/diy/ - Do It Yourself

This thread's digits brought to you in part by the TDA7468 I2C-controlled audio processor.

I'm thinking about starting a youtube channel for electronics that isn't cucked up with teardowns and such. A channel that actually builds/explains project, teaches a lil theory, etc.

>>1267719
Uh huh. Okay, have fun or something.

I want to learn some basic elec to maintain a UK workshop, stuff like three phase and appliance maintenance. wire stripping. Does anyone know a UK aimed YT series or book?

>>1267742
You will almost never be soldering on circuit boards in appliance repair or home wiring. That's more relevant to the qtddtot/sqt thread.
>wire stripping
Buy a $20 chinkshit automatic wire stripper and enjoy life.

I'd like to interface some microcontrollers with a shared bus signal. The bus voltage level stays at +5V when idle and it can be pulled down to 0V by any bus device. Each bus device has an open-collector output for interfacing with the bus. I came up with this circuit to accomplish this function. Do you think it makes any sense? Is there any easier way to do this?

Q2 would sense the bus voltage level. If any device pulls the bus down to 0 V, Q3 turns on and outputs a logic "0" into PA0 input pin.

When the micro wants to pull down the bus, it activates Q1 by outputting a logic "1" into PA1 output pin.

>>1268008
>circuit
Why don't you just use the DDR bit for data output instead of the pin bit?

>>1268008
the micro out/bus in looks ok, the bus out micro in what the flying fuck were you thinking?
if you want the real kind of cheat way of doing this just connect one pin directly to a digital i/o
when you want to drive it low, drive it low. when you want to let if float high set the pin as an input instead of an output, typically this puts the pin into a high impedance state which will let the bus be asserted elsewhere.

>>1268008
>easier way
Yes
atmel avr gpio pins are tri-stateable which means you can use them for output hi, output low, or input.
Use a pullup to keep the bus voltage at 5, and when you want to pull low, set the pin to output low. Otherwise set the pin as input.
Read the datasheet for data direction

>>1268008
The illusion of the 1 wire bus rests on the assumption that all bus devices have a solid common ground connection. This is no longer the case when the bus is long and picks up all kinds of interference from the environment. The robust solution is a differential (2 wire) bus that has no ground connection and is terminated according to the properties of the line, e.g. 100Ω for a twisted pair. The real challenge is the implementation of the collision protocol.

>>1268049
>The illusion of the 1 wire bus rests on the assumption that all bus devices have a solid common ground connection.
http://pdfserv.maximintegrated.com/en/an/AN148.pdf
dallas says 200M networks can made to work reliably for what it's worth, and the correct design of a 1 wire network is to have them share the same ground.
Yes I know differential signalling like rs485 can do much better.

>>1268089
>and the correct design of a 1 wire network is to have them share the same ground.
Easier said than done over any appreciable distance.

>>1268089
>share the same ground
Which makes it a 2 wire bus. 1 wire is a marketing stunt, technically it is a lie. Why do people parrot such obvious bs.

>>1268095
Why do autists keep belaboring this moronic point as if, for most PRACTICAL intents and purposes, ground can't just be assumed.

>>1268093
Couldn't you just drill a hole and drop a wire into the ground?

>>1268103
My house ground is literally just a cable soldered onto the water pipes, yeah, you could do it. Telegraphs used the earth as ground, that's why they only used a single wire.
It doesn't work for anything more complex than Morse code, there's too much interference. Even analog telephone becomes unintelligible.

>>1267458
Is that your debouncer? Wouldn't it be easier to use a Schmitt trigger? I'm assuming that he won't be pushing the button on the rocket device but rather on the remote control. A 74LS164 works if you can't get a 4017 for whatever reason.

>>1268104
>Telegraphs used the earth as ground
fun fact: they used it as the battery too

>>1268122
Answer to both: single 12V supply to match the igniters, only needs an 8-pin chip (unless we want to get into SOT23-6 and 74x1G logic), can drive the MOSFETs harder for better Rds(on).

Why are solid state relays that can do 120VAC at 15A so expensive ($25+)?

>>1268241
Because you're looking at legitimate suppliers. If you're doing something where reliability and liability aren't an issue, get cheap shit from china.

>>1268122
Schmitt trigger (two point switch) is a function, not a component. The LM393 is configured to perform that function via R2, R3 and R7. The output (1) goes HIGH when the input (2) is at about 4V and it goes LOW when (2) is at about 8V.

This is not really necessary because the 4017B (pic adapted to show that) already has that function built in for its two clock inputs and simple RC debouncing would have been good enough.

I had the impression that the original questioner wanted a sequencer which could be easily realized by configuring the 393 as a clock generator. A 555 could do likewise. Remote launch from the model bunker is also possible.

>>1268279
>Schmitt-trigger action in the clock input makes the circuit highly tolerant to slower clock rise and fall times.
Aw shit. Good catch anon.

Hey /ohm/ I'm a total beginner and have a silly question. Before you ask, no I'm not a student and no this is not my homework. I'm getting into it as a hobby.

I'm struggling to find the nodes and label them, and because of that I am unable to know which resistors are in parallel or in series.

If you have a resource I could learn from I'd be very happy; but I'd be very glad if you could explain it as well.

Could you label the nodes in the image to the left and explain why? Because I don't know when a node starts and ends.
I'd really appreciate it, thank you.

>>1268333
Have checked what your book's index suggests for "node"?
There are fancier explanations, but basically node = shit connected together. Thus, R1, R2, R3, R5 and R6 are connected together from their one end = node. Similarly, R1 and battery are connected together = node. Same with R3-R4 and R6-R5-R4-R2.

>>1268333
not sure if there's a more formal definition, but if I had to say just off the top of my head, a node is any point on the connection between two components. In other words, you assume the wire between components has no resistance (or is infinitely short), so that there is no voltage drop over its length. A node is then the entire length of wire that is at the same voltage.

To use your circuit, there is no component between points 1-2, so both points are at the same voltage. You can extend this to the negative side of the 10V supply. All of that is therefore one big node. That means that R6 is directly connected to the negative side of the supply, even though it looks like it's on the other side of the circuit.
Same for 3-4. The entire length of wire between those points is one node.
The reason why circuits are sometimes drawn with those "empty" wires is to make the schematic clearer or more simple to draw.

Hopefully I didn't just confuse you even more.

>>1268340
You actually helped me quite a lot. I'm still somewhat confused but I think I'm starting to get the hang of it. Thank you!

>>1268336
>>1268340
>>1268346
To add to the question, which resistors are parallel and in series and why? Thank you again, you're helping me quite a lot.

>>1268349
Two resistors are in parallel when they share both nodes. They are in series when they only share 1. In your circuit R3 and R4 are in series, while R6 and R5 are in parallel.
Additionally, if you look carefully R2 shares one node with R3 and the other with R4. So if you simplified the circuit by combining R3 and R4 into one resistance, that resistance would be in parallel with R2 (as well as R5, for the same reason). Never mind this if you still don't know about combining resistors, though that's usually the next thing you'd learn.

>>1268352
Makes sense. Just need to get the hang of nodes and then simplifying circuits will be a lot easier. You've made it things a lot clearer for me. I appreciate it.

If I ever become decent at this I'll make sure to help others in /ohm/ and just generally to anyone who needs help.

>>1268355
It would probably help if you explained how, for example, Wikipedia's articles on nodes and series/parallel connections are confusing.

>>1268355
A node is where a current can branch.

>>1268355

>>1268369
yo

>>1268399
series or parallel [^_^]

Why did my 3v button cell light up all these LEDs?

>>1268450
Because you connected them anode to (+) and cathode to (-) as you should.

If I want to design a step up flyback transformer running in discontinuous conduction mode how do I figure out the core reset time? Nothing tells me where to get the tr figure.

>>1268460
it's better if you solve for a maximum permissible inductance given a maximum on-time (or off-time but whatever) because it means you don't have to iterate. for example, simplified:
>f = switching frequency = 250khz
>dmax = max allowable on-time duty = 46%
>Vin = max input voltage = 180V
>P = output power = 50W
>min off-time = (1-dmax)/f ~= 2us
>Lmax = (dmax*Vin)^2/(2*f*P) ~= 300uH

i derived that formula by equating the inductor's stored energy in one on-time to the energy consumed each cycle (P/f). i don't think i've seen a datasheet do it that way but it works. there's much more to consider like peak inductor current and efficiency of course.

>>1268478
sorry Vin should be MIN input voltage. at max input voltage your controller will then lower the on-time to decrease the energy it provides to the output.

I want to build an attenuator that can be switched to match different impedances and speakers. I will be using 1x 4 Ohm, 1x 8 Ohm and 1x 16 Ohm resistor and a single 8 Ohm L-Pad.

Does pic related work?

I am ok with the fact that I will always lose 75% power.

How was your first week in electronics engineering or a field that taught electronics or anything related to electricity? Because I feel fucking hopeless. I've done well in everything I've put my mind to.

Not Electronics. It's been a week and I can't even understand the basics. I still get stumped at very simple circuits and struggle to find the total resistance and current. I can't even wrap my head around nodes and voltage drops. It gets worse, far worse.

Is this a normal struggle? Or am I just not built for this? I'm freaking the fuck out. Should I just bail and switch majors? Or is this a normal feeling? I have zero experience in electronics or circuits in general.

>>1268520
>How was your first week in electronics engineering

the sad fact is that the students who have access to an oscilloscope are 100x more able to understand the concepts than those who only have a calculator.

brilliant people can learn electronics analytically. the rest of us need something like a scope to keep up.

once the SJWs figure this out, the hood will be flooded with cheap scopes and you will be able to buy one for nothing at the thrift store.

>>1268520
nobody starts out grasping voltage/current/resistance. they'll get into AC and impedance before you understand DC and you'll be even more confused. it's normal, stick with it. if you want to be good though you have to cultivate your own interest and pursue knowledge outside of class. that applies to any engineering.

>>1268537
also this. imo the math is something you should learn as you approach practical topics that specifically require it. like the flyback question above. college isn't like that, you just have to bear with it if you want the big bucks and engaging work at the end of the tunnel.

>>1268537
I might do that then. I have a bunch of breadboards and components I bought off AliExpress.

>>1268541
Thank you. Just needed to be reassured it's somewhat normal. I do spend most of my free time self-studying because I don't want to feel behind.

>>1268541
>that applies to any engineering.

true, but EE is a bit different. mechanical or chemical engineers can read. EEs seriously need lab time, with scopes, spectrum analyzers, whatever.

as I said up there, an EE student with a decent oscilloscope has a great advantage over the other guys who do not. think. structural engineers? who the fuck has a device in their room to test the breaking strength of a steel beam? nobody, so they all do it analytically. but that EE guy with a scope and some chips and other components can learn, and be ready for the lab work.

>>1268520
are you the guy who was just asking about nodes a few posts above?
Perhaps if you're really struggling you could go see your professor or TA and have a 1 on 1 session. Be sure to rehearse exactly what you want to ask them.
Another important thing is to drop the defeatist attitude (sorry if the way I worded this sounds mean). Basically if you just keep thinking "i can't do this i'm too dumb", your mind will be busy with that instead of actually working towards understanding electronics. So try to stay positive.
Studying your course book will obviously help you, but getting info from other resources can also give you additional insight or make you understand a phenomenon in a clearer way. There's /ohm/, but there's also a lot of channels on youtube, as well as numerous subs on "the other website".
Other anons were talking about scopes but from what you said I don't think you'd need something advanced like that to understand the topics you're currently studying. I think a simple multimeter with basic components will do the trick and cost a tiny fraction.

Anyway, what do you need help with understanding?

