewed the power connection screws. I don't see any metal traces/pads around the screws on the underside of the board, could that still be the issue though? Screw included in pic for reference, the hole I pulled this one out of had the most white stuff, I'm not sure if it's just plastic from the power connection housing that has become brittle over the last 20 years or if it's something else. Still going to clean with WD-40 and a wire brush. I grabbed some dielectric grease the other day too, should I put some on the screws, and the actual power connection inside the housings as well that the car plugs into?
>pic related

>>2769332
>I don't see any metal traces/pads around the screws on the underside of the board
You're right. Those bolts are structural supports for the connectors. The white crap is plastic from the connector housing.
>should I put some on the screws, and the actual power connection inside the housings as well that the car plugs into?
You can if you want, but clean everything first and don't overdo it. Gobs of grease will attract more dirt.

>>2769334
Damn, I was really hoping I was wrong and that might be it. I'll still clean them along with the other screws that mount the board to the case and form connections just in case, along with replacing the fuse in the car even though it wasn't broken.

And I'm still open to any other suggestions if you have any, it's amazing it's giving me so much trouble despite working perfectly when it decides to turn on.

>>2769339
Did you check the relay? Sometimes the contacts stick together when they fail. Hitting a bump in the road can free the contacts and the relay will function until the next power cycle.

>>2769340
So I saw the relay mentioned in previous responses, I was looking at my car's fuse box and didn't see a relay specifically for the amp, there's a few relays but they're all dedicated to other equipment based on what I can tell. Am I missing something, like is there a dedicated relay for each component in a spot besides the fuse box?

Doing a ctrl+F on my cars manual only shows a relay mentioned once, and that's just talking about if you're towing you might need a relay, otherwise the manual only talks about fuses and doesn't even bother mentioning relays.

>>2769344
If it's not detailed in the manual then it's not in your car. The only other thing I can think of is a problem in the head unit. Because of the intermittent nature of the issue, it's probably a bad or dirty connection.

>>2769346
An old fren of mine had a custom stereo installation in his car back in the day, and one day his amp starting cutting out every 5 seconds at a higher volume, but would stay on at a very low volume. He fucked around with it for weeks and finally asked for help. Disconnected the speakers from the amp and checked resistance. One speaker disconnect slipped off its terminal and was flapping against the opposite terminal at volume, shorting the amp output. Crimped a new disconnect and it never happened again.

>>2769346
Is there a good way to test the connection from the head unit? I've found wiring diagrams for the plugs that go into the amp, but I'm not really sure how or what to test.
>fuse box and fuses
Ignore the flipped 30a fuse in the bottom right of the fuse box, it's for the amp and I had swapped it with another so I could test it to be sure once I put the amp back but I decided I'm just going to go buy some new fuses instead.

The top fuse has darker markings on each side and it's the one for the amp. Could that be causing enough of an issue? Testing the one with lighter markings shows a resistance of 0.1, the one that has darker portions from the amp shows 0.1 where I'm assuming the fuse box contacts it, but the darker areas show anywhere from 0.2-1.0 depending on where I put the multimeter contacts, and it jumps up temporarily to 40-60 when I move the multimeter contacts across the darker portions, but it finally settles on <1 and around 0.2 or 0.1 after a few seconds.

>>2769350
>Is there a good way to test the connection from the head unit?
I don't know much about newer (post 2004 lol) car stereos. First thing I'd do is clean the connectors and wiring harness, then probe for voltage, continuity and resistance depending on symptoms.
>Could that be causing enough of an issue?
Yes. The top right fuse looks crusty. It would be a good idea to replace them all. If the fuse sockets look dirty, spray them with contact cleaner and give each socket the old in-out a few times with the new fuse, then seat it fully. Based on your readings it seems the fuses are intact, but they're cheap and what you have is worn. Might as well give it a shot.

>>2769350
plug it into the car, turn it on, and measure voltages on the solder joints of the connectors

>>2769302
>find replacement screws?

those screws have zero corrosion.
they're just hip-hop colored.
you've been race trolled.

I have a cheap Chinese brushless DC motor and accompanying speed controller with unknown specs that I want to power from my Mean Well PSU. The PSU supplies 24V which I think is too much for the speed controller.

What do I need to decrease the voltage to, say, 7.2V? I've tested with that and know that it works fine. A regular power regulator would get fried in a flash due to the currents involved (I have no idea what level it peaks at, but it's safe to say 15+ amps). Would a buck converter do the job? What other alternatives are there?

>>2768700
ive tried finding one for my (old) thinkpad charger but no luck, i still need it so no cutting it up either

>>2769632
Are you a white heterosexual man, a chink with micro pp, or perhaps a tranny who will never be a woman? The reason I ask is because trannies can't suck chink dick hard enough, and they both love garbage products because they've never owned anything nice before.

>>2769517
buck converter, buy a premade one from fleabay

>>2769633
are you talking about the laptop or what? regardless, pinecil is a clone of a chink iron so your theory is already flawed
i dont feel like spending $60 on an iron if i only solder a headphones jack or replace a capacitor once in a blue moon, to import pinecil to europe i need to spend at least $40 + i dont know about import taxes if there are any and i dont even have a psu, meanwhile the chinkshit mystery box is $30 so if cant get a psu for <$10 i'm really too happy about spending 2x as much on something i barely even use

>>2769639
>i'm really too happy about spending 2x as much on something i barely even use
*i dont think there's a reason to spend twice as much on something i barely even use anyway

>>2769639
>>2769641
>barely use
Just buy a piece of shit iron for under $10 then. It'll be the same quality as peencel and t12. You won't even notice the difference. lmao

>>2769642
i have one and it's nigh impossible to do anything with it but it might just be the solder being total dogshit but if i ever wanted to do something like hand wiring a keyboard it would be nice to have a nice iron so i dont want to buy shit
i just need to find a psu that's not too expensive, i like the pinecil better

>>2769647
If you insist. Get a 24V PSU and plug it into the barrel jack. Disable the USB-C PD chip or use a switched DC jack.

>>2769649
Disable (or switch) the USB PD chip FIRST, then plug the 24V PSU.

