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Thread delaminated:>>2193842

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

>Project ideas:
http://adafruit.com
http://instructables.com/tag/type-id/category-technology/
http://makezine.com/category/electronics/

>Don't ask, roll:
https://github.com/Rocheez/4chan-electronics-challenges/blob/master/list-of-challenges.png

>Archive of Popular Electronics magazines (1954-2003):
https://worldradiohistory.com/Popular-Electronics-Guide.htm
>Some guy’s list of electronics resources:
https://github.com/kitspace/awesome-electronics
>Microchip Tips and Tricks PDF:
https://ww1.microchip.com/downloads/en/devicedoc/01146b.pdf
>Li+/LiPo batteries required reading:
http://www.elteconline.com/download/pdf/SAFT-RIC-LI-ION-Safety-Recommendations.pdf

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

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

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

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

>I have junk, what do?
Shitcan it
>consumer product support or PC building?
>>>/g/
>household/premises wiring?
More rules-driven than engineering, try /qtddtot/ or sparky general first
>antigravity and/or overunity?
Go away
>>
Peak voltage of 120VAC is sqrt(2)*120. Is this the same for the phases of 480VAC delta? sqrt(2)*480? What about wye?
>>
>>2202256
line voltage or phase to phase? For delta those are the same, but for wye Uline = sqrt(3)*Uph. So in a wye configuration if you have 480Vrms line voltage, the peak phase voltage would be (480/1.73)*sqrt(2)
>>
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Does anyone else know of IC's similar to the ADS7128/TLA2518 (as in ADC + GPIO all on one package)?
https://www.ti.com/product/ADS7128

I know I can achieve the same functionality with an MCU, but am after an integrated solution so there are less things to program ;^)
>>
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So my boss gave me a fancy equipment recently (see pic related and attached specsheet) and I'm not sure how I use this. The intention is to measure the vibration of a particular machine.

I am given:
3x single-axis accelerometers
1x microphone

I'm assuming that the accelerometers go into Ain0 -> Ain2 with the Microphone at Ain3 but I've also read that an accelerometer is also a tachometer so shouldn't I be putting that accelerometer in the tachometer input? Kinda confused but I'm glad that I'm getting some work experience in electronics at work.

https://www.mccdaq.com/PDFs/specs/DT9837-Datasheet.pdf
>>
>>2202256
So delta peak phase voltage is sqrt(2)*480, but for wye its sqrt(3)*480?This is referenced to what? The other phases? I need to read up on this more.
>>
>>2202267
>>2202260
shit. here's your (You)
>>
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Any electricians (i.e. tradies) ITT? If so, do you enjoy your line of work? I'm 28 and I work a dead-end job in healthcare and I hate it and I'm looking at alternative career options. I've posted in this general a few times over the years doing small projects and I could see myself maybe going to community college doing some some classes again and an internship.
>>
>>2202261
put an i2c io expander on the same bus
>>
>>2202280
Electricians and EEs deal with completely different fields generally speaking, you may have more luck asking in a thread where those guys lurk.
>>
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>>2202307
Everyone here is EE?
Or pursuing an EE degree?
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>>2202248
Anon it's 2015+6, you don't have to post melonin people anymore.
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>>2202328
Like how everyone on /g/ is a FAGMAN or grinding leetcode
>>
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>>2202328
I'm just a humble cook.
>>
>>2202328
i'm an ME but electronics is cheaper and more fun
>>
>>2202328
CPE, employed as an EE though
>>
>>2202280
I’m an industrial electrician but lately more PLC guy/system design. I like the good pay and travel for work. If you know the basics of electronics you don’t really need a college or internship I think, just some certifications on safety, industrial equipment and the relevant bus systems… We have a big shortage of electricians (Western EU) so many companies will hire first and train on the job
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>>2202328
No, I'm just a hobbyist but if I was smarter I wouldn't have dropped out of school and studied EE. I've had numerous friends ask me "why don't you become an electrician?" as if it's the same thing...it's not, far from it.
>>
>>2202328
I'm just a humble translator, trying to have fun with electro-things
>>
>>2202328
I did CS and math, but my school required a lot of EE courses. Enough that it would have been a CE or EE minor at other places. My only real application of that knowledge now is hobby stuff, and using external flashing tools for troublesome hardware.
>>
I'm looking at building my first ebike,
Can you use a lithium battery with this kit?
https://www.ebay.com/itm/234095225325

I saw a similar set of connectors in a shitty brushed e-scooter, but it was using lead-acid batteries and the charging circuit went through the controller (IIRC). A lot of the batteries I see on ebay come with a charger, so I assume I could just charge the battery outside of the bike/controller and be OK?

https://www.ebay.com/itm/402712329149
>>
>>2202306
As in have one IC for IO expander, and another for ADC? Not enough space on the board my dude
>>
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Is creating a basic, adjustable low pass filter circuit for audio applications as simple as what I've designed here, or is there something I'm missing?
>>
I want to store my FETs in plastic boxes but I'm too afraid.
>>
>>2202572
It'll work but take the ground off RP1, it will act as a volume control in addition to what you want which may or may not be desirable.
>>
>>2202355
I haven't went on /g/ much so I wouldn't know.
>>2202365
I hope you enjoy your cooking profession then. /ohm/ meetup where you're the lead cook.
>>2202382
That's interesting, you get to get a taste that many of your major probably didn't. My coworker at the electrical department I'm in is mechanical and she's completely lost hehe... Anything useful that carries over from your discipline?
>>2202413
Interesting, is there anything in particular from CPE that has been really useful in EE? Or does the extra coding experience really help?
>>2202454
I have a feeling that it was the environment that fucked you up in school rather than you lacking the "intelligence" for it.
>>2202457
BASED, I'm surprised to see so many people from non-STEM backgrounds doing stuff like this. Always nice to have different perspectives.
>>2202463
Whew, CS and Math, that's a really strong combo. I hope you'll be able to utilize it more, would learning how microprocessors work? No clue...
>>
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>>2202606
>I have a feeling that it was the environment that fucked you up in school rather than you lacking the "intelligence" for it.
Pretty likely, but I kick myself to this day even though I can't stand people. I've been doing electronics since I was 8 or so, I'm 31 now and still study whatever interests me, the fascination stemming from the fact that EE feels like an unlimited field. Every time I think I'm hot shit I'm quickly humbled but the drive to learn gets stronger.
>>
>>2202328
I'm a computer engineer, which is basically EE but with programming instead of power electronics in the last couple years. I've been working for ten years. Mostly microcontrollers and FPGA stuff. Its been a good career but I'm thinking of going back to school for an EE Masters. The programming industry has changed a lot and that bullshit is bleeding over into computer engineering.
>>
>>2202614
Not going to say much to you that you haven't already heard but do consider supplying that drive to learn more with college again :)
>>2202634
Any good resources/textbook on learning microcontrollers and fpga? I don't want to get too off topic but those two (at least the latter) is "preferred" for a shit ton of EE jobs nowadays and I definitely get what you mean by things bleeding over, at least on the academic undergrad front.
>>
>>2202258
Oh shit the 84s are out of stock now too? Good thing I bought 10 of them a few months ago I guess.
>I’ve never soldered anything surface mounted before
Buy a practice pcb or three from alibay or amazon, it's a good skill to have. I almost exclusively run 0805s and SOICs now, the only requirement is having a more delicate tip like a 1.2mm screwdriver tip (I use a T12 D12).
>otherwise I’d just have slapped an arduino nano on there
Good on you for not going down that path, too many electronics projects are left clunky and bloated due to how ubiquitous those things are. They're good for prototyping, but really not for anything permanent.
>>
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>>2202642
>0805s
i want to shill 0603s. they fit better on a board: the soic op amps in pic would be completely dwarfed by their passive networks if i'd used 0805s here. and if you start learning with 0603s you'll never notice the difference in terms of soldering difficulty. also 0805fags are confirmed doubleniggers.
>>
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What is the purpose of coiling a power wire? I've only ever seen it on old tube radios. This one came out of a 59 plaza

Also can I replace the ancient caps in this radio with run of the mill electrolytic or do I have to get different ones?
>>
>>2202660
>power wire
ground wire, rather.
>>
>>2202660
Cheap way to add an inductor.
>>
>>2202328
I'm a supermarket checkout operator with a physics degree, going into an assembly job soon though.

>>2202354
I think i'd get shouted at again if i posted that.

>>2202589
Tape aluminium foil to the inside of the boxes.

>>2202651
>i want to shill 0603s
Yeah they're definitely better size-wise, but you start to need actually good tweezers at that point, and holding the parts in place at the same time as soldering them gets more difficult. If I had a reflow plate I'd definitely go to 0603 if not 0402 (they fit even better next to SOIC).
>>
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>>2202267
> but for wye its sqrt(3)*480?
It depends on what is this 480V? line to line or across one phase? For delta these are the same, but for wye they are different. Conversely for wye the phase current and line current are the same, but for delta they are different.
It's easier to understand if you just draw it. Delta and wye is just about how you're connecting the phases to each other and to the lines.

But for example the difference in phase current between the two configurations is why star-delta starters are sometimes used: you can reduce the startup current of a motor simply by changing how the phases are connected (the power stays the same of course)
>>
>>2202642
>Good on you for not going down that path, too many electronics projects are left clunky and bloated due to how ubiquitous those things are. They're good for prototyping, but really not for anything permanent.
Different anon here, genuinely curious about this statement here. I don't have much experience with microcontrollers and plan to dive into those soon because everyone tells me to when I haven't done much application of what I've learned in books (diodes etc).
>>
>>2202699
the arduino platform is great for learning. eventually you'll want to do something that it doesn't support and you'll have to learn about the atmega's registers and architecture. once you're comfortable doing that, you're only a step away from just using a voltage regulator and discrete atmega (or any uc). that's really all the arduino hardware is aside from an easy USB programming interface.
>>
>>2202699
arduinos are a microcontroller on a pcb designed for use with the arduino ide, and many people that use them never learn how to design a circuit or pcb for a microcontroller, or move to another microcontroller, or use a different ide

>>2202705
>easy USB programming interface
i dispute even that, it requires a bootloader and ive had problems with bootloaders in the past. i think it would be better if everyone used cheap little programmer boards. the serial printing however is definitely useful for debugging among other things, for which maybe updi or whatever can work better, idk
>>
>>2202651
once I moved to ordering stencils for my boards I just use 0402's for most things.
>>
>>2202709
where do you get your stencils? i only just recently noticed that jlcpcb sells them pretty cheap. prior to that i've used oshstencils but holy fuck they're expensive now.
>>
>>2202710
I order them with my board with JLCPCB, saves on shipping.
10 boards and a stencil + shipping usually runs around $25. Cant beat that.
>>
>>2202705
If they are a good platform, should I start my electronics journey through them first? Everything seems a little but convoluted. I'm not sure if I should begin on arduino first or no microcontrollers.
So far I've done like half a clock with just IC on bread board
>>2202707
Where do I learn how to design a circuit? If by designing you mean like making a logic circuit through mosfets (or was it bjts) then I definitely haven't learned that yet. Do you have any reccomendation for a first one?
>>
>>2202714
if you've programmed in asm before or you're comfortable with godawful engineering software or outright malicious compilers then you should skip arduino. otherwise it's a good starting point but you shouldn't anchor yourself to it because it's really slow and even arduiono nanos are bulky and look unprofessional.
>>
Reminder to serve the ohmnissiah.
>>
>>2202328
I'm an out-of-work lawyer.
>>
I was reading the last thread and one of you guys mentioned metrology, wow, I didn't know people still remembered that profession. I wonder if there are any ways to tie metrology with electronics that are actually useful other than making sure it's within standards.
>>
>>2202720
Sounds good, thank you anon. I'll start with some arduino projects then. Any reccomendation or a list of them? I know that the list in the OP tells us to not use microcontrollers. Still, pretty excited at doing electronics stuff now that I have a job and can fund it.
>>
Should you stack a lower voltage power supply on a higher voltage one, for battery usage, or attach both to the power supply?
>>
>>2202732
connect an arduino to a heartrate monitor and a prostate massager
>>
>>2202762
I love you too, dad.
>>
>>2202730
>I wonder if there are any ways to tie metrology with electronics
Autocalibration? Measurement? Data logging? A great many things use electronic sensors one way or another.
>>
>>2202328
I started my degree as a CompE. I ended up switching to CS for my junior year because I was working in a CS lab and thought that I would be more fulfilled with a CS degree.
I then got my degree, but I also sustained an eye injury from something completely unrelated so now it's a fucking pain in the ass to analyze large blocks of text (specifically text like code which has lots of specific characters doing specific things).
So now I'm just a NEET who harbors some fantasies about making a small boutique endeavor to build eurorack modules and shit. I also sustained a couple other injuries though.
Truthfully, I spend more time sitting on my ass wanking about all the things I'm going to do than I spend working towards doing the things I want to do.
But in my defense, I am probably qualified enough to get on actual disability.
I'm also a drug addict.
My life's a bit of a mess, but I don't even give a fuck at this point. It's been a mess since birth and there's a very real chance society collapses soon, so who gives a fuck?
What was the question again?
>>
>>2202714
>Where do I learn how to design a circuit
start with the books in the OP, many can be found for free on various places, think i coincidentally saw AoE on lainchan's book thread

