/ohm/ - Electronics General: Prototyping Edition

[Anonymous No.2701116]

Thread revised:>>2693432

>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.

>Incredibly comprehensive list of electronics resources:
https://github.com/kitspace/awesome-electronics
Additional resources below:

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

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

>Archive of Popular Electronics magazines (1954-2003):
https://worldradiohistory.com/Popular-Electronics-Guide.htm
>Microchip Tips and Tricks PDF:
https://ww1.microchip.com/downloads/en/devicedoc/01146b.pdf
>Li+/LiPo batteries required reading:
https://buster-spb.ru/files/SAFT/li-ion_user_manua.pdf

>Books:
https://libgen.rs/

>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 (arguably has minor issues with mains grounding)
Horowitz and Hill, The Art of Electronics

>Recommended Design/verification tools:
KiCAD 6+
Circuitmaker
Logisim Evolution

>Recommended Components/equipment:
Octopart
eBay/AliExpress sellers, for component assortments/sample kits (caveat emptor)
Local independent electronics distributors
ladyada.net/library/procure/hobbyist.html

>More related YouTube channels:
mjlorton
jkgamm041
EcProjects
Photonvids
sdgelectronics
paceworldwide

>microcontroller specific problems?
>>>/diy/mcg
>I have junk, what do?
Shitcan it
>consumer product support or PC building?
>>>/g/
>household/premises wiring?
More rules-driven than engineering, try /qtddtot/ or sparky general first
>antigravity and/or overunity?
Go away

[Anonymous No.2701124]

>>2701116
That's a pretty cool looking board, Anon.

[Anonymous No.2701128]

Does anyone recognize this connector? It's off of my 3d printer extruder motor. I thought it was a JST connector but its too small. Ruler included for dimensions

[Anonymous No.2701136]

>>2701128
Maybe A2001(ph)

[Anonymous No.2701140]

what is this?

[Anonymous No.2701150]

>>2701140
Guessing it's a solenoid but idk.

[Anonymous No.2701199]

>>2701140
Probably showing what the connector looks like?

[Anonymous No.2701212]

Can one side of a transformer be used as a big ass inductor or the other coil is open?

[Anonymous No.2701239]

>>2701212
Yes, though silicon steel laminations aren't very good at high frequencies. Toroidal mains transformers may be better.

[Anonymous No.2701273]

Here's a power latch circuit I made. I just realised that when the FET is turned off, the op-amp's power rails are both at +BATT, and so it might pull the gate high. With a low enough value pull-down resistor R15 this shouldn't be a problem, but such a resistor means pulling the op-amp's output low via a resistor, which may or may not be bad for it.

[Anonymous No.2701324]

>>2701116
Im planning to make a remote controlled car.

How does store-bought ones work? How do I communicate between the remote and the car as simply as possible?

I've got a PS1 controller that I thought I could possibly use although I dunno how. I could easily find some alternative though.

[Anonymous No.2701326]

>>2701324
No, acctualy, using a PS1 controller seems cool and all but its above my skill-level to make it usable for this project. Im guessing, at least

[Anonymous No.2701330]

>>2701324
Most basic ones use something like PPM to modulate servo positions like in pic related. You need a RF oscillator, usually at 27MHz which you modulate with PPM and then decode at receiver. This is the old school way of doing this. Newer 2.4GHz modules use more advanced modulation schemes. You can also just use any of the shelf RF modules for le arduino and send digital packets to the receiver.

[Anonymous No.2701379]

>>2701326
You could take the PCB from a generic remote control and directly wire it to your PS1 controller buttons and sticks if you don't want to get deep into it. You might have to remove the rumble motors to make room.

[Anonymous No.2701390]

>>2700540
I've redesigned DC-DC a bit.
Now idle current is 1 mA instead of 10mA.
Load current is now 13 mA instead of 30 mA.
I've tried it before, but capacitors I salvaged were wrong capacity and since I didn't measure It never worked. lol.
But since I didnt calculate jack shit, well...

Doesn't seem to affect DMM accuracy, even on capacitor range (comparing this PoS DMM with Unit 210E clamp)

Should last more than 40 days of battery now. Which is shit result cuz microamps is where all shit at, but no microamps in romania

[Anonymous No.2701394]

I’m trying to understand how amp-hour and voltage work
I have an old video camera that runs on a 12V2Ah battery, how can I determine how much useage I can get on a full charge? Do I measure the amp draw when it’s on?
I’ve been able to get about 30 minutes out of it before it dies out but it seems criminally short

[Anonymous No.2701395]

>>2701390
I can hear it on AM radio too, like 4-5 cm away, I think its OK in terms of RFI.