Can i boost the inductance of a inductor by connecting a few of them? I need a 500mH one for a wah pedal but the closest i can find is 600mh, so i was thinking that if i could connect like 5 100mH ones maybe i could get it to 500mh. Sorry if its a stupid question but i couldnt find anything about it by googling.

>>2769655
https://www.allaboutcircuits.com/textbook/direct-current/chpt-15/series-and-parallel-inductors/

>>2769647
>it would be nice to have a nice iron

99% of the niceness of an iron is the tip.
if you buy a $7 weller or hakko tip, then file/grind/chew it until it fits whatever heater you have it, then you're good for the next 10 years.
or until your heating element dies, which is typ 2 years for a cheap one.

>>2769657
Thank you very much anon!

>>2769667
You're welcome, Anon.

>>2769657
I think that explanation is too simple, and there is other effects such as phase shifting going on.

>>2769693
Remove some copper from the 600mH inductor then.

>>2769693
im the op of >>2769655 and as long as its about 500 and will fit on the board it dosent really matter to me to be honest

>>2769705
forgot to attach the image, i dont mind building it on a larger board since im gonna 3d print the shell for it so as long as it wont get stupidly large

>>2769713
Can’t you just scale the R and C values to give the same results with a 600mH?

What happens if I have a fan thats rated for 75W (24v/3a) but only give it like 30w (24v/1.5).
I plan to use a speed controller and run the fan at like 20% max.

>>2769803
Short answer is it will spin slower.
Long answer is that you can't give it only 30W while supplying it with 24V unless you use PWM. As long as it's connected to 24V it will try to draw the full 75W.
If your power supply can't output more thank 30W then the voltage will drop until the fan no longer draws more than 30W. Theoretically, at least. IRL even the most chinkshit power supplies tend to have overcurrent protection so it's likely the PSU will just shut down on you.

Can pc coolers run for a very long time straight? Like, 10 hours or so? At full blast?

>>2769824
Yeah, why not?
The two-wire “PC” fans of the 1970s cooling your mini-computer would run continuously at full blast for months at a time.

>>2769824
>Like, 10 hours or so? At full blast?
That's pretty much what they go through every day for gaming addicts, and they usually last years.

>>2769655
wah pedals have a huge variety of inductances, 600mH should work fine
maybe just round down your capacitance a bit (there should be an RLC tank in the circuit)

>>2767459
Weird to not see Boylestad or Sedra and Smith in the books section (it was mandatory 1st year reading for us)

why does an opamp make these weird plateus

>>2769981
Can't really tell without seeing the circuit.

>>2769986
i... closed the tab...
it's something to do with it being a real op-amp though, ideal doesn't do that

>>2769925
oh thats good to know, every single wah schematic i found used a 500mH ones or some kind of opamp. I think im still gonna go with a few 100mH ones since its gonna be cheaper for me (theyre like about a dollar a pop), but thanks for the info im gonna try that next time ill be building one.

>>2769981
I've seen TL072's act like that if you bring them within 2V of the + rail, not sure about the exact cause

>>2770035
Transistor coming out of saturation?

If I see the magic smoke coming out of a motor, what are the chances it will fix itself if I let it rest for a while to retake its breath?

>>2770068
Might be ok, might be diminished, might be dead. Check resistance first.

>>2769647
>hand wiring a keyboard
Heh

>>2770130
is this yours? how usable is it?

>>2770132
Well, apart of testing it on a Arduino Nano (Every or something, I don't remember), haven't used it much. It's Full-NKRO, you can basically press any key kombination an it's gonna fire. No software debouncing, just two for loops, pull row, read column (or something, it was like two years ago).
The plan is to make a Freewrite clone but with a decent sized eInk screen (gotta waveshare 9.7" one that should be enough). I have a schematic on paper (an esp32s3, a RPi Pico W, the epaper module and a SD card reader, as well as some ready made circuitry to handle 3v3 - 5v comm) and plan to assemble it on breadbord later this evening, when the kids finally go to bed.
Here's how it looks from above

>>2770124
I turned powered it and now it doesn't work anymore. It's an electric fan motor, what are the chances it's the much cheaper capacitor instead of the motor itself?

>>2770142
Test the motor resistance. If it's infinite or extremely low then the coil is bad. Test the cap to see if it's short.

>>2770132
Look at pic rel. I actually soldered a 1cm wire to each of the pins (2.6x1mm... the horror), and then a diode for each switch. So like 300 solder contacts (?), all done with a TS101.
I don't recommend doing it this way. There's a socket for it which I'm definitely gonna use next time - plus, it will allow me to hot swap switches (200 browns are like 50 eurobucks on ali express).

>>2770146
Forgot pic

>>2770130
>1n4006
are those fast enough?

>>2770158
Yeah, no problem there.

>>2770130
What's the point of the diode spam?

>>2770193
Uglier version of this: https://www.crackedthecode.co/a-complete-guide-to-building-a-hand-wired-keyboard/

>>2770193
The way the keys are scanned through, holding down multiple can backfeed into other lines and look like another switch is pressed when it isn't. Diodes prevent that.

>>2770144
Motor resistance is infinite, in order to test the cap I'd have to cut some wires... If I power it and provide rotation by hand it doesn't keep on rotating, so the cap doesn't seem the problem as it should only affect the startup, right?
There's some damage on the insulation of the coil wires, could they have shorted out because of that?

>>2770392
>some damage on the insulation of the coil wires, could they have shorted out because of that?
Yes. Maybe it shorted and then went open after it cooled down. If the resistance is infinite then there's a break in continuity. If the coil was still shorted then you would get zero or very low resistance. The capacitor is probably fine.

>>2770417
Either way, at this point is either rewind the whole thing or buy a new one. Life sucks.

>>2770422
Yep. Sorry, Anon. If you decide to re-wind it then look up the jigs that people use so you don't have to do it all manually.

>>2770424
At that point I'm better off buying a new one. Not worth my time.
But thanks for the help diagnosing it.

Where can I find circuit diagrams of speed controller modules for power tools.
I have a burnt N800111 and I want to know if I can just build one instead of buying a new replacement part, they're quite expensive in my country.