>>2202730
have a look at marco reps' build of a cern-designed 8.5 digit benchtop voltmeter

>>2202732
>the list in the OP tells us to not use microcontrollers
whether microcontrollers are worth considering or not, or even the only way of going about a project is determined by the complexity of that project. many sensors use protocols like isp and i2c instead of being analog, and hence basically necessitate use of an mcu. driving dot matrix displays is also near impossible without an mcu or equivalent. discrete logic by itself is largely useless for anything practical and modern. that said, using discrete logic can make for a fun challenge all the same, and some people on youtube like ben eater do a great job of showing that. in particular, they can show you what goes on behind the digital happenings of a cpu, which i'd say is useful for assembly programming.
when it comes to analog electronics theres much more use for discrete transistors, particularly in the radio domain
>>
>>2202707
>and many people that use them never learn how to design a circuit or pcb for a microcontroller, or move to another microcontroller, or use a different ide

Yea that’s part of what I’m trying to learn with this. I’ve done a lot of projects that involved just getting a nano and soldering it on a PCB together with some JST connectors for I2C and read/write data through serial connection. Trying to do it ‘the real way’ this time though I still have to figure out how to program the attiny without arduino ide (probably avrdude something something and compile with gcc) but I’ll do that later
>>
Anyone know a good place to get somewhat cheap rechargeable 3.7v batteries?

I don't wanna get scammed on aliexpress and everything else is expensive.

A normal 18650 wouldn't fit in my project and a phone battery wouldn't have over charge and over discharge protection afaik.

I don't know if the thing I'm powering has built in protection or if it is in the battery that came with it so I wanna be safe and get one that has built in protection until I know otherwise.
>>
>>2202973
What about an 18350?
>>
>>2202973
Decide which form-factor you need, and hence whether you go for cylindrical cells or rectangular pouch cells. After a certain size you'll be packing together multiples to whatever shape you need so it's less critical, like with a hoverboard battery or power tool battery, both of which have a bunch of 18650s in both series and parallel. For something small, it's usually best to go for rectangular pouch cells, since their size is much more customisable. I've bought noname cells of ali before with no troubles, though I haven't fully tested them to see. There are name-brand cells even on ali, albeit mostly for larger cells like the ones used by quadcopters and the like. I got myself some 1300mAh 100C 6S CNHL batteries, and having a maximum continual output of 130A is kinda scary to have sitting under my bed. Consider asking the remote control general since they occasionally use low voltage cells. Otherwise electronics forums and the like, particular for custom model trains and the like, would be good places to look. The most expensive part is the shipping.
Actually you could see about buying some of those lithium-ion one-time phone charging packs I've heard about and salvaging the cell from them. I think they've been sold in 1st world countries cheaply at places like walmart or wherever.

You can buy both cylindrical and pouch cells with and without protection circuits on them, from what I've seen pouch cells are more likely to come with them. Even if they don't come with them it's very cheap to buy extra protection PCBs that fit next to the cells themselves, or to buy the ICs themselves for your custom PCB like I did. FYI, they use a DW01, FS8205, plus a TP4056 if you want to do charging too. You'll need more complicated stuff for cell balancing for series cells, but if you just want a single 3.2-4.2V cell then that stuff will be fine. At least within a certain current limit, I'd have to read the datasheet.
>>
>>2202973
>>2203001
In addition, I'd highly recommend looking at the circuitry inside whatever it is you need the cells for. Chances are it will be rather obvious whether or not there is protection circuitry included, and also what kind of charge current it's going to use. You could also measure what kind of current it drains from the cell. And in the event it wasn't originally designed for a lithium ion cell, ensure that it will run just fine at 3.2-4.2VDC.

Reverse engineering is a fun process that's good to learn in any case.
>>
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Hello, can you help me understand this laser level detector circuit.
What's the function of the op amps IC2.C and IC2.D?
>>
>>2203010
It’s a voltage follower, afaik it reduces effects of unknown or varying (cable?) resistance on the output end
>>
>>2203010
Buffering the output of the digital ~Q pins to drive LED indicators.
>Why tho?
The outputs of the CD4047 by themselves are unable to sink enough current to drive LEDs
>>
>>2203014
>>2203013
Thanks for the replies.
Why doesn't the OK Level indicator need one?
>>
>>2203016
OK LED uses a transistor. Notice it's from Q instead of ~Q
Probably the only reason they used the opamps was to save on parts, because there were two spare unused opamps which means they didn't have to use two bs170 transistors
>>
>>2203010
Are those LEDs being used as photodiodes in the photovoltaic region? Interesting, I usually see them used in the photoconductive mode. I assume the levelling laser is one of those spinning ones, such that the signal gets through those multi-pole high-pass filters. I think the 2nd op-amps are being used more as comparators though.

It's kinda odd that they're using op-amps in buffer mode to drive LEDs instead of using transistors though, especially when there's both Q and NOT(Q) available. I guess using a quad op-amp instead of a dual op-amp and two more transistors is arguably better, maybe.
Decoupling reset to V+ instead of GND is also kinda odd, maybe it's somehow better on startup.

Also as far as I can tell, the only reason they're using CD4047 oscillator ICs is to drive the buzzer, but even then the buzzer seems to be being driven regardless of whether it's aligned properly or not. Also using three oscillators instead of just one sounds kinda stupid, especially when diode logic and such could be used to combine multiple inputs into one enable line.
>>
>>2203049
>Also using three oscillators instead of just one sounds kinda stupid, especially when diode logic and such could be used to combine multiple inputs into one enable line.
This was deliberate so UP/OK/DOWN had different beeps:

https://worldradiohistory.com/UK/Elektor/10s/Elektor-2011-07-08.pdf
>The monostable times of the upper and lower MMVs are dimensioned to generate clearly distinguishable short and long beeps, respectively
>>
>>2203001
>>2203002
Thank you!

I've tested a bit and it seems I could fit one of those 50x30x10mm pouches. Maybe 2 but I don't wanna deal with balancing them.

The problem is those are pretty expensive on amazon (relatively).

I want to power a bluetooth audio receiver with it. There's lots of tiny electronics on that pcb and for a complete beginner like me it's hard to tell what is part of the power delivery and what is an audio filter.

If I manage to get it back out, I'll google some of the numbers I find on ic's. Maybe one of them is a bms.

I do recognize a little lifted board which has the bluetooth components on it though.

I didn't even think of putting an extra 3.7v bms in there. That may be the cheapest way I can go.

>>2202993
I've never heard of those. All I ever see people use is the big ones and some custom sizes they never mention.

I'll definitely take a look. Thank you.
>>
>>2203079
>>
>>2202606
>Interesting, is there anything in particular from CPE that has been really useful in EE? Or does the extra coding experience really help?
I work at an industrial machine builder, so most of the EE stuff is pretty basic when I'm designing the panel. The skillset that comes with being a CPE is very useful as I mainly deal with writing code and interfacing hardware.
>>
>>2203086
Looks like none of those are much thinner than the 18650 so they'll probably not fit. At least the ones in this picture.

My problem is the width not the length. I assume a decent pouch style battery would be ideal.
>>
>>2203113
>>2203086
Also if a lipo battery has a built in protection circuit, can I use 2 of them in parallel without a balancing system?
>>
>>2203119
If I understand correctly it should work perfectly fine but if it does work, why do people use balancing systems that discharge a single cell through a resistor instead of just doing this?
>>
Is there a tard-friendly way to design a simple board and have someone ship me the finished product? I have five little pieces that have to go on a board and barely understand what VHDL stands for.
I have dimensional constraints and that's it, don't care what it looks like or how the parts are positioned as long as they connect properly.
>>
>>2203310
I should clarify, I can solder the parts on myself, just need the PCB.
>>
>>2203310
Download a free PCB design program like kicad, learn to use it, send your gerbers to a board fab like jlcpcb or oshpark.
>>
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What could go wrong with VIPER28HN flyback power supplies?
Almost all of them do have bulged caps. Some have failed rectifier diodes, linear regulators and pwm controllers shorted at VCC pin. Most of the time replacing those parts fixes the unit but sometimes dont. All output voltages are good, even with a load applied but when connected back to the device it fails to boot properly.
>>
>>2202595
Thank you, that was exactly the problem I was running into. I don't have much experience with using potentiometers, should I leave the input floating or should I connect it to the audio input?
>>
>>2203079
>>2203119
you can put cells in parallel without needing any kind of balancing. balancing is only required for series sells.
>>
>>2203331
Check all of the pins in your wiring harnesses and make sure the board isn't shorting against something.
>>
>>2203331
and check/reflow the pin header connector's solder joints on the bottom of the board.
>>
>>2203310
hand solder it yourself. computer shit is inherently difficult
>>
>>2203333
If you mean the ground of the input, that goes to the circuit ground. The wiper of the pot goes to your signal. Study RC low pass filters and you'll get the idea.
>>
>>2203337
Thank you I didn't know that!
>>
>>2203337
Apparently that is only the case with cells that don't have their own protection.

According to what I just found on the internet, as soon as one of the batteries' protection activates some sort of feedback loop happens and one of the batteries will overheat and get damaged?
>>
>>2203391
I've got no problems soldering it, where I'm not yet ready is designing a PCB. Breadboards are the extent of my comfort level
>>2203330
I'll check out KiCad, thanks!
>>
The terms are irrelevant.

Most people refence whatever degree or degree program or the class description.


at my university, EE students did the following:

Pure CS
Circuit design
Microelectronics fabrication

ECE:

Circuit Design
Microelectronics fabrication
Solid state physics (including theory)
as per above, computational physics coding

CE

Microelectronics fabrication
coding


The name of the field is practically irrelevant these days. US Bureau of Labor Statistics no longer has a category called "Chemist"

People who, traditionally, would have been described as "chemists" are now either in pharmaceuticals/biochemistry or else they are referred to as "materials scientists"

"Materials Science" is now a catch all that is kind of like saying that a business is a "Technology company"
>>
>>2203508
The hyperspecialization of the academic world ironically makes the world weaker as even the most intelligent become siloed bugmen instead of making cross-disciplinary revolutionary inventions
>>
>>2203520

Thats fundamentally incorrect if you mean that people with seemingly different or unrelated training and approaches to problems are siloed in their fields.

In reality there is tremendous amount of crossing disciplines.

That being said, the hyper focus on certain areas of research is an acknowledgement that the scientific investigations of yesteryear are "childsplay" by comparison to modern science.

2nd year undergraduates can reproduce the work of John Bardeen and Schottky

Compare that to the 1980s and 1990s when Shuji Nakamura was working for NEC, developing novel semiconductors.

