/diy/ - Do It Yourself

when a circuit diagram shows two input and output terminals, what does the bottom terminal line represent?

pic related

>>1532179
ground, the 0V reference to which other voltages are measured (note the ground symbol)

>>1532181
shit, I feel like a dumbass now. I've been wondering for months now and never put two and two together.

>>1532164
you sure you don't want to spend the extra $150 on a proper logic analyzer like the Saleae Logic?

>>1532188
>Save the $150
>https://hackaday.com/2014/11/12/how-to-get-50-more-zed-from-your-rigol-ds1054z/
Awesome. Saves me $150 bucks plus I get the BW. Nice dubs too, mate.

>>1532183
Not sure. I do have plans on analog work (building audio filters and stuff), but I would also like to be able to work with digital logic as well.
What would I be looking for when buying a logic analyzer?
Do I need to use their software?

I never got an answer from the last thread.
Is there a formula that calculates the cutoff frequency of a passive RC filter based on the capacitor and resistor values?

>>1532207
f=1/(2*pi*RC)

I have a bank of micro switches on a PCB. When the switches are pushed you should get continuity on their pin out to test if the unit is good or bad. I`m seeing no continuity across the circuits on the test.

I`ve reflowed the solder, attempted to clean the contacts so far with no luck.

It's a simple circuit with few components. Just microswitches talking to each other and delivering a 12 volt signal in either polarity across 2 pins.

I've tested the only capacitor on the circuit with an Ohm meter and it tested failed shorted. Provided I`m retarded and my tools are trash.

Is this a possibility why the switch bank is fully non functional? is it safe to say replace this component based on this test?

>>1532208
He was asking about a band-pass, which means you have two RC filters in series with one another, which means the workings of one filter will affect that of the other filter. It's not a simple matter unless you make the first filter with an order of magnitude less impedance than the second.

>>1532227
Do you have pullup/pulldown resistors? Did you check that your soldering didn't melt the inner workings of the switch?

>>1532227
post picture so we can tell you where you are going wrong

>>1532244
guy who asked here
shit, I wasn't aware of the impedance having that large of an effect. Would the two filters, if not otherwise modified, choke the signal to unusable levels?

>>1532251
You can definitely get a usable circuit out of it, but going through the math to get a transfer function would help. Actually no it doesn't help, it turns out to be an ungodly mess, better to just plot it in spice. Pic related, V(n001) is using a second impedance that's lower than the first, while V(n005) is the other way around. Having them equal leaves you somewhere in between.

>>1532272

>>1532205
if you don't need more than 4 inputs (a single serial bus), the DS1054Z does serial protocol decoding fairly well. if you do end up doing any serious work with digital, you'll probably want a separate analyzer and desktop software, if for nothing else than the easy waveform file management
when shopping, look for a good fit between what you anticipate doing and: # of inputs, sampling rate, logic voltage levels, maybe triggering capability if you know what you want
there is third-party support for the Saleae. there are also clones that work with the Saleae software, but you should buy the original if you can afford it and if you like their software

>>1532251
more like they'd interfere unpredictably with the cutoff freq. you could add a buffer between the low pass and high pass, but you still won't get better than 1 octave selectivity, if that
there are other filter topologies. consider an active Sallen-Key bandpass filter, Pic related, followed by a detector of your choice. f(O) = sqrt((Rf+R1)/(C1*C2*R1*R2*Rf))/(2*pi)

>>1532244
Use a spreadsheet. If you need complex math then write a little program in whatever software supports complex numbers out of box, like gnu octave or matlab or whatever.

>https://www.youtube.com/watch?v=vgYLR1Rp5tI
How this PajeetTech tm works? The screw in the ferrite core forms a loop and gets induced voltage and high current (due to low impedance), but where the oscilations come from? How the two mosfets oscilate? Really makes me think

>>1532293
fug my image

>>1532105
that's disgusting, i'd give it a pass if temporary but given how much of it's there it doesn't look temporary

register update: removed a resistor and put a couple in parallel, werks as intended

>>1532293
From the thumbnail I'd guess he's got a high-frequency (resonant?) oscillator that feeds the primary of that transformer, while the secondary is just a single wire (bolt) in the middle that ends up at a much lower voltage but with a higher maximum current, which drives the "element". Basically a reverse current transformer. No clue what oscillator topology it is, but since it doesn't have any capacitor in it I can only assume that the "transformer" itself is acting as the delay element.

>>1532289
>oscilloscope and logic analyzer
Thanks for the help. I will keep looking around and plan my purchase around possible projects.

>>1532289
>>1532272
Well, my design/original plan was to make a 5-band frequency display using 5 lm3916 LED VU drivers + LEDs all lined up. Each 3916 would be preceded by a filter, so it would only measure for that specific audio band. For the first and last I would just use a low/high pass filter, respectively.

The middle 3 VU meters/frequencies are where I need to start using bandpass filters. It's just going to be eyecandy so it doesn't need to be ultra accurate, just accurate enough to provide distinction to the individual meters.

>>1532326
In that case you could probably get away with using similar values. Here's a filter with 2 10kΩ resistors and 2 10nF capacitors as trace V(n007) and the Q value isn't that bad.

<80Hz, 80-320Hz, 320-1300Hz, 1300-5000, >5000Hz sound like good divisions to me (powers of the 5th root of 1000 multiplied by 20). This would mean filter frequencies of around 40Hz, 160Hz, 630Hz, 2,500Hz, and 10,000Hz.

>>1532338
I can get it this good with the second filter having a ten times higher impedance (lower capacitance and higher resistance), but I think the bands might be too close to one another. Perhaps going for a steeper LC filter would be a better bet? Though it will be another complicated filter since a simple LC filter will have the same slope.

Is it normal to completely fumble your first attemptS at making a real project? (by real I mean no in a breadboard). I`m in my third and they either did not work at all or I tried modifying something and ended up shitting everything.

>>1532341
Perfectly normal. I fumbled like the first 3 and I still fuck up regularly, but that doesn't stop me from acting like a know-it-all on /ohm/.

>>1532341
hmm I didn't fumble that bad. my first project worked after 1 or 2 tweaks. frankly I was pleasantly surprised.

>>1532341
about half my pcbs don't work. i'm on rev 4 of my mosfet bridge rectifier. it doesn't help when you #yolo your $10 pcb order.

>>1532340
My knowledge of filters is probably obvious, so bear with me. Would adding a second-order filter help? I assume not because of the additional impedance

>>1532312
cheers. good idea, but still give yourself some room to grow

>>1532295
looks more like a cautery device to me, which is interesting in its own right

>>1532341
yes, but are you learning from your fuckups?

>>1532309
>>1532293

It's called a Royer oscillator, and yest it does have a capacitor.

>>1532386
that's amazing

>>1532341
Yeah it's pretty common. Even in industry we rarely get shit right the first time. Then there are times where everything works perfect on the bench but when it gets to the field fuckey shit happens, and then it's bodge city to make it work.

The key is to learn why your shit doesn't work, which means hacking it to make it work. It's ok to drill holes in your PCB, solder wire jumpers and hot glue components to the board with flying leads. As long as you figure out why your shit doesn't work then you done good. If you don't know, then get help.

Making mistakes, blowing components up, and doing hackey shit is part of the process.

>>1532361
This is the filter I'm using in my simulation. Adding a bunch more filter stages will work, in the same way RC filters are often cascaded together when you need a sharp cutoff in something like an RF upconverter. But the peak will keep getting flatter unless you keep changing the order of magnitude of the filter impedance. Once you get too extreme with these changes you'll start to get close to either the output impedance of the previous circuit or the input impedance of the next, which is a no-go. For example, you first cascade two low-pass filters then two high-pass filters, you'd want the first one to have an impedance of 10k, the next 100k, the next M, the next 10M. I'd be fine with that, but adding another two filters and the 100M and 1k will start to encroach on those external impedances and effect the function of the filter such that you'd be better off using op-amps to buffer your signal. Not to mention each order you go up means 4 new passives. Now spacing each filter apart by a factor of 10 may be a bit overkill, and you can probably optimise your filter further by making the frequencies of the low-pass and high-pass not exactly equal, so I'd do a little more research on cascaded filters. This looks like a decent starting place: https://wiki.analog.com/university/courses/alm1k/circuits1/alm-cir-cascade-rc

>>1532176
this thread's digits brought to you in part by the TA2176A 1095MHz SAW filter, for all you ADS-B plane-spotting faggots

Hey guys, I'm thinking of rewinding the resistive coil on this fuel sender as the part is no longer available. Anyone done this before that has some tips?

>>1532445
Use a lathe.
I have rewired a fuel sensor before, but I've wound a few coils enough to know that lathes make it so much easier.

>>1532451
I would if I had access to one, unfortunately I don't.

>>1532465
Do you have a drill? You could always rig one up.

Is it possible to detect a queef with infrared

>>1532451
It's not that many turns, I've certainly done more by hand.

>>1532468
>>1532487
As he said, there aren't that many turns. It shouldn't be that much of a pain to do it by hand.

what determines the state when powered on?
seems semi random, with either specific 2,4 or all of them on

Hello. I have acquired a 3 phase 380V 12kW kiln. The old owner recommended me to rewire it, because the wiring is old. I am also installing a Pixsys digital controller.
I have a few uncertainties I want to sort out before doing all that:
How thick should the wires, that connect to heating elements on the back of the kiln, should be? pic related
My calculations and online calculators give me a value of 10AWG to 14AWG, but I would like someone to confirm.
Should I use High temperature wire, like PTFE insulated wire for the back wiring? Currently installed wires have some kind of soft rubbery insulation.
Is there anything wrong with using the old 3phase relay with the new digital controller?

>order bunch of chinkshit electronics for my project
>package arrives
>80% of the items are missing
>the package was sealed so nobody stole it along the way

I am missing about $18 worth of items. Is that normal when buying components from ali?

If i got scammed it's just 18 bucks so i donẗ really care, but i would make me scared to order stuff in the future which would suck beceause electronics are incredibly cheap from ali ;_;

>>1532546
The heater will heat up the wires this increasing their resistance, calculate maximum recommended awg and then raise it by a step.
12kw at 380v is something like 30amps which is a lot of heat energy with even smaller resistances

>>1532551
>I am missing about $18 worth of items. Is that normal when buying components from ali?
Never had problems there, once a guy sent me a extra xmas component. Put a complaint, ali takes it seriously.

>>1532342
>>1532344
>>1532357
>>1532376
>>1532390
Thanks guys, it`s a linear power supply (lots of people here seem to be doing thsoe). What I have learned is that using pnp pass devices is a bad idea because its stability deppends more on low ESR than high capacitance value. My first 2 got bazooled because of solder fuck ups and accidents (perf board got so messy I just took stuff that could be used and threw the rest away). Today, I`ll make the same thing with npn devices. Thanks guys.