>>2770429
Most basic tools (angle grinders, drills) use basic triac circuits like pic related. It's basically exactly the same circuit used in light dimmers. Maybe some tools use different methods to reduce emissions (pulse skip modulation instead of pulse width), they can contain soft start features and various other things... But most cheaper tools just use basic TRIAC + DIAC circuit.

>>2770443
> triac
Whenever a speed controller fails, I just remove the thing and plug it into a literal light dimmer I put into an outlet box with a plug. Also great for controlling soldering iron temp (unless you have one of those newfangled usb-irons where you have to log into a cloud server with your soldering account an write a bunch of python code and upload into your soldering iron before using it every time)

The one thing you should definitely add is some suppression filters because dimmers are very noisy, I’ve had the take out nearby LED light bulbs. Incanescents and fluorescents were fine though.

>>2770429
As the other anon says, probably a TRIAC+DIAC circuit. It should be possible to buy a TRIAC that can handle the amps, bolt it to a similarly sized heat-sink plate, and solder the other components to it so it will work off the trigger like normal.

It may be that instead it has an MCU-controlled speed controller, which may have extra features like overcurrent protection, and may also make less electrical noise. Since your one is already dead, you can probably cut it apart and inspect what's in there. It might be potted, but probably only with a soft potting compound. Well, if it had overcurrent protection it probably wouldn't have fried the TRIAC.

>>2770488
For speed controlling a universal motor with an MCU, I found this app note pretty good:
https://www.nxp.com/docs/en/application-note/AN10496.pdf

>>2770488
It's totally potted in some resin or whatever.

>>2770443
The connector for it has 6 pins, seems like too many pins for such a simple circuit.

>>2770492
A hard resin? Bugger. You can dremel through that, but it's not really worth your time.

>>2770498
It's not that hard, I can cut it with an utility knife and have been doing so for the last 20 minutes or so, but I haven't made much progress.

>>2770499
Applying heat makes it tacky. There's several videos out there of people using desoldering blowers to soften it right up.

>>2770491
That was an interesting read, but it doesn’t address the fundamental problems with triacs, it’s just a fancy diac which nobody really needs.
Also they use a capacitive dropper to power their chip, which is a very bad idea, because on the SAME circuit, the triac drops high-frequency noise spikes which will get through the capacitor and kill the chip eventually.

When they say that opamps like OP07 can't work from a single rail and need a least a couple of negative volts, what does that mean in the datasheet specs? That the output cannot swing to 0V? It doesn't look like it can't. It says +- 12v or something similar.

>>2770541
So I simulated OP07 as a buffer, and sure enough, if the input is less than 1v it outputs 1v. For example if the input is 1mv it still outputs 1v. Which ds parameter should tell me that?

>>2770539
huh how would you replace the triac with a diac there?

Can I make a heating plate with peltier devices? I know they suck for cooling but are they any better than resistive heating at actually heating stuff?

>>2770556
No, it keeps the triac, but it acts in place of a diac, although it’s way more complicated.

Need to replace this pot. I think it’s 200k audio. What search term can I use to get this form factor?

>>2770493
Post a wiring diagram. Seeing what each of those six pins connects to should give context as to what the circuit inside is.

>>2770541
Those are the specs at a set power rail voltage, probably +/-15V. The input voltage range is at worst 2V from that, and the output range is at worst 3V from that. Wish they just defined “voltage from the rail” instead of “voltage from ground” in these cases. Especially when you’re trying to read a graph.

>>2770556
Discs do not replace triacs. The diac circuit is the component that defines the voltage threshold at which the triac turns on, this voltage is charging up a capacitor so it implies a time delay. The MCU replaces this by using its own ability to time.

>>2770591
Yes, but if a peltier device is 10% efficient at cooling, it will be 110% efficient at heating. And that’s assuming good heat sinking on the cold side. In reality it probably isn’t worth it, unless you might need to cool the area as well. Like a butter conditioner, or a lower power oven for an oscillator.

>>2770612
>Those are the specs at a set power rail voltage, probably +/-15V.
Ah I see what you are saying. It is not 3V, in practice it is more like 1V but yes that explains it. Some datasheets specify it as VCC-3V and VSS+2V or something like that. Damn it is confusing.

>>2770612
I was thinking of using the heater for home chemistry. Being able to reverse the polarity and rapidly cool down a system after having done whatever I had to do with it at high temperature instead of waiting for it to cool by itself seems like a nice bonus.

I have pic related that use to label spare parts. two weeks ago I connected a charger with the wrong polarity: I removed it almost immediately, tried to turn it on with AA batteries and it worked. Flashforward, today I turned it on and the bastard won't stop feeding the label. Even when it is off but with the batteries inside it continuously feed the label, even after turning it on the first time after inserting the batteries. What the hell could have happened with a two weeks delay? Is it a lost cause?

>>2770608
https://www.mouser.com/c/passive-components/potentiometers-trimmers-rheostats/slide-potentiometers

>>2770616
I had the happen with my Dymo when my work van leaked and water got into it. Did yours get wet? If so dry it out.

>>2770591
Use a quartz halogen floodlight.

>>2770644
Can you even still buy those?
I’m aleady hoarding my remaining incandescent light bulbs to use as electronic loads and current limiters.

>>2770646
Yes. I looked it up and saw PAR20/30/38 lights from various sites and the tube types in work lights and floor lamps at the regular places.

>>2770632
The slide pots are filthy, but not the issue. The part that's removed is the one that needs replaced.
Anyway, figured it out, just had to dumb down my search terms to "volume control" and found some.

>>2770615
Yeah that is the case where it’s valuable. Especially if you’re using it with a thermometer to give live feedback. You already have a heat sink on the other side for cooling, so you lose nothing by being able to heat it too.

>>2770616
Sounds like a dead MOSFET, assuming all else works. Should be an easy enough fix.

>>2770646
Even in the EU you can still get oven bulbs and 12V car bulbs. Might be worth considering radiative heating elements for/from a toaster oven. Light-based works fine for PCBs but for chemistry you might lose 90% of your power just passing through the beaker. I think IR gets absorbed by borosilicate, but I’m not sure if the near IR from a bulb follows that rule like thermal IR does.