It took years of painstaking work to figure out blue LED and laser diodes and all he was doing was commercial/industrial development research.

the problems are many many orders of magnitude more difficult than in the past and the expertise of modern researchers is dozens of times greater and more effective (multiplied by a greater and more efficient access to the preexisting knowledge pool and computational power and software aids)
>>
>>2203508
nobody cares, fuck off
>>
>>2203534
>the problems are many many orders of magnitude more difficult than in the past
"how can we make this blue LED 3% more efficient" might be an order of magnitude more difficult than inventing a blue LED, but it's certainly a less valuable pursuit.
>>
>>2203534
>That being said, the hyper focus on certain areas of research is an acknowledgement that the scientific investigations of yesteryear are "childsplay" by comparison to modern science.
Not that guy, but I wouldn't be so quick to discount historical work, you have to remember that these guys often had little or nothing to work upon in comparison to the information and research that was done in modern times; specialization was still a thing, Edwin Armstrong being an example with early radio. We build upon the ideas that our forefathers discovered and have far greater tools at our disposal to further development that they could have only dreamt of. That said I do agree that today's challenges are radically different and people who can branch out into other fields have an edge.
>>
>>2203464
>as soon as one of the batteries' protection activates some sort of feedback loop happens and one of the batteries will overheat and get damaged?
my experience hasn't found this to be true. In practice, the protection circuits of all the cells in the parallel group will trip in cascade.
If the current in one cell exceeds the limit, it'll cut off, then the other cell will immediately see the entire load current and also cut off immediately.
If one cell cuts off for undervoltage, then the other cell will immediately be dragged down and also cut off immediately.

I've made parallel packs of 2-6 cells and always found that when they cut off, they all cut off at the same time like that. Cells in parallel can just be considered one big cell.
of course it's important that the cells in parallel are identical cells, with the same capacity and same protection circuit.
>>
>>2203604
what happens when the load goes back down again? do they come on again quickly? can they constantly cycle on and off because of this?
>>
>>2203638
unless they've tripped for undervoltage, then yes, they should recover when the load is removed. though some protection circuits seem to stay in the cut off state until a charge is applied to the cell (whether single cells or paralleled), which is annoying.

They shouldn't cycle on and off because of that. It's possible that one might cut in before the other, but since the cells are at the same voltage, that won't cause a current spike by backfeeding the other cell.
at least, I haven't seen that.
>>
>1.5 hour bus commute
>8.5 hours of assembly work
>1.5 hour bus commute
is this going to break me? have i made a mistake?
>>
>>2202328
First year EE, gonna be dope
>>
>>2203646
Can you read in the bus?
>>
>>2203656
probably, but i can get motion sick
also it's jumping between 5 different busses on the way there so i gotta pay attention
>>
>>2203657
Same!

For some reason it is worse in buses rather than cars. If you're not already doing it, you can try listening to music or a podcast or something. That used to help me on my ~50 minute way to school back in the day.

This is pretty common knowledge were I live but in the off chance you haven't heard it yet, sitting in the front of the bus makes the motion sickness much better.
>>
>>2203680
>For some reason it is worse in buses rather than cars
>sitting in the front of the bus makes the motion sickness much better
from my cursory hopping about, i found that sitting further back, basically atop the rear wheels, was best for motion sickness.
>>
>>2203646
learn to love it wagie
>1.5hours
rent the cheapest apartment within a 15 min walk, it'll save your life
>>
>>2203695
i'll do that when i can, but stupid govment is in lockdown such that i can't move for another few weeks, so i have to tough it out until then
no clue why assembly of security keypads is an essential business, bet somebody got bribed
>>
>>2203696
>stupid govment is in lockdown
simply /diy/ an electric chair for your politicians
>>
>>2203769
actually i plan to make an electric toilet
it zaps your weenie through the stream of urine if it detects the seat is down but not being sat on
because there's too much damn urine splashed on the toilet seat, and i don't know which of my flatmates is behind it
>>
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Trying to upgrade my basic attack/release envelope generator circuit into an ADSR. I know that the attack & release potentiometers determine how fast the buffer op amp's input charges & discharges. I can't find any material outlining what the delay/sustain circuit is supposed to do.

Tried to throw something together but I can't get the D/S to work. Do I need to loop it back to the comparator input or something?
>>
>>2203787
Unless they're barefoot, they're probably going to be insulated enough to withstand whatever low voltage you throw at them. A better option is just to make a shaming klaxon.
>Sitting down
Aim better.
>>
>>2203789
>euro style resistors
ngmi
>>
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>>2203787
Devilish but I approve.
>>
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code monkey here relearning electronics through TAoE. I want some help in question 4.12 (pic related). Q9 & R5 are said to form a current limiting circuit.
>Iout = ir + ie
Q9 will keep Vr=R*ir at Vbe(sat) at max, so:
>Iout_max = Vbe/R + ie
>ie : less than 150µA
>Vbe : 0.7V ish
so : Iout_max = Vbe/R = 32mA

Am I doing it right ?
>>
>>2203946
forgot to add that ir is also clamped at hFE*150µA no ?
>>
Quick question for you electronics gurus:
>be me
>have tube guitar amp
>it releases the magic smoke
>fuses didn't even blow
>there's a burned capacitor inside
>it's across the high voltage secondary just before the rectifier diodes
>remove burned cap
>amp is fine
Power trans tests good, tubes test good, amp works as intended. It's my understanding this cap is intended to suppress transient voltages from lightning strikes etc, but I'm having difficulty understanding why that cap would go and not the mains or ht fuse as well. Am I missing something, or was it just a bad cap that took a shit on me?
>>
>>2203946
it's just Vbe/22ohm
>>
>>2203789
decay is just another release circuit (RC timer) that decays to the voltage set by the sustain potentiometer, which appears to be buffered with a diode.
The two switches are configured so that, on key press:
>release circuit is left open
>decay circuit is connected to capacitor
and off key press:
>release circuit is connected to capacitor
>decay circuit is left open
MS-20 schematics are another good reference, iirc they leave out the buffer
>>
To that anon in the last thread that asked if the UTP cable bridge worked, it didn't. Kind of
Maybe the caliber was too big but it kept slipping off of the hole in the pcb. But the times it didnt it worked really well
Also tried a copper tape fix but it didn't receive any signal
>>
>>2202328

Mechanical engineer with some automation background too.

One day, after being stuck at home for X weeks because of corona, I realized that if I can't go to the gym, I can at least use electronics/coding as a time sink and a hobby that I need a single table for when living in a shitty small aparment...
>>
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Why is rout 0 here? shouldn't it be vout/iout

neither vout is 0 nor Iout is infinity. Ideal OP amp by the way
>>
>>2204051
Rout is 0 since it's referring to the output impedance of your ideal opamp
also just fucking ask your prof next time
>>
>>2203646
A 1.5-hour bus commute absolutely destroyed me. I was getting serious insomnia and my heart would start beating really hard for no reason sometimes. I quit the job after 8 months.

There was a lot of switching buses so if any got stuck in traffic for five minutes I'd miss the next one and be an hour late. The job itself was super easy and boring but this was super fucking stressful. I couldn't hang out with friends or do anything else after work because I didn't get home until late and just wanted to lie down. On weekends I didn't have energy to do anything.
>>
>>2203968
>was it just a bad cap that took a shit on me?
most likely, yes.
The fuses probably didn't go because the capacitor failed open-circuit before the fuses had time to blow. You might want to change the fuses anyway after taking that kind of stress.
That capacitor might also be there to snub ringing from the switching of the rectifier diodes. Replace it and see if you notice any difference in hum noise.
>>
>>2203790
>Unless they're barefoot, they're probably going to be insulated enough to withstand whatever low voltage you throw at them
i'll use 1-10kHz AC from the bowel and into a mat with conductive fibres woven through it, the capacitive coupling should be sufficient
actually getting the voltage to the bowel would be the most difficult, but since the walls will be wet and conductive i may be able to send the power from the rim of the bowel if not the cistern

>>2203968
if that was a class x2 cap you should probably replace it with a new one even if it works without it. should help decrease noise if you've got noisy mains.

>>2204104
hopefully it will only take a week or two before i can move, if i had to do this for more than a month i'd quit by then. as someone who likes to get 9 hours of sleep it will be a struggle to shower and have breakfast and cook dinner and make lunch.
>if any got stuck in traffic for five minutes I'd miss the next one and be an hour late
i was wondering about this, are bus networks really not robust at all?
>>
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can anybody shed some light on what the zig zag trace is for?, it connects the two legs of a diode that feeds V+ into the boost-buck converter on an old mid 90's ECU I am working on.
>>
>>2204238
probably to add a small amount of resistance, either for current measurement, or for more of a snubber / inrush current limitation.
>>
>>2204244
Could be for correcting for propagation delay too, if I'm not mistaken. Pic unrelated just random tube porn.
>>
>>2204244
Thanks, I have another board that has this trace blown, there is a 220uf electrolytic capacitor right after the diode, the capacitor had leaked, I bet it was causing an intermittent short and fused the trace.
>>
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theyre charging 20 fucking dollaridoos + shipping + tax + tip for pic related. the MCU i want to put on it is fuckin $8. is there literally any other way to play with SMDs on breadboards? and if not, is it okay if the board says its for TQFP/VQFP, but the chip is LQFP? im not sure what the difference is, the board has 0.5 pitch, the chip datasheet doesnt mention what the pin pitch is, but its side length is 14mm with 25 pins, so 0.5mm seems plausible.
>>
>>2204343
>theyre charging 20 fucking dollaridoos + shipping + tax + tip for pic related.
might as well just roll a custom PCB prototype for that price. even if you fuck up and have to cut traces and re-wire some shit at least your board will be ready for rev2.
>is it okay if the board says its for TQFP/VQFP, but the chip is LQFP? im not sure what the difference is
thickness of the package, pitch is the same.
>the chip datasheet doesnt mention what the pin pitch is
highly doubt it, but it's possible if it's some old or chineseium part. what part is it.
>>
>>2204343
you could alternatively find some gerbers of the adapter and order a set of 10 for around $20 from JLCPCB
>>
>>2204367
>might as well just roll a custom PCB prototype for that price
not sure who i call about that, and i think it would have to be significantly less than $20 for me to go through the trouble.
>thickness of the package, pitch is the same.
ah ty ty
>highly doubt it, but it's possible if it's some old or chineseium part. what part is it.
its legit, part is STM32F405, common chip but looks like its sold out literally everywhere, gonna look for some other stuff i guess
>>2204368
>gerbers
unfamiliar with this term
>>
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>>2204376
gerbers are what PCB manufacturers use to make PCB's with. if you don't know that, making a custom board might be a little beyond you at the moment.
JLCPCB is a Chinese manufacturer and can make 100x100mm 2 layer boards for 2 dollars for 5 of them. Probably one of the cheapest out there. Shipping runs around $12.
>STM32F405
did you even check the datasheet, pitch is listed in package info.
>>
>>2204379
>pitch is listed in package info.
my mistake, i ctrl+F'd for "pitch" and called it a day
>JLCPCB is a Chinese manufacturer and can make 100x100mm 2 layer boards for 2 dollars for 5 of them. Probably one of the cheapest out there. Shipping runs around $12.
good to know for the future, but i dont think months of shipping is worth $20 to me if im just buying some stuff to dick around with, hence why im using breadboards
since i guess im looking for a different chip anyway, ill look for one with fewer pins, a 64 pin QFP to DIP looks like its only $7
>>
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>>2204387
>months of shipping
>>
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>>2204388
shows what i know, maybe ill look into making one of these so-called gerbers
>>
>>2204390
look into KiCad.
it's a free PCB EDA software, you use it to create the schematic and layout for a board.
Then from the board tool you can automatically export gerber files which are zipped and uploaded to various manufacturer sites for quotes.
Plenty of youtube videos to explain in more detail.
>>
>>2204343
etch it yourself instead
that or point-to-point to it using enamel wire
>>
>>2204392
thanks friend
>>2204409
i dont have sheets of copper and etchant lying around. i think my school has a PCB printer but i dont where tf it is and i would probably have to talk to someone.
i did briefly consider some janky ass wiring thing, but that just seems silly.
>>
do you organize components by size or function?
>>
>>2204470
function definitely
>>
What are some capacitor/potentiometer values, that you MUST have?
>>
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>>2204141
>>2204227
Thx anons. It was this little bastard that flamed out. Did a little digging and found out they're notorious for failing like this. Got a new kemet coming from mouser.
https://www.eevblog.com/forum/chat/old-rifa-capacitors-and-a-disaster-story/
>>
Whats the best electronic switch in terms of low capacitance (<10pf), fast switch speed (ns), and moderate to low Rds on (10-100mR)? These parameters seem to be mutually exclusive for Mosfets. What about any other types of SS switches?
>>
Found this:
>New SJ-MOSFETs with Very Low RDS(on)
and Ultra-low Qgd
Hmm. Never heard of SJ-MOSFETs
>>
>>2204564
social justice mosfets?
>>
>>2204527
Those gave me PTSD and every time I see one I get irrationally angry. Fuck RIFA.
>>
>>2204557 Krytrons is your only option.
>>
>>2204576
Lol. Maybe a low-power thyratron would do.
>>
>>2202248
how much electricity does it take to kill you? i dont know a lot about this but it seems fun
ill get some gloves and PPE though. also, is it better to ground yourself or not
>>
>>2204620
>how much electricity does it take to kill you?
This can be calculated using the ligma factor.
>is it better to ground yourself or not
yes
Welcome to /ohm/. Now kys.
>>
>>2204620
As little as 50V can give you a bad time, touching a modern ignition system at tens of kilovolts can give you a bad time. The path through your body is what determines how fucked you are, it really depends on many factors, do your research.
>>
I'm looking for a hand drill (wired? probably, I'm euphoric because too much kefir, but I don't mind battery-powered) to make holes for THT components, do you guys have any recommendations? What power range should I aim for? On what is the equivalent of my country's ebay, there are some dodgy chinese drills I'm not sure I should get or not.
>>
>>2204650
does your country have a cheap tool store like harbor freight in the US? a drill press is of course better suited for this, and once you have one you'll use it for all sorts of things.
>>
>>2204557
https://www.ti.com/switches-multiplexers/analog/products.html?pqs=paqs&familyid=520#p1143=1:1%20SPST
First one I picked TMUX621, has 3.5pF input capacitance and 100ns switching speed, and a 2ohm on resistance.
just search around if you need something else
>>
>>2204684
so the key word is a CMOS switch? is it basically one or multiple mosfets or whats inside them?
>>
>>2204557
what do you want low resistance for? if you want it for high current, then an igbt is likely a better choice than a mosfet. is the 10pf the input / gate capacitance, or the capacitance as seen by the load? either way that's really small. if it's for a gate capacitance i'd just get one with a higher gate capacitance and switch it with a high current gate driver. you can achieve single digit nanosecond switching times with the right combination of gate driver and fet or igbt.

