/ohm/ - transient electronics thread

[Anonymous No.1880918]

Thread not for new designs: >>1874921

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

>Project ideas:
http://adafruit.com
http://instructables.com/tag/type-id/category-technology/
http://makezine.com/category/electronics/
Don't ask, roll:
https://github.com/Rocheez/4chan-electronics-challenges/blob/master/list-of-challenges.png.png (embed) (embed) (embed) (embed) (embed) (embed)

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

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

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

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

>Li+/LiPo batteries
Read this first: http://www.elteconline.com/download/pdf/SAFT-RIC-LI-ION-Safety-Recommendations.pdf

>I have junk, what do?
Shitcan it

[Anonymous No.1880962]

>>1880918
what are the the most useful soldering iron tips to acquire guys?

[Anonymous No.1880963]

At least link the damn thread in the old one. Which, incidentally, is only on page 5 and so should be around for a day or so longer.

[Anonymous No.1880965]

>>1880962
I use D12 for fine work and K for THT and larger stuff. Conicals can suck my ass. Bevel tips like the Cs and BCs can be good for drag-soldering multiple pins, or so I've seen on soldering tutorial videos.

[Anonymous No.1881178]

>>1880962
D12 as daily driver, D32 for large pincount SMDs. Or you can faff about with those well-tipped tips for SMDs ... but they are usually a lot of hassle.

[Anonymous No.1881183]

>>1880963
Are you retarded, sir?

[Anonymous No.1881193]

>>1881183
not him but i'm retarded

[Anonymous No.1881237]

>>1880962
whichever one gets hot, fits in every hole and doesn't have to get changed, i.e. wedge

[Anonymous No.1881247]

>>1880918
>ac voltage spike
>waveform doesn't change sign at any time during spike
what did they mean by this

[Anonymous No.1881249]

>>1881183
I'm rearded

[Anonymous No.1881432]

>>1880918
>ruins your zero-crossing-based timing
Heh, nothing personnel.

[Anonymous No.1881463]

What kind of chip is this? There's 4 of these in a bootleg Neo Geo multicart. It's a BGA NOR flash chip but with weird adapter legs, and there's almost no info online about it. I've only found two possible model numbers for it.

F0095H0 - Four
BK58F0095HVX010A

[Anonymous No.1881486]

>be me
>getting into electronics
>get a cheap DSO because I want to play with circuits and see what happens inside
>"I can just use my smartphone to generate signals"
>this is the best my smartphone can do
Fuck you LG, and your audiophile-grade™ quad-DAC® of my ass.

[Anonymous No.1881495]

>>1881486
Anon, don't blame the equipment for your lack of knowledge.
That's what a bandwidth limited square wave looks like.
Human ears only hear frequencies up to ~20khz at best, so there's not much reason for audio equipment to have more bandwidth than that.
A 1KHz square wave only has 10 harmonics under 20KHz, so that looks exactly how one would expect.

[Anonymous No.1881502]

>>1881495
Well, that makes sense, thanks.
I'll throw in a book about signals along the others: would you kindly suggest one?

[Anonymous No.1881551]

>>1881502
I think these were the books my DSP professor recommended:
http://www.dspguide.com/
https://services.publishing.umich.edu/publications/ee/ (Signals and Systems)
I must admit though that I have not read them that deeply, since the lectures and class notes were top notch and I haven't needed to reference the books since.

[Anonymous No.1881564]

>>1881463
Those are called "interposers". When you fuck something up, or want to upgrade to a chip with a different land pattern, you use those. They are PCBs and wouldn't come with the chip.

[Anonymous No.1881586]

>>1881564
Good to know, but I need to know more about the chip itself. Even if I find a generic pinout for an 88 pin BGA in this weird sorta 'split up' configuration, it might just match up to this chip with no info on it.

[Anonymous No.1881619]

what would be the advantage of using one atmega1284p versus 2 atmega328p (the latter being cheaper, which is why i ask)

[Anonymous No.1881646]

>lipo charger arrives
>came with euro cable so gotta buy another cable or one of those travel adapters
>plug my 6s lipo's balancing plug into the charger just to ensure it fits
>it does
>won't come out
>really damn stuck in there
>get out my angled tweesers to lever them out
>alternating sides
>it's almost out
>just as it comes out the lipo makes a funny noise and the balancing plug looks like it changed color or something
>smells like a burnt insect
oh fuck oh fuck
Nothing's getting hot and the voltage across each cell is around 3.3V so I think I'm in the clear, still going to keep an eye on it for the next hour though.
Anyhow, who designed these damn plugs, there's not too much room for error if the crimps pop out of their housings like I suspect might have temporarily happened here.

Also on second examination, the smell is coming from the charger. I think I let the smoke out of the most expensive fucking thing I've ever bought from ali.

>>1881586
There's a lot of obscure in-house ICs out there with absolutely no documentation to be found. It's at least somewhat likely that you've got one of those. But if you scope out those pins with a logic analyser and/or trace those lines to ICs that do have datasheets, you might be able to reverse engineer the pinout and find a replacement with reasonable specs. Never done anything that nasty myself though.

[Anonymous No.1881661]

>>1881646
Ok, what's the chance I blew up something irreplaceable in this thing? I'd imagine that the balance lines go through linear MOSFETs or BJTs in order for them to do balancing, which should be turned off without any power going to the device. On the other hand, the sensing of the voltages will require some sort of voltage division, followed by an ADC (or MCU). If I were the designers of this machine, I'd have put TVS diodes to the V+ and 0V balancing pins after the voltage dividers, but fuck idiots like me I guess. Replacing an SMD boy like an SOIC is doable, though QFNs and BGAs are probably gonna be a nope. I'd be afraid that it would be impossible to find out which part is damaged, but judging by the smell it should be visible as a great big pockmark on one part or another. Gonna open it up later, gotta get some grub for now.

[Anonymous No.1881662]

>>1881661
Wait no, that would be TVS diodes to the logic rails, and a zener across the rails too. If I did hit existing TVS diodes and somehow sent 22V into every logic IC on the board I'm gonna be real pissed.

[Anonymous No.1881672]

>>1880918
rolling for challenge which i will obviously never complete

[Anonymous No.1881679]

Hi, moron here.
Just plugged in a LiPo battery into my ESP32 backwards. There was some magic smoke and the area near the battery plug stinks, but both of them seem to work. The only problem is the battery connector (or plug) seems "loose" now, touching it slightly causes a reboot. But the board works well on USB power.
I don't have another battery or a different ESP32 to test the current one with, so I can't verify what's broken exactly. If you had to take your best guess, which part should I replace?

[Anonymous No.1881694]

>>1881679
pls don't mock me, battery charger circuits aren't exactly some black box of mystery circuitry, they're common enough that at least one person on this general has the exact same ubiquitous model and has looked inside it

[Anonymous No.1881696]

>>1881694
No mocking intended, anon, I just saw your post now. We're both just idiots today.

[Anonymous No.1881768]

>>1881694
tantalum cap at ldo input? assuming ldo is still alive as "it works". What board/module is it?

[Anonymous No.1881780]

>>1881619
less board space, easier programming especially if you need to run a serial line between the chips, not having to choose a master chip with the associated lag between master and slave actions that need to be simultaneous (if applicable)

[Anonymous No.1881810]

>>1881780
>master and slave

It's 2020 anon, let's drop the racist terminology ok?

[Anonymous No.1881825]

machines don't care what you call them

[Anonymous No.1881888]

I'm planning on building a rechargeable battery bank of 18650 cells in a boom box that normally takes 6 D-cell batteries in series for 9v of input, up to 10 watts apparently.

If I wanted to charge the boom box off of USB-C power, what kind of circuit should I use? How many 18650's should I use? I have ordered cell compartments/holders and I need to know what kind of charging options I can buy.

Really I have a vague idea of what I need, but I don't know any of the circuitry terminology. I think I need a ~12v to 9v stepdown, several auto-balancing 5v-1a chargers for the cells themselves, and a charging port to break out to battery chargers internally.

Am I an idiot who has no idea what he's doing or is my head on straight? I've never dabbled with something I haven't just broken apart and glued back together into something else, I want to make this look and feel professional.

[Anonymous No.1881889]

>>1881888

forgot image of boom box. I figure if I'm doing all this updating, I'll add in a bluetooth receiver as well directly wired to the mic-in on the back.

[Anonymous No.1882038]

>>1881646
>>1881661
>>1881662
jesus fucking christ. How about a picture, eh? You're liveblog is annoying af.
> I would have designed it..
mildly retarded since you apparently cannot work a connector? Like you are literally blaming everything else in the world except yourself here.
There's literally no info in your posts. Take the thing apart, post some pics, and start measuring.

[Anonymous No.1882044]

>>1881679
possibly need to resolder it. Any time something which shouldn't be sensitive to touch gets sensitive, it means it needs to be resoldered.

But yeah, you should post the exact module you're using.

[Anonymous No.1882049]

Some said it couldn't be done.
Some said it shouldn't be done.
They may have been onto something.
It struck an arc easy when I touched the electrode to the workpiece, but it would immediately go out. I think my software was limiting the current too much and too soon. Not sure what caused the catastrophic failure, but my emitter follower makeshift 12v regulator blew, one of the FETs popped and the bypass cap lead appears to have turned itself into a fuse. The batteries (6s SPIM08HP) seem to have handled it no problem but I'm not sure I would recommend these batteries because they're a pain to wire up.

[Anonymous No.1882052]

>>1882044
GeeekNET ESP32 dev board.
During this process I realized this board has 10x higher current draw in deep sleep than what ESP32 is capable of, so I won't be using it for battery projects anyway.

[Anonymous No.1882145]

>>1882049
How do you balance current between them?
There is a reason commercial machines use single huge ass SCR and at most leave rectifiers on output.

In your case i'd series the batteries and use multi phase buck from some core voltage converter like PMP10393 to control current.

[Anonymous No.1882146]

>Clive is a juggalo

[Anonymous No.1882176]

>>1882052
the dev boards usually have regulators, LEDs, and even battery charging. Hence when you can connect a battery to it.
You probably blew out the charger but not the regulator.

[Anonymous No.1882179]

>>1882145
The FETs are just in parallel. I'm not entirely convinced they were the failure point though, possibly the voltage regulator failed first and then exposed the FET gates to either 24v or something too low (TC4421 has no undervoltage lockout) which blew them. The TIP31C got warm but not too bad during bench testing, but maybe when driving a real load it got too hot. The melted capacitor lead is baffling to me, but I guess it must not be meant to handle 100+ amps. There are burn marks near it so maybe there was some arcing that caused trouble.
>single huge ass SCR
SCRs would only work with AC input though right?
>multi phase buck from some core voltage converter like PMP10393 to control current
Sounds like a lot of work, I'm thinking for v2 maybe just a 1200 watt 0.1 ohm resistor in series with the battery. Power resistors are expensive, so maybe I can fashion some scrap metal into one.

[Anonymous No.1882209]

>>1882179
>SCRs would only work with AC input though right?

SCRs are DC (one-way) devices. you can get 'em supersized for extra fun.

[Anonymous No.1882210]

>>1882179
>SCRs would only work with AC input though right?

SCRs are DC (one-way) devices. you can get 'em supersized for extra fun in the sack.

[Anonymous No.1882226]

>>1882210
But it still has to cross zero like a TRIAC right? Are you thinking like this? Probably needs a real inductor instead of the halfass 4 turns around some flat stock I did.
>you can get 'em supersized for extra fun in the sack
For that price I could just buy a welder.