>>1268488
5P3T I'd say. Is that the 4Ω position and what do you mean by 'work'? Probably not constant input R. I would deconstruct the thing into 9 drawings (3 positions x L-pad down-center-up) and calculate the resistance seen by source and speaker.

>>1268563
Even the switch - I fucked it up. Thank you, I am working on the changes...

>>1268271
I'm afraid of housefire.

>>1268609
on the upside, once your house burns down you'll have nothing to worry about and you will be able to buy all the sketchy chinese power supplies etc.

On the other hand, no more address to receive shipments... hmm

>>1268609
Add a fuse.

>>1268563
I did not do 9 drawings, but 3 ;)
What do you actually mean by L-Pad down-center up? Does it matter? To me it seems like the impedance will be correct.

>>1268609
https://www.youtube.com/watch?v=DxEhxjvifyY

you should be. SSRs are a pain though what with the power dissipation. regular shitty chinese relays will last just fine.

>>1268563
By 'work' I mean: Will this circuit attenuate if amp and speaker impedance are matched via switch?

>>1268620
Maybe I didn't understand the L-pad.

>>1268617
>what with the power dissipation
Heat sink, what else. Relays cannot zero cross.

>>1268679
heat sinks are the part that makes SSRs a pain.

>>1267468
I'm selling some popup headlights on ebay and need to test the motors. There's a green wire and a gray wire and I've got no clue which is which. I tried looking it up but didn't find a straight answer. Is there a way to test or could I just guess? If I connected the wrong side for just a sec would it fuck the motor up?

>>1268673
I do not think that L-Pads work that way. I think they do not change impedance. See http://www.bcae1.com/lpad.htm

I am worried about the resistors that I want to switch in in series or parallel to match different impedances with a single 8 Ohm L-Pad.

>>1268682
Give it a try, it won't hurt your motor.

>>1268682
>There's a green wire and a gray wire and I've got no clue which is which.
connect one way for open - the other polarity for close
connect only momentarily!
having it trying to open or close when it's already at the end of that direction could damage it.
If it hums but doesn't move, reverse the connections.
A fuse or current limited supply wouldn't hurt.

>>1268682
How much do you want for them? I need a pair for my Volvo.

>>1268703
They're off a mid 80s pontiac firebird, i don't think they'd fit anon. They're actually pretty valuable, the motors are worth $50 each and the headlights themselves are worth about 100 each

>>1268682
One of them is probably a switch. Only tap the power supply to one of the leads and ground. If there's no sign of movement, or a significant spark, you probably just hit the switch.
You should really use an ohmmeter to test.

>>1268705
Yeah, I'll go to a scrapyard and get some other lights then. Of course they wouldn't fit right away, that's what angle grinders are for. I've been using Mazda pop-up headlights for three years, and it had fixed headlights before that.

>>1268701
Thanks for the tip, I tested them and they both work! Neat how reversing the polarity reverses the motor

>>1268707
Miata popups on a volvo? I need to see this

>>1268711
It's just a 740 pickup conversion with pop-ups. I'm thinking of adding gullwing doors too, but I'd need a rollcage first so it can pass annual inspections. I'll post a photo of the rust pile tomorrow, it's too dark now.

>>1268683
Yup, works differently. The 8Ω-L-pad presents 8Ω at the input side when the output side is terminated with 8Ω. For the 8Ω speaker no resistors are needed because that's the nominal value. For 4Ω you need 4Ω in series with the speaker to correctly terminate the output and 8Ω in parallel to the input to load the amp with 4Ω. For a 16Ω speaker you need 16Ω in parallel to the output and 8Ω in series with the input. Or so I think.

How do I control an electric oil-filled radiator heater (it's one of those DeLonghi models sold everywhere) remotely?

The idea is to have a ESP8266 hooked up to a temperature sensor somewhere in the room away from the heater and have the heater turn on and off based on the reported temperature.

I was thinking of using pic related, but it's only rated for 12A while my heater goes up to 13A.

>>1268803
Forgot pic. It's sold here: https://www.sparkfun.com/products/14236

>>1268803
Assuming you've got the low voltage side of things under control, just use a relay. Preferably a latching relay so you're not always sinking current into it.

So what's the point of the ESP8266 if you're going to have it turn on and off based on the reported temperature? To see what temperature it is on your phone and override it from there if need be? Or are you just using it for the temperature regulation? If you've got an analogue temperature sensor then dump the microcontroller and go with a comparator instead.

Will attached schematic allow me to switch between two different sensors?
I'd like to use more sensors than MCU has ADC pins without adding specialized ADC converters or bigger MCU.

>>1268803
>>1268806
Why not use a simple 16A relay module? Lots to choose from (I believe you even might find with ESP8266 module already built in with some).

>>1268556
No I'm not the node guy. I'm not even sure who you're talking about.

You're correct about the mindset. I need to stop being such a defeatist and try to power through it. Sadly the professor didn't even leave his email or phone number or even office hours, he's just a terrible professor really. We also don't have a course book that I can follow.

I go sit in class, understand nothing then go back home and search online for resources to try and understand what was taught in the class. I'm basically warming the seat up.

I just need decent resources for self-studying. Books that cover the basics in detail and problem sets with explained solutions. But I can't seem to find a book that covers the basics properly.

Regarding the multimeter, which one would you recommend? Something from AliExpress would be good. (Non-American/European)

>>1268827
For thermistors and other fairly high resistance sensors that approach should work fine. For the MOSFETs, pick something with pretty low on resistance and threshold voltage.

>>1268743
Thank you! The only change that I will make will be that in 8 Ohm mode I will 8 Ohm in parallel before the pad (as your first position) and 4 Ohm in series with the whole circuit. That way the maximum that the speaker will see will always be only 25% power.

>>1268827
Yeah, but why not use some analog switch IC instead, like 4051 or 4066? If you use them only for signal level switching, you don't even need ones with particularly low resistance.

>>1268823
>Preferably a latching relay so you're not always sinking current into it
>concerned about current
>for powering a heater
costanza-belittles.jpg

>>1268827
>>1268847
Daily reminder that the 74x1G series is absolutely nice. Only 15 ohms r(on) at Vcc=5V which should be well within 1% up to about 90degC, and saves you a ton of board space.

How is power effected in parallel resistors?
If I have five 47 ohm 1 watt resistors in parallel, I'll have about 9.4 ohms resistance but how much power will they be able to dissipate? Do they just add up to 5 watts?

>>1268868
They will be able to dissipate 5 Watts. You are correct.

If you had four 47 ohm 1 watt resistors and one 47 ohm 10 watt resistor in parallel overall resistance would be the same. You could still only run 5 watt on them as every resistor "sees" the same wattage, but the four 1 watt resistors cannot take more than 1 watt.

>>1268868
Correct. Each resistor has its own I2R.

>>1268870
>>1268871
Cheers.

>>1268853
>Daily reminder..
Do they pay well?

>>1268012
>>1268020
>>1268021
>>1268049
Thanks for your input, I wasn't aware of that feature in AVR ports.

>>1268840
>No I'm not the node guy. I'm not even sure who you're talking about.
>>1268333 If you're having the same problem maybe read through that comment chain
>Sadly the professor didn't even leave his email or phone number or even office hours, he's just a terrible professor really.
Well hopefully your uni has a website with contact info for each faculty member, but if your professor is really that bad then i guess it won't make a difference. Still worth trying though
>We also don't have a course book that I can follow.
Check the ones suggested in the OP, or "Introduction to electronic circuits" by Sadiku (that's the one we used in my classes). "Electronics a systems approach" by Neil Storey is also pretty good.
>I go sit in class, understand nothing
What are you not understanding? First months of first year is probably all about ohm's law, V=IR. Did they give you the water and pipes analogy? I'd say it does a pretty good job at getting the basics across, but beware that it quickly loses meaning with more advanced electricity concepts (eg phase angle, reactive power - which I hope you're not covering yet?)
>Regarding the multimeter, which one would you recommend? Something from AliExpress would be good. (Non-American/European)
I'm not sure about brands/models. I know Fluke is considered to be the best, but they're also quite expensive. Personally I've got an old hand-me-down multimeter from my dad.
Perhaps some other anon can chime in, otherwise stick around for a bit in the threads and someone else might ask the same question.

>>1268520
watch eugene's physics video's about electronics

I have a 2A brushed motor that I want to power from a LiPo. The LiPo outputs 36A safely, but will do more than that and then die if shorted. Do I need to put something in there to protect the motor from the extra amps/stop the battery from killing itself by overfeeding the motor?

>>1268827
>Why not use a simple 16A relay module?
Total hobby electronics noob and afraid of setting house on fire.

>>1268823
I want the temperature sensor to be on the other side of the room from the heater (to get a reading that's more comparable to what I'd be feeling in bed, which is 6 feet away from the heater).

>>1268915
Current is a consequence of electric potential difference (aka voltage), so what are the rated voltages of your components?
I take it the 2A is stall current? The motor will only draw that if it's stalling and if the battery's voltage is equal to the motor's nominal voltage.

>>1268915
>Do I need to put something in there to protect the motor from the extra amps
Electric motors draw the current they need/are designed for - not all the current available.
I have a key cutting machine with a 120v/1A motor.
It's plugged into a 15A outlet protected by a 15A breaker.
Why doesn't it blow up when I turn it on?

>>1268887
>unironically using DIP

does anyone know of a cheap device (40 bucks or less) that can regulate an alternator to 14.4vdc at 80 amps? hoping for a 1 wire solution (alternator pos to device to battery pos). mine blew its internal regulator and because the car is a shitheap that is probably going to be sold soon anyway i just need it to work for a while.

I have an HDMI cable that goes behind a wall to my mounted TV so its hidden. At least that was the idea, but the plastic cap fell off the end before the plasterer started work and now there is a bit of plaster in the HDMI cable.

If its fucked is it easy or possible to cut the end of a HDMI cable and replace it with a new one, it would be easier than re-routing the cable now the wall is plastered

>>1268362
> A node is where a current can branch.
No. E.g. in your picture, the connection between R3 and R4 is a node.

>>1268840
>Regarding the multimeter
https://www.markhennessy.co.uk/budget_multimeters/
You need at least two.

>>1268537
Cheap oscilloscopes already exist and are readily available online for under $100. I have three scopes and I'm a poorfag. I'm not really sure what you're lamenting about.

>>1268940
everyone should be able to solder qfns but dips are cute as fuck

LDRs tend to have very high resistance in total darkness, up to 1 MΩ. Would it be possible to make a current-controlled variable resistor by mounting an ordinary green LED and an LDR face-to-face? Then it would be possible to vary the resistance by varying the LED current.
Any applications for such contraption?

>>1269040
you can, and they sell them in a single package. they have a slow response time and i don't think they're very linear though so they're not generally useful.

>>1269040
There is already a component with an LED and and LDR or phototransistor integrated in a molded plastic package. It's called an optocoupler or optoisolator.

>>1269045
to clarify most optocouplers/isolators use photodiodes or phototransistors. packages with LDRs are relatively rare.

>>1269040
It depends on where you plan to use LDR, but it does not seem like reliable option in most cases. LDR has slow response rate, especially if has sudden sharp changes in light (maybe it has changed, but I highly doubt).
I'd try to use current sense circuit with FET as voltage controlled resistor.

>>1269040
>up to 1 MΩ
The cheap LDRs I use (pic) have more than 40MΩ which is the limit of my Ω-meter. The LED-LDR coupler serves as audio attenuator for the gain control of a low distorsion sine wave generator. Such couplers are still produced but are unreasonably expensive (e.g. NSL-32SR2, Amazon $12 each). I make them exactly as you said, small green LED glued to LDR in a piece of black shrink tube. The result is better than using a FET as variable resistor. Audio is possibly that last application for this type of opto coupler.