>>2770655
>passing through the beaker
but you could heat a thermal mass from underneath and put the beaker on top of that. Like a hotplate with a halogen heater.

>>2770655
>>2770644
What I want ultimately is more control over the temperature when compared with the normal resistive heating the commercial stuff has. Those either can't hold a temperature or do so without any active control on the equipment side, relying only on the thermodynamics of it being run in a planet with atmosphere.
After seeing the peltiers, they seemed like a good fit because of how fast their response is.
The light bulb is interesting but probably gonna be bulkier and I'd want to heat up some plate and then use that plate to transfer heat on to the system, because if I irradiate it directly, different chemical species in the system will absorb that at different rates and that might lead to funky results, for better or worse.
I've thought about inductive heating too, but seems more complicated than it's worth for this application.
Also can I modulate the power of the peltier with a pwm signal? If that works, then I think I'm off to buying a couple and get started experimenting with them.

>>2770668
Just get one of these bad boys and put that under your boiling flask. The heat comes out of that hole in the top.

I watched this show where this old guy beat his student for not knowing the difference between an erlenmeyer flask and a boiling flask.

>>2767459
im trying to fix this old keyboard.
it has some of the wires soldered directly to pads, not through-holes, pads.

do they make anything i can solder directly to the pad that will hold the wire better? Ive already had one wire come off

>>2770692
>not through-holes, pads

this is an image boards, dudette.
post a pic so we can make sense of you gibberish.

>>2770659
But that gets rid of the advantage of using a radiative system, that it doesn't care if the surface isn't thermally bonded to the hotplate. At that point it would be more compact to just use a conventional hot plate, or slab of aluminium with a silicone heater stuck to it, or whatever.
Easier to replace the element when it dies if it's a bulb, but it's far more likely to die due to vibration or damage or thermal cycling than a conventional element in the first place.

>>2770668
>control over the temperature
Conventional hot plates can have temperature sensors in the base, but I agree that's significantly worse than having a thermometer in the beaker itself. But personally I'd try to modify a conventional hotplate to use an external temperature sensor, like what Applied Science did with his RFID stir bars. An issue you may run into with peltier devices is their maximum rated temperature, which TPAI ran into recently.

>can I modulate the power of the peltier with a pwm signal
Yes, but you may get better efficiency by using a proper buck converter. I've even heard of people driving them with an MPPT circuit.

>>2770692
Not really. Solder a wire and cover it in silastic/neutral cure silicone/UV cure glue, it's the only way to be sure. You may be able to follow a trace back to a through-hole, but not in all instances. I'm guessing the wire ripping off delaminated that pad? Good luck repairing that.

>>2770694
here you go, science-man
https://en.wikipedia.org/wiki/Through-hole_technology

>>2770695
> I'm guessing the wire ripping off delaminated that pad? Good luck repairing that.

luckily, no. i used a wire 2 gauges bigger so it barely adhered to the pad.

>>2770707
>barely adhered

that's very odd
(like an Irishman walking out of a bar)
coz PCB pads are the easiest thing to solder to
made from copper, low thermal mass, made specifically for soldering to
so a pic would really help us figure out how you are failing so bad at something so simple

>>2770655
>>2770634
No water. It was stored at 0 Celsius for a while but the place wasn't really humid. I will start to check the MOSFETs, thanks for the hint

I'm looking at some audio schematics and a number of them start with an op amp that shorts output to -
Why do they do this?

>>2770707
>>2770711
Yeah that sounds like your solder joint didn't make good contact. Use higher temperatures and/or extra flux next time.

>>2770742
Consider the ideal equation for an op-amp:
>V_out = (V_+ - V_-) * Gain
Then we say:
>V_out = V_-
>V_out = (V_+ - V_out) * Gain
>V_out = V_+ * Gain - V_out * Gain
>(1 + Gain) * V_out = V_+ * Gain
>V_out = V_+ * Gain / (1 + Gain)
Since the gain is usually very large (preferably at least 60dB = 1000), we make the simplification:
>Gain / (1 + Gain) = 1
Hence:
>V_out = V_+
V_+ is used as the input. This is a circuit used for taking a high impedance signal that can't drive a circuit without losing amplitude, and buffering its current output without changing its voltage. The input impedance of an op-amp is usually rather high, in the 10s of MΩ at least, and the output impedance with feedback is usually in the realm of 1-10Ω. So you can buffer a very weak signal. Note that the above mathematics only holds so long as our assumptions hold. If the voltage input is outside the common mode input (or output) voltage range, it won't behave as expected. If you're operating at a frequency where gain is quite low, it won't behave as expected. If you try to draw too much current from it, it won't behave as expected.

This simple equation of an operational amplifier is very versatile, using resistors and capacitors and transistors one can make all manner of interesting circuits. Integrators and differentiators, adders and subtractors, logarithmic and exponential converters, instrumentation amplifiers and oscillators.

>>2770744
so high impedance -> low impedance. Got it.

>>2770677
Erlens aren't made for intense heating. They can crack or break in those conditions.
>magnetron
Different solvents have different dielectric constants and will heat up faster or slower under microwave irradiation depending on that. Plus it will fry any sensor I put in there and be hazardous to work with.
>>2770695
Conventional hotplates are prohibitively expensive for home chemistry in my country.
>max temp
Yeah, 100°C is too little, but I've seen some that can go up to 200°C which is much much better. I don't think I ever refluxed anything at that temperature and I can only remember one reaction I did which went above that.

>>2770742
unity gain non-inverting buffer

>>2767482
>not a sweet Q-factor

>>2770796
>sucking intensifies
Trust the plan or something.

>>2770711
this pad is about 2mm in width
its 14g wire
now, solder the pad, apply the non-twisted wire, add pressure, and the wires flare out. the wire is constantly trying to bounce back to its og shape and the solder is fighting to bond to wires and pad. thus a good joint wasnt made.

i used the wrong wire size, and even then, didnt twist it. it does take fucking columbo to figure out how i fucked up.not like this keyboard from 88 has full online docs on wire sizes to use and schemartics

I need to desoldar this SMD, only done THT in the past and some odd big SMD diode/LED soldering.
I only have a TS80p but will gladly aquire new gear.