[Anonymous No.2701399]

>>2701394
Yes, you measure average current draw when camera is operating. Then you calculate run time by noticing that
>battery has 2 ampere · hours capacity
>this means you get out of it 2 ampere · hours / x amperes = y hours
>where x is measured current draw and y is expected run time
This is only an approximation as actual run time will depend on health/age of battery, temperature, current draw...

[Anonymous No.2701417]

>>2701390
Reminds me of the black regulators
https://www.romanblack.com/smps/smps.htm
Simple, robust, low/cheap parts, easy to understand & fix

[Anonymous No.2701419]

>>2701394
Try closing the view screen or making it as dim as possible. I found that I could extend the life of the battery quite a bit.
Also, mine (sony handicam) can run indefinitely with the battery charger plugged in, so I can just use an external battery pack.

[Anonymous No.2701425]

>>2701212
Yes you can get a shock by touching the windings with a nine 9v battery and then disconnecting it while touching the two wires with your finger when the field collapses.

Probably better without the secondary winding, however, I suspect it would mute the emf to some degree.

Mostly it would be useful for limiting current (ballast), not as an RF choke.

Is this a MOT? I think those have shunts, but I’m not exactly sure what they are for… I’m guessing those harm the inductive effect. Also the windings are aluminum so induced eddy currents would turn into heat due to resistivity.

[Anonymous No.2701428]

>>2701395
> hear it on am radio
You could use that effect to make a remote(!) digital display of the performance after characterizing the freq and amplitude using a microcontroller.

[Anonymous No.2701450]

>>2701330
be kinda fun to make this with digital logic

>>2701390
see if you can steal a tl431 from an old smps too
maybe even a tl494

>>2701394
measure the amp draw
either it's about 4A (2Ah / 4A = 0.5h), or your battery is fucked, probably the latter

[Anonymous No.2701456]

>>2701399
Thanks I’ll do some measurements
>>2701419
I have a wall plug for this too for always on AC power, but there are times when I’m out in public
>>2701450
It’s a brand new battery, surprised they still make them for this vhs camera. Once I figure out the draw it probably drains fast because I do a lot of short burst recordings of a few mins at a time which means a lot of startup draw over and over

[Anonymous No.2701527]

>>2701428
Frequency is all over the place and depends on input voltage greatly.
So it's probably better to build a proper transmitter for this.
>>2701417
This one isn't that easy to understand. It's a joule thief circuit okay, but what's the frequency, does capacitor or resistor or both determine it.... What affects the oscillation at all

But once you figure it out, you can compete with Chinese switchers, you know, those death trap ones

[Anonymous No.2701528]

>>2701527
Like, what causes transistor to close? Core saturation? Doubt. So then what. Blocking generator is pain

[Anonymous No.2701678]

Just fuck my shit up OOH FUCK

How do I fix a PCB in KiCAD if I put the components in the wrong order in the schematic and now the connections are all wrong?
I don't want to rearrange everything

[Anonymous No.2701697]

>>2701678
If the footprints need swapping for one another, I'd want to swap them in the schematic instead of on the PCB. Worst case you might be able to propagate changes backwards by renaming footprints, but that's funky. You can select and delete all traces by doing the following:
>select all via ctrl + A
>right click
>Select
>Filter Selected Items
And so on.

You can also select all traces between two components by using the U hotkey, which is handy.

[Anonymous No.2701699]

Sources online are telling me you're best off building a constant current source with an adjustable voltage regulator. I'm just not entirely sure why this is.
With a fixed voltage regulator, I can just divide the output voltage by the resistor value, to get the current, and assume that it'll stop regulating when the output voltage reaches a certain value.
Am I missing something? Or am I interpreting things wrong?

[Anonymous No.2701701]

>>2701140
looks like a reverse polarity protection diode

[Anonymous No.2701702]

>>2701699
They both work basically identically, aside from two differences:

Firstly, adjustable regulators are designed to operate without their central terminal connected to a low-impedance path to ground, so arguably they may be designed to be more stable in such a configuration. I kinda doubt it's significant though.