[Anonymous No.1882253]

>>1882226
>But it still has to cross zero like a TRIAC right?

not sure what the question is. if you mean can an SCR only be turned on at 0 volts, then the answer is no, an SCR can be turned on at any voltage above zero. if you zero the load current by breaking the circuit, or make it negative, that'll turn OFF the SCR. the other way to turn it off is to short it temporarily.

[Anonymous No.1882265]

>>1882253
The input is 24v DC, it never goes to zero. So once I turn the SCR on, it would never turn off.
>if you zero the load current by breaking the circuit, or make it negative
Hard to do when the electrode has welded itself to the workpiece
>the other way to turn it off is to short it temporarily.
How do you short 400+ amps to 0 volts before the battery catches fire? With bigger SCR? I think the SCR only makes sense when the input is AC.

[Anonymous No.1882326]

Will I fail an inspection for using galvanized steel wire and a wire nut to extend a grounding rattail to a GFCI?

[Anonymous No.1882376]

>>1882265
>the SCR only makes sense when the input is AC
Rectified DC is more my thinking, for AC I'd use a TRIAC to switch on both half-cycles.
>How do you short 400+ amps to 0 volts before the battery catches fire
Remember that an LC filter will buffer a momentary enough short circuit at the expense of an increasing voltage. It's likely relatively simple to make such a circuit. Though personally I'd lean towards using IGBTs instead.

[Anonymous No.1882390]

>>1882326
This is /ohm/, we don't know anything about code. maybe check out the threads with tradies, or maybe SQTDDTOT.

[Anonymous No.1882431]

where can i get a comprehensive but cheap pack/box/whatever of various basic components like resistors/leds/etc?

[Anonymous No.1882462]

>>1882431
ebay will be your best bet.
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2380057.m570.l1313&_nkw=electronics+components+kit&_sacat=0

[Anonymous No.1882499]

>>1882049
Remember to use low voltage to avoid sputtering

[Anonymous No.1882531]

I have some open space to put a copper layer anime girl. Any ideas?
If it helps for inspiration, this is counting pulses off a hall effect flowmeter

[Anonymous No.1882560]

slowly but surely i am inching towards the finish line.
i have debugged the code on the left micro which processes the signal from the equalizer chip and outputs control signal for the right micro which handles the AC light pwm. i'm now about see if the AC light micro shits out the right signal and i hope to god it does, because if it does it, means it's all working and i'm finally done and can get back to the fuckhuge backlog of my other projects

[Anonymous No.1882570]

>>1882531
I see an acid trap on the red copper layer on the far left. For the anime girl, I'd go with Lain or Yotsuba Maybe Madotsuki or one of the Knight Sabers if you're into that.

[Anonymous No.1882581]

>>1882531
>I have some open space to put a copper layer anime girl. Any ideas?

Yeah. Try to project 10 years into the future, and you want to show a normal person some of your older work.

[Anonymous No.1882583]

>>1882581
what this anon's saying is you need to put asuka on your board because any other anime girl is embarrassing by comparison

[Anonymous No.1882608]

>>1882583
>>1882570
Good calls on both your parts.
I've already got boards with Aqua (valve controller), Holo (i2c breakout), and Ranma (thermocouple driver) in the same project.
>>1882581
You say that, but I've shown off much more egregious boards and it's only been positive. Including anything artistic at all on a board is like saying, "I have complete mastery over this system, and to prove it I'm going to decorate it with waifus." To normies, it's much easier to appreciate than a boring white plank.

[Anonymous No.1882609]

>>1882608
Let's get a nice render of that one

[Anonymous No.1882644]

>>1882265
I've used an SCR to do a spot welder with super capacitors. It worked ok.

[Anonymous No.1882739]

>>1882265
>With bigger SCR
No, my point was taking more care on how you handle all that current - either move some control to higher voltage or use better control.

Also using power resistor is a terrible idea, because youd waste all your juice on heating it.

Just find an old computer motherboard. Force enable vcore chip and use vcore to weld.

And tidy up that shit. Or molten capacitor leads will be least of your concerns.

[Anonymous No.1882742]

>>1882644
>>1882265
Also you can turn off SCRs with capacitors across them, the capacitor will short them.

[Anonymous No.1882746]

>>1882583
>>1882608
>>1882609
Asukafags are smelly and disgusting

[Anonymous No.1882783]

get the fuck out of /ohm/ you coomer weebshits

[Anonymous No.1882793]

>>1882783
What are you gonna do about it bitch?
Nothing, because you're a pussy with no power (pun intended)

[Anonymous No.1882831]

I'm going to make about 10 units of a arduino nano project and I want it all contained on one PCB I'm drawing up at the moment.
I'm going to order the components SMD'd on the baord by JLCPCB, so I'm also buying the parts from them.
All the parts are dirt cheap except for the FT232RL wich costs 5€ a pop, so can I just order one and crudely jumper wire it to the ATMEGA to flash the firmware to all the chips?
Kind of like a JTAG? I've never done anything similar before and I'm full of questions.

[Anonymous No.1882847]

>>1882831
You can use CH340, PL2303, CP2102 or any other USB-UART chip instead of FT232RL. I don't really see the point in using FT232RL in new designs anyway - for that price you could even buy a STM32 chip and turn it into USB-UART bridge.
>so can I just order one and crudely jumper wire it to the ATMEGA to flash the firmware to all the chips?
You can use any AVR programmer (USB-ASP, AVRISP MKII or any other device capable of programming AVRs) to write the firmware and it will work even without FT232RL - it's used for communication and Arduino bootloader (that you would need to upload using programmer anyway) so you can omit it, but then why even bother making Arduino Nano clone in the first place?

[Anonymous No.1882848]

>>1882793
Anon, don't mock the females.

[Anonymous No.1882878]

>>1882831
Any reason you aren't using a dedicated USB programmer in order to remove superfluous ICs from your PCB? That's what H3 is for. Removes the need for a bootloader and lets you change the fuses too. But as the other anon said, it defeats the purpose of making an arduino clone in the first place. Actually, I can't see why we need USB-serial ICs on Nanos to begin with. If they all just used USB programmers it would be perfectly fine, it's not like a USB-ASP is nearly as expensive as a PICKIT or STLink. I'm assuming you can send debug messages via ISP headers, right?

>>1882847
>for that price you could even buy a STM32 chip and turn it into USB-UART bridge.
Or for even cheaper, an ATMega8 like most Unos have.

[Anonymous No.1882912]

I feel a bit childish because it's simple stuff, but it makes me really happy to be able to measure first hand something as simple as a RC discharge cycle.

[Anonymous No.1883051]

>>1882912
Being able to mess about with a scope and see the reality of the theories you’ve been taught is pretty nice. Especially so for oscillator topologies and filters.
Similarly, I find intercepting a digital handshake with a logic analyser and comprehending the packets can be pretty cool too, especially with obscure protocols.
Constructing circuit blocks that are usually monolithically implemented (successive approximation registers, finite field error correction, op-amps, etc.) to verify how they work is also cool, like following the footsteps of those engineers that got us where we are today.

[Anonymous No.1883207]

>>1882912
>2 channel
>70MHz
Shoulda saved your money and bought a second-hand analog scope, saving up for a 4-channel digital. Even an analog with cursors should be easy enough to find.

[Anonymous No.1883220]

>>1883207
Only in america/europe you can find used scopes, in other places they are super hard to find.

[Anonymous No.1883228]

>>1883207
>analog scope
yeah and while you are at it use an old 17" CRT monitor for your computer as well since it has faster refresh rate than LCD monitors

[Anonymous No.1883232]

>>1883228
Analog scopes are still good you fucking retard. And they are usually 50% cheaper.

[Anonymous No.1883233]

>>1883232
And if you are lucky you can find better analog scopes for the same price. (Better in the sense of badnwidth and probes)

[Anonymous No.1883236]

>>1882608
>>1882609
Asuka gei

[Anonymous No.1883256]

>>1883220
Aus/NZ is pretty easy too. I bet same for Japan and PRC, HK, etc.

>>1883228
Have fun with your shitty digital scope's latency and poor functionality in XY mode. My analog scope also has a digital mode that lets me pause the trace and save the waveform anyhow, so no way am I changing to a digital scope any time soon.

>>1883233
My scope even came with an unused Hitachi probe in its original packaging.

[Anonymous No.1883258]

>>1883256
Yeah asia too. I was unlucky to be in South america.

[Anonymous No.1883263]

>>1883258
Are you brazilanon? Keep up the good work. I wonder what the ham scene is like down there?

[Anonymous No.1883265]

>>1883263
>are you the brazil anon
Uh I think I am, but I only help people here and comment on stuff. I'm away from brazil atm and my electronic stash so can't build much.
No idea about the ham scene, only people I've met that were hams had little-medium electronics knowledge (but knew how to operate and repair their radios huh) and were oldfags (50s onwards).
You need a license to be one and get your callsign and shit, pay a small fee and do a test (it's not hard from what I remember).
What we have is a problem with pirate tele-evangelist radios in some cities, e.g, hell de janeiro and sao paulo, that disrupt airport communications sometimes.

[Anonymous No.1883292]

>>1883207
Considering my level, I won't outgrow that scope for quite a while.
Beside, I've stalked the second hand market for months but prices were all over the place for slow old two channel scopes, and anything with storage functions easily went over 100€. In the end banggood had a discount week and I got that Hantek for 160€.

[Anonymous No.1883309]

>>1883232
For some things yes, but being able to record a trace and then zoom in to decode it is incredibly useful especially for looking at digital protocols.

[Anonymous No.1883316]

>>1883309
there's no arguing with the analog scope guys. they're massively coping. analog scopes are fine but the only reason to get emotional about them is if you're a nojob that can't afford a cheap rigol.

[Anonymous No.1883318]

>>1883309
You should be using a logic analyser for that anyhow. Far more channels, faster speeds, and cheaper. Got a perfectly good one from alibay for $7.

[Anonymous No.1883319]

>>1883309
>>1883316
>moving goal posts
>using a tool not made for digital analysis for digital analysis
>treating technical subjects as politics instead of working with the given parameters
ok

[Anonymous No.1883322]

>>1880918

[Anonymous No.1883325]

>>1883322
What am I at witness to? Some sort of pneumatic system with valves?

[Anonymous No.1883329]

>>1883319
>>using a tool not made for digital analysis for digital analysis
You're right, that antique junk you use is not made for digital analysis. My DSO is though, one of the many reasons it's better.
>>1883318
Yeah, I have one of those chinkshit analyzers too. It's pretty handy for checking i2c signals and stuff, but no substitute for an oscilloscope. And if you're spending real money you might as well get an MSO to get the best of both worlds.

[Anonymous No.1883334]

>>1883329
>My DSO is though
>get an MSO
Do you have one of those models with the logic analyser lead that gives you like 16 digital channels? Had one at uni, think it had MSO on the front, never used that feature though. While it looks neat, having a USB one is a bit more convenient for me (also pulseview is really good software for decoding protocols and exporting data) as I can take that data and manipulate it on the computer itself without messing about with flash drives or USB cables. Might be easy to use a USB cable though, never tried.
Having something seperate to the scope is also real useful, as I can dedicate the scope's screen to showing analog traces and have the digital ones elsewhere, so long as there's little latency between the two displays. This also came in real handy where I needed to probe the oscilloscope itself, which can't be done with the oscilloscope for obvious reasons.