Can you help a brainlet out? It`s for an amplifier thingy. How would I light up a led when this current limiting circuit triggers? The only way I could thing off would be to put the led in series but that is messy.

>>1532568
I read the exact opposite that ali treats buyers like trash. You only have a chance if the package gets lost, but if it gets delivered you are fucked since ali will ask you to get a stamped document from your post office to confirm the items in the package which is impossible since post office doesn't open these small packages so they will just tell you to fuck off.

>>1532395
sorry for the late reply, thanks for such a detailed answer. I'm gonna start hitting the books on filters before my parts get here.

>>1532571
In this circuit the LED would be the load and its current controlled by the properties of the circuit. Nothing triggers, nothing messy, all smooth.

hey, this is my first visit to /diy/. people said I should come here.

I'm wondering if I can cheat in a DC power supply using diodes to drop the resistance as in a parallel circuit while still reaping the higher voltage of series.

is this feasible or would it do nothing? am I simply skipping a step?

pic related.

>>1532576
it`s a currentr limit. I want it on when the current limit has been reached, when r_sense drop is about 0.6

fug
>run out of solder
>go to a store instead of ordering it since i need it now
>a 7/10 qt behind the counter
>tell her i need solder
>she asks me how big
>tell her some small one
>she can obviously sense that i am a lonely incel loser
>she easily talks me into getting a big ass 750g roll of an industrial grade solder knowing i am too big of a loser and too happy that a pretty girl is giving me attention to say no to her
>tell her thats everything
>"Oh, do you have solder fluid?"
>a what?
>"Solder fluid, you drip it on before soldering and it makes the connection much better, here let me add this bottle it's just $17"
>o-o-ok...
I am not even sure if solder fluid is a thing. She probably sold me a bottle of cat piss and is now laughing at all the stacks she goaded out of me.
I never used anything like that before and all my solder joints hold just fine.

The solder even has warning on it that it is for professional use only and you have to use gloves at all times and if you touch it you have to wash the living shit out of your hands immediately.

Fucking hell. Why do i have to be such a fucking loser? I knew i was being fucking played and i didn't even care as long as i got an attention from a cute pair of tits.
FUCK

>>1532628
It's called flux ya tard and the toxic shit is so much better than the rohs that you should go back and thank her

>>1532633
No you tardcake, flux is already contained inside of the solder wire and is gelatinous, it's pic related.
What she sold me is some weird watery pink fluid.

>>1532637
Post the label

>>1532637
Warning:
This product may contain chemicals known to the State of California to cause cancer and birth defects or other reproductive harm. www.p65warnings.ca.gov

>>1532642
that won't help it just says "solder fluid" on it

>>1532543
component tolerances

>>1532551
no, not normal. maybe customs took some of it? maybe they split it up into multiple parcels? check Ali's tracking page for your order

>>1532589
not a whole lot of room to do a lot of sensing down there
I'd probably add another Q2 and R2 onto the current sense resistor that turns the LED on and off, or maybe play around with making Q2 one half of a long-tailed pair. much depends on I(R1) and therefore Vcc and R1

>>1532628
>a store
did you go to a plumbing store or something
>for professional use only
everything useful has this warning on it
>>1532650
>zinc chloride flux
yep you went to a plumbing store dummy
maybe she'll let you stare at them for a second more if you return those items

this is my first ever post on /diy/. I have browsed here on occasion. you guys are legit.

I was wondering if I could use diodes to "fool" a DC circuit into sucking more current out of batteries, essentially giving them the resistance of a parallel circuit but getting the voltage of a series.

is this possible? am I missing something? I don't care about the batteries. I know they'll heat up.

pic related

>>1532637
>he doesn't know about liquid flux for electronics
tardbottle

>>1532678
no. diodes don't have "resistance", they have a current-dependent nonlinear voltage drop
anyway, y tho

>>1532688
how do you use flux like that?
pour it out into a dish and then scoop some up?

>>1532688
and what would you call the phenomena which is responsible for the voltage drop inside of the diode fren?

>>1532689
chug chug chug

>>1532678
What. You can just put the batteries in parallel.

>>1532689
foaming or dipping prior to wave soldering

>>1532690
band gap

>>1532688

I was talking about the internal resistance of the batteries. I want to have series voltage with parallel level amperes.

my goal is to get 240A at 24V (waste heat not yet accounted for) for as long as possible out of 16 or so disposable alkaline 1.5's

>>1532694
yeah but my voltage will be shit and I need the voltage to draw as much current as I can.

>>1532692
Yum yum yum
>>1532695
I see. Thanks.

>>1532690
It`s not a resistive thing, it`s due to bandgap.
>>1532696
>I was talking about the internal resistance of the batteries. I want to have series voltage with parallel level amperes.
Not possible.You are either in series or in parallel, it`s topology not electronics.
For lower internal resistance you could use capacitors. As we are in the retard realm, you could try making a homopolar generator, they make like mega amperes

>>1532690
all your diodes are reverse biased

>>1532696
*while using as few batteries as possible*

>>1532703
get two (2) car batteries. problem solved

>>1532700
ha ha. I'm a gardener not an EE. I dabble in this.
I'd considered the supercapacitor route but don't want to invest just yet, I want to use as few components as possible, and a homopolar generator while adding magnets and moving parts would leave me with miniscule voltage (afaik)

I know there are multipliers that work on AC to up the voltage using capacitors and output DC but I'm really trying to shy away from capacitors and AC. a low power DC only analogue to a cockroft walton or a vector inversion amplifier.

I'm in the learning process. really I just wanna suck the juice out of batteries as fast as possible.

>>1532703
Maybe if you told us for what where you planning to use that we could give you a solution. Like this>>1532704

>>1532704
mmhmm. I'd considered the lead acid route but even the smallest ones are too heavy.

I'd even considered making alternative batteries and began experimenting. made one from crap lying around the house in a closed cell, got .8V and .3A but for the weight alkaline still put it to shame. my next is going to be a metal oxide battery (mgoh?al2o3?) in an electrolyte made in it's dead phase, hook it up to a smart charger and see if it exploded.

>>1532706
magnetic coils @~.4ohm

>>1532705
>I'm in the learning process. really I just wanna suck the juice out of batteries as fast as possible.
Current is limited by impedance at that frequency, if you have zero load resistance the current will be limited by the battery internal resistance. If all you want is to drain batteries(god why) you could make tests (I`m assuming you have lots of them)
>make that arrangement that gives you 24v
>connect it to a switch
>buy a very big low resistance resistor somewhere, like 10W 0.1 ohm, or loads of 1W 1 Ohm
>connect it to the other side of the switch, start with 10 of those in series, like a 10 ohm load
>close switch, measure voltage across resistor for a while
>make the load smaller and make more tests
>dettermine the smallest resistance that avoid yur batteries going nuclear
you probably have a lot of drained batteries.
>>1532708
Just connecting them across gives you how much amps? Also you don`t need super capacitors for that, there are plenty of thousand uF 25v arround, you can put them in parallel.

https://www.youtube.com/watch?v=r-YZeOkllRg

>>1532713
I`ve done a similar aluminum battery thingy, it gave me modest 2A for quite a while. Also I`ve made one with iron and air, it worked too.

>>1532713
electrolytic capacitors don't have the energy storage I need. I'm looking for ultracapacitor capacities, like the 10KJ range, but without the added components. I've considered this in great detail. 8 3v 50f capacitors would do the trick (I think, they may not drain fast enough) but I just want to avoid it out of principle.

>>1532718
what did you use as an electrolyte? did you use aluminum oxide for both diodes and then charge it or did you go the galvanic route?

>>1532719
desu my dude, you should try making some other projects for a while until you get the hand of stuff, specially semi conductors. I don`t think that someone that suggested>>1532678 should play arround with 500A.
>>1532721
>what did you use as an electrolyte?
drain cleaner
> did you use aluminum oxide for both diodes and then charge it or did you go the galvanic route?
Diodes? It was a battery, there were no diodes in it. I just measured the short circuit current for a minute.

>>1532718
I made one with aluminum and iron but got .7v and .1A

my iron/carbon battery is still doing well after about a week, dropped by .02V but right now it's reading 2.2mA down from 3.2 and leaking like a motherfucker. electrolyte is vinegar and I know that my multimeter is broken. have a clamp meter but, you know, DC and all

>>1532722
>shouldn't play around with 500A
I used to build car stereo systems with a friend. we built a 4KW 12V 2ohm system with a kickerX, and were very safe.

>there were no diodes in it
I meant electrodes. I haven't slept.

>>1532722
also drain cleaner wtf? was it open cell? again what was your electrode? aluminum and HCL do not mix and most drain cleaners have that or sodium hydroxide...

>>1532727
your question makes no sense sorry. It was an air-Al battery, one electrode was carbon (well, technically air), and the other Al. I`ve used draincleaner because it keeps the Al surface fresh (it oxides in air and Al oxides don`t react), but when it`s not being used the drain cleaner corrodes the Al.>>1532730
Sodium Hydroxide. It corrodes the aluminum oxide in the surface, allowing the reaction to take place. But it`s quite a useless battery because it self destruct with corrosion.

>>1532733
must be pretty dilute or it would corrode the aluminum violently.

you know any chemistry? do you think mgoh2 electrodes would work with water as an electrode, then upon charge give an H2O2 electrode, an Mg anode and an MgO cathode or would the H2O2 react with the Mg too quicly or revert the MgO back into MgOH without shorting it? my other thought would be MgSO4 electrodes and dilute HCL (both being the reactants of H2SO4 and MGCL) would a currentrevert it as a lead acid battery or would it just explode?

>>1532733
and I meant did you start with your anode and cathode as the same substance and add a neutral electrolyte before charging it, but no, your zinc-air explanation is telling.

>>1532727
you weren't "building" fuck all, you were assembling consumer products
while you're lurking more, read some of the books in the "Principles" section of the OP

>>1532743
you for got to add "while not destroying $1000's of dollars worth of equipment, property or injuring anyone"

thanks for the help, asshole.

>>1532745
He was rude but he is right, that kind of thing is like building computers. When you are dealing with electronics YOU have to make the protection circuitry, mechanisms etc.. You really should grab those books man, the art of electronics is very good, even for EEs

>>1532707
>see if it exploded.
keep us informed anon

>>1532719
Supercapacitors (double layer caps) aren't very good for drain current, but for this kind of load I'd use a high-drain lead-acid or a massive homopolar generator. An array of 25V electrolytics isn't an awful idea. But at the near-6kW you're trying to pull, even a 240V 15A wall socket can't deliver. What the fuck is all this power for?

>>1532874
>Supercapacitors (double layer caps) aren't very good for drain current
nigga what

>>1532882
They have comparatively more ESR than standard aluminium electrolytics. There's a reason people usually make railguns with electrolyitcs, not supercaps.

>>1532688
>diodes don't have resistance

Why do I even bother coming to /ohm/?