Secondly, adjustable regulators are frequently lower voltage than adjustable versions, so you have a lower inherent dropout voltage and less power being dropped across the current-setting resistor. While this is the case in the most common regulators (7805 vs LM317) this doesn't really apply for something like an AMS1117. Though I'd still recommend getting the 1.25V adjustable version over the 1.2V set version just because it's more useful for other stuff. Though maybe you could get away with using the 1.2V one as an adjustable constant-voltage regulator, see point one.

Also this should go without saying, but linear regulators are not perfect for this. They get hot, have somewhat high dropout voltages, and have somewhat low maximum voltages. Constant-current switching regulators and op-amp+BJT regulators may well be the better option, or even just resistors if current isn't critical, depending on your circumstances. Linear regulators seem to fit the specs:
5V < Vcc < 36V
I < 1A
n_parallel < 4
For higher voltages you want BJT-based, for higher currents you want switching, and for high parallel counts you want something passively balancing using resistors or current mirrors. Though there are dedicated LED driving linear regulators that can handle much higher voltages, like the KP18001 or SM2082GA, which can conversely also be used as voltage regulators. Available from LCSC.

[Anonymous No.2701705]

>>2701702
This is awesome, thanks a lot. The list of alternatives gives me a lot to work with, I'll dig into those. I'm just wondering a few things with your explanation:
>this doesn't really apply for something like an AMS1117
Why, exactly? What should I look out for with such regulators? That said I guess I should just use the adjustable version with these, but it might help explain what I'm seeing.
>n_parallel < 4
Not sure what you mean with "parallel" here, I'm thinking of using a bunch of them to power different loads, not the same load.

[Anonymous No.2701706]

>>2701330
Neato, I might just use Arduino since it feels more versatile

[Anonymous No.2701714]

>>2701705
>Why, exactly?
Because it has fixed-voltage versions down to 1.2V. If you're stuck with old regulators like 7805s, obviously you don't want to be wasting 7V with your regulator (5V plus 2V dropout) if an LM317 can do it in under 3V (1.25V plus ~1.6V dropout on a good day). But the AMS1117 adj and 1.2V versions beat both and are pretty similar, hence why it's not a worthwhile distinction to make in this case.
Though I will note that the TO-220 package of a 317 will be able to handle more power than the SOT-223 of the 1117.

>Not sure what you mean with "parallel" here
A common use of constant-current supplies is powering LEDs. If you have 12V to work with but 21 3V LEDs, chances are you'll end up running 7 parallel strings of 3 series LEDs each. While the typical method is just to use resistors, if you want better regulation you can use a BJT current mirror to feed them all the same current. Or use small balancing resistors on each string to connect them, and a single current regulator on the lot. In your case it probably doesn't apply.

[Anonymous No.2701718]

>>2701714
>Because it has fixed-voltage versions down to 1.2V.
Oh, that's what you meant. I misread the message.

The rest makes sense now, thanks again.

[Anonymous No.2701722]

>>2701697
Yes, but it doesnn't do anything. If I click on change PCB from schematic it doesn't do anything, even after painstakingly renaming every component.
Looks like I'll have to recreate the PCB from scratch

[Anonymous No.2701724]

>>2701722
AAAAAHW GOD
now it fucking overwrote the fucking changes in the schematic FUCK this pos

[Anonymous No.2701729]

How stupid is it to design and put together my own bldc motor esc?
I want one that can handle 6~8s at low current for long range rc plane flight.

[Anonymous No.2701777]

>>2701701
Idk, it has no diode markings

[Anonymous No.2701833]

>>2701702
I think I’d summarize that with
For diy you’re almost always better off with the adjustable version. Period. Unless you’re making dozens of these, or you’re making a lot of, say, TTL boards and are lazy, or you can’t afford 2mm2 space for the extra sense resistor.

[Anonymous No.2701838]

>>2701777
Looks like the “no clean” flux needs to be cleaned off.

[Anonymous No.2701865]

So this is sort of cool. This is a disassembled exterior light stake from the dollar store. So for $1.25, I get a solar panel, a NiCad battery and an LED circuit.
I’m thinking about using three of these to power an Arduino nano. I assume I don’t need any charging circuitry for this, since the light panel outputs about 2.2 V in full sunlight. Is there any issue with a solar panel, consuming power, or is it just one big diode type element?