>if you're spending real money
Anyone with a real workstation is gonna have more than one scope anyhow, so personally I'd just get a legit standalone logic analyser, to go alongside a VNA and all that jazz. Alongside an MSO, for redundancy.

[Anonymous No.1883345]

>>1883325
It's a series multiplex of current sources (solar cells)

[Anonymous No.1883626]

>>1883322
cursed diagram

[Anonymous No.1883632]

>>1882608
>>1882609
based

[Anonymous No.1883660]

>>1883232
implying crt monitors arent good anymore?

[Anonymous No.1883664]

>>1880918
rollin for a project...gimme somethen good

[Anonymous No.1883665]

>>1883345
>It's a series multiplex of current sources (solar cells)

neat-o! i'll be printing that pattern on a t-shirt to replace my ''I've never seen a vagina'' t-shirts, given that both shirts say essentially the same thing.

[Anonymous No.1883696]

>>1883220
>europe
>>1883232
>And they are usually 50% cheaper.
I've just checked ebay and the cheapest storage scope is 200€ shipped. Old ass 20MHz CRO are listed easily at 100+€. The sub-100€ segment is entirely made of ancient scopes, usually sold without probes. This is the second hand market right now, probably because Dave Jones snatches ALL the good deals.

[Anonymous No.1883727]

>>1883632
If you post a pic of her strokin' yer dick... I'm out of here.

[Anonymous No.1883756]

>>1883665
I'm sure there's a vagina board here if that's your thing

[Anonymous No.1883818]

how many coats of lacquer do i need on my secondary coil?

[Anonymous No.1883822]

>>1883818
I can only suggest that you look for a spec-sheet on your lacquer. But I think I’ve seen paraffin wax used instead.
I also have a few questions, firstly why are the turns of your primary so spaced out relative to one another. The voltage across the entire primary shouldn’t be higher than 500V just due to common MOSFET technology, divide that by the number of primary turns and you should be able to get away with a far more compact coil, even with allowances for thermal characteristics. Secondly, is that secondary coil air-core? I’m pretty sure ferrite rods are more than insulating enough to not short out, but I’m not sure how they’d effect your resonant frequency, not what sort of a frequency they still work to.

[Anonymous No.1883826]

I am working on a coffee machine that is having trouble producing milk foam. Looking at the hydraulic schematic, I have determined that the culprit responsible for the problem is most likely a solenoid valve. What would be the best way to test this valve outside of the machine be? I'm thinking that since it's 120V 60HZ, the best way would be to use a cheater cord to hook it up to my isolation transformer, but I decided that it would be best to ask before I do it just in case I do something retarded. If this valve is bad, is this valve here a suitable replacement (https://www.ebay.com/itm/solenoid-valve-coil-120V-60-for-Jura-F9-Jura-F90-coffee-machine/383457242639?hash=item5947d52e0f:g:nhcAAMXQVT9SrdlM)?

Pic related, the specs of the solenoid valve in the machine.

[Anonymous No.1883828]

>>1883822
I used paraffin wax on one I built and it seemed to work ok, but since he will be dealing with RF level energy no many insulation's will do much.

[Anonymous No.1883829]

>>1883826

[Anonymous No.1883830]

>>1883822
12kV neon sign transformer is driving it. secondary is ~800 turns of 22 awg on a 4 inch pvc

[Anonymous No.1883894]

>>1883826
>https://www.ebay.com/itm/solenoid-valve-coil-120V-60-for-Jura-F9-Jura-F90-coffee-machine/383457242639
Looks like it will work fine as a substitute.

[Anonymous No.1883903]

>>1883830
Oh it’s not resonant or even switched? Suit yourself. Gonna slap some silicon stack diodes on the end for HVDC? Those diodes are surprisingly cheap. Could make a nice large capacitor for it to charge using, coincidentally, also paraffin wax. I’d worry about creepage on that PVC, it’s also not the best insulator. But it guess enamelling over it will help prevent creepage across either surface.
>22awg
Lightweight, I’ve got that 32awg wire lying about for this sort of project. Problem is the reel is too short for the voltages I want.

If that is running on such a low frequency, you’ll probably find the coupling to be very poor with that tiny primary coil.

[Anonymous No.1883963]

Which sensors to use for the movement of robotic joints? Hall effect / crank shaft, or what? Potentiometers/position sensors seem to deteriorate quite fast? Or something with LEDs and light sensors?

[Anonymous No.1883968]

>>1883963
What you want are called "rotary encoders". I'd probably recommend going for absolute position/gray code encoders as opposed to relative position/quadrature encoders, because sudden shocks or jolts won't be uncommon, otherwise necessitating a rather fast refresh rate. Not sure if hall-effect magnetic encoders are made like this, but optical ones definitely are. Note that gray code encoders are significantly bulkier, so maybe you don't want them.
There's also analog position sensors, that use variable magnetic coupling to determine position, but for this case I'd stick to digital unless you're trying to stick to using analog parts for whatever reason. If you are trying to make analog mechatronics (brushed DC motors, op-amps, comparators, etc.) that would be really cool though.

What kind of resolution are you looking for? As in degrees/arcminutes per step, or steps per revolution. I'm thinking no more than ~2mm of distance at an arm's length (~500mm) if you're building a robot, which would be 0.23° per step, or 1500 steps per revolution. Might want a reduction in there, which would render an absolute encoder somewhat pointless.

[Anonymous No.1883974]

>>1883963
>robotic joints
that's pretty general.. Anyhow, as the other dude said, encoders are the way. Or a servo motor (motor+encoder+some brains)

[Anonymous No.1883987]

>>1883968
>>1883974
Thanks, I'll look into all of that. Never really thought of looking for encoders themselves. I don't want servos or whatever motor with encoders in most cases, bc they need to much space. Most extreme use case will be the joints between fingers. I can't put in anything big in there. Will Cogley (Youtube) uses very small potentiometers for his new hand design, but they seem to fail after a while.

[Anonymous No.1883989]

>>1883968
When reading through this description of the encoder for the arm, I recalled that humans have something more like a accelerometer or gyroscope. Might be the better way to do it. I'm quite a beginner with that stuff, so don't really know much yet.

[Anonymous No.1883993]

>>1883989
>https://en.wikipedia.org/wiki/Proprioception
We sense several things
>movement
>load
>position
also remember that not everything need sto be sensed on site, you can use wires and shit (like bycicles). I know this is more prosthetics but there was one guy here who made his arm with mostly bike controls and it worked fine.
>https://www.youtube.com/watch?v=e5PlbGFCqps
Accelerometers and gyros are good but expensive and do not provide absolute data (it needs to be integrated over time and the starting point must be known), encoders do not neet integration and already give absolute results. There are also other ways such as RVDTs and some other autistic shit.

[Anonymous No.1883994]

I bought a magnetic Tachometer
I hooked it up and it works fine on its own, it sends the RPM to the little LCD screen

I have a controller board that drives the spindle its measuring, if you send it a pulse signal it will show RPM on the software

I spliced a fork off the signal wire, so black goes to yellow wire/LCD screen and another wire goes to the controller board.

You hook it up to the controller board, it works fine in the software but the physical LCD shows 0
Unplug it from controller board and the LCD comes back to life

Is there a reason why it isnt sending the same pulse down both wires, shouldnt they both work?
What do you think the "CS" hole on the PCB is, is it (or any other blank holes )there an output I can solder a wire into and wire the driver board at the same time?

[Anonymous No.1883997]

>>1883993
Okay, thanks. I'll look into it. I think building something with hall sensors or using crank shaft sensors will be quite usefull for most joints, got this video here explaining it: https://youtu.be/isYmSB3RqWM

[Anonymous No.1883999]

>>1883993
Also I wish there was more info on that guy on the video, but last thing I could find is that he used his mechanical arm to build an electronical arm to himself and never appeared anywhere again.
tl;dr
>deaf-mute /diy/ fag gets shocked and loses an arm, gets government prosthetics but they have like 2-3 motions and they don't allow him to solder or do shit
>builds his own with bike parts, gets taken to a research center where they are amazed and the only problem is the weight (regular amputees can't handle heavy ones) because he used regular metal from pots and pans
>>1883997
When we reccd "encoders" we just gave you a general idea. There are several types of encoders.
>magnetic
>light
>mechanical
>hall effect
The simplest encoder you can make is with LEDs and receivers + a marked piece of paper

[Anonymous No.1884002]

>>1883994
CS usually stands for chip select, and I don't understand your diagram. Why people refuse to make circuit diagrams in 2020?

[Anonymous No.1884007]

>>1883993
>>1883999
Thanks again, knew already about bowden cables but that guy with his prothesis is really impressive.
The position of the robots arm would be known if it goes down automatically if no force is applied, like a human one. I think the additional sensors might be rather complimentary, though. We'll see, have a lot to look into now.

[Anonymous No.1884013]

>>1884002
Thats the picture from the amazon listing, I didnt touch it thats the back of the little LCD that shows the numbers.
All I did was splice a new wire off of the yellow wire and put it into a different board

[Anonymous No.1884018]

>>1883987
>they need to much space
BLDC servos are actually more compact than stepper motors IIRC.

>>1883989
To use an accelerometer to detect position, you need to integrate the acceleration with respect to time. Twice. This is called inertial navigation. Because of quantisation error, random error, nonlinearity, aliasing, etc. this is very prone to drift over time. But for when you want accurate position tracking of something like an ROV (see /rcg/) they use a combination of GPS and inertial, with the GPS updating the inertial every few seconds or whenever, to get both fine and coarse detection.
For a single rotary or linear axis, you could use both an accelerometer/gyro and a coarse encoder in this manner, but for your multi-multi-axis setup, you'd need to isolate the accelerations of each motor with a bunch of nasty rotational geometry, which would be a right pain. But for tracking the position of an actuator on the end of an arm it might be somewhat useful.

>>1883994
Your controller board must be loading it down somehow. Add a couple of transistors or whatever to buffer the signal.

[Anonymous No.1884032]

I'm trying to repopulate the circuit board of a failed power supply and need help identifying one of the components. It seems to be an axial ceramic capacitor and the marking says MCS 012 Might also be MCS V12 or MCS O12. Google turned up nothing so I thought I'll try my luck here.

[Anonymous No.1884033]

>>1884032
Forgot to save image where i've marked the part.

[Anonymous No.1884036]

>>1884032
An axial ceramic capacitor? Never seen one of those before. Firstly, I'd trace the circuit in the vicinity of the cap to see what it's being used for and check that it's definitely a capacitor. Then, I'd see if I can infer what value it is from this context along with the dimensions of the capacitor itself. Then I'd scour through digikey for an identical package to further narrow down its value and possibly the meaning behind its markings too, using other components on the board as context for country of origin and tolerance. For small parts, markings aren't necessarily part numbers, but you should see a hint as to the marking scheme on the relevant datasheet.
t. never done this myself

[Anonymous No.1884042]

>>1884018
>>>1883987 (You)
>>they need to much space
>BLDC servos are actually more compact than stepper motors IIRC.
Good, but I think if I separate the encoder from the motor, the motor itself would be smaller and I could get creative with how to integrate the sensors.

[Anonymous No.1884045]

>>1884042
Likely correct, but you will end up with more backlash if you don’t mount the encoder directly on the shaft. You’re using BLDCs, right?