>>2204620
the amount of current flowing through your heart is what quantitatively kills you, the duration for which this happens and possibly the frequency at which it happens are also important to an extent. the current flowing through your heart is dependant on the voltage across your body and the placement of the electrodes. the body's effective resistance changes with moistness and frequency, higher resistance means lower current. at high enough frequencies the skin effect begins to become significant, which is where the electricity will flow on the outside of conductors and not through the middle of them, which will also reduce the current through your heart.

>>2204650
i find a little hand-held rotary tool is ideal for those, the low weight stops me from breaking the carbide pcb drills. a drill press is probably fine too, but a bulky hand drill won't be easy to use at all, corded or cordless.
>>
>>2204557
what are you trying to make.
unless you're doing some RF stuff, it's doubtful you need such low capacitance or nanosecond level switching speed.
>>
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>>2204738
I think it is as seen by the load, or rather drain to source.
Imagine R and L and a low or high side switch in series, and PWM is fed into the switch. If it has any capacitance, it will essentially become RLC in series. I'd like to be able to measure L based on the waveform and the L/R time constant, and I want that waveform to be as close as possible to pure RL in series.
I'd like to be able to measure down to uH. So ~100ns switching time should probably be OK. And low Rdson is also for accuracy, not for high current.
>>
>>2204760
this: >>2204779
yeah, those specs are totally arbitrary, i was just thinking whatever the lowest and readily available.
>>
>>2204779
>I'd like to be able to measure L based on the waveform and the L/R time constant
Ah, then the capacitance just needs to be insignificant enough compared to the R and L. You could tweak that resistance such that you could get away with a larger capacitance, though that may necessitate range switches.

As for transistor resistance, you could measure both voltage across the inductor and current (voltage across the resistor), removing the need for the transistor's resistance to be insignificant. If you're using an ADC then chances are it has multiple channels anyhow, so you'd just need a current sense amplifier circuit. This will probably also get rid of the capacitance issue, I think.
>>
>>2204620
24Vdc is the max rated industrial safety voltage. Beyond that you're on your own.
>>
I’m fairly confident in my design but I wanted to post here to get some feedback.

Pic related, of course. The purpose of this circuit is to channel the output signal from the PCB to an audio jack. Between the PCB and the jack, I want to have a mute button, followed by a volume pot, with an option to toggle on or off a low pass filter [which is controlled by another pot]

My main concerns are:
1. Would putting a low pass circuit in series with a normal volume circuit cause any weird audio glitches (like maybe the low pass pot would act like a volume pot or vice-versa due to how I wired it)?
2. I’m routing all of this to a switched audio jack; without anything in the jack, all sound goes through a piezo disc. Normally I’d measure the resistance of any speaker involved so I could substitute an appropriate load, but in this case I can’t because it’s not a speaker: measuring it with a DMM shows no connection, So I don’t even know if it has any resistance or not. Conversely, it appears to have a capacitance of around 80nF: should I instead swap out the load resistor for a load capacitor? Or should I just scrap the load resistor entirely?
>>
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>>2204861
Don't know why the image got flipped, this one should hopefully be upright.

Also, a third question: could I 'debounce' the noise from the switch by tying a 1M ohm resistor form the switch's center lug to ground? If not, is there another way I can do it without involving ICs?
>>
>>2204861
>>2204866
the volume pot and the lpf will affect one another (idk sim it), but not glichily. you'll just get the volume being somewhat dependant on the filter setting, and the filter frequency being somewhat dependant on the volume setting. to drop this dependance by a factor of 10 or so i'd use a 10k volume pot and a 100k lpf pot. possibly 1k and 10k if the signal voltage is low enough.

whether whatever device you're feeding the audio into will be fine with a 10k or 100k output impedance is another matter, it will have to go into something with a preamp or amp inside it.

>load capacitor
if it's a two-terminal piezo then it will almost certainly be driven open-circuit, and hence should work ok without any load connected. no clue about 3-terminal piezos. an 80nF cap will definitely work, but note that some caps might make a little bit of noise when fed an audio signal. if you do use no load i'd probably put a 100k resistor across it or something. any reason to use this amplified piezo output instead of the dedicated aux out?

>could I 'debounce' the noise from the switch by tying a 1M ohm resistor form the switch's center lug to ground
it's kinda not necessary, try it without and see what kind of noise you get. a 1-10M across that 100nF cap would be my choice for debouncing, a resistor from the middle pin wouldn't do anything, it would just be in parallel with part of the volume pot and make it slightly less linear.

>image flip
it's a metadata thing, you need to flip the image properly, most phones do it with metadata instead and that gets stripped by 4crunz so you can tell a phoneposter a mile away haha
>>
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>>2204881
Thanks anon, that really helps!

I'm trying to keep the piezo an option as it essentially acts as the speaker for this project. As I said before, this normally isn't an issue since I usually work with stuff with speakers, and in that case I can always substitute a resistor load.
Truthfully, just raw output into my digital recorder works fine up to a point, however I'd like to have the option to turn down the volume because there is some clipping at certain settings with this device.

I updated my schematic: is this what you meant?
>>
Is it a good idea to utilize a 30V MOSFET on a buck converter with an input voltage being a rectified 24V?
>>
>>2204915
I don't know why I asked this.
I was hopeful that the schottky diode somehow reduced the voltage across the drain and source.
>>
>>2204915
if you can guarantee the input never goes above 30V sure.
>>
>>2204915
no. switching converters ring. best practice is to use a fet with vdsmax 50% above your nominal switching voltage. your 30V fet might work but do you want to fuck around and find out?
>>
in KiCad, is there a difference between "pin header" and "pin socket"? my thinking is that its all just holes in the board.
>>
>>2202248
I bought pic related. I'm starting to solder more and wonder if carbon filters are a placebo or not. I just don't want to breathe in the flux smoke.
>>
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>>2204991
Whoops, here is the pic.
>>
>>2204991
the smoke is good for you. inhale and leave your anxieties behind.
>>
>>2202248
Is that Shannon Sharpe?
>>
>>2204893
yeah that should be fine.
>>
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>>2204343
alright, downloaded kicad and whipped something up, my school does in fact have a "CNC PCB Etcher" but its like the one machine they dont have any online tutorials for so i guess im just gonna show up and ask someone how to use it.
>>
>>2205002
can i ask why you want such an obnoxious a breakout? just design a full pcb and bodge it when you fuck up. it'll be easier than wiring that thing on a breadboard.
>>
>>2202248
Ebonics and negro electronics? Negronics?
>>
>>2205007
im diving dick-first into this, im not gonna try to design a functional circuit in one go, im just gonna keep rewiring shit until it eventually works. im not even sure exactly what features/peripherals the final product is going to have. this is the way real men design things.
its a mute point anyway, i misread the website and my school doesnt have shit, but at least i did fork over 20 fucking dollars yesterday and got the board.
>>
>>2205012
>this is the way real men design things.
it's not 2am and you're not drunk
>>
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This is my first time designing a circuit, does this seem like a reasonable way to lay out components? Are there any tips that would improve it?
I'm building a replacement control board for a keyboard using a Teensy 3.2 and a CY8C9540A-24PVXI 40-bit IO expander.
>>
>>2205018
it's fine, schematics are typically laid out left to right though. add some bypassing footprints for your $11 cypress monstrosity in case you need them.
>>
>>2205018
where traces snake about like that it's often better to just use labels instead. i use labels anyhow to denote which node is which, as it helps when testing my etched copper for continuity
>>
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>>2205002
no CNC router can cut that. fix your trace spacing or pay for etching.
>im not gonna try to design a functional circuit in one go, im just gonna keep rewiring shit until it eventually works.
no one does this though, copy the reference design of the dev board from the manufacturer. if there isn't one find something close and use that, pic related uses the 64 pin package instead of your 100 pin but usually the difference is just more gpio pins. then add stuff as needed.
>im not even sure exactly what features/peripherals the final product is going to have.
then figure out what needs to go in. real engineering designs the product first before building it. when we have questions about functionality we rig up a dev board sandwich to test sensors or whatever then spin a board.
>this is the way real men design things.
no, that's how an idiot who doesn't know proper theory or how to read a datasheet and use reference designs as a base does it. protip: 99.99% of engineering mistakes during the first phase of pcb prototyping are traced back to not reading the datasheet fully. so fucking read it, don't assume things, fucking read.
>>
>>2204343
who's "they", did you check ebay?
I'm seeing 44/48/64 pin QFP boards for like $0.20 each
>>
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How can I identify a PCB connector so I can buy a new one?
Approx. 1.15mm pitch, 15 pins.
No locking mechanism, one face is open, sides and back are not. Back side has little tracks for alignment.
Board was manufactured in the EU I believe.
>>
>>2205096
Nevermind, think I found it.
https://www.molex.com/molex/products/part-detail/pcb_headers/0533980371
>>
>>2205025
is there a way to make the labels clickable when you look at the pdf of the schematic? At work I sometimes have to look at schematics but the labels are not clickable so you have to sift through 40 pages of dense circuitry to find where the fuck that wire goes....
>>
>>2205159
if it's multi-page usually there are annotations next to the label to say which page they lead to. if not that's very poor design. you can also hopefully ctrl+f the label name/number. sometimes there will also be an index with all label names/numbers are listed with page numbers, in addition to the bom.
>>
>>2204571
>Fuck RIFA.
It's a fine design, it's just that they do fail short when stored in a barn that cycles between hot and humid to frozen and dry twice a year for 30 years.
>>
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>>2205184
So were Sprague black beauties or Sangamo redskins, epoxy/molding techniques weren't quite there so I really shouldn't be bitching but I have yet to see one that wasn't bad. Never seen a WIMA cap from that era go bad though, maybe it's a matter of time.
>>
>>2205251
I think it's just a matter of good luck in design choices for the types that still work.