Does anyone know any good books for audio electronics? I'm looking for something that goes into how exactly a circuit/component influences the signal and how that signal translates to tone. Difference between germanium diodes vs silicon, different opamps, different types of capacitors, etc.

>>1269148
elliot sound products is a website, not a book, but it has a lot of that.

>>1268941
Did you price out a new alternator at your local salvage yard? It may be closer to $40 than you think.

>>1268993
Sub-$100 scopes are fine for audio work and maybe watching an I2C bus, but almost useless for digital.

>>1268946
I suggest trying to pick it out first. If fucked, there are solder connectors available, if you've got a good soldering iron and technique for fine pitch work.

>>1268887
>>1268940

>>1269040
On this train of thought, I was thinking about making a linear optical encoder with binary printed in rows on a sheet of laminate, with transparent = 1 and opaque = 0, with 8 rows or so. I guess using photodiodes or phototransistors is preferable to LDRs then?

(the project in mind is a shitty hot-glue-gun 3D-printer without stepper motors, purely for the memes. might put a $5 multitool motor on the end too)

>>1269209
>I guess using photodiodes or phototransistors is preferable to LDRs then?
Yes. LDRs are slow as fuck.

How do I learn high-power AC electronics?

>>1269212
By learning low-power ac electronics first. When you understand switch-mode power supplies really well, you should be ready to work with higher power.

>>1269218
Any guide, syllabus, etc. for learning low-power AC electronics?

>>1269212
Start with the books posted by the OP.

>>1267468
My dumb ass was changing a bulb on my stove-top microwave and it ended up blowing up in my hand.

Now the microwave won't power on.

I checked the fuse up top (glass) and it's fine. My multimeter is a piece of shit and doesn't have a continuity test, but I saw you could set it to low resistance and see if it's near zero and it means the same thing.

So that's all good I guess. I saw you can check the thermal fuses as well, so one has a near 0 resistance and the other doesn't show anything on screen.

What the fuck do I do? It isn't my microwave.

>>1269238
The thermal fuse showing nothing sounds like it's gone open circuit. Wrap some copper wire around it to bypass the fuse and see if it works. If so, buy another one and solder it into position. Make sure you're not shorting a MOV or something.

Do you know why breaking a light bulb (presumably while the thing was turned off at the wall) could have triggered the fuse? Perhaps it requires a sense current through the bulb to operate, so perhaps putting another bulb or load resistor in the socket will help.

>>1267719
there already is a channel like that. keystone science, he makes cool projects and explains the theories without getting boring. his videos are short and to the point, shows you what you need and how to put it together and done. uploads every week

>>1269245
Well I left the microwave plugged in while taking the first one out and it actually blew up bulbs on both sides. I will see some time tomorrow if it just needs both bulbs replaced to work.

I'm beginning to think it's not the thermal fuse because there's no immediate signs that they aren't functioning.

Well I bought one of these pocket oscilloscope kits, and it looks to be in reasonable quality, though I may swap out some of the buttons for nicer ones. Is there any reason to use lead-free solder over 60/40? I have both, and was thinking that until I make a case for it I'll be holding this thing with bare hands making tin solder slightly more appealing, and I'd also like to get used to it. But since it requires a higher temperature, will it be more likely that I fry a component? Anything else to watch out for, like how flux behaves? Is tin pest a threat?

>>1269314
Oh yeah, I also got a USB soldering iron, an LCR meter that appears really useful (though I think I could definitely improve upon the ZIF socket, which requires resistor leads to be bent), and AliExpress's cheapest multimeter, an analogue one. I'm not sticking it in a wall any time soon.

>>1269314
The only reason to go lead free is if you're industrially mandated to. Worse in every way from every other standpoint.

>>1269315
Oh dear... did you buy le TS100 maymay?

>>1269320
Or if you eat it, but point taken.

>>1269322
That's not USB, I got an 8W USB iron in case I'm ever stuck without power I guess. A backup that I can use to fix my current iron.

>>1269314
>pocket oscilloscope
>usb soldering iron
>cheapo LCR meter

You got off to a bad start man. Ditch that gear as soon as you can afford to. You can find good used scopes for relatively low prices. Scopes that were considered high end a decade or two ago and are still perfectly good for hobbyist and student level stuff. A proper soldering station is a must too. You're gonna have a really hard time with a USB iron...

>in case I'm ever stuck without power
There will never be a situation where you are without power for an extended period of time and you DESPERATELY need to solder something. It's a waste of money, period.

The LCR meter/component tester is probably the most forgivable thing. I have one as well. They are good for quickly identifying components and getting rough values but useless for precision measurement. They also often have limitations. I use mine a lot to measure inductance of coils I wind and it's not very useful as it can't measure below about 0.01mH and likewise it won't read very large inductances or capacitences either. They also fail to discriminate between regular diodes and Schottky diodes and it's up to you to look at the Vf and guess which is which. Zener diodes often show up as two back to back diodes which is technically correct so not really a problem but it can't measure Zener diodes with a zener voltage above the battery voltage for the device, it will just show up as a regular diode. Transistors can be a bit weird too. I've had MOSFETs show up as capacitors and BJTs show up as diodes and other stuff. For all their faults these testers are still decent because they're dirt cheap compared to proper LCR meters and signal analyzers which are usually quite expensive, even for older pieces of gear. I'll give you a pass on this.

>>1269327
>Or if you eat it, but point taken.
oops

>>1269245
>solder it into position
>solder
Good luck.
>>1269320
The RoHS directive came into effect in July of 2006. Because of the problems with higher temperatures and tin whiskers there are exceptions for medical, military and measuring devices. Private use of leaded solder wire is not regulated, only industrial production. Since leaded and lead free solder should no be mixed you need two sets of tips and solder wire for repair work.

>>1269333
Oh I know what I'm getting into, but until I'm out into the workforce I don't think I can afford a decent scope. Same to a lesser extent with the LCR meter and multimeter. I've got a temperature controlled iron and a cheap DMM that are serving me mostly fine, the USB iron was somewhat of a curiosity buy, but I can see myself having to repair a PCB in the field sometime soon so it might see use. I'm always on the hunt for a nice second-hand 2-channel CRT scope, but their sellers seem to know what they're worth so I haven't found "that deal" yet. My desk doesn't have much room for one anyway. The scope is also half worth buying just as a little soldering practice, especially since I've not touched a soldering iron for the last few months.

With the LCR meter it treated a voltage regulator like a BJT and doesn't seem to be able to discern different series/parallel combinations of passives, but it was able to tell me the capacitance between a PCB and a sheet of anodised aluminium, which was neat. I mainly bought it for the hand-wound inductors, but being able to measure resistances higher than my DMM is nice too.

Pic related is the USB soldering iron's circuit. No clue what the crystal-looking thing is though, it has an open top through which I can see what looks like a coil or spring of copper. I think I broke it already, turns out that element wasn't meant to be pulled out. I'll see about replacing the missing element with a piece of solid copper wire. Though I don't think this 555 circuit regulates current/power very well, the LED looked like it had an approx. 50% duty cycle when the element wasn't working, 0.5Hz or so.

>>1269171
I was looking for a book mainly because I feel like they're more organized, the chapters generally expand on the previous ones, etc. But thanks for the suggestion, i'll have a look.

>>1269333
>I've had MOSFETs show up as capacitors and BJTs show up as diodes
Which is technically correct. :^)

>>1269315
>cheapest multimeter, an analogue one.
Not a good idea. Input resistance depends on range (ohm/volt) and is much too low for measuring voltages in electronic circuits. Standard is now a 10 MΩ input. Even the ubiquitous $5 2000 count ICL7106 based meter needs some correction (pic, exercise) and can derange the circuit while measuring.
>>1269361
>soldering iron's circuit
Maybe not the last version? Cannot imagine how that circuit could work.

I’ve been interested in electronics for years now and always enjoyed trying to repair old electronics but I’ve never really understood electronics so other than replacing visible broken parts I’m at a loss. I recently started building guitar effects stomp boxes and diy eurorack modular synths from kits in the hope I might learn something electronics based in the process but really all that I’ve learnt from that is how to solder a bit better and how to put the right components into the right places on the pcb.

I’ve tried reading a few books but they either seemed too complicated for me from the outset or I just didn’t click with them. I bought the Make:Analog synthesisers book but again it seemed lacking for a total noob...so I just started reading
>Getting Started in Electronics Forrest Mims III
This really seemed to click with me so so far so good, but I noticed while searching a few of the projects that some of the components are obsolete now which is going to be hassle for me.

So I’ve come here for help:
>should I stick with forest mimms or is there something more relevant/updated
>I eventually want to build my own synth modules and effects units so does anyone know of any books that will guide me through the basic building blocks based on audio electronics?
>Why do breadboards confuse me so much? Where is a good place to learn the basics of transferring basic electronic circuit diagrams to breadboard?

>>1269482
Didn't you start reading that Mims book in order to understand the theory better, instead of just getting a bunch of schematics? Most of the concepts in that book are still valid, even if some specific components are now obsolete.
The circuits in that book are simple, so generally you can find substitutes for the obsolete components, unless you're talking about something like clock LSI or top octave divider. I don't remember it containing shit like that, though.
That Make:electronics mentioned in OP should be roughly comparable, but with more modern components.

Dunno about audio shit, but someone asked the same stuff earlier ITT.

There's at least one breadboard simulator (Fritzing), but maybe you should explain what makes breadboards confusing.

>>1269482
What confuses you about breadboards? The only thing you have to know is that (depending on your model) there are a couple of power strips where all the holes are connected in a line. This is usually on one or two opposite sides of the board and are sometimes marked (+) and (-).
The other rows, more in the middle of the board, usually consist of about 5 holes all connected together, row by row.
The end.

As for the rest of your post, if you find anything let me know as well pls.

>>1269498
>Didn't you start reading that Mims book in order to understand the theory better, instead of just getting a bunch of schematics
I started reading from the beginning. He mentions skipping straight to the schematics if you want to get straight into building. Which I ignored and carried on reading about the component and uses.
I think I’m going to go ahead and buy the book (I’m reading it online right now) as like I say it clicked with me and I like his explanations. Just wasn’t sure how much of it might be obsolete now due to its age and would rather spend my limited time learning rather than searching for alternative components when I don’t really know much about anything yet.

>The circuits in that book are simple, so generally you can find substitutes for the obsolete components
Thanks. The circuits look like they will lend well to the sort of audio applications I’m looking to learn about. There’s plenty of sound/burst generators, mixers, audio amps etc so that should be plenty to get me started. I think I will get the Make:electronics book too

Also
>>1269499
I think it’s just the transferring a schematic to a breadboard that confusing. I get the general gist of how a breadboard works. Maybe I’m looking for something like a basic side by side schematic to breadboard photo, so I can understand the translation a bit better.

>As for the rest of your post, if you find anything let me know as well pls
What exactly are you looking for? Audio electronic projects?

Thanks anons

>>1269531
You just have to look at what components are connected together in the schematic and put those pins on the same rows. The hard part i guess would be that in real life legs aren't infinitely long but you can just insert a leg in an empty row and use a wire to "move" that node to somewhere else on the board. If that makes sense.

>What exactly are you looking for? Audio electronic projects?
See >>1269148. I've actually started building stompboxes as well recently, with a classmate. But I really want to understand how the circuits do what they do, not just copy schematics from other websites.

>>1269535
>If that makes sense
Yeah I think so. Maybe I need to put a bit more time into understanding schematics more clearly.
My breadboard (pic related) is slightly different to most as has the power rails along top and bottom, not that that makes any difference.