[Anonymous No.1884048]

>>1884036

[Anonymous No.1884049]

>>1884048
Definitly looks like one of those. I'd hate to desolder and destroy it though if I'm not sure I can find adequate replacement. It's a rather old board.

>>1884036
> I'd trace the circuit in the vicinity of the cap to see what it's being used for and check that it's definitely a capacitor

There 4 of them on the whole board. One of them is used to connect the output of a voltage regulator IC to the source of a PWM switch IC.

[Anonymous No.1884055]

>>1884045
I'm using nothing so far. The robot on the other pic wasn't mine. I'm looking into it, so I know what I have to learn and buy to try it out.

[Anonymous No.1884071]

>>1884048
huh
like the opposite of a MELF

>>1884049
>to connect the output of a voltage regulator IC to the source of a PWM switch IC
In series? Sure it isn't from the output of the linear regulator to GND?

>>1884045
>>1884055
Well, if you go with geared motors (a good idea to reduce the required holding current and increase torque) then you could put a standard encoder (20-400 steps per rotation) on the motor before the reduction and get no more backlash then otherwise. A motor with an integrated gearbox wouldn't skip positions or anything (like a timing belt might do between disassemblies), so an absolute encoder would certainly keep your position known.

Not to be discounted is the concept of visual tracking, though it likely isn't precise enough for high resolution, it may still be a good vector for feedback. The software for doing visual tracking is getting pretty interesting now that neural networks are starting to be used for this sort of thing.

[Anonymous No.1884095]

Asking out of ignorance, how can I test this component to determine if it needs replacing wihtout simply swapping it out for a new one and crossing my fingers?

[Anonymous No.1884098]

>>1884095
analyse the waveforms? Exclude all other components?

[Anonymous No.1884099]

>>1884095
Maybe test continuity to see if it's shorted

[Anonymous No.1884142]

>>1884095
Lift the Vout leg and tack a lead on, then power something with it.

[Anonymous No.1884143]

what is that thing called that big clive uses where he closses a lid on a thing that turns on 230V or opens the lid and it turns it off? and he can also press 3 separate things under the lid to connect each power wire separately

[Anonymous No.1884145]

>>1884143
i basically want something like that for connecting 230V to my test circuits and when i turn it off i want to see the power is visually disconnected so i don't get killed by a failed switch one day when i touch a wire that i think is dead

[Anonymous No.1884146]

>>1884143
Cliff quicktest

[Anonymous No.1884159]

>>1884146
>Cliff quicktest
>$70
>for a literal push switch
okay i take it back, i will rather die than feed the jew

[Anonymous No.1884172]

>>1884159
>>1884146
this thing is way better than my piece of shit diy mains box with binding posts. I wonder if it'd be practical to 3d print the key assembly with creative use of a battery leaf spring for the contact.

[Anonymous No.1884180]

>>1884172
yeah, i am thinking that as well
seems really easy, you can use a piece of thin metal and bend it to create the contacts, then put it into a 3d printed case and put another piece of metal in the lid to bridge circuit close and also ass some sort of spring into the lid to make it hard to close and make sure it doesn't close it self by accident when you are sitting in a bathtub and have the live wrapped around your dick

[Anonymous No.1884205]

>>1884180
>when you are sitting in a bathtub and have the live wrapped around your dick
Are you me?

[Anonymous No.1884216]

Recently bought pic related chink emulator
The audio dial is awful, tiny movements at the very start of the range give a massive gain in volume and then the remaining 90% of the range does hardly anything
Bit of a brainlet when it comes to audio but does this sound like they've used a linear pot when they should have used a logarithmic one?
If I bought an audio pot and swapped it out would it make the perceived increase in volume linear?

[Anonymous No.1884249]

>>1884216
You want a stereo logarithmic pot, probably 10k.

[Anonymous No.1884261]

>>1884249
Thanks
Does the resistance matter? I thought it just acted as a voltage divider.
Most of the pots I'm look at are 10k anyway though.

[Anonymous No.1884268]

>>1884249
>>1884261
Just checked and the original pot is 20k, would using a 10k pot make any difference?

[Anonymous No.1884278]

Yes, the difference is fine vs. coarse volume control. Higher resistance = finer control. So try a 50k log pot instead.

[Anonymous No.1884285]

Hey /ohm/bres, I want to fix this surgical head light, and I think I could probably solder over the shitty points on this wire, but I have no idea if the red and the green wires are anything important. I've only ever soldered wires that were 100% copper. The wire apparatus connects the head light to a 7.2 V lithium battery that allows variable light intensity via a knob switch.

wat do? Am I going to fuck up the red and green wires if I go balls to the wall and just solder?

[Anonymous No.1884298]

>>1884285
That looks like fiber, so you'll need optical grade solder.

[Anonymous No.1884308]

>>1884285
>another nigga using surgical pincers to do electronics
My bro. Best tools for soldering are those stailess steel pliers.

[Anonymous No.1884323]

>>1884308
"Hey, Randy. Go fetch my soldering pliers."

[Anonymous No.1884333]

I am using the LTC1707 buck regulator to step down from ~6V (4 aa alkaline cells) to 5V. I am confused about proper grounding. Initially I used a common ground and this caused Vout to be 6V when Vin was 6V so I knew I did something wrong. Then I re-read the datasheet PC board layout checklist where it mentioned segregating signal and power grounds. I probed Vout and R4 and sure enough it showed 5V. I did this on a breadboard but now I'm going to solder it more permanently. Should I be using this point on the resistive divider (R4 lead) to ground the rest of the circuit that will be using the 5V Vout? Also I'm unsure about the star ground formation. I gather it's when a single point connects the ground planes. So Since R3 is connected to power ground does this complete the star ground formation?

[Anonymous No.1884338]

>>1884333
please do not ground your feedback, anon. figure 7 shows you their intended grounding layout. basically you just need to connect the ground paths for the control circuitry passives directly at the chip's gnd pin such that they aren't sharing any trace/wire with the power ground. the reason is that traces have resistance, and the load current will impose fluctuating voltages on those traces wherever it flows, which will fuck up the chip's feedback if the signal passives are exposed to that.

[Anonymous No.1884339]

>>1884308
Dug into tweezers for a bit and now I kinda want to /diy/ something like https://www.youtube.com/watch?v=wcxNrJXnznc

[Anonymous No.1884357]

>looking into diy'ing that cliff quicktest
>notice that digikey has springs
>find just the right spring, only $6 for 5
>"MARKETPLACE PRODUCT"
>$26 shipping
go fuck yourselves digikey. at least give notice about this shit on the parametric search and not just on the product page.

[Anonymous No.1884379]

>>1884285
Same for headphone cables, that's coloured insulation atop copper strands, you'll need to remove this layer. Either by heat, chemical means, or possibly abrasion. Or just try to solder it with plenty of flux and hope for the best, the heat of a soldering iron might be sufficient to degrade it.

[Anonymous No.1884495]

>>1884338
I'm just so confused what's going on now. Grounding feedback is the only way I can get the regulated voltage. I've tried everything but all I can get is the input voltage. What else can I do to troubleshoot this

[Anonymous No.1884552]

You know how SCRs are basically an NPN coupled with a PNP such that they latch on? I know that because FETs don’t conduct through their gate so one made with two MOSFETs wouldn’t work as some sort of switching transistor, but it would still latch, no? I was thinking you could use these as memory latches, and since the gates are capacitive, it would be somewhat nonvolatile. Could add an extra cap to it to increase the lifespan.
Though I guess half of what I’m saying could just as easily be applied to a 2-transistor SR latch.

[Anonymous No.1884554]

>>1884552
Something like this?

[Anonymous No.1884582]

>>1884554
Not quite, I think the gate of the PFET would go into the drain of the NFET and vice-versa. With only two transistors, at least for setting. You’d need a way to unlatch them too, probably with a resistor between the transistors and Vdd and a third transistor to short them to GND.

I should buy a grab bag of 50 or so “complimentary“ small signal MOSFETs for messing about in a breadboard, I guess. I’m feeling the need to experiment with single bit long-life pseudo-nonvolatile memory, because pushbuttons are a lot cheaper than toggles. Might also be a path towards designing a toggle flip-flop that doesn’t require two SR latches in master-slave configuration.

[Anonymous No.1884601]

>>1884552
>>1884582
I had the same though a few years ago about Thyristors.
To my dismay, a quick internet search revealed that it had already been done and brought to market.
https://en.wikipedia.org/wiki/T-RAM

[Anonymous No.1884609]

>>1884333

[Anonymous No.1884620]

I wanna buy a bunch of these cheapass plastic screwdrivers for rf. The kind you get free with cheapass probes. I should be able to get a bag of 100 for like $5, but I can't find any on ebay

Where can I find these suckers for cheap?

[Anonymous No.1884625]

>>1884601
>T-RAM
Oh that's real neat. Wonder if we'll see it commercially any time soon? Though using BJT technology does mean the quiescent current will be higher than with CMOS SRAM.

>>1884620
Assuming you've already looked on AliExpress, I'd look on Alibaba or Taobao.

Personally I'd instead be looking for some sort of screwdriver bit set with the bits made of glass-fibre reinforced nylon. Does the handle need to be insulating too?

[Anonymous No.1884628]

>>1884625
>bits made of glass-fibre reinforced nylon
sounds expensive
>Does the handle need to be insulating too?
nah, I just don't want it to short when I awkwardly jam it around with my left hand. I'm a cheap piece of shit/miniature fetishist so all my potentiometers are these things

[Anonymous No.1884631]

>I been trying to learn electronics for almost 7 years on my own.

>I am fucking obsessed to the point I mostly watch YouTube videos about to topic

>To this day I have only fix one television and only because the problem was obvious (blown) caps

I been fidgeting with a Samsung smart TV and I can't find the solution, I bought I broken screen one and replaced all the parts just to see what happened and the problem persist even after changing the main board and power board

What the fuck can it be, I test the LEDs in the back and they light up independently but when I put the power supply to the plus and minus rail nothing happens.

I need to learn this craft, I am fucking obsessed, is consuming me but I am afraid I am not smart enough, is there a school a could go where I don't have to spend 2 or 3 years learning theory and instead just do a 1 or 2 month hands on training, I don't really want to become an expert to the point I design my own mother boards and projects even tho at some point I probably will, I just want to fix old electronics to either keep or sell

FUCK SOMEONE HELP PLEASE I AM GOING CRAZY

[Anonymous No.1884634]

>>1884628
>sounds expensive
It's bog-standard for any plastic that needs to be rigid. Basically all power tools use it as their clamshell, probably $10 worth and that's a lot more plastic than in a simple hexagonal screwdriver insert.
>all my potentiometers are these things
You know they're only rated to like 100 rotations worth of wear, right?

[Anonymous No.1884637]

>>1884634
that's fine all prototypes are shit anyways
much worse to blow $3-5 worth of pots on a project you never use

[Anonymous No.1884642]

>>1884631
Check all of your wiring harnesses and ribbon cables. If you see any shitty crimps or peeling contacts on ribbon cable ends, replace them. Otherwise it's a dead panel.

[Anonymous No.1884650]

Hey anons, I thought I would ask, how the fuck do I design my own FM receiver? I get the amplifier part but going from RF to IF and so on just goes over my head. I just wanna design my own for shits and giggles. Please just help me out here I want to learn these concepts

[Anonymous No.1884653]

>>1884637
>$3-5
nervous_laughter.gif

>>1884650
Look into how a "phase locked loop" or PLL works. There's one or two videos on youtube that aren't made by indians that get the basics down. They're really interesting circuits, using frequency for feedback instead of voltage.