I have an Apple //e that sat unused for about 20 years, followed by another 10. Was always stored in a climate controlled environment. Zero problem with the rifas, this despite the conventional wisdom in Apple collector circles being "omg don't power it on until you rebuild the power supply!" Like I said above I suspect it's an issue of repetitive temperature and humidity cycling. You probably have to derate the temperature range after so many years, and it wouldn't surprise me if all the ones you hear about popping their rifas spent at least one summer-winter cycle in a garage or worse.
>>
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>>2205278
I'll pop your rifa.
>>
>>2202248
https://www.youtube.com/watch?v=ShXNJM6uHLM
Damn will I ever reach this level in electronics ?
>>
>>2205294
Definitely how I'm gonna have to wait for a bus next time I'm in Chicago.
>>
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>>2205278
Wow, lucky. I had a IIc BNIB that I should've kept but I sold it 15 years ago like a retard and now they're worth a fortune; also had pic related along with several C64s. Pretty ballsy of you to keep capacitors with a known high failure rate but I have an HP 3400A with all original caps and it works fine though it could use a touch up on the calibration.
>>
>>2204620
Only 'ground' yourself through a high resistance. Forget whether it is 1M Ohm or 10M Ohm. Anyway, the resistor should be built into an antistatic work bench mat with wrist strap. If you buy something, check the resistance with a meter before using. For high voltage, best to keep one hand behind your back or in your pocket if you're new to this stuff.

Why these awful captchas? Most of the time I just give up. Trying again...
>>
>>2205318
>Pretty ballsy of you to keep capacitors with a known high failure rate
Truthfully I didn't know shit about the rifa issue until well after I'd started using it again last year. I'd dodged the bullet twice, I figure they're probably fine. Should probably pop the power supply open and check them anyway.

>I had a IIc BNIB
Nice. I always wanted one of those growing up. The //e is my dad's old one. I'm amazed the data on the disks is still good. I seem to remember the geniuses saying magnetic storage media would all be dead by now. I have not had one bad floppy.
>>
>>2204620
Some quick googling suggests developing 100-200 mA of current is usually lethal. Your internal resistance is about 300 ohms, whereas skin resistance is typically measured in tens or hundreds of k (but skin resistance is easily bypassed if the voltage is sufficiently high, if there are holes in the skin, or if your hands are moist).
>>
>>2205096
>>2205102
usually I put those parameters in mouser/digikey and start checking every datasheet in the results.
>rectanglular connector header male pins
>15 position
>1.25 pitch (1.15 isn't a standard pitch)
>1 row
>shrouded on 3 walls
pic related, 19 results and the second one is what you want.
>https://www.molex.com/molex/products/part-detail/pcb_headers/0533980371
>3 position
nope thats not it m8, always read the descriptions and check the datasheets
>>
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>>2205345
forgot pic
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>>2205345
>always read the descriptions and check the datasheets
This. Product photos for components are almost always wrong, or at least generic.
>>
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>>2205278
Same with my Osbourne. I opened it up, visually inspected that nothing looked toasted (also noticed nothing had been replaced), powered it on. Works perfectly. My Commodore PET needed a lot of keyboard cleaning, but also didn't need caps, but that was sheer luck because I didn't know squat when I got it.
>>
>>2205353
I've been kind of wanting to use my dad's old ZX81. I popped it open a couple months ago and found the keyboard ribbon was fucked. I know they make replacements, just haven't gotten around to buying one. Also don't know if anything else is bad in it. I figure not; like the Apple //e, it sat in a climate controlled basement for 35 years.
>>
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>>2205353
> visually inspected that nothing looked toasted (also noticed nothing had been replaced)
Be careful with that assumption as a general rule though, components can look OK but still be EOL. Grab an Mtester off of ebay if you want cheap piece of mind, ESR is quite important. Same goes for old drift-o-matic carbon comp resistors, they usually go high in value as they age and it would be interesting to know if it's due to humidity or degradation of the materials used. When I restored my Altec 353A I was surprised to see some resistors go up almost twice their specified values, caps seemed fine for a few hours but the coupling caps to the grids of the power tubes failed and it roasted a set of Philips 6L6GCs, needless to say I was pissed right off but happy it didn't take out the output transformers. Not trying to be a bearer of bad news, just want to save you guys potential heartache.
>>
>>2205369
>Not trying to be a bearer of bad news, just want to save you guys potential heartache.
Not at all, you're absolutely right.

If I'd known what I know now I wouldn't have even powered on the //e. I actually picked up another one last year but still haven't actually powered it on (I more wanted the monitor and serial card that it came with), and probably won't until I rebuild the power supply.
>>
>>2205369
That's good advice. I have an mtester, but I didn't know you could use those in circuit. Did you have to flash something special into it, or just use jumper wires and the stock firmware?
>>
>>2205078
iirc, i found a 100 pin on ebay for like $10, but since i was already buying shit from mouser it wasnt worth paying separate shipping.
>>2205051
>no CNC router can cut that.
yeah, i google what "CNC PCB" meant shortly after and realized that it wasnt feasible.
>copy the reference design of the dev board from the manufacturer.
if i was getting paid to do a job and produce a competent design, then i would probably do something like this, but im not sure that copy/pasting a working circuit is the best way to learn. you say that everyone does it, and im sure they do, but a good electronics designer should be able to look at any part of a circuit, whether he designed it or not, and be able to articulate exactly why the circuit was designed that way. if you start out by copy/pasting shit youll never get to that level. i think the best way to learn how to do it the right way is to do it the wrong way first and witness first-hand exactly what problems arise.
and im not sure if i need to say this, but i was being somewhat facetious with that "how real men design things" comment. and yes, ive read quite a bit of the datasheet in the past few days.
>>
>>2205399
Didn't mean to be misleading, you'll still have to lift one lead of the capacitor which on older boards you'll want to be very careful, traces lift off if you look at them the wrong way. People will say use a low heat on the iron for desoldering but that just increases the time the heat is on the board, increasing the chances of delamination. I've had good luck using more heat, lots of good quality flux and a decent solder sucker but YMMV, just practice on a scrap board and get a feel for what will work best for you and the equipment you have on hand.
>>
>>2205425
>but a good electronics designer should be able to look at any part of a circuit, whether he designed it or not, and be able to articulate exactly why the circuit was designed that way
true, however when I copy a reference design I also analyze it to see if it could be done better.
When I don't understand why something was done that way I search for an answer and reverse engineer the circuit, since obviously the reference design works.
I learn by analyzing working designs and working backwards to the theory as to why they were made that way but if you prefer trial and error that's fine too.
>>
>>2202328
Doing a BS+MS in EE
>>
>>2202730
Look into software defined radios, there seem to be a lot of applications with meteorology
>>
>>2202328
>>2202280
EE dropout turned electrician at 27 here. A big factor for me was not wanting to stare at a computer all day every day. I like to be moving around doing things indoors or outdoors. EE is also very math intensive and you're like me you will be asking what's the point of learning this very often. The downside of my current job as a resi sparky is that it's easy to learn how to wire a house and once you get it down it's very repetitive and boring. An EE probably earns roughly double what a spark with the same number of years experience earns here too.
>>
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>>2202248
So, I don't know shit about electronics, I bought >solar panel
>battery controller
>battery
>dc to ac converter
and now I want to do this :
>join second cable to the output cable of the solar panel
>connect ac converter to the end of the cable
>rejoin the two cables after the ac converter, thereby creating one path with the battery in between, another directly from the solar panel to the ac converter
>also, some sort of system to block current from flowing out of the battery when enough flows directly from the solar panel to the device
>plug device
does this work? is it ok to join cables coming from 2 different dc converters? inb4 why don't you just make everything go through the battery. I want to spare the battery, don't want 70 Watts of current going through while it doesn't need to during the day.
Also, last but not least, can I just clamp the cables together and put some protective tape on it or is there some other procedure that would be adviseable to follow?
>>
So, /ohm/, what jellybean parts do you keep on hand for prototyping new projects?
I want to stock my parts bins so that I can get started on new ideas without having to wait on shipping to get me what I need.
I know I can't reasonably stock everything I need, but if I could keep enough on hand that I can get started while the niche parts are being shipped that would be great.
>>
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>>2205666
2\
I tried to find some sort of device to measure current and then block current, but I can't really find what I need. I came up with a dyi solution detailed in picrel.
Basically the coil attracts the metal spring when the panel provides current, this pulls the string and the string pulls the lever of the switch, thereby blocking current from going from the battery to the device during the day/when enough energy is provided by the panel directly.
Also would it maybe be better to block current before the ac converter to avoid a (possible?) short-circuit, or is it ok do block it after?
>>
>>2205671
kek of course the switch wouldn't be put back when the current comes back, so I'll use a solid piece of wood or something instead of a string.
>>
>>2205666
>>2205671
No
Don't even try
There isn't any point at all
Get a dedicated solar charge controller that will do it all for you, assuming the battery charger can't bypass the battery itself.

Arguably you could use a small circuit (I'm thinking some sort of MOSFET circuit) after the battery and after the solar panel that switches from the panel to the battery when it gets dark, but if your existing battery controller can't do that you bought a shit one. The inverter going only at the very end.
>>
>>2205442
>you'll still have to lift one lead of the capacitor
Awe drat. I was hoping they find do some amazing near magic in software. Desoldering is not one of my strengths.
>>
>>2205777
There are in circuit testers but they tend to be expensive, like I said get some old scrap boards and practice, it's not hard to do, just takes some time and willingness to learn. A lot of this stuff is quickly becoming the responsibility of the owner to maintain because there are fewer and fewer people out there who are able to or willing to work on it, not to mention you'll have peace of mind if in the future something goes bad because then you'll have the confidence to at least attempt to repair it. CRT monitors and TVs are getting notorious for that.
>>
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Still learning KiCad, is this way of snaking something between connector pins a problem?
>>
>>2205833
no, everybody does this
>>
>>2202328
Yeah CE degree here. Currently employed at ADI.
>>
>>2205833
no, though if you need to increase the clearances for high voltage reasons it can be. the yellow circles around the pads show the clearance fyi, and kicad will never let you draw a trace that goes inside that

that said, if you're milling your pcb or etching at home you may find those details hard to reproduce. if those are 0.1" headers then just i'd use the smd bent ones instead. achieving a hole-less pcb is good for home fabbing them, and the pads are also narrower and so facilitate routing traces between them easier. i find that my hand-drawing of traces can definitely do 0.05" soic footprints if i'm careful, so naturally it isn't much more difficult to thread traces between 0.1" pads if they're of a similar size. i also smd mount dips on occasion for this reason.
>>
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>>2202248
I'm enjoying making these handhelds that I've designed. It is nice going from idea to finished project. I've made a few already.
>>
Are gu10 light sockets simply a twist-fit holder? There's no components in it? I'd simply be able to connect cables directly to the two prongs and into the wall?
Does it matter which of the two prongs the cables goes to? LED lights.
>>
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>>2205946
That's neat
Magnifier screens need to make a come mock
>>
>>2206133
come back*
lol
>>
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Do power supplies often smell very bad? Is it a sign that something is very wrong?

I just opened up this old 5v power supply I had lying around. (Hasn't been plugged in in roughly 4 years.) It has a very strong stinging smell to it.

Kind of like the burning smell of burned electronics but without the smoky smelling part. Instead the stinging chemical smell seems stronger.

There doesn't seem to be any noticeable liquid on any of the capacitors.
>>
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check
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>>2206159
>Do power supplies often smell very bad?
No
>Is it a sign that something is very wrong?
Yes.