>>1269361
The coil thing acts as a motion switch. If you short it the heater will always be on and the tip will not live long. Without motion the heater shuts down after ln(2)*200K*100uF=14 seconds. The touch point (T) may or may not trigger depending on what else you touch. It's a toy iron that gets way too hot but has very little stored heat. A joint on a ground plane may let the tip get stuck.

>>1269535
>See >>1269148 #. I've actually started building stompboxes as well recently, with a classmate. But I really want to understand how the circuits do what they do, not just copy schematics from other websites
I honestly thought building stomp boxes and synth modules (pic related) would help me learn about the circuits and how they work but it’s just a game of match and solder with the occasional check resistor value. Even the stomp box forums seem pretty baron of any knowledge for that sort of information so i’m guessing starting at the beginning might be the best idea.

>>1269550
yeah exactly. And I've actually come to realize that I fucking hate the practical aspect of electronics. Aside from the sense of satisfaction you get once your project is done and works (which admittedly is indeed quite fulfilling), the process of getting the right value components, put them all together, solder that shit not in a crappy way, etc. can be really frustrating I find.
So doing projects where it's basically just the latter part is no good for me. I want to design shit too, but to do that you gotta know your theory.

>>1269552
Yep totally agree. Soldering and putting together modules can be pretty relaxing, but after making 8 modules and a good few pedals I think I might start buying most of mine ready built for a while.
Same as you though looking to start experimenting and building my own. Will keep you posted here if I find anything, but for now I’m going to buy the Forrest mims book and have a go at some of the projects in there. Looks like a lot of the simple projects would lend themselves to audio use. I might give the Make:Analog synthesisers another read too as it seems there might be quite a bit there.

>>1269552
knowing enough to design something yourself is really not that hard, just read some datasheets and watch some video's about the basics, it is really not too hard to understand this stuff.

>>1269638
>knowing enough to design something yourself is really not that hard, just read some datasheets and watch some video's about the basics, it is really not too hard to understand this stuff.

Not the anon you are replying to but I think it’s the basics that throw me off. It seems like there is so much to take in as a newcomer to this that it just goes into a mind block. Like I found some PT2399 ic’s and it looks like I have enough of the other components to try out the echo schematic from the PT2399 datasheet (pic related) but now I notice there are 2 grounds 1 digital and 1 Analog and this has totally thrown me where the hell do they go? I guess I need to go learn about grounding as although I’ve read about it in the basics I can’t remember for the life of me anything about it

>>1269638
At least one of the music anons seems to be more concerned about circuits like the phase shifter, whose behavior is a bit less obvious to someone who's not well-schooled in theory.

>>1269656
Separate grounds are used to prevent spikes and bounces on the digital ground from coupling into analog circuitry as noise. This is one of the situations in which the physical topology of the circuit becomes critical. You'll want to keep each ground's connections together in each ground group, decouple each group separately, then route them together to a common point. Likewise the supply vlotages. It should resemble Pic related.

>>1269659
>Separate grounds are used to prevent spikes and bounces on the digital ground from coupling into analog circuitry as noise. This is one of the situations in which the physical topology of the circuit becomes critical.
Ok that makes sense

>You'll want to keep each ground's connections together in each ground group, decouple each group separately, then route them together to a common point
So keep the digital and analog ground separated until the end...I think I understand that.

>Likewise the supply vlotages. It should resemble Pic related.
Now totally lost again. Maybe I need to go back to switching a light bulb from a battery sorta basics.

>>1269656
Separate trace/path to the power input ground.

>>1269663
I think you get it better than you think you do. The main point being that the supplies should meet in one place and be filtered individually by the caps before they reach the devices on the other supply. Real wires have some resistance, that I've drawn above the wires here. Do you see the low-pass filters?

>>1269550
>learn about the circuits
Stomp-Ville is a fuzzy place.

>>1269670
>Separate trace/path to the power input ground
let me put this on the breadboard and see if I’m understanding

>I think you get it better than you think you do.
Thanks

>The main point being that the supplies should meet in one place and be filtered individually by the caps before they reach the devices on the other supply.
Ok That makes sense. So the supply needs filtering on both splits independently before the supply?

>Real wires have some resistance, that I've drawn above the wires here.
Yep that makes sense.

>Do you see the low-pass filters?
The Caps right?

I still feel well out of my depth here. I must have read your reply 50 times now!
Thanks for taking the time to explain anon

Here's my situation for anyone who might want to help with advice or specific resources.

I'm unsatisfied with the synths I've played with, but lordy them modular setups get me worked up. I'd like to make a hobby of building my own, or assembling kits and stuff. Supplementing my setup now and then with purchases.

I've done a slight bit of soldering/circuits many years back, and when getting my math degree, I did some shit like solving diff eq's relating to electricity, but that doesn't help me at all to get started really. I just held off a $500 purchase of a synth, and am now looking to invest instead in tools and whatnot for being a proper /ohm/budsman. Not all of that 500 needs to get dropped immediately, I should earmark some of it for building a case or specific supplies I need for whatever I build in the future (LCD displays, rails, wood, ...)

So, what getting started resources and tools should I look into? I'd love a suggestion of parts and tools and tutorials and texts that would work well for a semi-beginner whose aim is synths and audio, with ~$200 budget.

>>1269680
>I'd like to make a hobby of building my own, or assembling kits and stuff.

The or is pretty big in that situation. I’m >>1269550 and I’ve built all of those modules with a pretty minimal layout. 30w soldering iron, PCB holder with magnifying glass (helping hand) a cheap multimeter and soldering iron cleaner (sponge). When building from a kit you are basically just soldering the parts to the pcb in the right order.
I’m guessing with making your own synths you are going to need a lot more tools to make your own pcb’s, front panel, enclosures etc. Maybe a decent stock of electronic components and some basic knowledge of electronics (which I obviously don’t have)

This is a massive shot in the dark because googling and reading data sheets for like 3 hours have yielded nothing.

I'm using and STM32F429I-DISC1 evaluation board, and trying to make a USB HID device.

I think I need to set ONE of these to be enabled, but when I try to set up the internal one the Clock Configuration program in STMCubeMX can't come up with a solution.

What is the difference between internal phys and external phys? The reference manual doesn't say, and I don't know which I need to use.

What's a sensible way to create a +0.3V reference? Need one for generating sync levels for a video conversion circuit. Would be supplying a milliamp at most and should be pretty constant draw. Would resistor into schottky work okay?

>>1269685
Did some fiddling in Cube, looks like it requires you to have an external high frequency crystal enabled under RCC settings, then auto clock config will generate a working solution. Presumably it doesn't trust the RC oscillator to be accurate enough.

>>1269689
Thank you! That solved the clock issue at least, now to figure out how to get the rest of the HID stuff to work.

>>1269679
>So the supply needs filtering on both splits independently before the supply?
It's generally good practice to filter each branch separately when you have split supplies. You might filter the input power itself before it branches off, if the supply itself were noisy, such as a cheap wall adapter, but for a battery-powered circuit this isn't usually necessary.
>The Caps right?
Technically, the caps and the resistance of the real wire, but yeah, I think you got it.

>>1269680
If you're doing analog stuff seriously, you're almost certainly going to want a decent scope with multiple inputs. If you want to buy new, the Rigol DS1052 is bretty gud but costs a hair over $300 if you shop hard. The pocket scopes may be enough for you though.
You'll also want a decent multimeter for about $40, a good temperature-controlled soldering station, and some way of fabricating boards, whether that be outsourcing to a fab or doing some subset of the chemistry yourself.

>>1269685
The auto clock solver can't make tradeoffs for you, and sometimes you have to help it out manually. I had to do this on the F103 to get both the ADC and the USB running, by reducing the ADC clock from the 14MHz it preferred to the 12MHz I was okay with.
>which PHY
That board appears to be using the internal PHY, internal to the SoC.
>doesn't trust the RC oscillator to be accurate enough
USB requires something like 0.05% clock accuracy, so you have to use a crystal for that.

>>1269686
Use a plain old Si diode as a shunt regulator to generate 0.65V and put a resistive voltage divider across it maybe?

>>1269677
>Stomp-Ville is a fuzzy place.
Thanks I’ll take a look

>>1269692
What is the difference between an internal and an external phy? Is the external one external to the board?

I was thinking internal phy was something used to link peripherals within the board, I guess I was mistaken, thank you.

YES it seems like the HID device is now working, thanks for the help guys.

Now to figure out how to get ADB signals into the board for the converter.

>>1269692
>It's generally good practice to filter each branch separately when you have split supplies. You might filter the input power itself before it branches off, if the supply itself were noisy, such as a cheap wall adapter, but for a battery-powered circuit this isn't usually necessary.
Ok so for digital and analog circuits the grounds should be separated and power supply split and filtered unless using a decent power supply or a battery (I was going to use a battery to begin with).

>Technically, the caps and the resistance of the real wire, but yeah, I think you got it.
Excellent news! Thanks again.

Is pic related correct so far >>1269670?

Oops I guess I should have looked over the thread before posting, just got so excited! Great that there's other audio circuit anons here.

>>1269682
>basically just soldering the parts to the pcb in the right order.
I get what you're saying in your posts but honestly I could use at least a bit of practice with that.
With the enclosures, etc. I am considering that a separate pursuit, and just recently found a local makerspace that I'm thinking of participating in for that side of things.
You sound like you're maybe where I'll be in a few months, annoyed at just assembling kits but not sure how to progress? In situations like that I check into a couple different resources that cover the same topic, I find that reinforces what I'm learning really well, and each fills in some gaps from the others.

>>1269692
Okay, I'll look into scopes (assuming oscilloscope?) Luckily I still have a very decent multimeter from when I was a student. I will definitely need to understand more about my options for soldering station. What do you mean by fabricating boards? Oh, right like the actual boards the components are soldered into. Huh, I hadn't thought of that part.

>>1269686

>>1269694
USB is an analog bus in many respects. The external PHY would be a chip external to the STM32, connected to it via a purely digital interface with the USB signals on the other side, such as Pic related. Something much like this is embedded inside the STM32.

>>1269702
>basically just soldering the parts to the pcb in the right order.
I didn’t mean it to sound that bad, don’t get me wrong I’ve learnt a few things from it but from a electronics standpoint don’t expect to learn much in the way of electronics. Apart from some really badly labelled components that didn’t match anything in the assembly instructions it’s mostly just matching stuff up. My soldering has improved though I’d like to think.
For me right now though I’m wanting to learn more about how these things work so I can adapt them later plus it’s fustrating if you build something (vcf 303) and parts of it don’t seem to work so you check all the soldering for bad joints or bridging but all looks good and still doesn’t work...and that’s all you can do as you don’t know the first thing about where to look on the circuit for testing what doesn’t work.

>>1269713
That makes sense. Especially from a hobbyist standpoint rather than just wanting a product and incidentally assembling it

>>1269710
Thank you, I think I understand now.

I was thrown off a bit as well by why FS was under OTG_HS in cubeMX, but I guess that's just the controller or something.

>>1269713
You just trace things through, in order. Have some idea of what you should expect to see, put a scope or a voltmeter on it, and see if it checks out.

>>1269702
There are options for fabbing boards. There are a dozen manufacturers who will take manufacturing output from your pc board layout software and build the board to order, with varying options at varying price levels, usually priced per square inch. Boards can also be made at home if in a hurry and/or one can deal with or work around the lack of plated through-holes, fine trace widths, solder mask, or other features that are hard to fab at home but easy at industrial scale.