Making a 100MHz PLL will be a bit of a pain though, as most standard components are only good to 1 or 10MHz, so the phase comparator won't be able to use a 7400 or 4000 series XOR, and the VCO will need to be something odd anyhow.

[Anonymous No.1884655]

>>1884625
As far as I can tell, T-RAM went out of business somewhere around 2009.
Not sure who bought the patents.

>Though using BJT technology does mean the quiescent current will be higher than with CMOS SRAM.
That's certainly true of this simple 1T static SR-latch that I designed.

[Anonymous No.1884656]

>>1884655
Derp, image.

[Anonymous No.1884663]

>>1884655
>>1884656
However the patents that I can find for T-RAM describe a circuit more like pic related.
Each memory cell only consumes power when being read.
It's behaves like a pseudo-static RAM.

[Anonymous No.1884665]

>>1884650
look up how to use/make/drive a diode ring mixer.
The VCO may be an issue, but vackar oscillators aren't too hard to design

>>1884653
>100MHz PLL
curious, have you ever tried 3rd/5th harmonic synthesis? 20-30MHz PLL's are pretty cheap and easy to find

[Anonymous No.1884712]

>>1884656
>>1884663
Ah, neat. I don't really understand that second circuit intuitively though, so I'll mess about in a sim. But it definitely looks volatile. With any luck, the MOSFET-based one has a relatively long decay time with a 100nF cap. I want to make one with a few days worth of memory.

Or maybe I should just go full-retard and buy some of those magnetic memory cores, there's a youtube video of a guy making a non-volatile SR latch with a single one of those coils and I think only two transistors total. A magnetic core potted in a DIP4 package (same package as an optocoupler) would actually be pretty useful. Maybe use a hall-sensor instead of a reading winding, since I think they need to be rewritten each time you read them otherwise. Or maybe that's just a product of the topology those woven matrices of magnetic cores used.

>>1884665
>3rd/5th harmonic
For the VCO? You'd still need frequency dividers that can handle the full 100MHz on the input though.

>diode ring mixer
For FM? IIRC a mixer doesn't do anything useful to FM at all, only to AM.

[Anonymous No.1884754]

>>1884712
Jeri ellsworth has a couple very good videos both on semi conductors and also on magnetic memory.
https://www.youtube.com/watch?v=p7SkE5pERtA

[Anonymous No.1884768]

>>1884298
>>1884379
thanks for the replies. I'm doing some reading up now on optical wires and headphone wires before I go about chopping up my $500 light.

>>1884308
>stainless steel pliers
you got it boss

[Anonymous No.1884771]

>>1884768
Those aren’t fibre optics

[Anonymous No.1884814]

>>1884768
I have the bottom guy, pretty gud

[Anonymous No.1884827]

Why do "intro to cirucits" type things always seem to start with ohm's law? It's more like a definition of resistance than an actual law, and only particularly useful for dealing with one particular circuit element. Why not start with KVL or KCL or even p=iv which tell you something about the nature of electricity instead of just "what is a resistor"

[Anonymous No.1884888]

>>1884827
My circuits 101 at university started with topology

[Anonymous No.1884898]

i'm doing it brehs
it's going to be beutiful
$70 my ass

[Anonymous No.1884899]

>>1884898
Simcity? I see a traffic jam. Better build railroad tracks.

[Anonymous No.1884924]

>>1884712
It's definitely volatile.
The nice thing though is that it's self-restoring. Simply bringing the Output_enable line high causes the thyristor to restore the value of the capacitor.
I've made a few attempts at a MOSFET based one, but the only things I can get to work reliably are either putting a MOSFET inverting buffer between the capacitor and the thyristor, or just using two cross-coupled inverters.
They work, but at that point it's not that much simpler than 4T SRAM, so the advantages become rather moot.

[Anonymous No.1884926]

>>1884898
I'm interested, keep us posted

[Anonymous No.1884927]

>>1884357
Did you check Mouser?

[Anonymous No.1884930]

I have a nema23 stepper motor and this particular stepper motor driver (pic related)
What is the cheapest, smallest most basic controller I can get for it, preferably ran on 36V
All I want is a potentiometer for speed and a switch for direction.

I bought it cheap from a coworker who bought a 4 pack but only needed 3 for his router thinking I would be able to figure it out. Everything is CNC parallel port stuff, or Ethernet CNC stuff.

I just want to make a rotating welding table.

[Anonymous No.1884942]

>>1884899
it will be a ghetto cliff tester

time for a first 3d print to make sure i got all the dimensions right

[Anonymous No.1884954]

>>1880918
How do you deal with resistors if you're colour-blind? I can't find any app that's useful.

[Anonymous No.1884958]

>>1884954
A multimeter, and keep them all in organized drawers.
I'm not colorblind and I still don't like fucking about with color codes.

[Anonymous No.1884960]

>>1884958
Cheers anon

[Anonymous No.1884971]

>>1884954
Get a CRISPR treatment

[Anonymous No.1884975]

>>1884930
All you need is to generate a 5V pulse for every step, so you can just use a simple signal generator (and an SPDT switch for direction). Ali has some for like 3 bucks.

[Anonymous No.1884985]

>>1884971
Nah, I'm not letting doctors inject stuff into my eyes, until they've injected the same stuff into the eyes of a lot of other people and an acceptable amount of time has been allowed to pass since they received their treatment.

[Anonymous No.1884986]

>>1884985
being able to read color banding on resistors is 100% worth the risk

[Anonymous No.1885004]

>>1884927
unfortunately they don't seem to have any, but i'm bad at reading their catalog. mcmaster has what i wanted with (slightly) less exorbitant shipping but funnily enough they have a much smaller catalog for springs than digikey

[Anonymous No.1885016]

Hello /ohm/

I bought a cheap, handbuild guitar amplifier (schematic: pic related).
It basically works, except at high distortion levels (aka 'gain' or 'preamp volume') the sound cuts out in an unpleasant way. The distortion "vanishes" and the output volume level drops for as long as there is *no* new note being played. So it is somehow like an inversed compressor: When playing the guitar loud and hard, the sound is there, but as the note decays the sound suddenly drops by a big margin. There is no smooth transition between clean and distorted sound.
I don't know how to describe the problem in any better way and that is probably why I have not found anything on the googles.

What I have done in the process of trying to fix that damn thing without success is:
* rebuilt the whole amp and used new components except: power transformer, output transformer, choke, powertubes and filtercaps
* swapped preamp tubes
* used crocodile clips to insert a temporary post-phase-inverter-master-volume. I used the most basic one that I could think of: right behind the 22n capacitor after V3 I inserted a potentiometer that, when turned counterclockwise, cancels the signal and thereby reduces the output volume. This does not change the sound that much, but the feel of the amp. However, the problem of dropping from distortion into almost not hearable persists. I therefore conclude that the problem does not lie within output transformer and powertubes.

Maybe someone could help me google the problem, that would be of big help to me, or maybe someone knows this kind of problem and a fix.

[Anonymous No.1885035]

>>1885016
>handbuild guitar amplifier
Post pics of the board.

[Anonymous No.1885053]

>>1885035
This is the original board in a pic from the seller. As I said, I replaced that with a new one. Therefore the board, even if it looked funky, probably was not the problem as the problem persists. I cannot take a picture of my work right now.

[Anonymous No.1885073]

I cant really find a straight forward answer. Does the stm32f1 aka bluepill have 1 or 2 adc converters on board. Im assuming that the analog pins on portB and on a different converter than those on portA but I really cant find much on the topic.

[Anonymous No.1885079]

>>1885073
It has two 12-bit ADCs. It's all in the datasheet.
They share their channels, so both ADCs can be on any of the 16 possible pins, depending on how you configure it.

[Anonymous No.1885109]

>>1885079
>They share their channels
Ah so thats what that notation (adc_12) means. I was stuck on the assumption that they would be labeled adc1 and adc2 and couldnt properly interpret that. Thanks.

[Anonymous No.1885117]

>>1884930
logic gates + rotary encoder?

[Anonymous No.1885131]

>>1885016
You've got blocking distortion. One of the stages is driving the next one so hard that the grid is conducting. This places additional charge on the coupling capacitor, temporarily changing the bias of the following stage. I can't tell from the schematic which stage might be the guilty one, but you have all the classic symptoms.

[Anonymous No.1885136]

>>1884609
I know this is probably a simple problem to experienced people but I cannot for the life of me debug my circuit. Vin = 6V, Vout = 5.8V. It looks like the regulator isn't even on. Probing pin 2 shows < 0.4V. I tried pulling it up to Vin but same result. I'm so confused why this isn't working. I have the circuit on a breadboard like shown and I've re-done it like 10 times.

[Anonymous No.1885157]

>>1885131
Thank you for the response. I used your input and read a little bit about blocking distortion. While it kinda makes sense, it also does not: Why does it happen with my build? The schematic is correct and I have built the circuit to spec, it also happened before I rebuilt the amp. However, as far as I understand blocking distortion from reading a few minutes, it only happens because of a design flaw within the circuit, but that is not the case with this amp as perfectly working examples of with the same circuit exist.

I thought I had some kind of part failure or that something is wrong with the way that the amp is wired (like in layout or soldering joint), but definitely not with the schematic that was used to build it (twice).

[Anonymous No.1885160]

>>1885136
Have you looked at the datasheet for the regulator?
https://www.analog.com/en/products/ltc1707.html#product-overview

[Anonymous No.1885178]

>>1885160
Yes. What would cause grounding the feedback voltage to produce the correct Vout? When the circuit is normal the feedback voltage is slightly lower than the (wrong) Vout. I guess it would help to have an oscilloscope to dig deeper

[Anonymous No.1885190]

>>1885178
Did you post this schematic?
>>1884333
Look at SW and VIN. Does that look right to you?

[Anonymous No.1885261]

>>1885190
yes I posted it. It looks right - taken from datasheet pg 13, second diagram. Changed inductor value to meet current requirements, changed R3, R4 to meet voltage requirements. Am I missing something?

[Anonymous No.1885275]

>>1884954
>still using THTs in CE 2020

[Anonymous No.1885296]

>>1880918
When connecting wires to this, can I just connect the D-, D+ without power in/out?
The device I am reading data from has its own power supply.

[Anonymous No.1885301]

>>1885296
Connect the black wire too.

[Anonymous No.1885304]

>>1885261
Is that resistor at R4 out of spec or higher than 1% tolerance? Try a 500k pot, attach a load and adjust the voltage.

[Anonymous No.1885333]

I am just getting into this hobby and have two small projects I want to do (PCB related). Because of my location, I am required to use lead-free solder. Is there a general recommendation for this stuff, or am I just fucked? Is the generic 99.3% Sn / 0.7% Cu okay, or should I try one of those weird alloys like SN100C?

[Anonymous No.1885338]

>>1885301
>black wire
Are you referring to the grounding wire?
These two wires (D-, D+) have been soldered into the back of a pi. If I just plugged this into >>1885296, would it damage the port or the connector? Should I still connect the ground?

[Anonymous No.1885340]

>>1885338
Always connect the ground between devices.

[Anonymous No.1885348]

>>1885340
Ok so I need to plug D-, D+, GND but can skip on VCC right? Thank you and sorry for the redundant questions.