How do I handle this?

>>2770922
>How do

child's play.
take sharp knife, like an x-acto, press down diagonally on each pin
hack all of them off
blow off the chip, and use soldering iron to shovel away amputated limbs

>>2770925
I what sense? Like in between the legs and the pads or are you suggesting i amputate the chip? I then need to solder it to s new PCB, do you gugfest large blobs on the pads to compensate?

>>2770933
>I then need to solder it to s new PCB

you shoulda said before
so you can do it 2 ways, hot air and flux like in 1000 Louis Rossman videos
or the ChipQuick way: https://youtu.be/FTQqjggeklo

Semi related question:
What are some ways to desolder through hole components with the leads far apart or multiple pins with a soldering iron?

>>2770940
Chisel tip
Put tip under lead by the pad.
Tip will melt the solder on the pad.
Twist chisel tip and raise/pry lead up out of the hole
Repeat on other side.
Done.

>>2770940
>some ways to desolder

lots of diff tools exist, but i invented my own no-tools method.
get small cardboard box
melt joint with iron
quickly throw it against side of box
pick it up, and see joint is now completely solder free
box looks like a crime scene, with splatters of lead everywhere

I have a UPS that has a loud 14 khz buzzing noise. I tracked it down to a ceramic capacitor on the charging circuit. I replaced the cap with a surface mount capacitor because it's what I had on hand. The noise is quieter but i can still hear it. Would throwing an inductor in line help quiet it down or do I need a special type of capacitor?

Is this a broken panel or broken circuitry? Every other row of pixels is dimmer. Affects only the leftmost 20 cm or so, gets weaker the farther right you go. Second pic is from the middle of the screen where it looks normal.
Happens with both DVI-D and VGA inputs.
If it's the circuitry, what type of fault could cause this?

>>2770945
I have one of those suckers, but you can never truly remove 100% of the solder with it in order to free the component from the board. Sometimes it stays stuck by just a little bit of solder that can be broken off with a bit of persuasion, but replicating that is unreliable.
>>2770942
Guess I'll be buying some funny shaped tips and experimenting with them now.

>>2770940
stop soldering through hole
start soldering point-to-point on a ground plane

>>2770922
That SOIC-8? As well as what the other anon suggested, you may be able to reflow one or both sides at a time. One side at a time is kinda sketchy since you need to bend the thing up at an angle by 2-3mm to get the leads to seperate from the pads. Then reflow the other side and it falls off. That kind of force can delaminate the pads on the board, but maybe you don’t care about that. A wide screwdriver or knife tip can do this.
To get both sides at a time you’ll either need two irons or desoldering tweezers (each with a long edged tip), or to bend some thick copper wire such that it provides good thermal contact to both sides. Either way, you risk overheating the chip if you’re not careful.

>>2770940
Suck the solder out of the holes. Electric solder sucker irons are good for this, vacuum desoldering stations are even better. Wobbling the part while the remaining solder dries is a good way to prevent it from sticking to the part again.

>>2770997
Ceramics are known for this. Consider a film capacitor, if the value is below a few hundred nanofarads, though it will likely be substantially larger. If it’s greater than that, I’d inspect the circuit to see whether an electrolytic capacitor would be suitable. There are also ceramic capacitors designed specifically for having low piezo effect.

>>2770999
Interlacing circuitry or setting maybe? If the problem is in the circuit it’s probably a pain to troubleshoot, I’d likely leave it as is and use it where you want an aesthetic retro monitor. I tried to buy a 2nd hand monitor with a damaged green channel for $5 because the magenta screen was my kind of retro, but it turned out it only did that on VGA, on DVI it’s fine.

>>2771035
>not wire-wrapping

>>2771046
>>2770997
Ty. It's a 1kv 102k so 1000pF. I think I've seen blue film caps on smps around that value so I'll try one of them.

>>2771059
Ah 1kV. Does it actually need to be 1kV? 240-400V film caps are kinda common, 1000V less so.
>around that value
Where in the circuit is it? The value may be semi-critical, I wouldn't vary it by more than 20% without understanding what exactly it's doing. Maybe it's part of a snubber by the main power transistor.

>>2771046
>Interlacing circuitry or setting maybe?
The weird thing is that only a part if the screen is affected. There is no such setting in the osd menu.

Anyone knows where I can learn more about transformers? The way I'm thinking of them is that a transformers are bigass inductors. The primary builds up the magnetic field, and the secondary steals the flux. The voltage difference comes from the inductive impedance of the coils which form a crude voltage divider. How wrong am I?

>>2771129
Sorta correct, but electrically speaking ideal transformers don't really act like inductors. That's why we need transformers with air gaps. Maybe the books in the OP have good sections on transformers, check them out on libgen.

>>2771129
>The voltage difference comes from the inductive impedance of the coils

nope, it's simply ratio of turns
if 10 turns on primary produces a given level of mag field, then a single turn on the secondary will only capture 1/10 of that field
so the output voltage with be 1/10-th

>>2771138
If it’s only capturing 1/10th of the field, why is the current 10 times stronger in that one turn?

>>2771154
>why

preservation of energy
power out = power in, assuming 100% efficiency
in real life, it's around 90-95%

>>2771171
what is this thing(inside an ebike by the battery)

>>2771263
and this

>>2771263
>>2771264
That’s what makes time travel possible. Got a model number?

>>2771274
no its all in chinese. didnt find anything at least.

>>2771291
Well it’s probably the motor controller. It’s a guess based on the wire gauge and color.

Hi everyone
I'm struggling to find a male connector for my tig welder torch switch since it's 9 pin and this specific layout with a thread on the outside. It appears like a microphone connector but I'm not sure they would work. Is it possible to improvise something reliably by plugging the wires directly in the pins?

>>2771339
For context, here's the pinout on the machine's manual. I could be wrong but it seems I realistically only need 2 of the 9 pins for the machine to operate functionally. Pins 1 to 3 are variable control for pedal, while 8 and 9 are used for on/off control

>>2771339
Those are called DIN sockets/connectors.
https://www.amazon.com/HangTon-Waterproof-Connector-Aviation-Disconnect/dp/B07DL49FG5

>>2771339
>by plugging the wires directly in the pins?
It can be done if you really need to weld right now. Try to find a conductive rod that you can cut to length, solder your pot wires and footswitch wires to the rods, then insert them into the socket. Give 'em the hot glue treatment to keep them insulated from each other, and secure the cable so you don't accidentally yank it from the socket.