>>1269699
Digital and analog power buses should be separated at some point and filtered individually. You can add filtering on the upstream power supply if you hear power supply noise.
>pic related
I don't believe so. The conections to pin 4 and pin 6, plus the bottom of one decoupling cap, should connect to one point which you call digital ground, and the other grounds plus the bottom of the other decoupling cap should connect to some other point which you call analog ground. Then those two points are connected together at the "global" ground. It doesn't look like you have separate +ve voltage supplies for that circuit so don't really have to worry about that. Pic related, only some analog ground connections shown bc the drawing got a little cramped

>>1269401
Well I just traced it, so there could be errors.

>>1269549
Ah that makes sense, should've guessed Clive had done a teardown. Don't know how he got the tip off without breaking the thing though.

I might turn the soldering iron into an FM radio since it's got a tip that could be (replaced with) an aerial and a 3.5mm socket.

>>1269810
>just started watching bigclive's video
>he finds the iron doesn't work without the collet
>I screw the collet on since it was completely disassembled
>it works
thank.

>>1269821
Now I want to design a multipurpose soldering iron+radio. But since I often listen to music while soldering, I want it to do both at once.

How do those cellphone radios that use your earphones as the antenna work?

>>1269849
Guessing, a small inductor to ground acting as a low-pass filter for the headphone element return, with a few pf capacitor to the RF input of the FM receiver chip, handwave handwave, stereo audio out to the audio codec/mixer then to the headphone amp.

>>1269853
Sounds about right I guess.

I wonder if I'll be able to fit an FM radio into the package of a mechanical pencil or pen?

>>1269880
With very steady hands or an x-y table, maybe.

>>1269880
NXP (Philips) has a series of ICs for that purpose.Maybe STMicro too. BGA-packaged versions would fit easily to that size.

>>1269883
For that kind of thing I can probably get a high-precision PCB made (or maybe expose it with UV through a magnifying lens/aperture?), and just bootleg a hot-air setup with a paint-stripping hot air gun, provided the components are well held. That sort of IC requires solder mask, right?

Also I think a PDIP would just fit in there if I just used no PCB at all, so a SOIC definitely would. For a 10mm OD, 8mm ID that is. Not that I want to go without a board. Anyone used SOICs as through-hole components or bent their legs upright before?

>>1269895
The TEA5760UK looks like a better documented and easier to use chip, still only about 3mm square. A 2-layer thin (0.6-0.8mm) board with components on both sides seems like a good idea. The FM radio chip doesn't need much in the way of external components, but you'll probably want a small microcontroller to handle buttons for tuning and volume, a headphone amp, and maybe battery management and/or voltage regulation.

>>1269895
Even though this second chip is 0.6mm pitch, which gives more breathing room, one would almost certainly need at least two layers to get a good compact assembly while still having enough room for a pen. I'd send out for it, personally. I might even consider a Kapton flex substrate for something like this if it were more of a James Bond kind of job.

Well shit, anyone else had the threaded inserts come out with these "quick change" multimeter leads? I'll cut and solder a new banana on this end and screw the clip on the other, but I'm wondering if I should expect this to happen on the other ends? Putting the insert back in requires constant pressure and gives a minimum resistance of 15Ω or so, so I can't just glue it back.

>>1269908
Pic.

I'm making a lamp which uses lithium batteries in parallel to power the sensor module and the uC (an AtTiny85)

Would boosting the voltage (3.7 to 4.2 volts) to 10 or 11 volts and put LEDs in series of 3 be an efficient way to power the LEDs? It would be a pain in the butt to add individual resistors for each LED and have the brightness diminish with the voltage of the battery.

I would probably use a MC34063.

>>1269909
My meter has fixed leads with no plugs. So I plug the clips.

>>1269940
>3.7 to 4.2 volts
Most of the time it's close to 3.6V. Series or parallel depends on current and Vf (and its spread) of your LEDs. If you use the 34063 you should find a way to regulate the current rather than the voltage.

>>1269949
I meant boosting the voltage of the battery, which ranges from 3.7 to 4.2 to around 10 or 11 volts so I can put LEDs in series and avoid wasting too many resistors.

Vf of white LEDs is around 3 volts, so 11 volts and a current limiting resistor should do the trick, I guess.

>>1269940
Buck converter with all in series is a sensible solution.

>>1269957
Well actually its full range is 3.2-4.2 volts.

Got any feels to share, /ohm/?

>tfw grandad was super into electronics when I was but a wee lad
>he'd basically spend his entire day in his workshop, mostly working on HAM radio and audio circuits
>grandad dies when I'm still in high school
>only start developing an interest in electronics in my uni years
I never got very close to him because he was always a bit aloof and more into electronics than anything else. Just thinking of how much we could talk and hang out now...
RIP grandad

>>1269973
>a new local medical craze emerges
>alternating electric fields are used to help soothe irritation
>doctors are using primitive parallel plate capacitors hooked up to the mains
>it will take more than that to cure my haemorrhoids
>order the biggest supercapacitor I can afford from digikey
>try to insert into anus but I don't have enough leverage
>explain the situation to my black flatmate
>he agrees to help
>he forces the capacitor right into my lower intestine
>activate my low voltage high frequency oscillator
>the electrolytic capacitor was the wrong way around
>the positive signal goes to the negative terminal
>mfw the capacitor explodes
>mfw my flatmate's face
>mfw he popped a cap in my ass

>>1269988
tragic. Sorry for your loss

>>1269725
The more I look at this the more it makes sense

>>1269940
I'd probably use the onboard PWM and ADC to drive the switch before adding another component, if I had the pins to spare.

>SWITCHES!

How can I find the right switch for me?

I need either a 4P3T toggle switch or a 4P3T rotary. The problem: All these chinks on ebay and amazon, they don't know what they are writing about. They miss specification and proper naming.

When toggled my switch needs to handle 5 Amps (6 or 7 would be better ) at about 50 Volts. It does not need to handle ANY current while switching. Where do I find one?

>tl;dr
>4P3T 5-7Amps/70V AC
>Where?

>>1270144
>It does not need to handle ANY current while switching.
if that is true i would say probably don't worry about it.
4p3t sounds pretty common for a rotary, all the ones i have seen are either 1p12, 2p6, 3p4 or 4p3.
can only assume you are american, doesn't hurt to say if you want a supplier

>>1269940
How many pins do you have free? I'd probably try to use the onboard PWM and ADC to drive the switch before adding another component. One advantage is that you can easily regulate current with a single dropper resistor. Another is that you don't really need an additional PWM for brightness, if you compensate for If vs. lumens nonlinearity in firmware. Pic related.

>>1270149
I am European.
Thank you, I already thought so but I am still not sure. 7 Amps is a lot for a small rotary

>>1270165
Good idea. How would you calculate L, Ipk, ton and toff?

>>1269940
>>1270165
One more advantage of this circuit is that R doesn't need to be very large. Using the internal 1.1V reference, each count represents ~4mV, so 50 counts represents ~200mV. To get a reading of "full scale" 50 at 20mA from the representative branch, R can be 10 ohms.
>sensor module
What kind of sensor module? Maybe you can use the tiny to do the sensing for you.

>>1270186
I'd choose a timebase of 320kHz to start, just to keep the inductors reasonably smol. This can be gotten with a 64MHz PCLK setting, a 1:1 prescaler, and a period of 200. Just set the OC1B pin up for PWM and load OCR1B with the desired output level. A simple proportional control loop with some damping and a saturation detector (undervoltage cutoff) should suffice.
>How would you calculate L, Ipk, ton and toff?
The usual equations, cribbed here from a TI app note, assuming worst-case operation at 3.0V Vin with an pessimistic efficiency of 70% for the two strings of three-LEDs each with Vf=3.4V at 20mA:
duty cycle = 77%
L ripple current = 57mA
I(Lpk) = 40mA + (57mA / 2) = 70mA
L = 120uH
Isw(max) = 230mA
which is readily available in 5mmx4mm SMD packages rated at 0.4A.
BUT
when I run the same numbers for a 120mA load, the required inductor is only 39uH, also readily available in 5mmx4mm SMD packages rated at 0.8A. Weird. Can any power anons explain where I must have surely fucked up?

>>1269040
>ctrl-f vactrol
>zero results
What you're referring to is called a vactrol. They've been used for analog synthesizers, and they're relatively slow to respond, especially since they were often built with incandescent lamps.

>>1268612
>On the other hand, no more address to receive shipments
That's what PO boxes are for.

>Dear Surplustronics Customers,

>As of December 23rd, we will be shutting down operations of our Queen St branch.

RIP kiwi electronics.

What do I do with 600 1M resistors?

I bought a kit that said 600 resistors between 20 ohms and 1M ohms and instead they gave me 600 1M ohm resistors

>>1270149
>>1270144
I feel really crazy right now:

I am working my way through the APEM 600 series of toggle switches, I found the specs on their site as a pdf (http://www.apem.com/int/index.php?controller=attachment&id_attachment=636))

I found the 644H/2 switch, which they say has the following electrical functions: "on-on-on".

As a double pole, I'd expect it to have 2 rows with 4 contacs each. But it does not
>pic related

Apparently, you have to wire it in such way, that one lug is connected to the other sites middle lug. But then it is not a double pole anymore. Why do they call it double pole? Why do they say "on-on-on" when it's clearly 2x "on-off-on"?

WTF is wrong with switches and switch-terminology?

>>1270333
>I found the 644H/2
third digit is 'function'
note below your switch in pdf
> * Function 4 : SP in DP case - see end of catalogue.
>>1270333
>WTF is wrong with switches and switch-terminology?
Nothing

>>1270318
You could mess around with long-duration RC circuits, or do something with high voltage.

>>1270333
Perhaps the centre ON is connecting both terminals together? Like a make-before-break switch but with a detent in the middle as well. Though in this case it's odd that there isn't a "ON MOM ON" switch to perform the normal make-before-break function.

>>1270338
Third digit is not function, the I, II, III refer to positions on the diagram.
> * Function 4 : SP in DP case - see end of catalogue.
This refers only to the "ON ON MOM" and "MOM ON MOM" switches.

>>1270338
>second digit is number of poles
>switch is NOT a double pole

>SP in DP case
WTF include in 64* series instead of 63*?

Does not matter, I do not care.

I found this switch on different pages looking for either "DPTT", "DP3T" or "double pole on-on-on".

These term clearly mean "two connections, three positions, three contacts"
>see wikipedia https://en.wikipedia.org/wiki/Switch#Contact_terminology

You are literally defending APEM eventhough they are shitheads who name a switch wrong which then gets included on various webshops in the wrong categories which in turn makes it almost IMPOSSIBLE to find "real" DPTT switches.

>>1270340
>>1270341
He reread and chickened out of his post, but two replies too late.

>>1270340
Actually I think >>1270338 is right in that sense as 644 is 6=series, 4=poles (4 means 2 poles!) and 4=function (on-on-on).

It also refers to the 644H as specification.

Still, it is an absolut bullshit naming.

The switch works the following way:
In position 1 both up lugs are connected to middle, in position 2 one lug is connected up, the other is connected down, in position 3 both are down.

You can now put a bridge from down to middle, then you have 3 positions.

BUT ONLY ONE POLE is left.
Therefore it is a SPTT switch.

But it gets included on every page as DPTT or on-on-on because APEM shitheads (and other manufacturers) have a fucked up name scheme

>>1270343
>>1270343
Yeah, but I know what he was thinking. But if you think about it, it is bullshit...

Hey, fairly new to electronics but I'm learning fast. I have an idea for a product thats not been done, but could be a useful little thing. Does anyone have a book or YT series on basic electronic product design stages? I need to know things like how to calculate the force required to move something and how much power that will need and use ect.