[Anonymous No.1885354]

>>1885348
Yes, skip the red wire.

[Anonymous No.1885357]

>>1885354
Thank you so much for helping out a newbie anon.

[Anonymous No.1885366]

>>1885357
You're welcome. Happy birthday.

[Anonymous No.1885379]

>>1885333
I don’t see why you have to use one alloy or another, but in general it will solder just fine, with a slightly higher temperature. There are certainly some minor differences though, like which fluxes you can use, and the time you can linger on a component before damaging it.
t. contrarian

>>1885340
Not him, but because it’s a differential pair is it actually strictly necessary? I’d still do so though.

[Anonymous No.1885393]

>>1885304
yeah it's Vishay Dale 1%. I also verified the capacitor ESR is in spec and inductor DCR. I don't have a 500k pot unfortunately. Any other ideas are appreciated but I have another voltage regulator to try and come to this when I have more time

[Anonymous No.1885398]

While im not using an arduino i remember reading that their timers dont increment in interrupt functions. Is that arduino specific or should I avoid time sensitive things in a interrupt. Im tracking clock cycles.

[Anonymous No.1885417]

>>1885398
I'm pretty sure that's Arduino specific.
The timers are completely independent of the CPU core.

[Anonymous No.1885457]

>>1885379
thanks anon, that's reassuring. I'll do some more research and go from there.

[Anonymous No.1885472]

>>1885417
yeah i think the arduino uses interrupts to keep time and not clock cycles. I could be wrong.

[Anonymous No.1885497]

Ive been staring at some functions written in assembly for the first time and sometimes I see \n\t and sometimes I dont. Whats the difference? Example
> __asm__ volatile ("CPSID I\n");
and from a different library that does the same thing
> asm volatile("cpsid i");

[Anonymous No.1885574]

Anyone have a schematic for a basic AM tx?

[Anonymous No.1885586]

>>1885574

[Anonymous No.1885598]

>>1885586
nice thd bro

[Anonymous No.1885599]

>>1885157
>>1885131
>>1885053
>>1885035
Quick update: I really do not think that my problem is blocking distortion. I checked all gridstoppers and they are all to spec. Voltages are within tolerances.

Also the distortion that I am hearing does not buzz, it does "suddenly" happen. Instead, it everything is normal, the amp sounds nice, except for the decay of a played note where at some point there is a massive loss in drive with a "farting out" sound. It is not farting out when driven hard.

[Anonymous No.1885646]

>>1885586
My issuebisbthat modulation transformer, where am I supposed to source that?

[Anonymous No.1885647]

>>1885599
Maybe the guitar or cable? Is your speaker okay?

[Anonymous No.1885656]

>>1885647
Tried with several different speakers and my self build powersoak, cables, guitars.

[Anonymous No.1885664]

>>1885379
>because it’s a differential pair is it actually strictly necessary?
Yes.

[Anonymous No.1885669]

>>1885656
How do the tube sockets look? Have you tried a fixed resistor in place of suspect pots (for testing)? Just throwing shit at the wall here.

[Anonymous No.1885671]

>>1885669
Sockets look okay and there is no bad sound when touching them with a wooden stick.

I have not tried changing the pots for resistors. I hope that I have the time to try this and other things next weekend.

But still, it buggers me: I rebuild the whole damn amp except for OT, PT, choke, filter caps and powertubes, and yet the problem is still there, *but* the powertubes and the PT cannot possible be part of the problem because the problem is also there when on very low master volume settings. This leaves only V1, V2 and V3, but I also changed them and rebuild the gain stages and phase inverter to spec.

Thinking about it this really only leaves the big capacitors, but I measured them and they were fine.

[Anonymous No.1885672]

>>1885646
scavange cores on old boards you find int he trash, they are my main source of inductor and inductor cores.

[Anonymous No.1885687]

>>1885671
Maybe the distortion gain stage is picking up noise. Ferrite bead or extra shielding?

[Anonymous No.1885692]

>>1885687
But noise is not really the problem. If anything it is like a positive feedback loop. The original design does not require any extra shielding as the amp is relatively "low" gain, therefore I have not shielded anything.

[Anonymous No.1885710]

>>1885586
Could I sub out the Mod transformer for an optocoupler?

[Anonymous No.1885743]

>>1885710
Here's a circuit, but bandwidth limited (400Hz-18kHz freq response).

[Anonymous No.1885754]

does anyone know of any good whitepapers on using switchers to power precision analog circuits? i know all modern lab equipment does that, and it's probably mostly down to good grounding, high frequencies, and output filtering, but i'm very averse to the idea because it's a hard thing to characterize theoretically with a strong confidence level.

[Anonymous No.1885758]

>>1885754
Drive a linear regulator with a high-frequency switcher?
i.e. 5V switcher to 3.3V linear regulator.
input and output filter/ripple caps

[Anonymous No.1885862]

>>1885754
capacitance multiplier

[Anonymous No.1885935]

Can you recommend me some resources to learn about impedance matching for PCB designs?
Mostly for non-RF digital signal stuff.

[Anonymous No.1885982]

>>1885862
thanks for the idea, this seems feasible to calculate. i never noticed it but bjt datasheets list their parasitic capacitance. it shouldn't be too hard to get a ballpark on the frequency limits of a capacitance multiplier and add a choke to handle any noise above those frequencies.

switcher emi is still a nagging thought for me though, where it's somewhere between "bullshit emissions compliance requirement" and "actually a concern". i guess lab equipment just solves that issue with aggressive shielding.

[Anonymous No.1885987]

>ordered too few of one type of capacitor for a project but have leftovers from a project I abandoned
IIRC, you can use a cap that's at a higher rated voltage than the original, but you have to match capacity. Is this correct?
It's a capacitor replacement for a computer motherboard.

[Anonymous No.1885990]

>>1885987
that's correct if they're same type of cap and you're not substituting a chink cap for a rubycon. in certain situations a higher capacitance is also acceptable, and in other situations it really doesn't matter as long as you're in the same order of magnitude, but you need to understand what it's doing there in order to make that call.

[Anonymous No.1886023]

New to this. If I'm using solder wire with No Clean Flux, do I still need to use liquid flux? I'm working on brand new PCBs with new components.

[Anonymous No.1886043]

>want to get some cheapo turn signals for my motorcycle so I don't fuck the originals up if I dump it but it only has a 6 volt electrical system
Would pic related work fine because LEDs have a low power draw or would I have to put in a transformer or something?

[Anonymous No.1886044]

>>1886023
Lead solder & good flux always makes better joints and it's easier to fix mistakes. Maintaining a clean tip on your iron + temp control is just as important.

[Anonymous No.1886045]

>>1886044
OK got it. I'm also not sure what needs to be "tinned" and when, it seems like everyone has a different answer

[Anonymous No.1886047]

>>1886043
You need to know how much current the LEDs are drawing at full power and use a boost converter that can continuously supply the same amount.

[Anonymous No.1886050]

>>1886045
You typically tin leads/wires to minimize heat time for sensitive components and small wires. All it takes is a light touch and the joint is made. Sometimes you tin a single pad to tack a component in place so you can solder the other leads without moving the component around. Watch videos and practice. Drag soldering is fun.

[Anonymous No.1886059]

>>1886050
Thank you anon.

[Anonymous No.1886065]

>>1886059
You're welcome, fren. While you're still here, you should know that desoldering wick is essential (I like NTE), and a solder sucker (or vacuum desoldering tool if you have the spare cash) makes doing things a lot easier.

[Anonymous No.1886115]

>>1886065
>desoldering wick is essential
Maybe for SMT work, but a lot of the time I find a good suck or two does more than enough work on a thru-hole board.

[Anonymous No.1886150]

>>1884620
>Where can I find these suckers for cheap?

use search terms like Alignment Tool Kit or Alignment Trimmer.

[Anonymous No.1886164]

Is it ok to connect this tip to a soldered part? Will that be enough to connect the wire to that point? I just want to check before I solder the part in.

[Anonymous No.1886166]

>>1886164
Sorry what I mean by connect is just letting the tip touch the soldered part.

[Anonymous No.1886183]

>>1886166

often a soldered joint will have a crust of flux or other crud, but if you push it hard, it should make a temporary connection. if the wire is too soft to push hard, then make an indent in the solder joint with some pointy thing.

[Anonymous No.1886186]

>>1886183
Thanks for the response. Yeah the point is rigid since its supposed to be for breadboards.

[Anonymous No.1886215]

>>1886150
thanks fren. Unfortunately, I'm not seeing any dirt cheap grab bags, but at least now I know what to call it
ffs, it's just stiff plastic

[Anonymous No.1886280]

>>1880918
Any /tube/ dudes here? Can any one point me to to resources to learn to design pentode circuits? I am pretty good with triodes and have designed circuits with them successfully, but information about their operation and implementation seems to be much more forthcoming than for their five element brethren. I have something I need to design and build which requires a pentode driver and I could just use some off the rack schematic that every one uses but that isn't any fun for me and I don't like building shit that I don't completely understand.

Thank you.

[Anonymous No.1886343]

Hey guys, I need some high level help.

I got all the shit I need to solder together pic related (at least I think so, pic is from: http://www.synthdiy.com/files/2001/madm.pdf).). I'm going to have my brother (EE-type) help me put together this week, as I've never even soldered before. I'd basically like to work towards building a modular set up, but the very first thing I'd like to do is build a drum machine. So I have a couple questions.

Do I even need this power supply to build a drum machine? I'm following this tutorial: https://www.youtube.com/watch?v=5DKU1m5_b_8, but it's more about building a Eurorack. I play bass so getting a little drummer buddy would be awesome, and I want to do that ASAP.

SO, I started looking around and saw Look Mum No Computer had a pretty cool build: https://www.lookmumnocomputer.com/projects/#/big-button (check the page for the video, towards the end it's pretty sweet). Is this something my planned power supply could play nice with? I'd probably grab something like the arturia keystep or microbrute for a similar MIDI controller.

[Anonymous No.1886345]

>>1886343
Oh, I was also looking at this cute little guy, who may be more within in my budget and tooling ability: https://www.youtube.com/watch?v=ZlRS7v69S70

[Anonymous No.1886381]

>>1886343
the point of that power supply is to deliver regulated (ripple free) +/-12v power to whatever you need. If you already have a ripple free +/-12v supply, you don't need to make your own.
IIRC, pc power supplies have regulated +/-12v power, as well as +5v. So just use one of those. Even a +12v wall wart would work if you put a 10uF electrolytic cap and 100nF ceramic cap from the power supply to ground (bypass caps) to filter noise

It's not really rocket surgery, synths are easy

[Anonymous No.1886389]

>>1886215
go on AliBaba and find a manufacturer that makes them or makes something similar.
use the site to contact the sales rep and tell him what you need. they'll give you a price quote.

[Anonymous No.1886392]

I've been working with through-hole components for years as a hobbyist and have been making and fixing mostly drone PCBs. Now with many PCB houses having the assembly as a service, I've started experimenting with SMT stuff.

But how do these companies make assemblies like this? Where do they find all these connectors, for example? What catalogs do they use? And these wires... god damn... I have hard time finding reliable silicone wires. WTF is this silver shit anyway?

[Anonymous No.1886395]

>>1886392
>>>>>1884979

[Anonymous No.1886462]

Do any of you have a favorite wire-to-board connector?
I've been annoyed enough at bad connectors that I'm willing to shill out for good ones, but I've done a few boards recently where half my BOM is expensive overkill molex stuff. And build quality / how solid the connection is isn't something you can really read off a datasheet.