What does this do? You put in logic values on the input pins, then toggle the latch enable or output enable and the output pins will have the state on the input pins until something else? I have about 100 of them, I don't know what to do with them.

>>1532934
you're correct but it also has a tristate pin for turning off the outputs to allow bus multiplexing.

>I don't know what to do with them.
put 30 in series and apply rectified mains. report back.

>>1532874
>massive homopolar generator
Actually a very small one. You have no idea of the current they give.

>>1532934
>100
did you chink yourself? they're useful ingredients in a discrete-logic CPU if you're into that sort of thing, or for I/O multiplication
otherwise
>I have junk, what do?
Take it to the recycler.

>>1532939
Am I correct in assuming this was used with memory chips that had 8 address pins?

>>1532941
I was thinking more for that amount of energy storage. 10kJ of storage in a flywheel means about 2kg of copper.

>>1532945
some Intel system designs with multiplexed address/data buses used '373s to latch one byte of the address so those same lines could be reused as the data bus

>>1532953
>>1532945
ex.

>>1532719
>the 10KJ range
>I've considered this in great detail.
>8 3v 50f capacitors would do the trick
That would be 1.8 kWs, what's your trick?

>>1532678
what you want is an electronic load. it helps if you know basic op-amp theory but the jist is you use a potentiometer as a variable resistor to control the gate voltage of a mosfet and therefore the current across the drain-source.

>>1533053
Don't forget the resistor from the potentiometer to the 12V rail and the change from a 1Ω to a 0.01Ω, unless you want a significant voltage across that thermal-drift prone sense resistor.

I was trying to read the voltage on a lipo battery the other day and every time I connected it to my multi-meter, huge sparks would fly and the meter went whacky. Then I realized I'd left it on current measuring mode....

>>1532934
>I don't know what to do with them.

consider sending them to the weirdo making a CPU out of transistors. i dont think he quite understands the work involved in recreating something even as simple as a 6502.

Ok today I put a bunch of sticks in a tin can and roasted it over a compact gas cooker for half an hour and ground up the resulting charcoal. I mixed it with some water-based enamel paint and applied it on either side of some 1mm holes on a 2-sided PCB. I blew through the holes to get the gunk all the way through, while prodding through the holes with a 0.7mm pencil lead in order to keep them open. I'm mixing up a copper sulphate solution at the moment so I'll be able to check if I can plate the thru-holes. From a simple glance the holes look fairly thoroughly coated on the inside, but I've no idea how continuous the electrical connection is through them. Among the 7 holes there's at least one connection though, since I'm getting a couple kΩ from side to side. Chances are I'll have to grind up the charcoal more finely, since I basically took a pebble to a bunch of charcoal on a concrete floor and bashed it. I might try taking one of my salvaged shaded-pole motors to another tin can, filling it with those magnetix steel marbles, and making myself a shitty ball-mill, if I can figure out end-support and sealing the opening.

Is this the fastest way to go about making plated through-holes? No. Am I having fun? Yes. Am I highly autistic? Maybe.

>>1533158
I grind my actvated charcoal in a coffee grinder. You can buy it in fish stores, also sieve that shit nigger. You could also go full retard, drill hole, glue carbon in it, and drill hole on carbon.
>trying to measure current using lm328 diference amplifier
>gain of 10
>r1 =10k ohm
>r2=100k ohm
>Rshunt=0.1 ohm
>for some reason the inverting pin, connected to the low side of the resistor through the 10k one has a higher voltage than the non inverting
>as current increases the output just goes to 0.6 because why not
>wiring seems correct
>opamp is working
kill me

>>1533184
I'll check my pet store next time I run out, but I only have normal food processors.

>>1533153
but i'm not trying to make a 6502(yet)
just something that werks and is hopefully turing complete

>>1533184
why this doesn`t work? It`s suposed to measure current. The current in the 0.1Ohm resistoris 18 A, as you can see it indicates a voltage drop of 6V / 10

So whats the best way to stabalise a t flip flop?
I have read all about metastability, and understand why it oscillates, but the only solution i have come up with is to feed the output to a d flip flop with inverted clock. Is there a better way?

>>1533216
6V/20 *

>>1533217
This was my solution, but it seems wasteful and theres no guarantee the t flip flop will stabilise on its correct output (!q)

>>1533216
The voltage attributed to "wire" reads 6.06V but there is no test point called "wire" in the circuit. 6V/10 is 0.6V and 6V/20 is 0.3V, yes. But what does it mean in this context?

If you want to understand what happens, remove the 1Ω resistor (no load) and look at the output voltage of the op-amp. What do you expect and what do you get?

>>1533278
0.1 ohm is a shunt resistor for measuring current, the circuit is a diference amplifier, the voltage dividet is to bias the inputs. I am asking why it does not work as it should.
>I=0.1*drop
>drop= i/10
>(v1-v2)*10/2 is what the opamp should output

>>1533099
this is why I love my B+K 2704A that's nigh-on 30 years old by now, even if it is short on digits

>>1533278
that's not how falstad works

>>1533286
the op amp pulls as hard as it must/can in order to see the two inputs equal. in a negative feedback configuration, the - input of the op amp is effectively a "zero"-impedance voltage source equal to the + input whose input impedance is "infinite"
short the two 10k resistors on the inputs of the op amp, then the circuit works (assuming you have a rail-to-rail output op amp irl)

>>1533217
you probably should take your feedback from the slave FF in order to satisfy setup and hold time requirements

What acid do you guys use for etching? How do you deal with waste and fumes?

>>1533388
HCl + H2O2
>waste
regenerate + reuse
>fumes
ventilation

>>1533395
What kind of ventilation are you talking about? Scale of working in a closet with the door closed to fume hood.

>>1533400
I work by the window in the kitchen with a fan blowing out, on low speed

>>1533286
>(v1-v2)*10/2 is what the opamp should output
No, 6.06V is correct but your numbers are wrong.

>>1533388
Citric acid + hydrogen peroxide. Just dilute it and dump into your sink.

>>1533438
curious, does the copper citrate just precipitate out of the solution?

>>1533388
(NH4)2S2O8
sitting in a jar
no fumes

>>1532957
So they're useless today?

>>1533664
not useless, but I wouldn't buy 100 of 'em without a project specifically in mind

>>1533670
Shift registers on the other hand...
(yes I bought 100 of them)

>>1533673
>yes I bought 100 of them
based and SPIpilled

>>1533158
I tried this like 4 years ago, I gave up because the result was so bad. I managed to get some copper to deposit inside the vias, but all in all it wasn't worth the trouble. There are maybe 4 or 5 guys on Youtube that can get it done. What you need is electroless copper, or electroless paladium.

In Brazil it's impossible to get the activator, judging by the roof on your picture I think you'll have ease getting this kind of chemical:

https://www.tifoo.de/en-uk/palladium-activator

First you drill your board with a CNC, then you etch it a little bit in acetone (it also helps clean everything), then you wash it with IPA, then you dry it, dip it into the electroless activator, let it dry, bake it in the oven for a while and then you'll be able to plate the holes with a solution of copper sulphate (root killer) and vinegar.

You'll need an h-bridge and an arduino or something. You don't plate it with a constant current, you pulse it and reverse it on the next cycle. The result is a perfectly plated via.

https://www.youtube.com/watch?v=fY0AjzKLA-8

>>1533673
One of my clients wants a macro pad with like 25 buttons. I designed something with a bunch of 74hc166, it works perfectly for this. I probably could get the same thing done making a grid with the MCU pins, but this way it becomes scallable with adding another board on the same bus

>>1533679
I'm pretty sure getting the chemicals to do electroless would be way too much, but I'll definitely look into it. I'll just try my best to optimise this process. But for now even getting an electroplating bath to work is proving difficult. It's pulling copper off the anode, but the cathode is just making hydrogen bubbles instead. I'll try adding vinegar to my solution.

>>1533679
Tifoo don't ship to me either, so I may have to make up a solution of tin and palladium chloride, which sounds like more effort than it's worth.

>>1533689
>I'm pretty sure getting the chemicals to do electroless would be way too much

It's not if you're in a good country:
https://www.caswellplating.com/electroplating-anodizing/electroless-plating-kits/electroless-copper-plating-kits/electroless-copper-kit-1-pint.html

I think there are cheaper solutions out there.

The electroplating bath needs to be acidic and have Copper II sulphate. If it does, you can quickly plate anything that is conductive.

>>1533217
use a longer input pulse. The reason a t-flip-flop oscillates is because the input pulse is too short for it to stabilize. You can use a simple pulse extender on the input to do this.

>>1533694
>needs to be acidic
Well it might have been faintly acidic due to the NH4+ ions in there, but now it's probably basic thanks to all the hydrogen gas I've been making. Even that site doesn't look like something I'm prepared to spend money on just yet.

I'm sure that I can get good results with the carbon powder method, I've already tested my paint binder for heat resistance and water resistance, so I just need to grind up the carbon fine enough and mix it in a consistency that has low viscosity but sufficient conductivity.

>>1532176
help me /ohm/
you're my only hope for solving this ~7 year old mystery
Long story short a while back i used to be into racing Rc cars and one of my power supplies blew out
I rigged it to run again by shorting the blown "thing" and it seemed to run normally
But it's been bugging me, what was the thing that blew?
I've asked my EE friends and nobody knows
Here are a few pictures if anyone knows what it is.
This one is of the 2 prongs
and no they do not attach to the nut on the back. I wrapped them together with a threaded cap back in the day to short them

>>1533760
showing the PCB holes
I couldn't find anything on the PCB with a similar outline

>>1533762
side view

>>1533763
it almost looks like a blown LED but I don't remember there being one and if an LED goes out it shouldn't stop the whole system from working right?
sorry for blurry photos. camera sucks

>>1533765
Here is the clearest picture that I got of the thing

>>1533762
the RH silkscreen suggests it's a resistor of some uncertain type. i haven't seen the H suffix before. maybe a varistor?

>>1533774
That would explain why it worked when I shorted it.
>Varistor
Holy shit I think some of the old char remains had a disk shape. I bet it was a varistor.
This is the best help anyone has offered in 7 years of asking EE people. Thanks!

>>1533774
I'd say it's almost certainly a PTC thermistor. It blew open and stopped the entire circuit from working like a fuse would, meaning it was in series with the voltage source, which is how PTC thermistors are used. In fact, they're used as resettable fuses, though why it blew is a bit odd. Perhaps it failed partially closed and overheated.

RH is nowhere in this page: https://en.wikipedia.org/wiki/Reference_designator but it's a fair guess that it is some sort of resistor.

>>1533782
oh no wait the charred remains of a PTC thermistor look more like what I saw

>>1533786
Yeah I think a varistor wouldn't make much sense in series with the rest of the circuit, they're usually used in parallel instead since they have voltage-dependant characteristics not current dependant characteristics.