That's a dying power supply, one of the caps is leaking, that's the smell, the electrolytic is burning off. Do not use or trust this board, until you've checked and replaced the bad caps.
>>
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>>2203010
Are the AST pin numbers wrong on the CD4047s or are the labels wrong instead?
>>
>>2206159
if it smells like over ripe fruit kind of then its caps. electrolytic capacitors smell like that if they are venting. same with lithium ion cells. same reason. the chemicals they use often make that smell
>>
>>2204967
>is there a difference between "pin header" and "pin socket"?
use the 3D view feature and you'll learn the difference real quick
>>
>>2206377
i meant before you solder anything on, is the pcb itself effectively the same
>>
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Made a 4 bit adder!
>>
>>2206380
Beautiful <3
>>
>>2202328
2nd year BS EE student

anyone frequent alternative sites that have content/discussions like /ohm/?
>>
>>2206379
In some footprints the holes are smaller on the socket side, since the socket pins are usually flat while the header pins are square.
That doesn't appear to be the case for the kicad default 2.54mm footprints, but you can check for yourself just by opening the footprint editor.
>>
>>2206433
there's a bunch of diy electronics subs on r*ddit, though for some reason I never found good discussions there.

Also hackaday has a forum i think
>>
>>2205833
the only thing I would say is center the track between the pins for more clearance.
>>
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Where can I buy a few NRD connectors, but like the 'socket' part?
>>
>>2206228
>50 Hz
ngmi
>>
>>2206380
Make another and combine for 8 bits!
>>
>>2206496
the socket is just a standard JST connector.
>>
>>2206561
awesome thanks
I'm obviously new to this, searching for nrd connectors only took me to the jst site where it directs you to contact a sales rep, didn't realize that was also a connector type lol
>>
>>2206515
I took it apart and was running out of wires. I ordered more to do just that, and then to hopefully build some sr latches.
>>
>>2206590
get a spool of 22ga solid and a cheap wire cutter/stripper
>>
>>2206590
You working through Ben Eater's videos or something?

You should check out Kime and Mano's Logic and Computer Design Fundamentals. That was the text we used when I did computer architecture 1 in undergrad. Wish I still had the lecture packets and shit. Of course we did everything on paper or in simulation; it was in the CS department after all, so wiring shit up wasn't in the cards. Still, this stuff gets me so nostalgic. It's been like 16 years.
>>
>>2206591
I have some but it's slow to cut and strip all the wires I need.

>>2206599
Kind of. He's just giving me some ideas to try out. My goal is to make some kind of computer though, with some kind of video out and gamepad input.
>>
>first day of new work
>go outside to catch bus at 5:45AM
>bus was 10 minutes early and already left
>wait for second bus
>get on
>get off in middle of town
>walk 100m to the next bus stop
>halfway there I see my next bus driving already 5 minutes early
>run across road and wave hand at bus, he’s already left the stop
>catch it at nearby traffic light
>knock on the window
>driver looks at me
>drives off
>stops at nearby stop for other passenger
>sprint after it
>he picks up that passenger and drives off before I get there
>wait 15m for next bus
>catch it
>one more transfer later I’m at work
>5 minutes to spare
>get into the building
>wait around for 20 minutes
>get 20 minute safety briefing
>spend the next three hours tying electrical wires in loops and putting them in plastic bags
>turns out they forgot to tell me to go to my lunch break
>come back from lunch
>2-3 more hours of wire tying and bagging
>get moved to a testing jig
>spend rest of day putting freshly soldered boards into a testing jig, and analysing the circuit while waiting for it to do its thing
Am I in the electronics industry now guys? Gotta take the busses home again but my phone battery is real low.
>>
>>2206624
>My goal is to make some kind of computer though, with some kind of video out and gamepad input.
Don Lancaster, TV Typewriter Cookbook (1976).
>>
>>2206635
I'll check it out.
>>
>>2206635
I love the story about the name. Guy is in hospital, friends want to help him get online (in the 70s!) with a modem. Hospital has list of approved items: televisions are approved, typewriters are approved... "What are you bringing in?" "A television typewriter!" "Checks out."
>>
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I got one of these fat guys that i was given but dont really use since i have a newer tabletop oscilloscope. I dont have any differential probes though and i want to make some measurements on a flyback converter loaded from mains, but then it occured to me: I can use this one for higher voltage measurements right? The 10x probe says 600v and the other test tip says 1,5kv, and the voltage scale on the scopemeter goes up to like 1kv/div
>>
>>2206701 I am using hantek 2c42 (chinkshit with similar specs) with 600v power inverters with no problems on stock 10x probes
>>
>>2206634
Is this you? >>2203646
You've really got to get a place closer to work before the commute breaks you. It sounds like they're giving you shitty co-op student work too. Are you at least being paid well?
>>
why does onsemi have a 'request datasheet' button instead of giving the datasheets?
>>
>>2206810
I wouldn't know, I just google for "part name pdf" and I know I've gotten onsemi datasheets in with the others.
>>
>>2202280
Are there no electrician jobs which interest you? Electrical work is such a large field without going into electronics, though the most interesting ones probably involve flying around and doing jobs on site far away from home.
>>
>>2206701
You can use an isolated scope as a differential probe, but you are hanging a large amount of parasitic capacitance on circuit node connected to the ground connection.
>>
So if I'm trying to power some basic things in my shed until the spring (light, exhaust fan, battery charger, shop vac, etc) via extension cords. After winter I'll have an electrician do it right.

This is my daisy chain:

25' 14/3 125v/15amp/1875w
100' 14/3 125v/13amp/1625w
Culminating in the shed at a heavy duty yellow jacket surge protector 6' 120v/15amp/1800w

What are my effective safe load limits here and how do I calculate them? Should the outlet these are connected to have its own surge protector strip and will that limit loads as well? Am I retarded for doing this?
>>
>>2206640
>>2206642
I want to say I've read that the original Apple Computer was essentially a TVT clone (and the Apple II was an improvement over the TVT).
>>
>>2206367
>>2206340
Thank you!

I've heard about dead capacitor-smell being a little sweet-ish but this just smells 'spicy'. Not sweet at all.

I don't know how to describe it in english but it burns my nose.

In any case I will throw away the board and use a normal (unopened) USB wall wart with a buck converter instead.
>>
It seems I have murdered a 3.7v liIon cell but I have no idea how.

Earlier today everything was working fine. Then I took apart the (semi diy) bluetooth headphones it is in and now the cell shows 0.4v and the headphones won't stay on for longer than a second. Even when plugged in.

I soldered some things when I had it apart.

The first one was me desoldering and swapping the cables, on a switch to the bluetooth receiver board.

The second one was shortening and resoldering the cables from the battery to the board.

Both of those were done because the cables I used before were really brittle.

I also replaced the hot glue that's holding the switch in place.

I was careful not to short anything (especially the battery), I kept the soldering iron away from it (the wires are about 0.5-1cm long but I didn't heat them much), and the hot glue got maybe 1.5cm close to the battery at the closest point.

It did take me a while to solder the wires from the switch because there was hot glue on the solder holes of the bluetooth board. Maybe the heat somehow damaged one of the components on the board?

I've soldered to that board quite a bit and I don't think this time was any worse than back then.

I've also used electrical tape to make sure no metal is touching the battery. Just to be safe.

I know the entire thing is janky as fuck but until now it has been working very well.
>>
>>2206969
The time frame between it working perfectly fine and measuring 0.4v on the cell, was about 10-15 minutes.

It doesn't seem to have it's own protection electronics but I think the bluetooth receiver does since it came with the cell installed.

I have a bigger battery on the way (this one does have protection built in) and I would like to avoid destroying it in the same way.
>>
>>2206714
yeah that's me
paid minimum wage, but that's like 14.20 USD/hr
as i said in >>2203696 the lockdown prevents me from moving
i'd planned to have already moved by now, fate had other ideas.

1 hour in the moring to get ready and 2 hours in the afternoon to shower and make dinner and tomorrow's lunch, i have very little time for myself if i want a fulfilling 9 hour sleep.
>>
>>2206993
Oh fuck this morning the first bus was early and missed me, and the second bus was cancelled, so I had to walk to a different stop and wait for 40 minutes. Probably going to be late to work, eat my ass.
>>
>>2206944
Well it did use a classic TVT-style video architecture from before proper RAM chips were available.
>>
I just found out about CD4048. It's a pretty interesting logic IC. It allows digital control of logic. The same IC could be used in eight different operating modes just by driving three control inputs.
>>
>>2207089
You could probably implement this sort of thing with an EEPROM.
https://youtu.be/BA12Z7gQ4P0
>>
>>2206971
>>2206969
Welp looks like I fixed it.

Seems like my solder joints were shit.
>>
>>2206634
Sounds exactly like an intern job I had in a mine.
The pay and contacts were pretty good but it wasn't worth it.
>>
>>2207092
Or a shift-register and a multiplexer.

And if you're feeling really adventurous:
http://blog.notdot.net/2012/10/Build-your-own-FPGA
>>
EVERYTHING IS FUCKING OUT OF STOCK
AND IT WILL TAKE UNTIL THE END OF 2022 TO FIX THIS
I HATE THIS SO GODDAMN MUCH
>>
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message of the day from ali
>>
>>2207089
>>2207092
imagine being so autistic that rather than use a small 8bit MCU to drive whatever moderately complex logic you use a bunch of descrete trannies and eeproms like it's 1970.
at least use a CPLD and learn some verilog, which is a skill that will actually be useful in the future.
>>
Someone explain resistors to me. So If place a 4 Ohm resistor on a 12V battery, its 3 Amps flowing through the circuit yes, a piece of wire may be like up to 1200A and blow the wire/battery if a lipo because low resistance.

But something with high resistance also heats up and would burn out too...

So high resistance = heat up and burn through
Low resistance = heat up and burn through

Assuming both connected to power source and thats the only load.
>>
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>>2207188
>So high resistance = heat up and burn through
>Low resistance = heat up and burn through
no, what your missing is power dissipation.
the voltage across a resistor is V=I * R but power dissipated in watts by the resistor is W = I^2 * R = V^2 / R. pic related is a 1/4 watt resistor, if you wanted to put it across a 12V battery and not burn assuming it's directly across the terminals and not in series with something else it would be 1/4 = 12^2/R.
then R = 576 ohms. The lowest resistance you can go is 576 before you start to dissipate more power then the resistor is rated for and it burns.
>>
>>2207045
Today I’m taking the time to reverse engineer the boards being tested as I wait for the programmer. Pretty sure the 8 of one transistor and 7 of another is being used to multiplex a 7-seg display, the placement of resistors isn’t right to be multiplexing a keypad. That said, 33Ω resistors (marked 330) in series feels rather low, I assume that means 3V LEDs running on a 3.3V rail. I’ll look up the part numbers once I get home, the MCU has there other ICs that I don’t really understand. One is a 4-line communications transceiver, one might be SPI memory of some variety, no clue about the third. I’m more interested in what I think are TVS diodes, and are placed on all the off-board connectors. I should probably buy a hundred of them for my own projects.
>inb4 I violate the NDA

>>2207188
>something with high resistance also heats up and would burn out too...
This is incorrect. Put 10 million ohms across a battery and you’d need laboratory-grade equipment to even detect the heat produced. Your fingers have 10-100 times smaller resistance and you don’t explode when you put your hand across the terminals of a 9V.
>>
>>2207187
>at least use a CPLD and learn some verilog, which is a skill that will actually be useful in the future.
imagine wanting to develop useful skills in EE
go to college if you want that
>>
>>2207222
kek, they don't teach you anything useful during a BS in EE.
it's all math and theory, but that doesn't get you too far when you need to make a working product or getting a prototype board to turn on.
>>
>>2207232
>math and theory
>not useful
ah yes, i forgot i was in /ohm/
>>
>>2207243
most EEs are code monkeys anyway. the only difference is instead of web development they do embedded stuff. do you think they will say oh wow anon you've learned the laplace transform thats awesome, now please design a new revolutionary device for us. kek. best case you will picking ready made stuff based on datasheets and maybe add some capacitors. and maybe punch in some numbers into a proprietary calc tool to do some calculations. so much for the hard math. you will forget all of it in a few years anyway.
>>
>>2207294
>you will forget all of it in a few years anyway.
this. i needed to do calculus recently but i've forgotten how so i wrote a program to do it for me.