[Anonymous No.1886467]

>>1886462
1/4" quick connects are great if you can accommodate the size. they use friction retention so they might not be secure enough for your cruise missile or your vibrating buttplug, but i haven't seen one actually come loose.

[Anonymous No.1886477]

>>1886392
There are companies that do nothing but make custom connectors and cable assemblies like this.
Companies you've heard of like Molex also make a ton of different stuff that isn't advertised, but if you are an important customer and ask nicely they will sell them to you. Often it's not "I need connector xyz" more like "I need to carry 12x 150mhz signals at 200ma each and it can be no bigger than 12mm by 5mm" and the company rep says "yeah we got a warehouse of these xyz connectors that should work"

[Anonymous No.1886506]

>>1886345
That's pretty cool. I've been meaning to get into diy synths too. My favorite instruments have always been drum machines.
Fuck I may jump on this train too.

[Anonymous No.1886558]

>>1886462
RAST IDC & JST for low power stuff, disconnects or terminal blocks for higher power applications.

[Anonymous No.1886561]

>>1886506
Yeah that drum machine looks fun, also a nice intro to Arduino’s. I think I’m gonna buy the components for it today.

[Anonymous No.1886602]

>>1886477
thanks anon.
I guess there's a whole submarine industry that only big companies get to work with.

[Anonymous No.1886605]

Why haven't I seen this before?
https://youtu.be/xPBeEi4SE68?t=886

He's doing a solderless circuit on paper where the power rail is just some copper.

[Anonymous No.1886626]

>>1886602
i can imagine that pic being cheaper than wires but it still feels so wrong

[Anonymous No.1886637]

I'm not sure what flux to use. I have both Type RA flux, and a No Clean Organic flux. I'd prefer to use 99.9% IPA for cleaning, but I've read its bad to use that for cleaning the Organic. Also, my solder has a hydrogenated rosin core (supposedly "No Clean").

[Anonymous No.1886640]

>>1886626
>feels so wrong
imagine the waste from the production of that thing... over 90% of the sheet is wasted.

[Anonymous No.1886643]

>>1886637
I'm just going to use the No Clean Flux, and the cleaner recommended in the data sheet (MG 4140), which appears to just be ethanol, IPA, and acetate.

[Anonymous No.1886648]

Sorry I cant post the full schematics or the PCB here but I need to find this part on the PCB.
Any help or guide on how to find this part (or any parts) would be greatly appreciated.

[Anonymous No.1886649]

>>1886648
J3 should be listed on the schematics, that is just showing that those two pins are tied to ground. Those lines meet at that junction, just to make the drawing cleaner.

I'm also a retard but I'm pretty sure I'm correct in this.

[Anonymous No.1886653]

>>1886649
Yeah I need to connect a line to the ground and was suggested to connect it to the circled part.
How does one identify a the trident looking part on a PCB? Sadly the schematic doesnt say what the J3 is.

[Anonymous No.1886654]

>>1886649
>>1886648
Just to clarify this, the 'dot' on the schematic is to indicate the nets are connected, not necessarily to ground (in this case, the net is connected to ground, so it's connect).

Schematics will use a 'dot' to indicate "connect these wires" when the cross. Sometimes you have to cross wires and not connect them on a schematic, using a 'dot' tells the reader "These connect".

If two wires cross on a schematic, it's hard to know if that's just because drawing in 2D is hard or if the wires actually connect. The dot makes it clear they connect.

[Anonymous No.1886655]

>>1886648
Dot just means they're on the same node, i.e. are connected to the same wire

[Anonymous No.1886660]

>>1886649
>>1886654
>>1886655
Original pic poster here. Thanks for the response. I should have been more clear when I drew my circle. I need to find this general area (green circle). How do the trident looking parts usually look on a PCB?

[Anonymous No.1886665]

>>1886660
A schematic isn't a 1:1 visual representation of a circuit. It's just telling you how/what is connected. If you post the rest of the schematic it would be easier to help you.

[Anonymous No.1886668]

>>1886665
I see. I cant post the schematic here so I guess this is the furthest I get. Thank you.

[Anonymous No.1886672]

>>1886668
Look at the PCB for the J3 marking near a 3-legged component or connector with 2 of the 3 traces connected on the board.

[Anonymous No.1886673]

>>1886672
>2 of the 3 traces connected
to the same trace (probably ground)

[Anonymous No.1886677]

>>1886673
the "trident looking parts" is a symbol for chassis ground.

[Anonymous No.1886715]

>>1886673
>>1886677
>>1886672
I have an update. I didnt realize the ground was just located on one of the pins on the power cords. It makes sense since its a chassis ground and I feel like a one digit iq retard for taking this long to figure this simple thing out.
Thanks anons.

[Anonymous No.1886823]

>>1886280
Fun with tubes, Merlin Blencowe, Radiotron Designer's Handbook. Good luck.

[Anonymous No.1886851]

>>1886637
>I'm not sure what flux to use

i'm not happy with the helplessness of questions like this. another dude was asking whether they should use external flux when using fluxed solder, and when to tin a wire.

all these questions are easily answered in 3 seconds of trial and error. try it: if it works, GREAT, if not CHANGE, you fucking la-la mama's boys.

[Anonymous No.1886890]

>>1886823
Thank you. I could probably get away with my incomplete knowledge and some experimenting but I would rather not.

[Anonymous No.1886954]

>>1886851
it's not their fault. they've been raised on fear mongering, advertising, and guilt tripping weak leadership and told to never trust their instincts, only trust what the nice smiling salesman tells you and follow the rules.
Self sufficience is about breaking rules, quesitoning authority, and occasionally setting things on fire. And good little boys don't set things on fire.

[Anonymous No.1886977]

>>1886954
Extremely based

[Anonymous No.1887055]

>it's not their fault. they've been raised on fear mongering, advertising, and guilt tripping weak leadership and told to never trust their instincts, only trust what the nice smiling salesman tells you and follow the rules.
Self sufficience is about breaking rules, quesitoning authority, and occasionally setting things on fire. And good little boys don't set things on fire.

[Anonymous No.1887073]

I want to start using LiPo batteries for my projects so I don't have to run a USB cable to them or jam a stack of traditional batteries inside. What do I need to know to get started? I'm not looking for much, just something that'll power an Arduino and some neopixels to start off with. I've read the link in the OP already so no sense in pointing me to that again.

[Anonymous No.1887101]

>>1887073

kinda obvious choice. 5 volt goodness, ubiquitous, no design needed. useful for all gadgets under the sun.

[Anonymous No.1887112]

>>1887073max current limiting
cc cv charging, max out current and parallel/serial connecting is all you need to know to safely use lipo.

[Anonymous No.1887118]

>>1886626
>>1886640
But it looks so damn good

[Anonymous No.1887130]

finally some time to work on my shit
i finished the case design and i'm printing it now
then i will add the clips and wires inside and it will be done
i really hope i don't electrocute myself

[Anonymous No.1887136]

>>1887101
They're fuckhueg though, and you can get some pretty tiny and cheap LiPo batteries without having to take one of those apart and hope you don't wreck anything in the process

[Anonymous No.1887141]

>>1887101
This, except just buy a lipo or 18650 and solder its wires to a dedicated power-bank-style PCB. The sort that does charging and discharging. Normal lithium ion PCBs do only charge or discharge, not both at the same time. But if you're fine with that and don't need a booster to get >3.2V, simple TP4046 charge modules are dead-cheap.
There's also the option to not include a charger and charge it with a dedicated external lithium ion charger. But that's usually for cases that require balancing (more than one cell in series) and higher-power batteries in general. But they're more finicky, especially about what charge current they're set to and what order you plug them in
On that note, if it turns out that I've permanently destroyed my lithium ion charger due to plugging things in the wrong order, I may just use a single TP4046 to charge each series lipo in my 6S separately.

>>1887130
Shit you're doing this quick as. What do you plan on using for the contacts? I'd want to use something that won't work-harden or wear away from continuous actuation, but still give a real-positive affixation.
You're just using binding-posts for the output, right? I'd consider adding some suppression caps and/or chokes, and a MOV. I'd definitely want to add a PTC thermistor as a resettable fuse, for the situation when too much current starts flowing through the contacts and causes the plastic body to heat up and potentially soften catastrophically. Adding a GFCI circuit to it somehow would be ideal for safety reasons, but that would complicate it stupidly.

[Anonymous No.1887155]

>>1887141
>What do you plan on using for the contacts
springs
there won't be anything extra as far as wiring goes it will simply work as a switch, just like the original, i will maybe add a fuse like the original has if i'm not too lazy

[Anonymous No.1887362]

>>1886890
No worries m80, also check out >https://mysite.du.edu/~etuttle/electron/elect27.htm
>Cool386 if you're into radio
Also, don't be afraid to experiment man. What kind of power supply are you working with? Elliott Sound Products has a very useful and basic high voltage supply on his project pages; couple that with a pre-regulator and capacitance multiplier you can get rid of the shitty, expensive choke and the performance will beat something like a griefkit turd. Using an IRFP460 for the pass transistors and a horizontal output transistor for the cap multiplier makes it easy to get stupid amounts of power.

[Anonymous No.1887448]

Does an external module exist that can turn your oscilloscope into a spectrum analayzer?

[Anonymous No.1887460]

I have an old, like suuuuuuuper old probably 50 years old dehumidifier that was plugged in in this place I'm renting, it worked fine few weeks ago, I went to go plug in earlier today and I felt my whole right arm go numb and vibrate when I turned it on? I assume it was a shock, it felt like my arm locked up, then after like 3 seconds my arm was fine? Is this worrying? It's been about 2 hours, just wanted to ensure, I should be fine to avoid going to ER or anything correct? I feel perfectly fine, just wanted insight I haven't been shocked like that often hence why I'm not even sure if it was a shock although pretty sure it was. The only shocks I know are like little pricks on fingertips which hurt. This didn't hurt it just vibrated and numbed my arm, kinda felt like it locked up but not really. Again am perfectly fine now.

[Anonymous No.1887462]

>>1887362
I was going to use an antek toroid, 300V, 50VA, with a full wave bridge. Should be sufficient for my needs. I've never had problems with this sort of setup before and I like the simplicity.

[Anonymous No.1887465]

>>1887448
brief googling suggests that you can dump your scope's memory over its ethernet or usb ports, or at least that's evidently true for the ds1054z. then you could easily write an fft and gui for your pc. i think you'd have to find some gay dsp library to lpf the raw data too.

[Anonymous No.1887475]

>>1881810

this better be ironyposting you faggot nigger

[Anonymous No.1887490]

>>1887448
What exactly are you expecting? No, you can't just plug some $10 chinkshit into your shitty 50mhz scope to turn it into a $20k spectrum analyzer. I suppose you could put a frequency mixer on it to display higher frequencies, but it probably won't be very helpful unless you know what you're doing.
>>1887465
ds1054z (and most decent scopes) already has an FFT feature, you could just turn it on if that's what you want

[Anonymous No.1887655]

>he doesn't have a live optical fourier transform connected to his analog scope screen

[Anonymous No.1887672]

>>1887655
>his scope doesn't have wireless probes

[Anonymous No.1887716]

>>1880918
Whats a good setup and projects for beginners? Im more interesting in mechanical side of electronics like motors, servo systems, and the like.