>>1533788
>>1533774
>>1533782
Thanks everyone
I'm gonna go buy a PTC thermister and see if it works with it.
I'm not a EE major so I don't know too much about electronics but I am trying to learn on my own.

What size would you recommend that I get? Does it matter much?
Any size is probably better than a short I'm guessing.

>>1533795
It looks like it's on the mains side of the circuit since it's next to a bridge rectifier and a bunch of large caps, so first make sure it can handle the voltage. Then measure/look up the maximum current the thing will handle, multiply it by ~1.5-2, and go for that as a current rating. The maximum current of a PTC is a function of its resistance and power dissipation rating, but usually they state both resistance and current ratings. Otherwise they'll state a power rating at which they trip, which you can use to convert one to the other via P = RI^2. Don't confuse this power rating with that of the entire circuit.

>>1533679
Why do you need to pulse it and reverse it instead of doing DC?

>>1533842
Oh yeah, this is also something I was wondering about. I'm guessing it's to substitute a levelling agent?

>>1533854
Because gas bubbles form if you use DC, if you control the frequency and pulse duration you can make them very minimal. Usually they are hidrogen bubbles. and it`s PULSED, not AC. If you try plating with AC you only get warm water. The bubbles are a problem because they flake off the plating.

Why are there diodes on some cherry mx keyboards?

>>1534001
Probably because of this. http://machineryequipmentonline.com/electric-equipment/switch-principlesarc-suppression/

The traces on keyboard pcbs are long enough to have noticeable inductance.

>>1534001
diode matrix prevents backflow so keypresses don't trigger the "wrong" key on the other rows/columns.
not sure though would have to see the circuit.

>>1534054
>have to see the circuit
sweet16 4x4 keypad, row-column matrix, one diode per key.

>>1534066
if in series with the switch, then the diodes are there for ghosting prevention

>>1534054
So if instead of going with diodes I went with two 74hc166, I'd be able to press all the 16 keys at once and not one of them trigger the other?

>>1534096
BTW, even though the diodes are like a penny each, soldering two soic16 by hand takes less time than soldering 16 diodes so it's a better approach in my opinion. I think I'll make a "macro-pad" arduino-like with all the pins broken out

how do i make a clockless t flipflop without calacitors an shiet
google is useless

>>1534096
you could do that I suppose, with appropriate changes to the firmware
but you might also consider e.g. eight BAT54 dual Schottky diodes in SOT-23

>>1532571
Ok finished the power supply, weirdly this limits current way before it should, so instead of using 0.3ohm for a 2 amp limit I ended up using a 0.1 ohm for a 1.4 Amp one.

First circuit I tried to test it was a joule thief, and that is my first oscilator too, Managed to get 60V out of 1 V, and if you degenerate the emitter you can make a tiny sinewave at ~700khz. Thanks gang. I think I`ll make a expanded thing volt meter for the power supply, because measuring the voltage with a multimeter is kinda annoying.

>>1534283
How stupid would be to use something like this as a voltmeter? It should be temporary, but it`ll prolly end up being permanent because of lazyness. The alternative would be 2 LM339 to compare in 2.5 increments from 0 to 20.

>>1534289
if it works and it suits your cost/size restrictions, it's good enough. it's more or less what those mains voltage testers do anyway
>alternative would be
LM3914 maybe?

>>1533053
ah, yes, the good old oscillating design by Dave Cucks

>>1533962
What about using a voltage lower than that required to reduce hydrogen? Though looking at it now it appears to be 0.34V which I don't think is sufficient to get copper plating for whatever reason.

>>1534111
Ok first of all, a flipflop should require a capacitor as part of its edge-triggering circuit, otherwise you'd have to add a bunch of propagation delays which sounds like a waste of transistors. Secondly, you can't make a clockless flipflop, the very definition of a flipflop is that it's a latch that's operated synchronously, i.e. on a clock. Thirdly, you'll want to make a JK flipflop/latch and tie their two inputs together, you won't be able to get just the toggling functionality with any less transistors. Finally, what the fuck are you doing just buy some 7400s or 4000s.

>>1534289
I'd use resistors a bit larger than that, maybe 3k7 or even 10k.

>>1534334
I've never had such a topology oscillate.

>>1534360
>Secondly, you can't make a clockless flipflop, the very definition of a flipflop is that it's a latch that's operated synchronously
a flip flop flips and flops, it is a latch.
for example an S-R flipflop has no clock, it has no need for a clock

>>1534360
>I'd use resistors a bit larger than that, maybe 3k7 or even 10k.
yeah sure, I just put there for expressing the idea
>What about using a voltage lower than that required to reduce hydrogen? Though looking at it now it appears to be 0.34V which I don't think is sufficient to get copper plating for whatever reason.

m8 I got no idea, All I did was to try plate graphite leads used in thicc mechanical pencils with copper (with that blue mix they sell for plants that has zinc and copper sulphate) so I could weld them, the bubbles fucked everything. It`s not hard to make it pulse, you can make it with a 555
>>1534308
>LM3914 maybe?
Thanks, I already have the 339 on hand but if I find that on time. Nice little chip that lm3914, never knew it existed.

>>1534370
Look up the actual definition. A latch is just made of two gates, usually NORs but also sometimes NANDs. Then a gated latch is a latch with two AND gates added onto it that serve to enable or disable the latch depending on if the third input "enable" is on or not. Then by putting an edge-trigger circuit on this enable pin, you obtain a flip-flop.

>>1534374
What frequency do you use? I've got a breadboard unit with 1kHz from an internal 555 which would make things a bit easier. I could aways whip up a little 3.5mm headphone jack pigtail to my phone and use a frequency generator to feed some sort of 0-5V comparator, which would be handy for tuning the frequency.

>>1534392
>What frequency do you use?
1khz to 50khz, could not get to work, the copper plating always could be scrubbed off by looking at it`s general direction. I don`t know if it war the fertilizer mix I had, or the current (aobt 1/2A). Just set the frequency & duty cycle that makes the bubbling stop. You can look up the chemistry to get an idea of what you are getting, because you can measure current you can see how much copper is getting transfered and the like.
Take what I`m saing with lots of salt, my electrodes failed miserably and I don`t know much about chemistry, only electronics.

>>1534392
i don't need to look up the definition i already told you it's a latch; nothing to do with clocking necessarily like i explained for example an SR type flip flop doesn't need a clock.
i don't need a technical explanation of how you think they work thank you.

>>1534427
SR flip-flops do have a clock, SR latches do not. There is a need for an SR flip-flop, anytime you use them with synchronous logic, though for the most part they're replaced with JK flip-flops.

>>1534374
the LM3914's been around for 40 years

>>1534392
>what is a DFF
you have to go back

>>1534470
A D flip-flop is still clocked, it's made with an SR flip-flop but with an inverter from one input to the other. The D and JK gated latches are variations on the SR gated latch, and the T is a variation on the JK FF. You definitely can't make a D without the gate on an SR latch, and I don't think you can make a JK without the gate either. Have I missed one?

Where do you guys get your PCBs made? I've used ExpressPCB before, but I don't want to be locked in to their software.
I'm thinking of giving pcb.ng a try.

>>1534501
Are they all overseas or domestic?

>>1534508
pcb.ng is in New York, apparently. ExpressPCB, I have no idea.

>>1534510
Hmm...thanks for letting me know.

>>1534452
Queer. Where I'm from latch and flip flop are synonyms
Anything with a clock I would call ' gated '

>>1534510
I looked up ExpressPCB, and the closest I could find was a P.O. Box in California. I doubt they work in the Post Office however.

>>1534513
I don't find that terribly surprising since diagrams of FFs with clock inputs tend to be that of simple gated latches, ignoring the semi-analog edge-triggering circuit. Not that there's any symbol for a triggering circuit. I'm assuming the triggers in ICs are made with propagation delays and not capacitances.

>>1534514
If you want to send a letter addressed to a post-office, where do you deliver it?

>>1534519
>where do you deliver it?
You don't deliver it - the Post Office does.
If it's addressed to a PO Box, it's placed in the rented box at the Post Office.

how hard is me half-assing unit conversion and dimensional analysis going to fuck me over in chemistry and physics

>>1534522
how hard is me half-ass *learning* unit conversion and dimensional analysis going to fuck me over in chemistry and physics

>>1534526
If you can't get into stoiciometry then I suggest that you study up on algebra more.

>>1534526
Not gonna lie, a good 80% of chemistry and physics is trying to get to the right set of units. But that involves knowing what equations are needed to move to those units.

>>1534522
Unit conversion you don't need to remember that much of, just knowing magnitudes (i.e. torr is larger than Pa) and having a reference sheet of the conversion constants should suffice. With any luck, you're in a field of physics that only uses SI units and so won't have to bother, but occasionally eV or AMU or Angstrom will turn up, and in chemistry you'll constantly find yourself trading mL for L, Pa for Bar, etc.

Knowing how to do a dimensional analysis is really handy, especially for proving that using the pound as a unit of force and mass is ill-advised. You don't use it often, but when you've combined 5 different equations together with even more fundamental constants and are getting a value that shows the gravitational lensing from the sun means you should be able to see the moon 3 times over, it's pretty handy to just substitute a bunch of units and figure out where the problem lies. I haven't done a dimensional analysis to an equation with different units for the same quantity before, but I suspect this would be handy for figuring out where you missed a factor of 1000 if it isn't immediately obvious. More so if you're converting from mutt units.

TL;DR use Planck units lmao

>>1534471
meh, DFFs are not quite an SR flip flop. commercial HCMOS designs use two transparent latches in series, made from two inverters and two transmission gates. when the clock goes high, the latch at the input closes and the latch at the output opens. I tried to look at a 74LS74 transistor-level schematic for a sec but there was a lot going on and I won't have time to dig into it for a bit

>>1534501
OSHpark if you want fully domestic service
lcsc.com if you don't mind waiting for China
>pcb.ng
intredasting econo assembly service, and they can afford to offer those prices from Brooklyn no less

> Error: Audio streams are not allowed.
what a load of shit

Beat detection. Is there any other way to do this besides the crude method of bandpass filtering the bass or the really complex method involving a shit-ton of digital signal processing? Preferably analog.

I thought I read something about phase shifting the audio with analog delay lines and summing it or something but I couldn't find much information about it.

>>1534610
bandpass, schmitt trigger comparator, done? Digital wouldn't be so bad if you've done Z-transforms before.

>>1534610
bot muzak? test with reggae.

How would I convert a NO switch to a NC switch? I have a pot with a built in NO power switch which i want to use to turn off an LED when rotated counter clockwise but its the reverse of what id like

>>1534615
With a single NPN transistor and two resistors.

>>1534614
Sorry, I'm not a drug addict.

>>1534615
Short the LED.