>>2207146
it's not going to be fixed in 2022 anon, this is the beginning of the collapse.
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>>2207146
>not making everything out of jellybean parts
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>>2207146
>>2207308
>>2207329
Out of curiosity, how has the shortage affected everyone so far?
>>
>>2207348
Found it difficult to get good ADCs and DACs, there were no USB audio codecs at all, bunch of MCUs were price inflated or out-of-stock so I deliberately bought more obscure ones, there were no LM13700s, no CH340Ns, no base NTMFS5C628NL FETs, think that's everything. Was buying from LCSC. Really missing that audio codec now.
>>
>>2207191
>>2207198
So higher resistance = less energy turned into heat? That doesn’t make any sense.
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>>2207387
It's not about energy, it's about power. Power is energy consumed per unit time, and is defined by P = I*V. Less current at the same voltage means less power. If you want to know energy dissipated as heat, multiply the power by the time elapsed.

If you have a 10Ah 12V battery then:
-a 1MΩ resistor will draw 12µA, and dissipate 12*12E-6 = 144µW. It will take 10/12E-6 = 833,333 hours or 3 billion seconds to drain completely, and across this time it will dissipate 3E9*144E-6 = 432,000J.
-a 1Ω resistor will draw 12A, and dissipate 12*12 = 144W. It will take 10/12 = 0.833 hours or 3,000 seconds to drain completely, and across this time it will dissipate 3,000*144 = 432,000J.
The energy is the same regardless of how long it takes to dissipate, because that's how the math works out. This is conservation of energy at work, and in reality this means the battery carries a certain amount of energy. In reality that voltage will usually slowly droop as it discharges, for a 6S lead acid it goes from 14V to 11V IIRC. In the case that the voltage isn't constant, or the current isn't constant, then instead of:
>E = t*V*I
you get
>E = integral{V(t) * I(t)}dt from t=0 to t when fully discharged
This latter equation will also work for AC circuits, though having the V(t) be a constant sinusoid makes things a lot easier than they could be.

FYI 432kJ is equal to 120Wh, which equals 12V*10Ah. The entire math could either be done with hours as the time unit or with seconds as in SI units. I prefer seconds, but in some cases it's easier to stick to hours instead.

And again, find some other way to explain why your finger doesn't melt when you touch it across a battery.
>>
>>2202280
I worked as an electrician for a little bit, even got all the certificates and shit (what a waste of time) but it was too tedious and boring. It's not a fun job, you are literally a monkey that runs wires through walls and screws them into light bulbs and outlets and other shit. Even a retard could do it.
So after about 2 years i went into IT instead which i enjoy much more and now work as a programmer, and i also make EE projects as a hobby. (wouldn't want to be professional EE tho because you have to work on boring shit they tell you to instead of making whatever you enjoy)
>>
>>2207348
i have no problems getting any components except micros... which is of course the most important part so i'm fucked anyway.. i mostly use two micros, atmega328p for 80% of my projects since most projects don't need a ton of cpu power and it's cheap, and them stm32f4 for rest of my projects which need to GO FAST.. both of them are out of stock everywhere. the fucking microschop lists them in stock as "ARRIVING SOON - jun 2022"
THAT IS NOT FUCKING SOON CUNTS
and whats even worse i can't order shit from lcsc anymore due to stupid greedy cunts implementing mandatory VAT and customs shit for EU orders and dumb shits at lcsc can't be bothered to register themselves as vat payer
>>
>>2207418
use attiny1614s, they have very similar specs to the 328ps, less progmem and pins but more ram. there are surely other avrs if not other similarly specced mcus with still in stock that aren't too hard to program. also use esp32s, they're not as good as stm32s but damn they're cheap for 32-bit mcus, plus they have dual i2s and dma and a fuckton of ram.
>vat
lmao i don't pay vat on lcsc and customs haven't caught on yet
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>>2207420
i use esp32 for projects that need wifi or bluetooth, but for projects that don't it seems like a waste, i don't need dual core cpu to blink a led
atmega328pb is my favorite because it is very simple and super robust and becauce i just it so much i know it inside and out so i am 100% guaranteed i won't get any unforseen problems since i know it so well
>>
I want to make an electric kart which can go FAST
torque is more important than the top speed, but it should still be at least 80km/h (yes it's a death machine)
I don't really know how much the kart will weigh in the end so how do I size my motor? What kind of motor should I get?
I have a project car at the uni which is just a toy car with 2 motors on each back wheel connected to a battery through a motor controller which is connected to one of those development kits to control the speed through a PWM. From what I've worked on it seems the actual electronics isn't that hard, the hard part is getting your motor and battery requirements right.
Anything I'm missing?
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>>2206026
Holy shit it worked.
The diying can begin.
>>
Yeah this pretty much sums up what my friends hear when i try to talk with them about my EE hobby
https://www.youtube.com/watch?v=aW2LvQUcwqc
I have to get less normie friends
>>
>>2207348
I only build circuits as a hobby, so not as bad as it could be I guess, but putting a hobby on hold for years is pretty shit either way. I can still get most parts if I am willing to get them from obscure sources (rather than my single stop at mouser or digikey before), issue is only that this means I need to pay shipping for each of them, which adds up.
Overall, very annoying but at least it's not an existential threat for me.
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Can someone help me with this circuit that I cobbled together, I need to know if it works before I order the parts and pcb
Here is the paste to the datasheets and the pcb design

https://pastebin.com/dd7zJVku
>>
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well, another project finished
this will be super handy for debugging network cables in the apartment building with internet troubles i am trying to figure out

and now onto the next grand project
>>
Is there any downside to an open ended wire with 5V on it used as a water level detector? There won’t be any current since the negative end goes into an atmega328 input. Asking because all I see online are magnetic float switches etc. Should I add a pull down resistor? It’s not all too critical I just want to know if the water level drops too much on a plant
>>
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what are my options for:
circuit 1 current -> circuit 2 fet open
circuit 1 no current -> circuit 2 fet closed
doesnt need to be isolated, just want minimal/no affect on the power of circuit 1

please forgive my retardation
>>
>>2207610
You can detect water/no-water with the ADC input of an atmega. I have a system that has been running for about 20 years that uses two stainless steel screws that go into a PVC pipe to detect when water is flowing. I apply 5 volts to one of the screws through a 100k resistor and measure the voltage at that screw. Ideally, when no water is present it should read 5 volts, but I have a bit of leakage. Pic related is the result. The low parts of the plot are when water is flowing and the voltage at that screw is lower. The scale on the right is the 8-bit ADC reading, where 255 would be 5v.
>>
>>2207623
>I apply 5 volts to one of the screws through a 100k resistor
And the other screw is connected to ground.
>>
>>2207623
would it be able to detect a levee break early enough if kartina hits again?
>>
>>2207623
Thanks, you mean like a voltage divider? 5V-100K-*-Reservoir-GND and measure at *?
>>
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Can anyone help solve this issue? I'm working in an industrial plant. They have a 120v sensor 500' away from the PLC, the problem is that the signal back from that sensor is run in a conduit with over a dozen 480V motor leads. The result is that, when those motors are running, that tiny little sensor input wire is being mogged by EMI. If would placing a resistor in pic related help mitigate the false-positive EMI-enduced readings?
>>
>>2207696
aren't there standards for designing cabling solutions that handle signal cables next to power cables?
>>
Anyone got an idea for something I can practice my soldering and other diy skills on? (dremeling holes for usb plugs or something like that)

So far I have turned some headphones into bluetooth headphones.

A lot went wrong but now they work and I learned a lot.

Right now I'm planning to convert some old speakers to bluetooth using the same bluetooth module I used for the headphones and a buck converter to get the 9v the speakers need from the 5v I have.

If I connect the bluetooth module (built in USB battery charging circuit) and the BMS I took from an old power bank both to the same 2 batteries in parallel, will that work out just fine?

I could also connect the power bank BMS' output to the bluetooth module's USB input but I think it doesn't turn on without having a battery connected.

I could keep the tiny 200mah battery included with the bluetooth module but then I fear it would constantly drain the power bank.

The reason I need the power bank BMS at all is because the cells don't have built in overcharge/overdischarge protection and I need to get power for the speakers from somewhere.

Maybe I can find a trace somewhere on the bluetooth module that has a constant 5v on it when it is turned on. I don't know if that even makes any sense though...

Anyway. Sorry for rambling.

If anyone has an idea for my speakers or something similar I could attempt, please let me know!
>>
>>2207698
Yes, in fact the client's current controls spec says to route motor cable and PLC IO in separate conduit. However, this particular building is like 20 years old
>>
>>2207696
A resistor will probably work purely as an attenuator, reducing both noise and signal.

If the 480V motor noise is at specific frequencies it might be filterable.
>>
>>2207708
Well the the motor leads are actually driven by VFDs, so theoretically I do know the frequency of all of them. How would the resistor reduce the signal? In nominal operation, the wire coming back from the sensor goes to an Input module, which has it's own sinking resistor to sense for the input signal. I think the issue here is that the internal sinking resistor is just too low resistance, and isn't drawing enough current to overcome the EMI. So upping the resistive load on the circuit should get the loop to a higher current, overcoming the EMI
>>
>>2207703
>practice my soldering
get a perfoboard and a bunch of header pins?

Also why do you double space every sentence?
>>
so if i put two linear regulators in series, one as CC one as CV and hook it up to a lipo battery will it charge it safely? it seems like the perfect setup
set the CV ldo to 4.2V, set the CC ldo to 1A (which is recommended charge current for the lipo) and let it rip
>>
>>2207723
Yeah, so long as you have enough dropout voltage to do so. An LM317 on 5V won’t work, FYI.
>>
>>2207723
just make sure you're not blowing up the regulators
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>>2207711
Not that anon but I also don't see how adding a resistor would do you any good either. Maybe if your signal-to-noise ratio is decent and you're just getting false positives because your PLC is way too sensitive with their readings.

>So upping the resistive load on the circuit should get the loop to a higher current
??? If you wanna increase the load you should decrease the overall resistance. By adding an extra resistor you'll just be attenuating your signal even more.

IMO your best bet is filtering the noise out like the other anon suggested. You can look into shielded cables too, I suppose (ferrite beads probably won't do much in the range of frequencies you're working with).
>>
>>2207772
>you're just getting false positives because your PLC is way too sensitive with their readings
I believe this to be the case, the module only needs to see like 5-10mA to register the input
>>
>>2207774
>>2207772
So I'm thinking that by adding the resistor, the EMI current won't be strong enough to actually register at the module, but will register if the actual sensor contacts close
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>>2207780
Well, the proof is in the pudding.
That sounds like something that should be configurable on software though.
>>
>>2207786
I don't think the sinking resistors built into the module's input terminals are variable, but that's a good thought, I'll check it out
>>
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>>2207799
This is the schematic of the input module, and the red circled button, for all intents and purposes, can be regarded as my sensor
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>>2207696
Is the cable shielded? If not, that may help (a lot). We had this design where an encoder cable ran all the way along a huge 480V lift motor (frequency regulated) and a simple shielded cable solved all interference problems.
Lapp sells some braided shielding sleeves which you can pull around the cable but it’s like $4 per feet.

If you can’t move/replace the cable I’d say try and solve it in software (moving average, outlier detection, 2oo2 or whatever)
>>
>>2207807
Based Allen Bradley guy
>>
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>>2207807
>for all intents and purposes
I hole-hardedly agree, but allow me to play doubles advocate here for a moment. For all intensive purposes I think you are wrong. In an age where false morals are a diamond dozen, true virtues are a blessing in the skies. We often put our false morality on a petal stool like a bunch of pre-Madonnas, but you all seem to be taking something very valuable for granite. So I ask of you to mustard up all the strength you can because it is a doggy dog world out there. Although there is some merit to what you are saying it seems like you have a huge ship on your shoulder. In your argument you seem to throw everything in but the kids Nsync, and even though you are having a feel day with this I am here to bring you back into reality. I have a sick sense when it comes to these types of things. It is almost spooky, because I cannot turn a blonde eye to these glaring flaws in your rhetoric. I have zero taller ants when it comes to people spouting out hate in the name of moral righteousness. You just need to remember what comes around is all around, and when supply and command fails you will be the first to go. Make my words, when you get down to brass stacks it doesn't take rocket appliances to get two birds stoned at once. It's clear who makes the pants in this relationship, and sometimes you just have to swallow your prize and accept the facts. You might have to come to this conclusion through denial and error but I swear on my mother's mating name that when you put the petal to the medal you will pass with flying carpets like it’s a peach of cake.
>>
>>2207836
I used it right though you dingus
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>>2207829
Nah none of the cable is shielded, I'm not sure how I can solve it via software, when those motors are running, I literally have my input driven high 100% of the time. So I can't even write some debounce code
>>
>>2207713
I do paragraphs to make it easier to read.