[Anonymous No.2701927]

>>2701865
Assume this is adequate circuitry for this thing. The solar cells generate ~2.2V in full sun, so I'd use 3 of them. Current output I assume is low, so no need for anything fancier to balance/limit the charge. Current hookup is 1 cell to 1 battery, but that seems overly complex, vs just connecting the solar cells in series and using them to charge the whole thing.

[Anonymous No.2701938]

>>2701927
Vin will only accept voltages above ~6-7V, because it's a 5V linear regulator. The smarter method would be to just connect them directly to the 5V pin, assuming the NiCd cells will clamp the voltage to no more than 5.5V. Could drop to 2xPV 3xNiCd if it isn't clamped, or just use a clamping zener. An Arduino Nano can run on a Vcc of anywhere from 2.7V to 5.5V, though at a lower voltage I doubt the CH340 will act properly, and you may need to turn down the clock frequency in the fuses. I'd also desolder the power LED or its resistor, it burns like 2.5mA constantly so it's bad for battery powered projects where you're making the MCU sleep.

[Anonymous No.2701946]

>>2701938
OK, I was wondering whether Vin or 5V would be the better point to go in. I didn't realize the 5V pin on the Nano would take undervoltage down to below 3V.
I'll check the Vout on the solar panel + batteries once it's built. My assumption is the batteries will clamp the solar power voltage down but it's an easy check.

[Anonymous No.2701965]

>>2701946
Hey, I also just made a battery holder for my project.

[Anonymous No.2701969]

>>2701965
Looks nice. What does it do?

[Anonymous No.2701980]

>>2701965
Nice.
I reverse engineered the stock lamp holder for 4 cell. Parametric design, so can make it 3x if I want. And 3D print them in about an hour.
Being able to design and 3D print circuit holders and cases on the fly is transformational to doing electronics projects.

[Anonymous No.2701985]

>>2701969
Milli-ohm meter, just assembling it now. We'll see if it works, I didn't prototype this circuit, just the previous one that required a higher voltage.

[Anonymous No.2702013]

>>2701985
Good luck. It'll be a nice addition to your toolkit if it works.

[Anonymous No.2702023]

>>2701985
>it doesn't work
fug

Ok so there's two parts to the circuit, one is the current source (Q1,2, U2A, resistor networks), the other is the battery cutoff circuit (U2B, Q3). Firstly, the battery cutoff circuit doesn't latch on. Even though the divided battery voltage is higher than the 1V divided reference, the FET somehow turns off as soon as I take my finger off the button. Gotta scope that to find the issue later.
Secondly, while the current source seems to work at 10mA, for both the 100mA and 1A settings it falls drastically short, getting only up to 36mA and 40mA respectively. Also the divided voltage reference drifts up from ~1V to ~2.5V on these higher current settings, no clue what's going on there.

Knew I should have used a PFET.

[Anonymous No.2702027]

>>2701980
What kind of materials are suitable for the contacts? I considered using copper tape but just ordered a holder as part of an order anyway. Perhaps cutting smart pieces from tin cans for protoboard mounting could have worked. A couple of triangular flaps bent backwards for support, through-hole pin and another flap on top bent down to act as a spring against the battery.

[Anonymous No.2702034]

>>2702027
It's best to just buy spring contacts in bulk, or extract them from battery holders or toys or whatever. Anything else won't have the springiness and strength. You should be able to get away with spring steel (I have a bunch from a vacuum cleaner's internal spool) but it's a pain to cut and form. Drilling it is a no go, so you'd have to make it captive some other way. Otherwise I can think of using a seperate material for the spring and for the contact, maybe a piece of FR4 or sheet metal or whatever backed by a printed TPU buffer. Nickel plate whatever you use for corrosion resistance.

[Anonymous No.2702046]

>>2701927
>>2701390
You need this. Dodgy PSU.

[Anonymous No.2702062]

>>2702027
I will steal them from the devices I'm tearing down, and designed the holder to use those parts.
That said, there are designs on thingiverse that make the plastic the spring, which allows you to use copper as the battery terminal.

[Anonymous No.2702064]

>>2702062
https://www.thingiverse.com/thing:456900
Says use abs but I've made plenty of flexible things with pla.

[Anonymous No.2702089]

>>2702064
Looks good, thanks!

[Anonymous No.2702119]

I've been thinking. I want FM headphones, and FM transmitter that is powered just from audio jack.
How the fuck do I get power from it? Make computer play 20 000 Hz sine (or more if possible), and then have a high pass filter that feeds transformer, which is used to step up 2 Vpp to smth more higher I can use for driving NPNs easily?