>>1270444
>force required to move something
F=m*a
>how much power that will need and use
P=F*v=F*s/t

>>1270144
>Where do I find one?
Nowhere if not at surplussales.com (pic)
Use a standard 4-3 and 12 cheap 10A relays.

>>1270618
My circuit handles passive AC. No active currents, no DC and no external current source.

>>1270444
No real series as such, but you could find crowdfunded projects that have copious updates, especially some of the earlier ones where they aren't so shy about disclosing technical details, and read their blogs to get a feel for the process, and a sense of some of the shit that (inevitably?) happens along the way, like cost overruns, core components going obsolete, regulatory concerns specifically radio, and the dozens of outsource vs. insource decisions.
One great example is the RadioPopper remote photo flash trigger, initially released 2009 or so. Read way back in their blogger to get to the juicy stuff, from kitchen table to shipping product.
A less successful example is the ZPM Nocturne espresso machine, which you can google up in all the bitter glory.

>>1270618
>surplussales.com
Addition: That page is awesome! Thank you

>>1270621

Great answer, thanks

>>1270620
What do you mean by no active currents?

Is there a second switch in series that's controlling the 5+ amp load?

I soldered some pin headers onto a pcb the wrong way and have fucked the pcb by removing the fucking thing. How fucked is the pcb guys? Will I get away with trying to solder on new pin headers? Looks like the metal rings you usually solder to have fallen off!
Pic related

>>1270664
In the worst case you can run a wire from where the delaminated bits went to where it should go. They used to do post-design engineering changes in higher-end gear all the time that way.

>>1270687
Excellent news. Just poke a wire in the hole and fill with solder?

>>1270622
This seems to be the cheapest option. For 'dry' switching you can parallel the switches and arrive at 8 amps. Additionally, a contact at rest can carry an even more than the 2A specified for each switch.

>>1270693
Nah, solder the connector in as normal, then, if you don't get continuity between that pin of the connector and the other places it connects to on the board, tack a thin wire from the non-connecting side to the places it should connect to but doesn't. Kinda like Pic related, but you could just run it all the way to the distant component if you wanted.

>>1270703
Oh yes I see. But where the hell is top right going as there is no trace coming from it?

>>1270707
is there a trace on the other side of the board going to it?

>>1270707
Possibly nowhere, or possibly to an internal ground plane which you would have to find somewhere else on the board. Look on the other side of the board or check the schematic?

>>1270718
>>1270727
Looks like there’s a trace on the other side that goes to a leg of the ic or the other way it goes to a resistor so I’m guessing I can run a wire from each and connect to the pin on the header?

>>1270747
Right, in fact, if you still have continuity between the two as the board is now, you may be able to get away with wiring to just one or the other. Install the pin headers and see.

>>1270747
You need more flux, friend. I was having a little trouble soldering the other day, so I cranked the heat up a little and covered the board in flux and everything just flowed like a dream. But it wasn't no-clean flux so now I've got a sticky mess all over my PCB. I'm going to have to buy a can of PCB cleaner.

>>1270749
Continuity is there it seems so that’s good. Need to get some new headers as destroyed those ones getting them unsoldered!

>>1270755
The soldering was fine it was trying to unsolder the 8 pins at once that was a cunt and destroyed the pad. The second one came off much easier as I heated all 8 pins at once instead of trying to solder suck each point

>>1270759
Did you use solder wick?

>>1270765
Nope. I do have some desoldering wick though. I thought the solder sucker would be ok but it didn’t work very well as you can see

>>1270755
What kind of flux was it? You might be able to get by with an alcohol wash, or hot water.

>>1270770
Personally, I'd probably go for the heat gun to get dual-row pin headers out.

>>1270786
Rosin. I bought the stuff anyway since I don't want to get any water on the board since it might get into the electrolytics and inductors.

Now the entire board is sticky because I can't get the dissolved flux off.

>>1270841
Maybe now it should be safe to hit it sparingly with water, which shouldn't cause any problems with inductors or caps as long as you dry it well afterward.

>>1270841
You can wipe it with alcohol, but if it's no-clean just leave it and do better next time.

Lets say I got something like this small motor to build a prototype for something.

https://www.maplin.co.uk/p/15-3v-small-motor-yg13p

This is just something cheap that I can buy in a shop, now lets say the prototype worked and I needed to focus on miniaturization, where do I look to find something with the same output, but as small as possible (if there is anything).

>>1270928

tiny powerful motors can be pulled out cell phones (the vibrators) or toy drones (quad-copters). real drones use brushless motors which require special drivers but toy ones use just regular 2-wire brushed DC motors. of course, they're also available as replacement parts from various web sites.

>>1270928
You could either try to find motor manufacturers who do custom builds in the quantities you need, which I hope are large, or you query full-line distributors to find a part that meets your specs. You also prepare to consider alternatives, like gearing or running at a higher voltage.

>>1270928
you could look on sites like banggood for cheap spare quadcopter motors (make sure you get brushed motors), but I personally like these motors, https://www.banggood.com/Orlandoo-135-Brushed-Gear-Motor-wReduction-Gear-OH35P01-OH35A01-EP-RC-Cars-NS0500-p-1194050.html?rmmds=search&cur_warehouse=CN, they also have them in places like hobbyking and you can get them with different gear ratios.

what simulator would people recommend for simulating stuff like flip flops, logic gates and shift registers, It would be awesome if it were interactive so you could flip switches while it is running but this isn't strictly necessary. I have used tinkercad circuits in the past but it is just too inaccurate and slow. I am looking for something like LTSpice but for logic. (I do need something where you use real existing IC's and not just some program where you just chain logic gates).

>>1270786
>Personally, I'd probably go for the heat gun to get dual-row pin headers out.
That might be handy in the future, thanks.

>>1270948
Logisim seems to be quite popular, but afaik it does not have a good library of "real" ICs.
PSpice has decent libraries of many logic families, but isn't interactive.
Multisim is kinda interactive, but I don't know about its libraries. Well, at least it is worth checking.

>tfw I want a pinhole camera to be as small as possible but everything from china has screws and shit around the camera so you can sneak it into changing rooms.

I just want a pinhole camera that I can wire up to a rechargeable battery and can be viewed by a phone app. It can be long and thin, but it cant be wide.

I’m interested in electronics as a hobby (I’ve just started learning) and was wondering what sort of jobs it could lead to? I’m thinking of taking a day off work a week to study something new so eventually I can change jobs. Are there any lower end jobs in electronics that I could do after a year or so of learning?

>>1270978
How about the USB gooseneck cameras made for looking around corners and into engine bays and such?

Anyone know where to DL the 2nd ed of Make: Electronics

>>1270928
>same output, but as small as possible

>>1271070
>https://ia600702.us.archive.org/16/items/MAKEElectronicsLearningThroughDiscovery/MAKE%20Electronics%20-%20Learning%20Through%20Discovery.pdf

>>1271094

Thanks

If I am doing small beginner electronics, is something like this ok, or do I need something that is specifically for electronics

https://www.banggood.com/ProsKit-1PK-501E-Anti-corrosion-Long-Nose-Plier-Stainless-Steel-Mini-Practical-Needle-nose-Pliers-p-1025168.html?rmmds=search&cur_warehouse=CN

>>1271093

ok, i want to buy one.

what the fuck is a chf in human dollars.

>>1271200

Pretty much exactly the same, 100 bucks.

>>1271208

jeez. who pays 100 dollars for a microscopic motor, no matter how awesome it is?

>>1271215
muh swiss made

>>1271215
Medical implant makers, perhaps.

How bad is this for a nigger rigged arc welder? Am I going to get electrocuted somewhere down the line?
Is there something inherently wrong with using a triac dimmer as a power controller for the primary windings, other than the obvious fact it also drops voltage so it won't strike an arc on low settings?
Please ignore the abysmal woodwork. The mess of thin wire are three $1 chinkshit thermometers built into the front panel to monitor secondary temperatures.

>>1271215
>microscopic motor
Midsize, comparable 1W model. There are 8mm and 6mm versions.

>>1271264
as i understand it the chopped triac waveform will impact the quality of the weld in the same way sine/square waves do.

Ok /ohm/ I need a scope. What do I get?

>>1271285
rigol ds1054z unless something new is out

>>1271285
What are you going to do with it? What's your budget?

>>1271287
K thanks

>>1271275

I keep hearing that, but could you dumb it down somewhat for me? Like, it'll stick more, the arc will be harder to strike or sustain, something like that?
Also, I want to inscribe a basic current scale on the potentiometer so that I can use the appropriate electrodes, how should I go about that? I shorted the output, put a clamp multimeter on it and started ramping up the power, but it always read zero. Where did I fuck up? I had it set on ACA in the 200A range.

>>1271292
Transformers work best on a perfect sinusoidal voltage, because of the whole circular derivative thing. By using a triac, the waveform is no longer completely sinusoidal and has sudden starts. By instantly increasing the voltage like this instead of ramping it up gently, you're creating a huge fluctuation in the magnetic flux, which can cause your output voltage to spike or bottom out where it shouldn't, assuming an imperfect, real transformer. Not sure why it displayed 0A, maybe you tripped your breaker?

On this note, how hard would it be to make a simple diy switched-mode constant-current and constant-voltage buck converter that can handle 200A or so?

>>1271292
i'm not a welder, just an ME with some basic knowledge. i was curious though so i googled around. there's not much available in objective technical terms (see pic related, fucking "buttery") but it seems that square waves penetrate better and aren't susceptible to losing the arc at zero voltage crossing. a triac dimmed waveform will be different though. you'll have long dead periods on most settings where i guess the arc could die and then be reignited by the sudden spike at turn-on a few ms later. so you might get a unique flickering effect. i have no doubt that triac controlled diy welders are properly documented somewhere though so you don't have to listen to my retarded speculation.

If I prototype a program on a bog-standard Arduino nano and want to put it on a PCB with a (presumably ATMEL/Microchip) microcontroller on it, how easy is it to transfer this code, and what in the way of header pins do I need to put on the PCB? What selection of microcontrollers can I use for this?

Never used uCs before but I just realised that the 4 DIP14 circuit could be done with a uC instead, and I'm pressed for space.

>>1271301
>>1271306

Thanks.

>>1271306
>i have no doubt that triac controlled diy welders are properly documented somewhere though so you don't have to listen to my retarded speculation

Not really, so far (while I was designing the thing) I've been able to determine that it is doable, has been done before, and apparently worked for the people who did it despite half of the other people swearing it's impossible to use a triac to control a highly inductive load and even more impossible to control a welder by regulating the primary winding.
It would be way too much to hope someone would go and compare it to an equivalent welder that is not triac controlled.

>>1271301
depends on what your input voltage is, but it would be more difficult than your regular nigger rigged dc-dc because milliohms matter, you need to be diligent about power dissipation, and your shunt is going to be a low voltage noisy mess so the traditional peak mode current control probably won't work well and you'd need to implement something more obscure like average current mode.

>>1271301
I think the hard part would be finding the inductor that could handle so much dc current and so much ripple.

>>1271310
If you've never used micros before, best stick with the same chips the arduino IDE explicitly supports, but you can change up the package type as you see fit. Also, if you'd rather use the in-system programming capabilities of the ATmega chip itself, you don't have to burn an arduino bootloader, and you can just bring the SPI bus and RESETn out to a header (there's a standard pinout for this, which you can adhere to or not), then program it with your choice of AVR programmer. See section 28.8 of the datasheet, "Serial Downloading"

I have a 6-7volt LED I am driving at 600mA (700mA max)

anyway just wondering
is it better to have the resistor by the battery or by the led itself? I was thinking it didn't matter... but maybe it does.
for my project it's easier to have it attached to the battery output instead of near the LED

>>1271320
You could just use a beefy transformer without a secondary for the inductor.