One giant block of text makes people not wanna read it.
>>
>>2207841
lerk moar, mr. balloon hands
>>
>>2207852
You post the pasta when someone uses the idiom wrong, fagboi
>>
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>>2207853
Who, me? No way. Not ever.
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>>2207842
Your motors are probably in the 20-100Hz range too right? Makes it kinda difficult to even filter properly, let alone find an industrial off the shelf filter. If it takes you more than say 5 hours to find/implement some other solution it’s probably cheaper and faster to just start pulling a new cable
>>
>>2207879
Yea most of the VFDs are running between 40 and 70 Hz, some are probably dead nuts on 60Hz too, which makes filtering practically impossible
>>
Bad news lads.
>>
>>2207886
analogbros...
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>>2207886
Gonna start using discrete everything.
>>
>>2207886
does this mean i don't have to learn opamp circuits anymore?
>>
>>2207896
Just get discrete transistors and make your own.
>>
>>2207885
This might be a stupid solution, but try just twisting the wire a bunch.
>>
>>2207886
time to start drift-compensating your chinese lm358s, boys. your favorite chopper amp will never be in stock again.
>>
>>2207915
What's your reasoning lol
>>
>>2207918
>>2207915
Do you mean to twist the signal wire into a coil lel
>>
>>2207696
Wouldn’t this cause some kind of impedance mismatching issue?
>>
>>2207926
Not sure what you mean. From the PLC's perspective, it's just looking for some current to generate some voltage across its input sinking resistor. In this case the current is coming from EMI instead of the intended circuit
>>
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i want to start putting together my own guitar pedals, but never worked with eletronics before. my problem is with this part list capacitors, im trying to find these on tayda eletronics and most aren't there or labeled completely different. for example 100n and 2u2, i did not have this problem looking at the resistors.

any help on how tayda lists there stuff?
>>
>>2207946
you mean you are confused by the fact that 2n2 means 2.2nF or what? I'm not sure what i understand what your problem is exactly.
>>
>>2207949
im aware that 2n2 means 2.2nF, but when doing ctrl+f for 100n: no results, 2.2uF: no results, 10u: no results, so im confused on whether am i looking at this wrong or tayda doesn't have what im looking for.

hope that makes sense
>>
>>2207952
>2.2uF: no results
https://www.taydaelectronics.com/capacitors/electrolytic-capacitors/2.2uf-25v-105c-jrb-radial-electrolytic-capacitor-5x11mm.html

most people here buy parts from lcsc, or you can get capacitor kits on aliexpress.
>>
>>2207952
looks like you need to type 100nf, then i get a bunch of results. Never used tayda though. Looks a bit poopoo desu since you can't even filter/sort results
>>
>>2207703
what BT module did you use?
>>
>>2207956
thanks! i was looking at film box capacitors my bad
>>
>>2207961
you'll have to take a look at the kit you're building, you may actually need a film capacitor. a good BOM should tell you.
>>
>>2207962
im getting parts for several, and in one of the sheets it specifies the type, most on this site are blank so i don't know what to assume
>>
>>2207886
The beginning of the end.

>>2207892
I dont think it matters. they will jack up prices for everything.
>>
>>2207617
Could maybe use a BJT b-e junction like a current sensor, and just a high-value pull-up that turns on/off the FET. If that 0.7V drop and c-e current interferes too much with the original circuit’s current, you’ll likely need to use a current sense resistor and an amplifier circuit. A comparator would probably be required too.

>>2207918
Twisting the signal wire pairs would make them more immune to magnetic noise. Might be possible to do without replacing the cable if the existing cable is flexible enough. Though I think it should just be replaced with a length of CAT6.
If it’s the electric field coupling the noise then optos are a better solution, if not shielding. I think electric field noise is worse at higher frequencies while magnetic field noise is worse at lower frequencies, but I may be wrong.

>>2207957
>filter
Use Octopart for everything.

>>2207964
You can get all those sizes as ceramic capacitors, but I think an audiophile would use film caps for the smaller ones and tantalum capacitors for the larger polarised ones. If you’re doing tht parts then you’ll probably go for ceramics for small and aluminium electrolytics for large polarised. Ensure that the voltage ratings are higher than you need, but don’t waste money getting something too high.
>>
>>2208018
>Though I think it should just be replaced with a length of CAT6.
Can you run 120VAC through cat 6?
>>
>>2208019
yes but you can't tell anyone you did it
>>
>>2207959
August mr230b

Specifically because it supports aptx low latency.

Buying it used on amazon cost about 2€ more than a board using the same bluetooth ic would have cost on aliexpress but this way it has the built in USB charging circuit.
>>
>>2208118
Also I'm using an avantree dg80 to let my PC transmit using aptx LL.
>>
you guys told me to get a 1ohm resistor to measure the internal resistance of my batteries, well I got a few 10W ones, as you guys told me it would be Current = Voltage / Resistance.

So it should dump 1A into the resistor regardless of voltage.

But my battery measuring at 15.8V dumped over 15A of current straight into the resistor
>>
>>2208223
>it should dump 1A into the resistor regardless of voltage
this is incorrect, 10W is a maximum rating, not some obeyed specification. the resistor's only relevant obeyed specification is 1Ω. as you said, current = voltage / resistance, so in this instance current = voltage / (1Ω + ESR). if the ESR is much less than 1Ω, the 15.8V battery will dump almost 15.8A.

if you want to measure current from a battery, you just put the current sense resistor in series with your load and measure the voltage across it. Then use that current and thevenin's theorem to calculate the ESR of the battery.
>>
I want to prototype and repair and modify electronics as a freelancer. Anyone have experience doing this? How easy is it to get business?
>>
How do you guys test ccfl drivers and other hv components like flybacks? Draw an arc or use ringtester? Tell me your protips
>>
>>2203696
>no clue why assembly of security keypads is an essential business, bet somebody got bribed
Is it a contract manufacturer?
We stayed open because we manufactured boards for medical devices a few times and so we said we were a medical device manufacturer even though we hadn't done any in years
>>
Hi /diy/,
i want to connect an aux out audio signal to a mic in. I understand that the line level needs to be lower. Can I simply just use a voltage divider to lower the audio voltage level? Do I have to disconnect the mic bias? Thanks
>>
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I'm tired of being an IT cuck but I love repairing electronics. Do you think becoming a consumer electronics repairman would be a good idea, or is it just as soul crushing?
>>
how much do you need to know physics and circuits to be SoC designer?
I know vhdl and the basics of electricity but I couldn't design any kind of circuit with breadboard and components.
>>
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Going to start my first electronics project with a friend and we have two completely different ideologies. We're roughly on the same level, never touched much electronics or even got our hands dirty.

They want to start big with projects that'll involve fpgas/labview/solidworks etc focusing on robotic arm that'd involve control systems, and I just want to start small with something along the lines of a temperature-controlled fan. Do you guys have any project recommendations that's between the two levels? Maybe swarm bots or something but I feel like that's moreso microcontrollers (which I also have no experience with) or should I just begin my journey with microcontrollers?
>>
>>2208388
Not that many electronics that are worth repairing these days. Phones are basically impossible to repair except die the screen, most appliances aren’t worth the trip to a repair shop and even TVs usually just get thrown out rather than repaired if they’re >3 years old.

What would you want to repair? Maybe some niche stuff like high end washing/kitchen machines or power tools?
>>
>>2208456
>What would you want to repair?
The place that's hiring has literally everything. Washing machines, TVs, Radios, Laptops, PCs, Toasters, Microwaves etc. I'm thinking it's a good opportunity to gain some experience.
>>
Let's say I have central PSU with two voltage levels, and I connect both of these to another circuit, should I also join the grounds on the second circuit? Or don't join them anywhere but on the central PSU?
>>
>>2208358
no
>>
>>2206993
What the fuck man? You have an EE degree and you took a minimum wage job doing work any teenager could manage? You should be looking for a new job not a new home that shortens the commute. I also had trouble finding a good job right after graduation and worked at shitty startups for a few years. I felt like I had it bad but it was a lot better than what you've got.
>>
>>2208460
Oh if you found a place that has work like this, definitely do. Probably one of the best hands on ways to learn electronics
>>
>>2208460
Home appliance repair is usually just a matter of replacing parts until it works or the client doesn't want to pay anymore. Any diagnostics and repair are going to be more electromechanical than electronic—as soon as anything electronic in the device is broke, they just replace the whole damn board.
>>
>>2208408
You should literally just pick a project and do it. If you run into something you can't understand (and you need to understand it to make the project work), read or seek advice until you do understand it.

There's nothing in particular wrong with either of your approaches. Your colleague's ambition is great to have provided he can recover from failure when it happens. Your reservation is also great to have provided you can push yourself from small, simple projects to more complex designs.

MCU stuff is perfectly acceptable to work with, though you should understand that it involves abstracting a great deal of the low-level electronics. That can be a great thing if you don't want or need to bother with the low-level stuff. But it can also be frustrating if you don't like black boxes.
>>
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>>2208408
How about building a modern version of analog television (google it, it's interesting device) like this? If you spin the fast with all leds on, it will produce an all white (or whatever colour your leds are) image. If you put every other led on, you'll see many circles or lines, depending have you bent the wings. If you calculate a time from spinning speed, you can show any picture just by showing it in "loop" line by line.

Should be pretty cool project but doesn't need any expensive parts. You need a microcontroller at least to control lines and maybe some memory chip (write whole picture in memory, then read out very quickly) to get enough speed for drawing lines and maybe also some mux ic to control all the leds
>>
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>>2208670
And of course if you get this working, you can start adding features like auto-sync (see the pic, you then understand what sync does), "pixel" brightness adjustment (with PWM), multiple colors and so on
>>
>>2208670
>>2208673
kek for a moment I thought you were suggesting making a mechanical television
https://www.youtube.com/watch?v=ridI7O5VF-Q
>>
Who is forced to strip in order to make ends meet?
....
Electricians
>>
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>>2208734
Was this a crossword clue?
>>
>>2208118
Next level to practice: buy CSRA64215, the chip that mr230b is based on, and build a poor man's mr230b.
>>
>>2208562
I don’t have an EE degree, that’s the problem. I was under the impression that this job wouldn’t be as large scale as it is, but all the soldering and troubleshooting here is automated by machines. The boring dexterous jobs are all that are left for entry-level staff like myself.
I agree that I should quit though, I consider my knowledge to be at least comparable if not equal to that of an EE graduate. Since nobody will hire me (god I wish I had an offer like >>2208460) I think I’ll live off my savings and try my hand at freelance work. If I could earn money by converting an old stereo to have Bluetooth, or adding a mod-chip to a console, or making a prototype product for someone, I’d jump at it.
>>
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>>2208785
I have a PP degree.
>>
>>2207089
>I just found out about CD4048
Hmm, that looks like the predecessor of PAL chips.
>>
>>2208779
Without a hot air station, I don't think I'll get very far haha.

Unless you mean getting a board with the ic already installed. But that's basically the same as buying the mr230b except I'd have to get an extra USB battery charging circuit in place of the USB c breakout board.

It's not even any cheaper!

I have thought of getting a 2 copies of a bluetooth receiver board that supports tws.

That way I could convert my old speakers to truly wireless stereo. (Instead of having a wire between them like I'm planning to do right now.)

Honestly, that sounds like it would be fun! I just need to do some research on what receivers to get. (I would like to avoid one that uses a chinese voice to shout things like "bluetooth connected.")

Also if anyone has any tips on how I can identify cheap (used) speakers that might sound a little better than the 10€ "at least they work" ones I have right now, I would be very grateful!

Thank you!
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