>>2771343
Thanks a lot, are they all universal in diameter? Mine is around 16 millimeters if I remember right
>>2771350
I have the switch and a cable with 2 wires, my idea was to solder or crimp some insulated pins and plug them directly in #8 and #9

>>2771353
>are they all universal in diameter?
No, but they come in 16mm.
https://www.amazon.com/Lsgoodcare-5PCS-Female-Aviation-Connector/dp/B01N333F99
> my idea was to solder or crimp some insulated pins and plug them directly in #8 and #9
That'll work. Just make sure they're fully inserted.

>>2771263
Inverter?
>>2771264
Black metal box.

>>2771357
I received an afg, oscilloscope, and dmm for free, the guy only provided a single bnc to bnc coax cable for cables. I assume the ac to dc NA power cables are pretty standard might even be able to search the house for an old latops, 1 MΩ/20 pF input probes seem to be a minimum of 60 cad, im not sure what else (or if thats even) needed for probes, making sure its atleast 60MHz for the 1002b. And idk if there are other interesting add-ons to look into

>>2771436
>I assume the ac to dc NA power cables are pretty standard
Still gotta match the voltage, and match or exceed the current rating. It's probably 12V 1-2.5A centre-positive 2.1/5.5mm, which is pretty damn common, but laptops usually use 19-24V with a larger plug instead.

>>2771441
Thanks, all good advice is welcome even for dumb things, ill look at their datasheets for that

I often see laser diodes driven with a constant current, but then that constant-current is PWM'd, as opposed to just adjusting the current. I get that lasers don't work at very low current values, but I don't know to what extent that would effect a laser like this in normal operation. My machine shouldn't need to go below 20%, though having a very low power rating as a pilot beam is pretty handy. I have a 30W electrical power laser diode and I'm considering replacing its 12V-only driver board with a custom one that can handle 24V. Maybe I just design it so it could do either and test it out.

Also if someone can recommend me a seller/brand of laser diode (sub-$200) that actually has a tight focus that would be cool. Sick of astigmatism.

aw yeah, beam width compensated svgs with less visual artefacts and processing time

b r e h s
where can i get film that i can print on for uv

>>2771633
as a mask for uv exposure?
ebay/aliexpress waterproof inkjet transparency / laser transparency
don't really recommend using an inkjet though, getting exposure dialled in is a bit of a pain and you go through expensive ink kinda quickly. even then the contrast isn't brilliant. the dry film photoresist is also kinda shitty in quality when you buy it from the chinks, got a bunch of thin spots in mine. liquid etch resist smells like death, not recommended. that's why i'm using a laser engraver to burn away an etch resist or solder mask instead. a router is even better since it can drill holes precisely too.

>>2771350
>>2771353
Got it figured out this morning, thanks guys
Now I only need to figure out how to make a variable amperage control foot pedal for future use. It's supposed to have a potentiometer sort of like the ones used with sewing machines but I'm not sure which value it needs

>>2771636
is it fine for the mask to be adhesive?

I am getting a cnc that I will use for making pcbs. I am a bit worried of the dust, apparently it is quite bad for you. And it will run in my living room

You can oil the surface which catches most dust apperantly. I am also planning to enclose the machine with a box while it is working, i will make it somewhat air tight by wrapping it with plastic. And then wait a bit for the dust settle after the work is done, and then wipe it with a wet paper cloth or something

Would that work? Too paranoid?

>>2769359
>>2769350
Alright so I'm back again. I ended up switching out the radio fuses with new ones, both 20A and 30A. My amp ended up working perfect for 2 days afterwards. On the third day it didn't start with my car twice, but on the second time I hit a bump once again and it randomly came on for the remainder of the time I was driving. Going to pull the fuses again soon and see if any of the ones I replaced already look burnt/dirty/corroded.

I'm assuming that the amp working great for two days after plugging it back in and replacing the fuses means it might have been some sort of power connection issue/resistance issue? I bought some contact cleaner as well, but any suggestions on how to best clean the fuse connection without fucking anything up, or if I should use something besides contact cleaner that would promote a better connection if that's the issue? Honestly I'm at a loss, I thought I had it fixed. Could it be a faulty ground, and if so any ideas on how to find out where my fuse box is grounded to? I'll report back once I pull the fuses again.

>>2771727
Spray some WD-40 into the fuse sockets and scrub them with something non-conductive. Place some rags around and underneath so you don't overspray. Check the contacts with a flashlight for any remaining grime, then give them a blast of contact cleaner and insert the new fuses. If everything works well, you might want to put dielectric grease on your fuse contacts to prevent ingress of moisture and dirt. The only other thing I can think of is loose fuse holder contacts.

>>2771735
This is one thing I’ll never understand… why some people think it’s a good idea to insulative oil, wax and silicone films on electronic components and contacts.
No actual switches, potentiometers, plugs, pins, sockets, relays (mercury wetted and whatnot) come like that from the factory for good reason—it makes poor contact.

>>2771807
I'd say it's making poor contact right now and dielectric grease isn't going to affect conductivity. If anything it will delay the problem from returning, or prevent it entirely.

>>2771815
>dielectric grease isn't going to affect conductivity
so long as the contacts are clean before you grease them.

>>2771717
Maybe? I'd worry that it would peel off the photoresist when you go to develop it. I guess you could stick it to the peel-off backing of the photoresist, but I think that's best peeled off before exposure.

>>2771724
>And it will run in my living room
They're also noisy, I'd want to run it in a garage. If that isn't possible, I'd definitely want some sort of dust extraction system. Be it a vacuum on the end of the router, or a negative-pressure enclosure for the entire router. Oily dust sounds like a mess to clean up, I'd just use water and ensure the electronics are up and out of the way of any splash.

>>2771727
Again, anything stopping you from probing voltages on the amp while it's still plugged in?