[Anonymous No.2702130]

>>2702119
There are radio soldering kits with a 3.5mm plug and 9v battery connector everywhere. Check your local supplier.

https://www.instructables.com/Easy-and-low-cost-FM-transmitter-DIY-kit/
https://www.aliexpress.com/item/1005002311533080.html

[Anonymous No.2702138]

>>2702130
> 9v battery
you don't seem to understand. I want to power the transmitter from the audiojack. You can extract quite a bit of power from it.
50mW. Plenty enough to power single transistor oscillator of any kind and since most BJTs act a bit like varicap, u can adjust bias with your audiosignal to make FM.

[Anonymous No.2702205]

>>2702119
>powered just from audio jack
Never seen that done before, I guess you'd have a resistor, followed by a pair of diodes to make a positive and negative rail. If the resistor is too small, it will start to distort the incoming signal, but if it's too large it will limit the available power too much. Maybe an inductor will work instead of a resistor.

[Anonymous No.2702209]

>>2702119
The (in)famous, justified and ancient rohm BA1494 only needs 3 mW and a 1.25 V supply. I’d just use that.

I’d probably try and charge a tiny supercap, maybe you can forget about the lossy high pass filter altogether, although the music would “fade in” as it built up charge.

[Anonymous No.2702210]

>>2702119
>>2702119
The (in)famous, justified and ancient rohm BA1404 only needs 3 mW and a 1.25 V supply. I’d just use that.

I’d probably try and charge a tiny supercap, maybe you can forget about the lossy high pass filter altogether, although the music would “fade in” as it built up charge.

[Anonymous No.2702218]

>>2702205
>Never seen that done before
Exactly. Which is why I want to try. Even if it would have shitty range, its a cook gimmick.
>, I guess you'd have a resistor, followed by a pair of diodes to make a positive and negative rail
Problem is that audio signal is like 2 Vpp. After diode you'd have 1.2 V. And if you have any sort of capacitors, you get distortions, because headphone output has somewhat high impedance, like 50 ohms or so.

Originally I had a great idea to use some sort of shitty power supply. Joule thief (blocking generator) can run with voltages as low as 0.3V if feedback coil has more turns, but then I just realized I can cheat and just wind some sort of low pass (or high pass, cant really fiugure out what I need) for 18kHz or 20kHz, make laptop play that frequency and make transformer produce higher voltages, like idk, 2 or 3 volts which you can rectify to smth more reasonable and then place the transmitter.
Idk. Blocking generator SMPS idea sucks too, because if you put capacitor and diode on the audio side, you get distrotions due to... shit powerfactor? lol. But okay, you can just not put capacitor, and put in on the output, but then shit sucks too dont remember why.

But im pretty sure it is possible. 50 mW of powah. Transmitters consume less than that (maybe 10mW), and shit all over the house no problem.

Other way is to ditch silicon entirely. Find some oldfag, break in his house, threaten with knife, steal all his germanium diodes and transistors...

Also, what about JFET, what kind of threadshold voltage do they have? Maybe they are better suited for this shit than BJTs.
>>2702210
That's a pretty nice IC. I wonder if I can get it somewhere cheap, or modern alternatives.

[Anonymous No.2702230]

>>2702210
>these things are sold locally for $11
hm

>>2702218
>After diode you'd have 1.2 V
>0.4V per diode
You thinking of using germanium diodes? Because at the 1-10mA range a silicon diode is going to be 0.6V at least. Schottky diodes might be better for forward voltage (0.25V or so), at 25C reverse leakage should be down in the tens or even ones of µA.

There might even be enough voltage to run a synchronous rectifier using very low threshold-voltage MOSFETs, though at that point you'd just make a switching regulator.

[Anonymous No.2702244]

>>2702230
>You thinking of using germanium diodes?
They are kinda hard to get.
> at 25C reverse leakage should be down in the tens or even ones of µA.
Maybe.
Idk.

[Anonymous No.2702253]

>>2702218
Generate a sine wave at high amplitude over one audio input channel and use that for your transmitter power supply.