[Anonymous No.1887718]

>>1886345
Gonna build this, why is the teensy 3.6 so expensive though? Can I replace it with something else?

[Anonymous No.1887719]

>>1887716
get an arduino, a uln2004 board, and one of these chink stepper motors off ebay. electromechanics aren't cheap so start small and read your theory.

[Anonymous No.1887821]

an exposed 3.5mm plug like in pic related seems slightly unsafe to touch. but assuming the current is negligible and the voltage also negligible, it shouldn't hurt to touch it, right? and i currently do not have a multimeter on hand to measure the current...
please correct me if i am wrong

[Anonymous No.1887866]

>>1887821
Anything under 24V you certainly won't feel. Up to 36V or so is considered certainly safe. I start noticing a voltage at around 50-60V. 3.5mm headphone jacks usually use around 0.1-1V, less than any common battery. While it's AC and not DC, it still doesn't make enough of a difference. You'll be fine to touch it.
Though personally I'd flood the thing with epoxy (or hot-glue or whatever) to ensure the wires don't short and to give some strain-relief.

[Anonymous No.1887906]

>>1887821

[Anonymous No.1887941]

What desktop power supply should I get?

[Anonymous No.1887962]

>>1887906
As long as you don't start sucking it off it'll be fine.

tongue is 6kΩ
A wrench essentially has no resistance
Skin is around 100kΩ

You can grab both ends of a 9v battery, rub it on your balls, do whatever and you'll feel nothing. Grabbing both ends of a car battery does nothing either.

Regardless >>1887866
>Though personally I'd flood the thing with epoxy (or hot-glue
is correct

[Anonymous No.1888079]

>>1887821
>an exposed 3.5mm plug like in pic related seems slightly unsafe to touch
you have to be 18 to post here. please find a kid safe board.

[Anonymous No.1888146]

How do you debug without serial. I need to test if I configured my adcs correctly.

[Anonymous No.1888194]

>>1888146
LEDs

[Anonymous No.1888198]

>>1888194
I was thinking of that. But its a 12bit adc and getting that information wouldnt be fun. Im probably just going to send a pulse to an esp32 and have that print to serial.

[Anonymous No.1888214]

>>1887490
I'LL HAVE YOU KNOW FAGGOT THAT MY SCOPE IS 200mHz!

[Anonymous No.1888234]

>>1888214
>mHz
wew

[Anonymous No.1888264]

I'm still learning about electronics. I've got a little audio amp (LN 386N) on an old computer (Otrona Attache). The schematic says that it's output hooks to the computers main connector that moves all the voltages around (J501). Also in line with the output is a 10 ohm resistor connected to a .047 uf cap then to ground. I slipped my multimeter and discover that audio out on the connector is shorted to ground. Is it normal for the little voltage used by my multimeter to tell if something is open or shorted to get through both these components, or would be a different problem?

[Anonymous No.1888301]

>>1888264

[Anonymous No.1888339]

>>1888264
If the output is shorted, check wires and connectors, solder joints, and replace C506 & C504. If that doesn't help, the LM386 is bad.

[Anonymous No.1888371]

>>1888264

if there's a speaker connected, you might be reading the resistance of the speaker, which could be very low, like 3-4 ohms on DC. this would look like a short to a noob.

[Anonymous No.1888372]

>>1888371
>>1888339
Alright thanks anons I'll check this stuff out

[Anonymous No.1888448]

anyone that posts on /tv/ will find that they have to reboot their modem on occasion. i got sick of that so i made a wireless switch with an esp8266 and other trash i had sitting around. it'll regularly read a flag off my webserver and power cycle the modem if the flag changes. it's meant to be controlled by a script that also clones the router MAC and clears cookies. i haven't spliced it into the modem's wall wart cable yet but it works on the bench.

i learned from this that you can use a sot-223 as a through hole part if you're aggressive enough. you can see it cowering under the esp.

[Anonymous No.1888450]

Additive synth anon here again. I just realised that instead of adding a bunch of waves of harmonic frequencies, with differing phase shifts and amplitudes, you could equally add a bunch of waves of the same frequency, with differing phases, duty-cycles/skews, and amplitudes. With square or triangle-sawtooth waves, not sines. You’d still need the complicated phase shifting stuff, but not the frequency multiplying PLLs, hence no need for a bunch of VCOs with JFETs or vactrols or whatever. Anyone seen a circuit like this before? Not sure what a variable skew triangle/sawtooth addition would look or sound like though.

[Anonymous No.1888464]

>>1888450
You could use a quadrature oscillator and then adjust the mix between in-phase and out-of-phase components to get a variable phase shift.
I'm doubtful you'll get as wide a range of timbres out of this, but I'd be curious what sounds it's capable of.

[Anonymous No.1888538]

>>1888464
Yeah but that only works with sines, and they’re near impossible to alter the frequency without altering the amplitude. I already have a triangle-wave-based solution for phase shifting, just shift a couple of comparators within the range of the triangle wave with pots, and use them to set and reset an SR latch (plus some edge-triggering circuitry). Adding a couple of spiky peaks atop the triangle wave to stop the comparators from missing their trigger entirely helps. Driven with an integrator+Schmitt trigger oscillator.
To get a 50% duty cycle (as in my previous design) you set one comparator threshold voltage to be the inverse of the other (with an inverting amp or double-gang pot or whatever), but for this I’d just have a seperate pot for each.

[Anonymous No.1888563]

>>1888538
Actually maybe I’d want to create a 3-level symmetrical (i.e. odd harmonics) return-to-zero wave like inverters will do, using four comparators and two latches. Both pairs of comparators always triggering on opposite points just like what I described for the additive harmonic synth.

[Anonymous No.1888587]

>>1888448
>you can use a sot-223 as a through hole part if you're aggressive enough.

it's not like you invented anything new. transistors have been bending the knee for thousands of years.

[Anonymous No.1888629]

>>1888448
>webserver
Why not just use a 433MHz module and not faff about with all that? Could use a lot less power too, and it's not like it needs to have a global range or anything. If you have the webserver do the other shit like the MAC and cookies then it makes more sense. I guess you're just powering it off the DC input? Guessing there's both a linear regulator and a MOSFET in there? Better be doing low-side switching.
>sot-223 as a through hole part
I'm more fond of the other way around, using DIP14s as DIIC14s, using TO92s as STO92s and the like. Hand-etched PCBs beat protoboard, and if you do full-SMD then you don't need to worry about plated through-holes. Even with a 2-sided board, you can do vias with copper wire and still not worry about through-holes. Haven't yet made 2D footprints and 3D models for KiCAD yet though.

[Anonymous No.1888733]

>comparator setup has output voltages that aren't quite symmetric about 0V
>integrator thus has slightly different gradients on its wave
>schmitt trigger thresholds at slightly different levels
>resulting triangle wave oscillator isn't centred about 0V
>my voltage threshold mirrors don't work properly
This is all in a simulation, but I imagine it will be an issue IRL too, perhaps even with a rail-to-rail comparator. I could just add a couple diodes and resistors and call it a day, but I think that would need buffering, and my resulting frequency would still be somewhat dependant on the supply voltage, so I figure I should use some actual voltage references as a part of my schmitt trigger. I have some TL431s, but I'm unsure how I'd create a schmitt trigger that just bounces its output between two voltage references. I think the most feasible option is with an op-amp or two on the output of a normal schmitt trigger, alongside some diodes to make a pair of greater/less-than gates, but I'd still have slew rate to worry about.

[Anonymous No.1888736]

Looking for advice on a good high power lamp.
I like going out in the fields / woods at night and looking at the wildlife so want a fairly high power light.
I've been getting a few of the cheap CREE knockoff flashlights like pic related and although they're decently bright, the batteries last like 10 minutes.
I've tried modifying a few to plug into my 10000mAh USB power bank and they work for a while but eventually burn out (I think there's a shitty PWM circuit in them that goes bad and causes the lamp to flash eratically)

I've been thinking about maybe making something myself but wanted some advice.
I'd like something that I could recharge (Are sealed lead acid batteries a good idea?)
I'd be using a fairly high power COB so I'd need to step up to 36 or 52V.
Ideally I'd want to be able to just use conduction to keep the COB cool.

Or if anyone would could recommend a decent off the shelf light that can hold a charge for an hour or two.

[Anonymous No.1888739]

you know that "thummm" noise a crt makes when you turn it on? how would i recreate that sound with an analog circuit? would i need a vacuum tube?

>>1888736
>pwm
might be because youre running a 3.2-4.2v circuit on 5v
diyperks on yt has made a few cob flashlights, probably plenty of other examples too
lead-acid is heavy so probably not what you want for something even remotely portable, go for lithium

[Anonymous No.1888745]

>>1888739
Cheers, I'll take a look.
Majority of stuff I could find on youtube was like "look at this thousand watt portable sun I made that needs liquid cooling and has a battery life of pi seconds"

[Anonymous No.1888762]

>>1888745
>look at this thousand watt portable sun I made that needs liquid cooling and has a battery life of pi seconds
sorry thats what i was referring to
but any 50w cob is going to have that kind of effect
20w should be acceptable with no fan at all, but it still might get too hot to touch, making mounting difficult
most professional high-power torches have heat-sink fins built into the aluminium case for a reason

what kind of form factor are you aiming for?

[Anonymous No.1888765]

>>1888762
Pretty much a standard flashlight or a spotlight style one.
Remember 15 years or so ago you could get spotlights, they'd be rated as like 1 million candlepower or whatever.
I had a six million candlepower one in my teens and it was stupidly bright.
I'm assuming they were halogen bulb or something but they don't appear to exist anymore.
At the time, every petrol station used to sell cheap ones

[Anonymous No.1888830]

>>1888739
>you know that "thummm" noise a crt makes when you turn it on? how would i recreate that sound with an analog circuit?
degauss circuit

[Anonymous No.1888973]

Very basic questions. Typically people replace the capacitors on older electronics (computers, game systems) they want to preserve since they leak.

Two questions: Is this a problem still with new electronics? (aka will I have to recap a current compy I like?) Second, when you recap an old device, how long until I should recap it again or are good modern capacitors generally considered permanent fixes? Thank you

[Anonymous No.1889023]

I don't know if I should bother asking or wait for the thread to die

[Anonymous No.1889026]

>>1888973
electronic components have a MTTF or MTBF (mean time before or to failure)
the only device I had to change capacitors was the integrated psu of my monitor somewhat 7 years after purchase and only when it started flickering 10 mins after each power on.

[Anonymous No.1889059]

Whats the quickest, most compact way of cutting 5v to like 1.5v
AKA going from High pin to Low pin signal, without using a buck converter board?

[Anonymous No.1889063]

>>1889059
I have half idea, voltage regulator?

[Anonymous No.1889064]

>>1889059
Is this is for digital signals and not power?
If you just need to do signal level conversion, you can go with the classic bidirectional mosfet level shifter.

[Anonymous No.1889066]

>>1889064
Here’s a single supply version, although the low side is biased for 3.3 volts, so you’ll need to re-work the voltage divider.

[Anonymous No.1889070]

>>1889064
im >>1884930
I ordered a pulse generator board and a buck converter to cut my power supply from 32v to 5v for the pulse board
The driver requires a high and low pin signal to actually pick clockwise and counterclockwise rotation though, so im trying to figure out a way to simulate high and low signal

I should be able to send 5V to it for high signal, then cut it below 3 for low correct?