>>2771727
https://www.onallcylinders.com/2017/09/29/ask-away-jeff-smith-clean-replace-corroded-fuse-boxes-cure-random-non-battery-related-power-loss/

https://pawlikautomotive.com/a-paradox-a-complicated-simple-repair/

lets say im charging 10 18650 cells each 3.6v in series so they are 36v

lets say my source charger can only output 5.6 volts(but enough current). what happens to the cells. do they still charge up? or only some of them(the closest physically to the source current or based on some other critera)?

>>2771859
>do they still charge up?

no current will flow into the cells.
you have to surpass the total voltage present before any electrons start moseying along.

>>2771859
Side note: A fully charged 18650 measures 4.2V. Do you have a 10S BMS board?

>>2767459
EEs like to get into pissing contests about how much harder an EE major is, compared to a CS major. But that seems like cope to me. If CS majors get to work on fun projects and still get paid a reasonable salary, it seems like the EE majors made the dumb decision.

>>2772002
>dumb decision

what's really dumb is retards acting as arbiters of other people's life choices

>>2772002
But I don't want to cut my dick off and dye my hair blue. Plus I shower daily.

Let's say I need controlled impedance for high speed signals
Let's also say I'm a broke ass motherfucker
I can specify the stack up and layer thicknesses in my CAD, and board houses often specify what thicknesses they can accommodate

Assuming I get my differential pairs right, with a given off-the-shelf stack up supported by a board house, will the resulting PCB have pretty-close impedance on the layers without having to specify a fucking ridiculously expensive controlled impedance board?

banned from eevblog again

>>2772062
> need controlled impedance
For what? HDMI? The tolerances are not that critical for short PCB to connector runs.
> broke
I guess you have no ability to test it eh?

>>2772047
Yeah, but every EE class and EE lab has a stripper in it. (wire stripper)

Is there any picture book for connecting gears, nema 17 motors and rails, 8020, etc... Something like pic related but actually practical.

I'm not a fan of 'art of programming' type abstraction.

>>2772114
https://www.youtube.com/playlist?list=PL_6VEfozyAFfN1L6HgAeYErpjqd4n8VXr

https://www.youtube.com/watch?v=ZhDO16FDmxA

>>2772062
Is it DDR4 RAM? There is a lot of documentation out there on hi speed DDR as opposed to 10 or 15 years ago, supposedly Just find the right guide or book for whatever signals you are trying to route.

>>2772131
Yeah, I've been watching more things like https://www.youtube.com/channel/UCsOFElmDD3e8l-RGCabCZ9g but I was hoping there was a book out there. I can't find anything. It looks like it's all locked up in instructables or youtube videos.

>>2770925
>>2770938
Anon inadvertently changed my life recommending chip quick.
I'll always remember this post.

>>2772464
Did you remove the excess alloy from the pins before soldering with fresh solder (and clean tip) to the new board?

>>2772464
Geez, this shit seems to be a bad idea.
By their logic, you could use mercury… it won’t hold any more heat than regular solder would

>>2772501
Yeah, there’s no way you want any of that quickchip junk left. Who knows what it does to the joint over time, even in minuscule quantities.

What a retarded and wasteful idea. Just get a square qfn tip like we had for DIP.
In fact, get the DIP version of the chip and put it in a socket.

>>2772580
fuck, that's genius. why don't these come with every soldering kit?

>>2770999
>>2771046
>>2771117
I've done an experiment. I have working monitor that is very similar to the broken one, a P23T6-IPS. The broken one uses an LG LM230WF3-SLP8 panel, the working one an LG-LM230WF3-SLB1. The connector for the backlight is different, but the one for the display looks the same.
So I use the circutry from the working one on the panel of the broken one. (But still using the broken one's ellectronics to power its backlight)
Turns out, that while the connector is the same, the signalling must be different, because I got only garbage on screen. I don't think the effect is there, though it's hard to say with the garbage on screen being horizontal lines itself. I don't think I see the shimmering, but to be honest, I can't really get a good viewing angle

Any ideas for further procedure?

>>2772618
https://www.panelook.com/LM230WF3-SLB1_LG%20Display_23.0_LCM_overview_12258.html

https://www.panelook.com/LM230WF3-SLP8_LG%20Display_23.0_LCM_overview_29413.html

Both displays are LVDS, 2ch, 8-bit, 30 pin interfaces that run at 5V. Take the LVDS connector from the dead panel and put it on perfboard (or buy a breakout board). Then re-route the signals to the monitor mainboard. Alternatively, make your own cable.

>>2772626
Either my you didn't understand my post or I'm not understanding yours, but I think what you are suggesting is what I have done.
I hope this explains what's in the picture.

Connected like this, the panel showed horizontal green lines.

>>2772633
>I'm not understanding yours

since a straight swap doesnt work, he's suggesting you modify the order of the connections.
it's only 30 wires, so by making a new combination every second, it'll only take 34.04 years worst case.

>>2772646

How much of a meme are anti-static mats? I've built a dozen computers in my days and never experienced problems. Worked on wooden surfaces, been mindful about clothing materials, touched faucets or elements before just in case and never experienced problems.
Never seen anyone on the internet using one either. Who buys them?

>>2772675
Some sensors are extremely sensitive to static, as well as transistors and ICs. If you work on a production line then you're required to use ESD mitigating tools. Beyond that, it takes a lot of effort to kill electronics with static discharge. Electroboom did a thing with that Canadian faggot where they tried to kill RAM sticks with a static generator.
Here it is: https://www.youtube.com/watch?v=nXkgbmr3dRA

>>2767944
>>2767963
>it's generating 5V and 15V
Test the transistors and optoisolator.

>>2772709
All of that is fine if it's still generating the 5 and 15V through T831S. The other transformer T901S that makes up the CCFL inverter is switched by Q903/Q904 off the 15V rail. Those transistors aren't very big so are a suspect part of the circuit, so is anything else that deals with the higher voltage section.

>>2772723
If it's not Q903/4 then maybe the power button is broken.

>>2772675
>>2772679
In canada, it gets dry and everyone is walking around on rayon carpets. We used to blow-out keyboards right through the key caps on a regular basis, and it would kill the keyboard ROM in the PC.