Laptop wasn't charging so I tried continuity testing on pic related power cord.
Live hole - live prong beeps
Ground hole - ground prong beeps
But neutral hole - neutral prong *doesn't* beep.
Is it supposed to be beep? Is this why laptop isn't charging?
Many thanks

One more thing,
Charger adapter and charger port in laptop says "20v".
But newly ordered (unofficial) battery says "max 11.2v".
Battery website however says the battery is compatible with my laptop(Thinkpad L412).
Am I good to go?
Just like watt depends on how much a device pulls does volt also depends on battery max voltage rating?

>>1534635
Neutral pin to neutral pin should beep, sounds like a failed cable.
>>1534637
The 20V supplies the laptop, it does the conversion down to battery voltage inside.

Charger OUTPUT and pc INPUT should be the same voltage, and same current (same power) is advisable because computer makers hate people and sometimes they shut stuff off if they detect lower power chargers etc

>>1534651
>>1534647
Thanks

>>1534629
Switch parallel to LED?
Not complicated enough.

>>1534612
If you're looking for beats you need a rapid change in low frequency content. Probably lowpass, peak detect, highpass, comparator.

>>1534625
citation needed
it depends on the music, of course, and may require tuning for each song/album/artist/genre. just pay some guy to tap tempo

>>1534782
fine for four-on-the-floor EDM, maybe, but I don't think that would work with highly syncopated rhythm sections

>>1534785
I'm a music scrub. What's the difference in the signal?

Anyone know on average what`s the turn relation of those tiny xformers they use in chargers? I want to make one of those ozonizers big clive made but I only have a couple +600v caps laying arround and electronic stores arround me are terrible and jewish

>>1534831
Probably not less than 10:1

>>1534831
I say this because I want to avoid using a 30 stage CW generator, and just step it up with a xformer.

Can ohm recommend a reasonable cutoff frequency for an RC first-order low pass filter that precedes an amplifier chip?
Right now i have selected a 10k resistor 300pF capacitor combination which gives me 53kHz cutoff.

>>1534851
>Can ohm recommend a reasonable cutoff frequency for an RC first-order low pass filter that precedes an amplifier chip?
what. It depends on what you are filtering duh

>>1534854
I understand the value should be somewhere in the range of human hearing and the beginning of radio frequency range (that's what i do not want), but that's a huge range imho.
I've seen values as high as 400kHz being used in schematics i've studied, but that seems ludicrous to me.

>>1534860
It depends upon what you want to keep and what you want to filter out. It also depends upon which is more important: not affecting the low frequencies or removing the high frequencies. Also, the frequency response isn't a step function (a first-order filter has a response of -6db/octave), so frequencies below the cut-off frequency will still have some attenuation while frequencies above the cut-off will still be present.

>>1534786
significant. the other anon got it mostly right with "sharp changes in the low-freq levels" but that depends on the mixing treatment and also can vary by tempo. try listening to some songs with the treble turned all the way down to get some idea, or look at them on a waterfall visualizer as they play

>>1534837
the transformers themselves probably wouldn't handle it. that's why backlight inverter transformers have all those separate secondaries in series
gumdrop caps should handle high voltages without much trouble or expense, and UF4007 shouldn't be too ridiculously expensive if you can find them

>>1534860
not ludicrous, if they're only there to prevent strong broadcast AM from coupling in, or higher-frequency oscillations (exactly what freq is layout- and amp-dependent) from destroying the amplifier, or if they really want to avoid touching the high end
imagine your cap is a frequency-dependent resistor, then X=1/(2*pi*f*C). you can then imagine your RC LPF is a frequency-dependent voltage divider so Vout=Vin*(Rb/(Rb+Rt))
300pF and 10k gives -2.8dB at 20kHz, which might or might not be objectionable, depending on your speakers

>>1534890
>a first-order filter has a response of -6db/octave), so frequencies below the cut-off frequency will still have some attenuation while frequencies above the cut-off will still be present.
>>1534894
>300pF and 10k gives -2.8dB at 20kHz,

Thanks for the details. This is exactly what i needed. So i'll go higher with the cutoff frequency.

>>1534837
I think once you start getting close to 1kV your transformer is likely to start arcing between windings unless you take a lot of care to properly insulate them. I had issues with arcing at a comparatively low 300V in a flyback converter. Secondary was probably 80 turns of 24AWG magnet wire on an MPP toroidal core and it arced over and shat itself. I probably had to unwind about 20 turns to get all the damaged wire off and at that point the transformer would no longer function properly and did not achieve the voltages I wanted.

With some care it's probably possible to have a transformer step you up to the range of 600V to 1000V but after that you really should be using a CW multiplier to achieve higher voltages. I'd actually suggest not going all the way to 1kV as that'll allow you to use 1N4007 diodes which are rated for 1kV and are relatively cheap.

>>1534737
The thing is, ive tried putting the pot parallel to the led but i cant get it to turn off that way. I did manage to short the led with the pot but the wires from the pot got hot really quickly. I'll have to try the transistor method

>>1534903
>that'll allow you to use 1N4007 diodes which are rated for 1kV and are relatively cheap.
With the CW I only need stuff that can handle 2xPeak mains.

>>1534907
Yeah that's true but I thought you didn't want a 30 stage CW? By using a transformer and CW you can get an equivalent voltage with less stages.

What's the best and most straight forward Osciloscope I can build with a Rasperry Pi 1 and an Arduino UNO

>>1534921
There is no such thing.

>>1534921
>Serial.println(signal);
>delay(10);

>>1534921
The best instrument you can build with those two items will be a piece of crap worse than the cheapest USB oscilloscope on changgood.

>>1534921
your thread is over there >>1521740

>try building all the LC oscilators I can find on the webs
>none of them work
>only the fucking joule thief work
O-o-ok, it`s not like I want to play with radio

>>1534921
>I have junk, what do?

>>1534937
you need to get some fresh memes, sweetie
also, how are you observing them to see if they work?

>>1534945
rigol ds1102

>>1534963
best place to probe is near the input of the feedback loop, through a large resistor. do they do anything when they start up? any ringing at all? what kind of board are you building these circuits on?

is there a downside to charging supercaps with voltage higher than the cap is rated for and stopping when the cap reaches the rated voltage?ie charging 2.7v cap at 5v
google says it's "fine"
is there any degradation/whatever?
surely running 220v into it for 2 seconds aint good so where's the limit?

>>1534969
breadboard. I think the capacitances are fucking things up, I`ll try to solder a oscilator on copper pads and see if it works.

>>1534903
MOTs don't seem to have a problem with that, and those eBay "taser modules" go really damn high (though I'm not sure how much of that is due to a transformer). Ignition coils too. You just have to wind in one direction only so your first secondary windings are the furthest away from the final windings. Using an insulating transformer core would also help greatly.

>>1534921
>What's the best and most straight forward Osciloscope I can build with a Rasperry Pi 1 and an Arduino UNO
Sure. Just design a high-speed data acquisition front end built around a high-speed FPGA and lots of dual-port graphics RAM, programmable low-noise amplifiers, and a rubidium oscillator timebase, and you can use the RPi to display the data. Shouldn't cost you more than about $100000 in parts and design NRE. Get busy!

>>1534904
Okay so I managed to connect the pot switch parallel to the led the right way everything is fine except theres some bleeding current to the led when its off which is weird its drawing only 0.1ma about as bright as a highlight marker. i wonder if the mosfet has something to do with it i noticed with a gentle touch to the top of the mosfet increases the current that is barely read by the multimeter but led noticeably changes in brightness

>>1535064
Post a circuit diagram, jesus

>>1534974
>solderless breadboard
I got a Colpitts oscillator to work, once, like that. it used an air-core inductor wound on a pen, and ran on 12Vdc. it was about as stable as Maggie Gyllenhall in Secretary. I never could reproduce the feat
I definitely recommend carving up some copper-clad and trying again

>>1534971
the cap cares only about what it sees. presumably it won't be seeing the full supply voltage because excess voltage is being absorbed somewhere in the charge switch and/or supply circuitry

>>1534971
Only the voltage across the capacitor matters.

But you also need to consider the power dissipated by the capacitor's ESR. If you just attach a voltage source to it and rely upon a combination of the source resistance and the capacitor's ESR, you're likely to fry it. In short, the ESR determines the maximum charging current and thus the minimum charging time.

Also: charging a capacitor via a resistor results in half of the energy ending up in the capacitor and the other half dissipated by the resistor (regardless of the value of the resistor).

>>1535127
But to put energy into a cap so fast that the ESR builds up heat without going overvoltage, you'd need to keep pulling current in and out of it, at which point the extremely high capacitance will make this very difficult. I'm not saying that it's impossible, but that it's very unlikely to come across such a situation.

Would this allow me to control the speed of a small 12V computer fan? I'd imagine you'd change the voltage by tightening/loosening that little screw onboard, right?
https://ebay.to/2AFoQyw

Anyone got a source for cheap bucket-brigade devices?
Everywhere I see Panasonic mn3xxx and they are like $20 for 1 chip. Trying to get more than 1 of these.
Otherwise I will have to make some physical delay lines.

>>1535144
that's a trim pot, and yes

>>1535149
analog BBDs are a bit of a boutique part. what's wrong with the PT2399?

>>1535158
yes that's how I control the voltage or yes that would allow me to control the 12V fan?

>>1535149
oh wait, check the synth DIY shops. this guy has a couple analog BBDs (but you have to do your own clock generator)
https://electricdruid.net/product-category/other-synth-parts/

>>1535161
yes, both

>>1535171
I probably need a multimeter to tell what voltage I have it adjusted to as well, right?

>>1535158
>PT2399
Digital.
Looking for analog. I will keep this in mind though when I need a digital delay.
>>1535162
Exactly what I am looking for. I hope he ships outside UK affordably.

>>1535173
no

>>1535186
How else could I tell?

>>1535193
An arduino could work in a pinch

>>1535194
I think it'd be easier to measure with a multimeter, no? I don't have any arduino chips on hand

>>1535193
>How else could I tell?
You're controlling fan speed.
Turn the knob until the fan turns at the speed you want.
Why would you care what the particular voltage was?
If you want to monitor something, a tachometer would be more appropriate.

>>1535202
Forgive my general lack of electronic knowledge, but wouldn't it potentially damage the fan if I ran 20V through a 12V fan?

>>1535204
most people want to slow the fan down to make it more quiet
Why would you connect anything to a 12v fan that can pass 20v?
If you're trying to speed the fan up, anything beyond 12v is more than it was designed for.

>>1535206
that's the point. if I have no idea how much voltage is coming out of the regulator I won't know whether or not I'm exceeding the 12v that the fan was is designed for. It's for an enclosed prop and it won't always be on, so I'm not super concerned about noise but more so about how much air it can push out.

>>1535208
If it starts smoking, tune it down a couple notches.

>>1534983
Not saying you can't have secondary voltages on the order of thousands or tens of thousands of volts with a transformer without arcing over. Of course you can, power grids wouldn't work if you couldn't. It just takes more careful design. You can't take a jellybean ferrite core and a few windings of haphazardly placed cheap magnet wire and expect it to handle 2-3kV without arcing.