>>1271329
>6-7V
>600-700mA
>resistor
That thing will be wasting a lot of power, especially if it's on a 12V battery. 3-4.2W to be precise.

>>1271334
nobody asked those questions

>>1271215
Maxon motors are ridiculously nice, way too nice for the purposes of anybody posting on /diy/. These are motors you'd buy for precision instruments or biomedical devices.
It's probably a waste of money for anything this anon is doing.

>>1271292
>I shorted the output, put a clamp multimeter on it and started ramping up the power, but it always read zero
Then something is very wrong. Does it buzz like a motherfucker and dim the lights when you do that?
Did you remove the magnetic shunts from those transformers, or leave them in?
Even with the shunts in, you should expect serious current when you short the output. Not just in the secondary, but serious current draw from the mains. I sometimes blow a 15A breaker with my two-transformer welder, and you've got three.

I'm working on a small device to turn any soldering iron into a digital temperature controlled one. While it is designed with low voltage DC portable irons in mind, you could use it with an AC iron if by rectifying the mains or doing some more code.

You first calibrate the tip by having the microcontroller cycle through a series of duty cycles (a few hundred) of the heater until they reach thermal equilibrium and measuring the temperature with a thermocouple that you wrap to the tip with a bit of wire/foil, and measuring the voltage V (pic related). This voltage varies as the resistance of the element changes with temperature. Note that the element must turn off for a split second before the voltage is read by the ADC. This continues until it reaches a maximum safe temperature or 100% duty cycle. This builds a voltage-vs-temperature profile that can be used to convert the voltage at every measurement cycle into a temperature that is used to tell the FET to be on for a cycle or off.

I figure PWM control isn't necessary if the switching frequency is high enough. The main downside would be the calibration time, but since the temperature is based off the internal resistance of the element itself, it should be really quick to respond.

Is this a good idea/has anyone looked into this before?

>>1271482
What does your free-air calibration achieve? Soldering irons are used for soldering, you know.

>>1271488
it achieves a relationship between element temperature and the voltage measured across the sense resistor, or in other words, a graph of the resistance of the element with respect to its temperature. Regardless of what you're doing with the iron, this relationship will remain the same.

>>1271488
To elaborate, the different duty cycles were just to get a series of constant temperatures for use with calibrating, by no way are these duty cycles meant to predict the actual duty cycles to use to achieve a specific temperature when soldering.

>>1271329
The current flow is the same in the wire either way.

>>1271334
I'd worry about core saturation. Transformers are rarely specced for dc current capacity, let alone optimized for it.

>>1271490
I think you'll find that it won't respond very quickly to heat loads on the tip unless the tip and element have a very small mass and are well-coupled.

>>1271491
I like it and have wanted to do the same thing.

Then again I have a shit understanding of electronics and fear this is either how it's always done, or its a stupid idea.

I also want some sort of fore grip so I could hold it more like a pencil. Like layers of ceramic and plastic or something.

>>1271490
>>1271491
Oh right, that makes sense. Well, I would worry about drift over time, and how much resistance/temp change you can actually detect.

>>1271492
Well in either case it can't be much, if at all, worse than a tip with thermocouple inside it. Heat capacity of the tip is a source of inaccuracy of any temperature controlled soldering iron, hence why this is primarily designed for use with small battery-operated or USB soldering iron. I'm the anon who bought one of those USB irons the other day and got to thinking that it would be nice to have one of this size but digitally temperature controlled for much cheaper and more diyable than the TS-100.

The circuitry would need to be external from the iron unless you want an LCD and buttons under your hand, which still might be possible if the iron has a transparent body.

I wrote a smidgen of code to test the calibration by feeding it a bunch of points on the temperature-resistance graph and getting it to tell me what temperature a few random resistances were, which worked fine. I'll try and get it onto an arduino in a month or so.

>>1271496
Drift is a problem, but recalibrating the thing every month wouldn't be too much of a problem. Cycling through only 16 or so temperatures would probably do the trick, and would take only a minute or two, depending on the thermal mass of your iron.

>>1271494
I think the real advantage of this is that you're directly measuring the temperature of the element, which is the hottest part and the part that breaks first if you overcook it, meaning you could use a 4Ω element hooked up to rectified mains voltage and keep it at a decent temperature, so long as your sampling frequency is high enough.

A 4Ω iron (like the USB one) would be 7200W on 120V mains, and 28,800W on 240V mains, and so if it had the same geometry as an 8W USB iron, which heats up in 10s or so, would take only 2.8-11ms instead. You'd want a sampling frequency of at least 100 times faster than this of course.
>tfw you're so close to the kilowatt iron

And I wouldn't put the power supply for a high-power iron inside it's handle for obvious reasons. It will be pulling 20-80A instantaneous current through those MOSFETs after all.

>>1271482

this is completely unnecessary as every iron is already temperature-controlled through a feedback loop involving your eyes, your hands and your brain. you apply the iron, then the solder; you see the solder melt, and you remove the heat when it does. it's BETTER than digital, it's fucking WETWARE.

>>1271482

this is completely unnecessary as every iron is already temperature-controlled through a feedback loop involving your eyes, your hands and your brain. you apply the iron, then the solder; you see the solder melt, and you remove the heat when it does. it's BETTER than digital, it's fucking WETWARE, harnessing the power of 100 billion billion neurons.

>>1271523
Have you ever used a temperature controlled iron or soldering station? It's a world of difference. I don't see anons out there constantly pointing their laser thermometers at their soldering irons and flicking on and off the switch on the go when they need to change the temperature.

The point of temperature controlled is that your iron is hot enough to melt the solder but not so hot you delaminate pads and burn components, which happened to me often before I got a temperature controlled iron. If you leave your non-temperature controlled iron to the side while you strip some wires or bend some component legs then the iron's heating up while you do and when you put it back to your PCB it will be possibly upwards of 400°C.

>>1271530
>It's a world of difference.

been soldering for 30 years. whether it's a crappy Radio Shack, or a high-end Weller workstation, it all works the same once you've acquired the skillz.

>>1271520
>You'd want a sampling frequency of at least 100 times faster than this of course.
Good luck commutating that level of power.

>>1271533
>t.churns butter manually

>>1271533
>been soldering for 30 years. whether it's a crappy Radio Shack, or a high-end Weller workstation, it all works the same once you've acquired the skillz.

well no it does not. but then you're one of those old farts who still says "wetware".

I bet you say "automagical" as well.

>>1271533
Hey pops, ever try 0402 with that fire starter from Radio Shack?

>>1271534
>Good luck commutating that level of power.
Yeah... I don't suppose anyone's got a 450V 100,000µF capacitor lying around? Looks like I'd have to limit the duty cycle on the power strokes of the kW iron to something less than 1% every 1/50th of a second, otherwise I'll get mega ripple from the rectified mains. That or put it through a buck converter down to 24V or so first.

I have a small flexible tube, and I need to be able to move it. My idea is a number of wires (2-4) controlled by a motor (or whatever is best) that pull whatever wires necessary to lift in the direction required. So the picture is the tube (Black) surrounded by 4 red wires that the motor (or whatever is best) will pull to lift the tube.

My question is, a motor has 2 directions, forward and back, if I go with 3 or 4 cables, how do I get it to control different wires?

I feel like I have asked this terribly.

>>1271550
Consider two motors, one for the x axis and one for the y axis, and together controlling the z axis.

>>1271433

Sure it buzzes, and the voltage goes all the way to 48V at full power (15 from the smaller ones and 18 from the large one). With the output shorted, it killed the 16A breaker when near the top of the settings (I have 20A outside, but I was trying this out inside), but it read zero all the way until the moment the power went down. I guess I probably just fucked up somewhere with the clamp meter.

>>1271433
>>1271568

And yes, I took out the shunts.

>>1271569
What kind of shunts do you use for such a high current load anyways? 1mΩ?

Is there any Software that will help me design the mechanical part of my product? A bit like the Incredible Machine, but somewhat more useful.

>>1271583
I think the Autodesk one has mechanical simulations, but it does cost something. There is a free CAD program called DesignSpark mechanical (for Windows only) that looks pretty neat, though I’ve no idea what it’s capabilities are.

I dug out my sister's old-ass keyboard. The sound works fine on the inbuilt speakers but is terrible when I use headphones - one ear barely works and there's a staticky sound accompanying each note. I opened it up hoping there'd be an obvious bad connection but no luck.

What are the odds of somebody with no electronics experience fixing this, or should I just get a new keyboard? Pic related is the problem board, in case it helps.

>>1271662
>fine on the inbuilt speakers but is terrible when I use headphones

the headphone jack is probably fucked, you can get one off ebay for like $1. or steal one from some trash electronics.

>>1271665
Cheers, I'll try that.

I'm trying to decide between taking an Electronic Circuit Design and Intro to Power Electronics class.
On the one hand, there's quite few aerospace contracters in my area that do a lot of power electronics and it's interesting.
On the other hand, lots of analog guys are retiring now, however I'm not sure if all the analog jobs will just be outsourced anyways. Additionally, I'm interested in signal processing, DAC/ADCs, etc. and think maybe taking a class on analog design will help my domain knowledge. And, the lab and lecture are in the same building so I don't have to run around campus.

I guess my question is, are analog design engineers going the way of dinosaurs?

>>1267719
>>1269247
He could explain theory with some practical applications/experiments so people can design/build their own stuff.

I know there are channels for this too, but when we talk about youtube style (personality) matters a lot. So it's not about what he explains, but how he explains it.

>>1271662
>barely works
a drop of ethanol or three

>>1271583
>s there any Software that will help me design the mechanical part of my product? A bit like the Incredible Machine, but somewhat more useful.

AutoDesk's Fusion 360 product is free for hobbyists and students and it does CAD/CAM/Simulations in that version. The paid/ultimate version has some nice-to-haves, but I've not been limited by the free version at all.

(If you do electronics, it integrates with Eagle too.)

>>1269247
>there already is a channel like that. keystone science

Applied science is like this too.

I have one of these, it's better than nothing and I won't be heartbroken if I fry it.

Leaded rosin-core solder is cheaper, easier, and more reliable than lead-free.

For cases, there are several on Thingiverse if you know someone with a 3d printer. I built a li-ion battery and usb charge controller into mine so it's self contained.

The best thing about this kit is it's cheap enough I won't be heartbroken if I kill it while using it. (I'm the person building the EDM, and working with ~30-100V DC at amps around a rotating spindle above water so killing it is always a possibility.)

>>1271533
Someone's never used a Metcal.

>>1271609
>>1271758

Thanks for the tips, going to try them both out.

>>1271771
another opinion, i use unigraphics with integrated ansys at work which is as professional a package as you can get. at home i use solidworks which has a really easy flow simulation package and is easy to pirate. would recommend either. important tip if you're brand new: meshing is important. read about it.

>>1271568
Your clamp meter must be fucked, then.