>>2772727
Or the logic board.

>>2772723
>a suspect part of the circuit

"When you have eliminated the impossible, whatever remains, however improbable, must be the truth" - S. Holmes
so, if something is suspect, you test it to eliminate suspicion.
apparently you're too chickenshit to measure the CCFL voltages directly.
(if you cant trust your meter, add 10M in series to limit damage)
or you can try something like this
or the equivalent pulled from some old electronics
personally i've been using some lil 12V boards taken from old-time scanners for decades
and it's only killed me once or twice

>>2772768
No the actual smart way is to just convert to LED, which was the first response to the OP (who isn't me).

>"eat" branded pcb
hmm

>>2772795
>convert to LED

sure, but it's usually noble and valiant to diagnose the disease before operating.

Gonna do an order of PCBs soon, recommend me some useful general-purpose circuits. I'm already doing a 4046 dev-board, triac+zero-crossing board, motor driver boards, a few others probably. Maybe an instrumentation amp dev-board? I will be working with load cells sometime soon so it's a good idea I guess.

>>2772733
Similar thing happened to the OG Atari 2600. Their answer was to put foil behind the switches but it didn't work (it was the controller ports getting zapped). The 4050 buffer IC was the found to be the ESD sensitive component, so a diode + cap on each controller port fixed the issue.

>>2771724
>>2771826
They don't make that much dust. Most of the time you are only cutting traces (which is technically only supposed to remove the copper layer), not milling the pcb. Small boards you can just wipe off the pcb with a damp rag. If on the other hand you start milling wood or aluminum, then it might make a mess.

It is all going to depend on how much material you remove.
>>2772675
I'm pretty sure I fried an RPI4 with static electricity.
>>2772816
Current sense board.

>>2772884
>Current sense board
Hmm, I'll be putting sense resistors on boards that have MOSFETs anyhow. Having a standalone current sense board would be pretty handy, but I think that's trivial enough to make prototypes at home.

noob here, is it at all possible to identify this component? from a sound bar if it makes a difference

>>2773028
Should be this.

https://www.onsemi.com/pdf/datasheet/nup4202w1-d.pdf

>>2773028
What’s the circuit context? Is it connected to the battery? Looks like it might say 4202 (see if you can find other photos of this product’s internals) and it’s probably a SOT-23-6 (verify that with measurements), see if you can find a matching part in the SMD codebooks. Verify the markings and context on LCSC, assuming there’s a datasheet.

A quick search brings up the TPS54202 buck converter, check the datasheet if the connection of the nearby passives and the ground node match up.

Hi,

This is my first time doing a PCB. I'm using Altium designer and it's for my capstone project in school.

I am wondering if it's standard to do a GND pour like this and use burried vias to route to my GND plane.

Also I just generally feel overwhelmed, so if you see any glaring errors please tell me. I've been watching youtube tutorials and trying to do this myself.

>>2773037
>SC70
>getting 4 legible letters
Doubt. Also the SMD markings for that chip are wrong.

>>2773120
Is that a DFN-8? If so that's some tiny bullshit you're doing. Plan on hand-soldering? If your fab house is fine with those clearances then go for it. But while electrically it's fine for the IC's power requirements, consider if it wouldn't be good to also have some ground fill on the top layer, stitched to the actual ground plane with vias near components. Not a big deal if it isn't a low-noise or high-speed application though. Don't forget to do some anime artwork on the solder mask.

>>2773134
>Is that a DFN-8?
this one is 8-SOIC, but I do have a few fine pitched components on the back side I still need to populate. I will be using PCBA so no worries about hand soldering.

I have imported the fab house design rules into Altium and am leaving a conservative amount of clearances.

I just feel like I'm bound to mess something up and this whole thing is stressful. I wish it didn't have to be this small but the whole board is only 30x30mm driven by my client's requirements.

Anyways, thanks for the pointers. I'll add some ground fill on the top layer like you advised.

pic related is my progress so far. All this aligning is really triggering my OCD and I keep redoing it a million times.

>>2773139
>SOIC
Oh, any reason the pads go that far beneath the IC?

>I just feel like I'm bound to mess something up and this whole thing is stressful
You can always add redundant footprints, especially series and parallel footprints in analogue sections of the board. Maybe you need to add a frequency rolloff in a feedback loop.
Assuming that's an MCU there, double check the datasheet to ensure you're putting signals on pins that can actually handle them. I put PWM outputs on timer pins on a project, but chose secondary timer pins that had half the resolution of the primary ones, locking me to 8-bit PWM instead of 16. Also if you have any PMOS FETs, ensure they're in the right orientation. That was a time consuming mistake.
Also consider if voltage will go anywhere strange if you plug your programmer into the programming port while the board is connected to its intended power source.
And think if any strange forces will be on that SMT connector or button. Using parts that have locating holes would be stronger if it's necessary.

>I'll add some ground fill on the top layer like you advised
Adding a top ground fill will increase the stray capacitance for nearby traces, which might be a problem if you've got multi-MHz signals, otherwise it's fine. Double check PCB layout guides in datasheets and appnotes for the major components involved.

>OCD
Put the QFP on a 45° angle.

Happy St. Patrick's Day

>>2773142
damn thanks for the pro tips man! I copy and pasted into my notes. I guess I just have to try it and learn from my own mistakes too.

How much of a change is a component tester? I've got a multimeter and a osciloscope (1 channel) and I usually make do with those but I get a lot of components from scrap boards and it's a bit of a pain to check everything after desoldering to see if they're good or bad and to sort it all out.
Thinking of getting myself one.

>>2772626
Well, connected it up again, but better his time. Now I have:
Board A ---- Panel B
Board B ---- Panel A
for the displays, but
Board A ---- Panel A
Board B ---- Panel B
for the backlights.

Connecting it up like that gives me a good picture on the panel from the working monitor, and pic related on the panel from the dead monitor.
I also noticed a buzzing sound coming from he circuitry that is on the broken panel itself (the stuff the LVDS connector plugs into). No such buzzing coming from the working panel. There is also no buzzing when the broken panel is connected to its original board.