>>1535212
Well a jellybean inductor is working fine for my 500V boost converter.

How do I turn a circuit schematic into an IC layout?

My professor had us do a lab to turn an inverter schematic into a layout but I have no idea why he drew the boxes the way he did.

>>1535211
I can't afford to wreck a couple fans to figure out the right setting to not burn them out, I'm on a budget damnit!

>>1535217
Yeah but that's only 500V. Not 3kV.

On a somewhat unrelated note how much power can you get out of your boost converter at 500V? I only ask because I'm working on 200V double ended flyback converter that I ideally want to be able to output about 20W and right now I'm having trouble getting it to put out more than 5W before the voltage drops out. If you are getting close to or over 20W out of your design I'm curious about it.

>>1535221
It's for a geiger counter, so it's got a 10MΩ in series with it anyway. I haven't tested it for power output, but it shouldn't be all that impressive.

Tried changing the frequency or increasing duty cycle?

>>1532566
>>1532546
this is three phase stuff, you can use a thinner wire.
assuming power facor is one, itll only draw 18 amps. just use a wire rated for 25 and higher. check ampacity table, youll be fine.

>>1532546
use a proper contactor for three phase shits. i say get a new one.

>>1535220
So stick the damn multimeter probe deals in there and see what the numbers say. Is it like 12v automotive stuff? Any automotive stuff is cool going to 14v at least. I’m too lazy to read but it’s a fan so I’m sure you won’t have any problems going a little above.

I’m retarded and even I know this ain’t rocket surgery.

>>1535144
you should be able to get 16V atleast. i mean the capacitors will let you atleast.

>>1535220
You start at a low setting, and wind it up slowly. To figure out which end means higher or lower voltage, use your tongue.

>>1535204
it's a step-down only. if you start with 12V you will not get more than 12V out of it unless something is very, very wrong

>>1535218
presumably those boxes represent the different masks (ion implantation, metal resist, etc) you would be asked to create if you were doing a run of chips
>how do I
you're asking for a short course. so, here you go https://www.ucsc-extension.edu/certificate-program/offering/physical-design-flow-netlist-gdsii

>>1535243
I'm still not totally sure what power source I'll be using but most likely it'll be 12v so in that case it shouldn't be an issue. thanks anon

>>1535227
Can't find my schematics for some reason but I was using a TL494 as the controller. I had voltage feedback to one error amplifier on the chip via a resistor divider though I did intend to replace that with an optocoupler later. The second error amplifier was not used though it will be in the final revision for current feedback via a current sense transformer in series with the primary, I didn't have a suitable core for it at the time though. I think the switching frequency was about 200kHz. I think the turns ratio was something like 9 turns primary and 72 turns secondary. The effective permeability of the core was 60.

>>1535248
lmao I was using a 555 timer and a single comparator at constant duty cycle. Your frequency might be too high for your inductance, lower one or the other.

>>1535197
It would be easier to measure with a multimeter by far. If you're posting on this thread you should buy or be looking into buying a multimeter.

>>1535250
I believe I already have one knocking about somewhere, I'm just not sure on the quality and such

>>1535251
I've never seen a multimeter that can't do a reasonable DC voltage measurement

>>1535252
I think it's more about how low it goes. The one I've got is for home electrical stuff.

>>1535251
set it to about 8V, then hook up your fan and play it by ear
it's probably not gonna bitch if there's a 10% excess of voltage anyway

>>1535253
>how low it goes
?

It's almost definitely just an ADC hooked up to a microcontroller. And it's probably got decent resolution. It's going to be just as comfortable at low magnitude as high. Take your measurements with it and if it seems wacky come back

>>1535253
See >>1535252

If it can’t do that, it probably isn’t a multimeter. They’re <$20, or free with purchase of a 79¢ bag of zip ties.

>>1535255
Most likely what I'll do. Luckily the fan I ordered came in a two pack, so if I fry one I'll still have another to play with
>>1535256
>>1535258
I ordered the actual electronics tonight. If I've got the right meter I'll use that, otherwise I'll probably just play it by ear and hope I stay below the fans max. I'll be honest, I'm only sort of stumbling through my project here but this stuff usually works out well so I'm sure I'll figure it out. thanks ya'll

>>1534937
>try building all the LC oscilators I can find on the webs
>none of them work

Have you tried reading a book?

>>1535220
Fans are cheap. You can pull them out of old computers. I have a pile.

>>1535283
People do not read books unless forced. Fortunately there are oscillator circuits that even run with low quality parts like the one depicted. The simpler the circuit, the more likely it will work.

My favorite is the emitter-coupled oscillator that has no frequency-dependent components apart from the parallel LC resonator, just two transistors and one resistor to adjust the loop gain. It always works, needs only 1.5V and is self-limiting to about 1Vpp. With a reasonable Q inductor it runs on a few microamps.

>>1535315
>emitter coupled oscillator
>JFET

>>1535318
That's why two paragraphs.

>>1535320
I'm sorry for being retarded

>>1535283
>Have you tried reading a book?
Yes. It worked on copper clad, thanks other anon.
>>1535315
>The simpler the circuit, the more likely it will work.
True. The blocking oscilator is lovely

>>1535211
>If it starts smoking, tune it down a couple notches.
lol genius advice /ohm/
sounds like you really know your stuff here

>>1535344
That isn’t purely /ohm/ advice, it’s life advice.

>>1535320
>>1535315
Thanks, the problem was using those bread boards. Pease was right after all, solder is the best language.

I actually like reading, it`s just that my thing is motors and history, getting into radio and control now. How does the feedback work on the colpitts oscilator? I can`t see a path to the base. (I`ll post the circuit next).
It started ocilating at 6v, and achieved the peak value of 1.8V at 8 V. The operating frequency seems to be 530Khz, later I`ll try something in the Mhz range. That armstrong oscilator seems cool.

>>1535382
Circuit.
>>1535372
>>1535211
2 (two) tripfags on /ohm/. I really hope it`s just bepu talking to himself, because we do not deserve this. Btw, keep shitposting and I`m ratting your wife out to Maduro.

>>1535315
This is the RLC oscillator and how it came to be.

At the top is a traditional low voltage 'long-tailed pair' RF amlifier, a combination of a common collector stage that increases the input resistance followed by a common base stage with little reverse transmission, both coupled by the common emitter resistor.

If you connect output to input (red line) you introduce a positive feedback and given enough gain, the circuit oscillates.

At the bottom you see said oscillator in PNP form with the LC circuit grounded. All you need to do is adjust R so that the loop gain is >1 (clean sine) and it doesn't clip too much if not intended for harmonics.

There's also a symmetric version with two separate LC circuits that can generate two different frequencies at the same time.

>>1535144
kinda, but if it's a 3- or 4-wire fan, it's not meant to be controlled by changing the voltage, it's meant to be PWM controlled with the third wire (optionally measuring the speed with the fourth wire).
I thought there would be nice little modules to control one of those with a pot, but I'm not really finding any.

>>1532176
Alright guys, complete idiot question here (I didn't get useful results from google): I want to power a 24V DC motor from a PC power supply. The psu in this case has a +12V and a - 12V wire so I thought that I could supply 24V from those two. The +12V line has a 19A rating which is plenty for me, on the other hand, the -12V line has only 0,3A. Can any of you tell me what amperage can I expect using these two, or if I can use the psu like this at all?

What are 36V and -36V used for in amplifier circuit?

I know transistors need external power source to get them into active region, but from my knowledge, it needs DC, not AC voltage to operate?
But since voltage is being taken from transformer, and filtered through capacitor (4700uF, 50V), I presume it is taking AC without DC (filtered through capacitor)?

it is complementary-symmetry amplifier and 2 main transistors on the far right are:
NEC 2SB541
NEC 2SD388

>>1535466
you can expect 24V 0.3A

>>1535472
Thanks, that doesn't sound good. I tried it out of curiosity a while ago and it could power the motors (two pretty large linear actuators with some load on them). If I continue to use it like this can it damage the motors or the psu?

>>1535470
You get DC out of that. AC goes into 1 and 2 , full wave rectified DC comes out of 3 and 4 and is filtered by the caps both of which are connected to the center tap which is grounded. It's a little confusing looking at it at first but it works the same way any other bridge rectifier does.

>>1535475
more likely the -12V branch of the psu

>>1535478
Alright than maybe I'll check out what it can do on 12V, if the motors aren't too slow like that I'll stick to it. I really apreciate the help, thank you!

>>1535483
What really jumble the mumbles with motors is over current (that lead to heating). Unless you really go crazy with the voltage the insulation will do ok.

>>1535382
cool, glad it worked for you. based Pease
>motors and history
cool, just stay away from Ayn Rand, she was a whiny little social parasite who didn't know dick about either one
>path to the base
it's a common-base arrangement. it moves the rest of the transistor around the base instead

>>1535476
Thanks, now it makes sense.
Why are capacitors connected on the center tap and ground, and not connected directly on secondary of the transformer?

Also on the sidenote, since I am changind the transformer since it is too old and too loud, should i go for toroidal, or stick to the blockish conventional transformer?

I have KAF-1030 transformer laying around, and it doesn't buzz or hum so I wanted to use it as a replacement for this one. is it a stupid/smart idea?

I bought a new cheap soldering iron.
After 4 or 5 sessions I removed the tip to clean and lots silver powder-sand like substance started falling from inside!
What is this and how do I prevent it from happening again?

>>1535491
Did it stop working? If not, it`s ok. Some heating elements are wrapped in that.
>removed tip to clean
No need to do that, just remove excess solder when you ARE soldering so it doesn`t get in your way.

>>1535490
The center tap IS ground and both caps are connected to it. The cap on the bottom connected to the ground node has a line that also connects it to the center tap. The reason this is done like this is to get a positive and negative rail. If you had no center tap you could get a positive or negative rail but not both.

I dunno what's good as far as replcament transformers. Any mains transformer with the same power rating, turns ratio, and tap configuration of your old one would be a good start

>>1535493
Oh, ok thanks.
It is working good enough for $1.5.

>>1535490
to avoid crosstalk to the other rail and to keep both rails and their derivatives stable with respect to ground. consider what happens during a low (<1/2 line frequency) bass note, for example
>should i go for
I can't see any real reason to go toroid

How can I replace this switching scheme with solidstate stuff?

They're two relays and the signals they switch should be isolated from the circuit controling them.

>>1535512
how about a 74LVC1G19
>isolated
and two optoisolators of your choice

>>1535490
The KAF-1030 transformer may have different windings and it produces ±42.5V after the rectifier. Transformers barely age and vibrations often have purely mechanical reasons. I would first fasten all screws and then listen again.
Service manual from elektrotanya.com

>>1535512
The signals are already isolated from the circuit controlling the relay coils.