>>1271678
>I guess my question is, are analog design engineers going the way of dinosaurs?
You'll notice we still have dinosaurs around. We call them birds. Likewise, I believe the balance of analog design engineers will shift toward the silicon end of the food chain.

i need to build a choke for an inverter filter, i only have access to electronics junk boards on downtown and 'generic' toroidal cores from local vendors, i guess i can search for damaged power supplies and shit like that, any ideas ? where else can i find big toroidal cores ? also is there a way to determine the minimum number of windings for the core ? i know that whitout a datasheet or knowing the material i'm basically fucked

My phone keeps showing that my headphones are connected even though they are not
I tried all the methods to clean the female port
No success till now

>>1271548
Ok, so if I instead just run it off AC, bypassing the DC capacitor problem, I run into another small problem. That is, the left circuit lets me measure the voltage (and hence temperature) very easily, but driving the FETs requires a voltage relative to the live wire, not the neutral wire. The changing voltage of the live makes this a problem. On the other hand, the circuit on the right makes it dead simple to drive the FETs, but putting an ADC to the sense resistor is a good way of putting mains into your microcontroller, and if you divide it down it will still be relative to the changing voltage of the live wire which you need to correct for, likely introducing error into the temperature measurement.

Is there an easy way of doing the first method with some sort of MOSFET driver?

>>1271978
>no pic related
There are high-side driver chips which you could use to drive the MOSFET, or even some optoisolators that are fast enough.

>>1271978
oop

I'm making an RGB brightness control, and I was about to start soldering 3 555s to PWM an RGB led strip, when I came across a diagram that shows a pot controlling led brightness. I tried it, and it works just fine. Is there any reason not to go the single pot route? The only drawback I noticed is when I turned the pot down it didn't quite make it to "off" smoothly. I don't mind that at all.

>>1271978
>>1271983
You'll end up building something referenced to the live side of the supply, whether it's a driver circuit (left side) or a sensor circuit (right side). I think the driver circuit would be easier, all told, as you can use optoisolators to do your switching for you. Consider the TLP2745 which can drive the gate directly, given a gate driving supply of 5-30Vdc which you can easily develop however you like.
Also be sure the holding current on those MOSFETs is acceptable, and don't forget you can use the body diodes to eliminate the external diodes by just hooking the two MOSFETs in series, if they are rated sufficiently for it and you have the heatsink to handle it.

>>1271993
>it didn't quite make it to "off" smoothly
Smoothness of control is one reason. Another is that PWM control wastes much less power than a pot would and also scales to more LEDs much more easily.

>>1271981
Ah, after looking around I found a few high-side driver circuits and modified one into this, the zener stopping the gate voltage from getting to high if that's ever a problem. But I realised that I'll need FETs with particularly low drain-source resistance, and probably low gate charge/capacitance too. Driving a lot of power through 4Ω for even a short amount of time isn't easy.

>>1271997
I'm assuming that the body diode isn't rated high enough, but I can always change that.

>tfw the kW iron is further than you thought

>>1271997
I had built another control before and the led strips weren't making it to full brightness. I did some research and I guess the 555 hogs some of the voltage? So I ordered some MOSFETs and I'm still waiting for them. I just tried 2 colors at once and I guess I bought the wrong kind of RGB strips. They are all separate diodes. I'll save the MOSFETs for the good strips once I find some. Thanks for the advice, wise man.

>>1272002
You can make a better PWM circuit with 1 555 timer and 3 comparators.

>>1272003
I don't think I've seen that circuit yet. I don't have any comparators as I haven't had the need to use them in any projects.

>>1271999
Yep, you're going to need something better than garden-variety FETs for this.
Usually the body diode's maximum continuous rating is on par with the maximum continuous drain current. If you're trying to push amps, mind your thermal design.

>>1272002
>555 hogs voltage
You're not trying to drive them directly off the 555, are you? You're going to need a transistor on the 555's output to drive all the power that load wants.
Interesting, I've not seen strips where they were separated like that.

>>1272005
It's a good idea to have a dozen or so comparators and op amps around just because.
Basically you use the 555 as a triangle-ish wave generator and connect its trigger/threshold inputs to additional comparators, which are each connected in the plain old comparator-with-hysteresis configuration each with their own reference voltages.

>>1272006
No. I had a TIP31C's base connected to the 555's output pin. I wasn't using any resistors as the 12V strips I was using already had them built in. The circuit worked perfectly, except the strips (those were white ones), never went to full brightness, whether I used a single segment, or the full 5 meters.

>>1272007
Ok, then. I'll add them to my shopping list. Any good all around units I should buy? My projects are low voltage (no more than 24V) and mostly light based (for pimping out my arcade machines and building nifty gadgets), as well as modifying old boom boxes.

>>1272005
>>1272007
The advantage being that you can certainly get a 100% or 0% duty cycle so long as your potentiometer can output more than the middle 1/3 of your source voltage. Putting a 47k resistor above and below a 50k pot should do the trick, assuming that's the pot's real value. I haven't ever tested the minimum and maximum voltage that a 555 makes on its RC circuit, but the documentation says it should be from 1/3 to 2/3.

With a well-tuned op-amp oscillator you can get something much closer to a real triangle wave, so if you want you could use a quad op-amp IC and use the other three op-amps as your comparators, but that also brings up problems.

What did you mean by "comparator-with-hysteresis"?

>>1272008
Was the emitter tied to ground, or was the collector tied to 12V?

>>1272011
I tried it both ways. Both ways yielded the same results

>>1272012
That's odd. What was your base resistor and what kind of current is the LED strip meant to pull?

>>1272008
>TIP31C
Doesn't have great current gain, and maybe you should have also added a hundred ohms or so to the base (assuming 1 A load).
Good all-around comparators for low-voltage circuitry: the LM339/393 are good, same circuit, just with 4 resp. 2 units inside the IC. For op amps, LM324/358, same deal. They're also pretty good for audio and such, in the event you should need it. I would suggest some IRF520 or IRF540 MOSFETs too, as they're better switches than most bipolar transistors.

>>1272011
You know, like hysteresis, man. Probably not strictly necessary for a comparator but I got in the habit while using op amps, so, shrug.

I honestly don't remember the resistor value. I had measured the current per 3-LED segment to about 48mA. I had also measured the voltage being delivered to the strip at around 9-10V if I remember correctly.

>>1272015
>10V
That's barely above the limit where blue or white LEDs light up. You'll need to get a good stiff 12V to power those strips, which probably means you'll need some thiccer wire.

>>1272017
*blue or white LEDs in series sets of 3

>>1272014
I understand R2 is that resistor that nobody ever told me had to go on the output of a 393, but what's R3 for? Also what is that software?

>>1272015
You might be dropping a substantial voltage across your TIP31C.

>>1272019
R3 is to pull the reference voltage on + a little higher when the output is on so that power supply noise etc. doesn't cause the output to flicker. Probably not even needed, just a habit I got into with op amps. Feel free to omit.
>that software
KiCad, kicad-pcb.org

>>1272019
Someone in here did tell me I was dropping too much voltage on the TIP31C, so I did some reading and some crazy mofo on some page suggesting we all throw away all TIPs was talking about 30N06s, so... I kept my TIPs, and ordered some of those too try them out. I'm still waiting for them.

>>1271541
>you're one of those old farts who still says "wetware"
No, he says "skillz". That 30 years had one extra zero.

>>1272063
^ this anon probably uses 555 timers unironically

>>1271993
Just using a pot is okay for a few LEDs, but when you try to run a large string you'll need something able to handle more power without burning.

>>1272024

the most likely reason you're not getting full brightness is the 555 is giving you maybe 90-95% duty cycle instead of 100% because of minimum resistor values allowed for Ra and Rb. as i recall, there's a variation to the usual 555 PWM circuit that does go to 100%. seems to me it involves using pin 3 as feedback, and taking the output from pin 7.

but a much simpler way to get full brightness is just to bump the power supply voltage by a couple of volts. this will over-ride any losses by any elements you have.

>>1272063
>That 30 years had one extra zero.

no, 30 years is accurate as far as being paid to do it, but there was a previous 7-year stint as a low-rent hobbyist, where having to make do with cheap tools is what develops god-like ''skillz''.

>>1272069
Where were you buying 1206 SMD in 1987? Your oggument is invalid.

>>1272070

eye-hand coordination and dexterity are transferable skillz.

Does anyone have a guide on how to link a small DC motor to things.

I want pictures of how you connect the shaft to stuff to transfer the power.

>>1267468
What are some good beginner Boolean Algebra books/resources? Because I'm kind of failing to do basic problems desu

>>1272096
I've seen people use thin bits of flexible tubing, possibly vinyl, as a coupler between two shafts. It can't bend much, only 10° or so at low speed, but it's much cheaper than brass coupling blocks. Apart from that, stick to a standard shaft diameter and you should find all sorts of hardware for it, from gears to bushings to wheels. Search online for "2mm shaft pinion gear" and that sort of thing.

>>1272097
Digital Fundamentals (Thomas L Floyd) is what we got for an entry-level textbook for a pretty informative class on logic gates, Karnaugh maps, and applied boolean algebra. I never needed to use it since I played enough Minecraft, but assuming it has similar contents to what we were taught in lectures, it should be a good read.

Anything in particular you're stuck on?

>>1272014
If you have a 393 you need no 555.

>>1272096
depends how small but you can get aluminum spring couplers with set screws for less than a dollar each on ebay.

>>1272096
Two of these and a piece of shrink tube.

>>1272096
You gotta find yourself a mechanical engineering 101 text.

>>1272149
This is also very true.

Anyone have experience with buying rotary encoders online? I'm looking for something with a very light detent and around 20 or so positions that can go the full 360°. Is there some measurement of detent strength, or any keywords I should be searching with?

>>1272547
The cheapo EC11 rotary encoders all over aliexpress are specified at 2-15mN·m. I can say that the detents are not nearly as strong as those of, say, rotary switches. I have a 64mm wheel on one and I can barely feel the detents as I rotate it with two or three fingers.
Best advice is to order a cheap one with known "strength", get it in your hand, put a handle of the appropriate sort on it, and go from there.

>>1272555
Sound fine for what I'm looking for. Do they have buttons in them? Some of the EC11 posts on Ali state they have a button while others do not, and a button would help.

>>1272621
The ones I've got have a push switch actuated by pushing the shaft inward with about the same force as the 12mm tact switches I have at hand.

>>1272655
Sounds great, thanks!

Who's the dirty faggot that's gonna create a new thread now that this one is past the bump limit?

>>1272707
You're looking pretty sexy, honey bunny. I'm off to bed.

>>1272149
20kHz is too much for that weak gate drive. Suggest C=33n, 200Hz is fast enough for LED dimming.

>>1269203

Kek

I added a BK8000L Bluetooth module to this bad boy that's been sitting in the garage for too long. I'm getting insane noise due to the common ground. I've been researching the module and I guess it's a bitch that needs a separate power supply or a different circuit for the amp. I can't modify the already existing amp circuit on the boombox, and I've decided to change the BT module to something more agreeable. However, I'm not too knowledgeable on BT modules. Are there any modules that can run on a common ground circuit without being a noisy bitch?

>>1272827
Ground is always common. What you need is differential to single ended. Headphone output goes to AUX input of your boombox.

Sorry if this is a bad place to ask, but what field of electrical engineering has the most opportunities? Would I be wasting my time if I take analog design electives at my uni?

>>1273041
The future is mixed signal plus micro mechanics. One trick ponies we have enough.

>>1272906
That's what I did. There was no aux input on the boombox, so I disconnected the tape players, bypassed the preamp, and it was working just fine with rca inputs. Once I connected the BT receiver's outputs into the new "aux in" the beeping noise started. The BT receiver has a few GND connections and the noise gets a bit lower if I connect all those to GND, but it doesn't go away completely. If I power it from a different supply it sounds wonderfully clean,though.

>>1273067
This needs to be an FAQ or something.
Single-supply audio DACs generally drive their output grounds to a voltage between the two input rails. You need to isolate the supply with an isolated dc-dc converter, or the output with a transformer or THREE capacitors, so that the grounds don't try to fight each other.

NEW THREAD

>>1273089
>>1273089
>>1273089

NEW THREAD