>>1535533
Yes but how do I do it with solid state components, like >>1535521 instead of the relays? The USB 5V drops from 4.8 to 4.2 when 4 relays are on, I think my D- pullup isn't requesting all the current my circuit needs

>>1535527
thanks, I couldn't find schematic anywhere...

I took amplifier apart and reconnected it and as you suggest fasten the screws. Problem is internal, because it is not "buzz" sound, but hum which suggests laminated core wore off (we're talking about transformer that is from 1972)

Fun fact, original electrolytic rubycon capacitors are still alive and working to this date.

One question, what you mean by differeng windings. what would happen if I make some step-down voltage on the end and get 36V from 42.5V, isn't it basically same voltage and sine wave then?

/o/tist here
i'm trying my hand at building a pi-based digital dashboard. what would be the best type of screen for visibility in daytime. lcds are nice but they are kinda hard to see in bright daylight.

>inb4 just get torque or some other obd app

>>1535539
>running relays from USB power
those must be big (oversize?) relays, or shitty and/or long cable. why not an external power supply for the coils, or (if that's really not possible) smaller relays driving coils of larger ones?
pls post more context

>>1535548
prob anything with a non-glare face and adaptive brightness (you might have to add your own light sensor and do whatever needs to be done to the panel or video)

>>1535553
Short cable, regular Song Le relays. I think my MCU is identifying itself as a low power device. Ideally I'd use an external power, but I don't remember this happening with an Arduino. They're just for signal, I could simply get smaller relays and nothing else, but I can't do this right now.

>>1535478
Now that I think of it what about connecting two psus in series to get 24v from the two +12v branches?

>>1535568
those coils nominally require 70-90mA each (depending on variety). four should be well within the 500mA limit
I think that particular cable may have especially thin power wires. have you got a thicker one around to try?

>>1535573
probably not due to common grounding
proper 24Vdc PSUs are $5 and up

>>1535568
There are quite sensitive signal relays, e.g. DPDT 5V(>3.75V) 178Ω <=28mA.
>>1535573
That would be possible if both PSUs are 'floating', no common GND. I guess most people would advise against that. 24V 2A laptop PSUs are really not expensive.

>>1535548
OLED, just like your pic. I have a Sansa Clip mounted on my dashboard, and its OLED display is very nicely visible in daylight, but not too bright at night.

>>1535581
>>1535579
I found out what was the cause. The USB Configuration Descriptor was set up for 100mA max power draw.

MAN, 91 FUCKING MA FOR A SINGLE RELAY. Fuck this shit.

I have some small signal relays, they're the same size as that white one but they're orange and really expensive today because they're not manufactured anymore, or something?

>>1535466
What if you used a 1:2 transformer to get the voltage from 12 to 24v? Or just a cheap 24v psu? I use a 5a one for my CNC Router, it gets a bit hot but it can drive the motors just fine

What does this do? It came in a kit my wife gifted me for Christmas. There's no markings besides +/out/-

>>1535616
it's a temperature and humidity sensor.

>>1535616
Seems like a DHT11

>>1535617
>>1535626
Thanks, DHT11 it is.

So ozone generator guy here, making a CW generator is a pain in the ass, soldering 4 component to the same point ughh. As another way to waste my time I`m trying to make a very high voltage low current blocking oscilator. Current efforts allowed me to generate 250 rectfied and filtered DC with 2 V. Tomorrow morning I`ll try to make a toroid with higher turn count. Maybe if I make 5x600V little transformers I`ll be easy. But manually threading all that wire is really that much easier than soldering 40 capacitors and 50 diodes? Really activate your almonds huh

>>1535633
>I`ll be easy
I`ll get it working** what the fucg

>>1535457
It's only a 2 wire fan, this one here https://www.amazon.com/gp/product/B07DKXWYVM/ref=ppx_yo_dt_b_asin_title_o01__o00_s00?ie=UTF8&psc=1

>>1535384
>I really hope it`s just bepu talking to himself
Pretty sure it is.

>>1535653
what are you running it off of?
If you have a 12v power supply I recommend one of these:
https://www.amazon.com/WINGONEER-Controller-Regulator-Switching-Indicator/dp/B06XHGP58T
This does basic PWM, it's got a classic 555 timer in it.
If you have less than 12 volts you need a boost converter, not a buck converter.

>>1535597
cool, did you need to reprogram the USB-to-serial IC to get more juice? did it work? (I'd think that programmable current limiting would cost too much to bother with on the host side, but I learn something new every day)

>>1535633
manual toroid winding can be relaxing, once you get into the zone

>>1535653
meh, third wire's probably the tach, fourth is the PWM control

That's the big issue, really. I'm trying to figure out if I can even get a 12V power supply in the space I need it in. I'm only pulling about 9 amps throughout the whole thing, but I need 12V to run the fan at max speed. All the 12V batteries I can find are made for much more powerful devices than what I'm working with.
>>1535661
Third and fourth? I only see 2 wires on that fan

>>1535633

presumably you have, or can find on the curb, or at the thrift-shop, some old gadget from which you can pull CCFL inverters that'll give you 1500-2000V with almost no work. i've pulled mine from old HP scanners, which is convenient as the high-voltage circuit is on its own separate PCB. see this video for inspiration https://www.youtube.com/watch?v=SK0p1PFiXI4

>>1535662
>>1535660
Meant to reply to you for the top one

Is it possible to run, for example, two 6V batteries together to have the equivalent of one 12V battery?

>>1535665
Yes

>>1535668
Is there a name for how to do that or is it just how you'd expect to run batteries together?

>>1535671
The technical term for it is "put your batteries in series"

>>1535672
alright thanks anon

>>1535662
>I'm only pulling about 9 amps throughout the whole thing
what is the thing?
Can you use a lower voltage fan?

>>1535679
It's a prop for a cosplay. It basically boils down to a fan, fog/vape device and lights in a tube. The lowest voltage fan I could find which could still pull enough air is 12V and so are the lights

>>1535681
what are you using to power the rest of it?

>>1535683
I'm looking between 12V lipo battery packs or a couple smaller batteries run in series like the anon above mentioned

>>1535684
You can get to 14.8v with a lithium-ion pack. which really is your best bet, because you need it to be light and portable. IDK if you can get pre-made lithium-ion packs like that, but you can get a holder for 4x 18650 cells and a BMS module, something like this or similar:
https://www.amazon.com/Diymore-PCB-Protection-Integrated-Circuits/dp/B0711J3PBR
One of these will protect your pack from overcharging, over discharging, short circuiting, and will make sure the cells are balanced. There are lots of variants. make sure you get one with balancing, and before you put your cells together, charge each one up so they start off all the same.

>>1535694
This might all be too much to fit into the space I have. I'm looking at running 3 of those 3.7v batteries they use for vapes and shit like that for a total of 11.1v since then I wouldn't need additional hardware to step down the power for the LEDs

>>1535697
>11.1v
Just remember that it'll fall to 8 volts or at most 9 volts as it discharges.
Your LEDs will probably be OK up to 16.8 volts (a 4 cell pack) if they have switching power supplies, if they don't, you can put a small resistor in series because that's all they'd have anyway.

>>1535853
Do you think it'd be better to run a 4th battery in series for 14.6 total? Would that potentially negatively effect the fan?

>>1535854
I'm sure the fan will be fine, it probably won't abruptly blow up if you go a few volts over spec, just maybe die by overheating eventually, but since you're just PWMing it down anyway, that's not an issue.
I'd go with the fourth battery, if you don't have room, you could use shorter 18350 batteries instead of 18650s.

>>1535858
I'm more worried about horizontal room than I am vertical. I have the whole thing planned out so that it just barely all fits together now with the 4 batteries, so it shouldn't be an issue. I've just gotta figure out to properly secure the top battery connectors, among a couple other things. It looks like it should all fit together, but I'm not so sure about how to properly and safely use lithium ion batteries. From what I understand, if the batteries drain completely, they'll probably not charge up again, right? Do I need to add in some sort of indicator or shut off for when the batteries reach a certain level to prevent that? What would I look into for this?

>>1535861
you need to get one of those BMS boards, which will cut it off before it gets too low (or too high).
If you buy an off-the-shelf pack, if you can find one the right size you need, it will almost surely come with that protection circuit built in.
like this one: https://www.ebay.com/itm/10A-14-8V-16-8V-4S-18650-Li-ion-Lithium-Battery-Charger-BMS-Protection-Board/352522926219
some of these will balance the cells, some won't. But all of them will cut off the battery when any one cell gets too high or too low.

>>1535866
Brilliant, thank you anon. I think that's actually the last component I need, providing nothing goes AWOL on me

>>1535870
Just remember, before you connect all your cells together, make sure they're all freshly charged. that way, they start off balanced.

>>1535875
Makes sense. I was looking at some of those Chineseum chargers on Ebay earlier, I think they'll be the easiest to work with in that regard.

>>1535861
Or just use 1-3 cells with a variable boost converter that you use for the purpose of speed control in the first place?

>>1535879
I'm retarded anon, can you explain that further? How could I get 12V output from one or two 3.7V batteries?

>>1535881
>boost converter
dc-dc converter that transforms a low voltage into a higher voltage.
but the power is constant, so the current goes up. you said your whole setup is going to draw 9 amps at 12 volts? the boost converter is going to be pulling 12-13 amps from the battery as it runs down. (and it needs to be rated for that kind of current, too)

>>1535881
A small boost converter board (similar to what they use to step the lithium ion voltage in a power bank up to the 5V for the USB output) will step the voltage up to whatever you set it to.

https://www.aliexpress.com/item/boost/32873124342.html
This one is 2A max, takes an input anywhere from 2-24V, and outputs anywhere from 2-28V depending on how you set the multi-turn trimpot. You can desolder this trimpot and replace it with a potentiometer on long wires to mount it somewhere practical. Instead of PWMing the fan, by turning the thing down to ~8.5V your fan should run at about half power. You'll only be able to turn it down to the minimum cell voltage though, but 3.7V should be slow enough that you'd be fine with the next slowest speed being off. If not, you could go for a buck-boost board that can step the voltage down as well, but it won't be as cheap as this one. By using just one cell, or multiple cells in parallel, you'll be able to get away with a far simpler protection circuit, one without balancing lines. You'll also need some form of charge control IC, for which the tried-and-true TP-4056 is a good option, though there are options that are built into the protection circuitry.

>>1535889
>>1535891
I looked at my parts list again and it actually is only gonna be using somewhere around 5 amps rather than 9 after I swapped out a part.
I would imagine 4 batteries at 12V would last infinitely longer than 1 or 2 stepped up though. Would a step up really be worth it for the bit of extra space? I'm not sure... so far my design seems relatively roomy, but it has to be for airflow.
How complicated is the protection circuit I'm looking at now with 4 batteries in series? My original idea was actually to just take the batteries out to charge them and use a third party charger, but if it's not too much more complicated I wouldn't be adverse to including a charger in the unit.
Would a boost converter be the better option overall?

>>1535896
>How complicated is the protection circuit I'm looking at now with 4 batteries in series
not complicated at all, the off-the-shelf board does everything you need. protected with that, you don't even need to be too careful about charging it, because it will protect from overcharge. if it's a portable thing, building a charger in might not be worth it, just hook up an external charger when you need to.
one of those generic imax chargers will charge it just fine.
I'd say the boost converter is not the best option, unless you can run most of your loads on the lower voltage 8-12 volts and only use the boost converter for the fan. You actually get less capacity from a battery the more current you draw from it. And when you get up over a few amps, boost converters get more expensive and waste more power as heat.

>>1535900
I'll probably go with the buck converter, simply because I understand it better right now so I think I'd have more success with it, and it sounds like about the same difference desu.

>>1535896
If you need 4 cells and your fan is fine with the maximum voltage then there's no reason to go for the boost converter. 4+ cells with a fixed voltage buck converter is also a fine way to go. If you were only pulling 1A or so I'd recommend putting 4 cells in parallel and boosting them since the BMS circuit would be easier, but at higher current it's slightly more efficient to put them in series.

>>1535928
I don't necessarily need 4 cells, although it'd help for battery life. I've already ordered the buck converters, although I asked to cancel the order if they haven't already shipped them so I can have more time to figure out my design for sure. I'm probably gonna end up with them regardless, but pausing the order doesn't hurt.

Anyone here know about the control loop employed in hobby servos? I expect it to be some sort of P or PD type since the Integrating is already done by the pot. But which is it or is it something else? And the hardest question: Is it standard or does every manufacturer kinda do his own thing?

>>1535961
Probably very standard, but what's stopping you from looking at their datasheet or taking one apart to see? Any IC they have will almost certainly be dedicated and/or non-programmable, so they'd be pretty easy to reverse engineer.

>>1535991
Been doing that in the meantime. I don't quite comprehend it at the moment though.
http://www.willingtons.com/files/electronic/m51660l.pdf

>>1536010
I found this article useful, also covers the old M51660:
http://sound.whsites.net/articles/servos.htm

Is insulation tape a good enough substitute for heat shrink tubing?

Neutral wire of power cord wasn't passing continuity test so shortened cable, soldered and taped as pic related.
It passes continuity test now.

Will tape melt under 240v?
Book (Make : Electronics) recommended heat shrink tubing but heat gun is so expensive!

>>1536051
Voltage does not make stuff melt, heat does.
You don't need a heatgun by the way. Most hair dryers are sufficient for shrinking heat shrink tubing.

>>1536056
>>1536051
So are lighters

>>1536051
Too late for shrink tube, just use tape.

>>1535930
>ausing the order doesn't hurt.
with electronics it's always good to have parts on hand so you can prototype things when you get an idea.
Order early, order extras. especially when it's general purpose stuff like power converters, those are always useful.

>>1536051
now that you taped each individual wire, wrap the whole thing in tape to protect it. and you'll be good.
also, don't use shitty electrical tape, it'll get nasty, stiff, and unwrap itself over time. you can't go wrong with scotch super 33 or 88.

>>1536056
>>1536059
Thanks! Will try that next time
>>1536067
>>1536080
Thanks, is there a more "generic" name for super 33? Can't find it in my country

>>1536199
Can't recognise the plug, is it .in or .za?

>>1536217
.in
.za looks very similar though

>>1536221
Thanks. I looked for 'Scotch Electrical Tape' and found
3M Scotch Super 33 Vinyl Electric Tape, 10 meter, Rs 185 at indiamart.com
Amazon.in also has Type 88 (slightly thicker than type 33) but looks expensive.

>>1536199
>is there a more "generic" name for super 33
No. It's a grade of electrical tape manufactured by 3M.
Just use the highest quality electrical tape available in your country.

Hey y'all, electronics noob here. I've got a bicycle with a dynamo that puts out 6v AC for the headlight, and I wanna add a small battery to the system so the headlight stays on when I'm stopped at a light or whatever. Cheapest way to convert 6vac to 6vdc? Would pic related work? I have no idea what values the components should be.

I also found a 12vac to 12vdc module online, but nothing for 6v. What would happen if I just used that?

And lastly, once I get the voltage to be DC, if I put the battery and the light in parallel, would that charge it while I was moving, while also keeping the light on, or would it just drain the battery? Thanks in advance my dudes

>ran out of hookup wire

>>1536077
Yeah, but I'm kinda tight on cash right now and this is the only project I have running at the moment, so I'm not super concerned with having extra components just lying around.

>>1536365
Full bridge rectifier works fine, although you'll probably get 5.4V DC or so out. You can get diode packs that have all the connections for you. I don't know enough about batteries to answer that part of the question but if we assume a battery would act like a capacitor then yeah, replace the cap in the schematic you posted and you're good.

>>1536365
that's about as simple as it gets
diodes: any 1N540x (x=1..8) should work. note, with normal silicon rectifier diodes, you will be losing >= 20% of your voltage. better use Schottky rectifier diodes like 1N5822 instead, though slightly more expensive. they will drop about half the voltage that the plain old rectifier diodes would have dropped
cap: strictly speaking, it's optional in this application but see below
>would that charge it while I was moving
yes, and it's more than likely you would overcharge it at some point without proper charging circuitry. lead-acid or NiCd batteries are the most able to stand up to that sort of abuse, but without better characterization of the dynamo/lamp/etc. I wouldn't advise a noob try even that for something as important as their ride (and I'm too lazy to engineer it)
>and would keep the light on
load-sharing is something that a lot of people half-ass. i don't recommend it
the easiest way, and actually not too half-assed, is to add another diode to prevent backflow into the battery as in Pic related. whichever source has the highest voltage (battery or rectified dynamo) at any instant is the one that will supply current to the load. yeah, you'll still take the battery out and replace/charge it. a USB power bank would be pretty good for this, in fact, if you don't mind undervolting the lamp a bit when stopped
now, about that cap: imagine a line representing the battery voltage at about 70% of the way up the waveform. assuming a full charge, about half the time the battery voltage will be greater than the rectified ac voltage, thus the battery will supply the load. the capacitor helps decrease that fraction of time. a 25V or greater cap, at minimum 220µF, will help (mind the polarity, + to +)

>>1536365
Battery charging is tricky. Every kind of battery has a way to charge it without kaboom. For Li ones there are loads of charging circuits in ali or ebay that are almost plug and play. Also if that 6v AC is what you measured with a multimeter, it`s likely the peak voltage is higher, maybe after the bridge and capacitors there is enough head-room for a linear regulator. Also a very nice little thing for bike lights is the joule thief circuit, you can use capacitors to store the extra juice for a while too.

Need your guys help. My led is receiving a PWM signal but a very strange one, its only lighting up the led every 7 seconds. What's wrong with my circuit? There's nothing in there that would allow such a low frequency. Everything worked fine when I created a prototype using jumper wires. I get the feeling it might be a problem with the diodes (either damaged it from soldering or wrong orientation) but I'd like some advice before I attempt desoldering and soldering different diodes because that section of the circuit is a real pain

>>1536467
I don't know what the fuck I'm looking at, but I'm guessing it's either the overcurrent protection doing whacky shit on that board to the right, or your resistor or cap in the 555 circuit have broken/are the wrong value.

Can someone give me a little bite of guidance? What should I search for to learn about remote control? I have a working 20mhz transmitter I made here (it uses very little power, max range is like 5 meters) and I wanted to switch something on/off with a radio signal. When I search for ``radio controlled switch`` or ``remote control switch diy`` all I get is RC boats and IR remote controls. I have a couple of those Nrf24l01 transceivers and they work fine, but I want to stop being a digital plebeian and go analog.

>>1536482
The alibay 433MHz modules are pretty cheap.

>>1536467
now that's what I call design for manufacturing
do you even have a meter with diode test function?

>>1536482
>go analog
y tho, it's shit, and you're going to want to digitally encode your signal anyway for reliable triggering
look up the HT12D/HT12E decoder/encoder pair and get an idea of how they work. lots of folks used these with an on-off keying transmitter/receiver pair like Pic related to open garage doors etc.

>>1536480
I changed the power source and nothing changed. My prototype was working fine and i used the exact same resistor values, pin 2 capacitor was 25nf still theres no way doubling the capacitor would change the frequency from 5k hz with the prototype to this but thanks for the help

>>1536486
I do but I couldnt figure out what values determine if the diodes arent working. In diode mode I get 2.6v on one side and 0.6v on the other for both diodes. That means theyre working correctly right? Could I also use these values to deterine the orientation? The soldering process destroyed the markings on top so I dont know for sure if its in the right direction anymore

>>1536492
>0.6v
good diode conductivity
>2.6v
hopefully, just the rest of the circuit around them
>determine the orientation
yes

>>1536487
It's possible that your soldering damaged one of the timing components, especially since you seem to be soldering SMTs by hand. Thermal contraction of one of the joints could have broken a resistor or diode.

>>1536461
>>1536438
>>1536458
Neat, thanks y'all. Yeah, I was aware of the possibility of overcharging the battery, and I plan on putting a weed wacker engine on this (it's a Mad Max meme project thing), so it'd probably happen pretty quick. Don't those power banks have built-in charge controllers though? Though I was measuring 10v on that dynamo right now hand pedaling it with the light on - I assume that going into a 5v power bank would be not good.

Regardless, think I'll go with that suggestion >>1536458 made.

Also, anyone have any retarded ideas for my stupid apocalypse bike? Taking all suggestions as of now

>>1536512
>Don't those power banks have built-in charge controllers though
yeah, and I haven't seen one yet that charges and discharges at the same time (they tend to share a single inductor and controller for both functions). I was mainly thinking of ease of off-vehicle recharging
also you might want extra power for the Lord Humungus megaphone and signal processing

>>1536518
Ah, gotcha.

Good point. I'll strap a deep cycle marine battery to the back and maybe put a subwoofer on it, too.

>>1536503
>>1536506
One of my diodes was in the wrong direction. My led looks like is finally receiving a proper pwm signal but my pot switch is no longer working and its working as a dimmer only in certain ranges. More problems but at least im on the right track now

>>1536537
I'm guessing the thing still worked because of the reverse leakage current through the diode?

>>1536538
I think so its strange that it lit up the led exactly every 7 seconds. Maybe the mosfet was responsible for that? Electricity is weird. However I think I still may have to replace the smd diodes with spare through hole diodes because after cleaning everything up the potentiometer is not dimming correctly and my guess is the heat damaged the diodes

>>1536245
Thanks

Hate to ask but is there a cheap /ohm/ recommended multimeter for a beginner?

>>1536666
I have a few of those free ones you get from harbor freight. They're about 4-5 dollars and work fine for simple projects. One of those should work fine for a beginner. If you decide you want to try some serious stuff, though, invest at least 20 dollars on a better one.