[Anonymous No.2702281]

>>2702210
>BA1404
> G Forrest Cook had(has) an entire website devoted to the BA1404. I was an early enthusiast, hearing about the BA1404 from Don Lancaster's Hardware Hacker column in Radio Electronics/Electronics Now magazine in the late 80s.
> June, 1992 edition of Radio Electronics has the "ultimate" BA1404 circuit in Lancaster's column, on page 72 - it's almost verbatim, the Pioneer CD-FM-1 CD-to-FM modulator.
> G Forrest Cook's website: transmitters.tripod.com/links.htm

Really miss internet 1.0. It wasn't as flashy but the information it had was way better. Always wanted to build a pirate FM transmitter, but I think we're well past the time of relevanance.

>>2702034
Got curious and started looking. For AAA-type clips you can source them though AliE for ~10cents a clip, already formed and ready to solder up, in a few different configurations. It's def'n one of those things that's easy to steal out of devices you're tossing for whatever reason.

[Anonymous No.2702289]

Does any one know about how loads depress cell potentials?
If I have a cell under constant charge and load, I know I can't trust the measured cell voltage; It'll increase if the load is removed, and decrease if the external voltage is removed. What equations should I apply to predict how the cell responds though.

[Anonymous No.2702306]

>>2702289
Batteries can be modelled as a voltage source in series with their internal resistance. In picrel, Vin is the unloaded voltage (determined by the cell chemistry) and R1 is the internal resistance. The load resistance is then modelled as R2.

[Anonymous No.2702335]

>>2702306
Thanks for the tip. If I understand this properly, the cell voltage can't rise above potential measured over the load, since the load's effective resistance is greater than the cell's internal resistance under normal circumstances.

[Anonymous No.2702373]

>>2702335
>If I understand this properly,

nope.
typ cell internal resistance is a fraction of an ohm.
loads tend to be in range 10-10000 ohms.
open-circuit voltage is always higher coz there's no voltage loss thru internal resistance.

[Anonymous No.2702386]

>>2702373
>typ cell internal resistance is a fraction of an ohm.
>loads tend to be in range 10-10000 ohms.
That's what I'd expect, yeah.
>open-circuit voltage is always higher coz there's no voltage loss thru internal resistance.
I mean in the case where an external voltage is applied to the load+cell from an external voltage source (i.e. an adaptor).

[Anonymous No.2702390]

thank you for recommending me the dunlop picks they proved very handy they're good

[Anonymous No.2702410]

Guys I've got 4 of these NEC k3793 MOSFETs inside a Mazda piezo ecu and all 4 of them got no hint of continuity between gate and either drain or source. I think they're toast. On the ohmmeter it reads ol not even mega ohms or smth. Am I wrong? Tested out of circuit.

[Anonymous No.2702428]

>>2702410
That sounds normal. There should never be continuity from gate to either of the other pins, and there should only be continuity between drain to source when there’s a voltage (usually 6-15V) from gate to source. There should be a measurable diode from source to drain.

[Anonymous No.2702456]

is there an easy way to import a KiCad PCB into Fusion 360 with silkscreen? the .step export from KiCad does not include silkscreen. i googled it and found suggestions to try kicad export to kicad .vrml --> freecad + kicad step-up plugin --> .step, but i must be retarded because i cannot figure out how the FUCK to get it to work.

[Anonymous No.2702475]

>>2702390
I learned that trick back in the Nazi Merchant Marine Cubscouts of America in 1973 during a line-crossing ceremony. Glad it helped you, Anon.

[Anonymous No.2702497]

Any resoirces or methods to be better at reading electric diagrams anons

[Anonymous No.2702502]

>>2702456
Why do you need silk screen? Isn’t it an option to just copy the project, change the silkscreen layer to edge-cuts or copper or mask, and import that via FreeCAD? Bad for repetition though.

[Anonymous No.2702505]

>>2702502
>Why do you need silk screen?
project with multiple PCBs and board to board connections. it's confusing trying to line things up and route physical wires in Fusion 360 when i can't see a silkscreen with detail on pin numbers.

[Anonymous No.2702517]

>>2702502
Silk screening is or people with weak minds that can’t remember where the components go.
It’s a holdover from the 60s and 70s where they took semi-literate randos off the street to hand-assemble and solder PCBs (they had PCBs in the capacitors too) with 60/40 which ended up increasing violent crimes.
Nowadays, silkscreening isn’t necessary for anything, and in fact it makes it harder to obfuscate the circuit in commercial boards so you can’t repair it.
Today, I only see silkscreening in one-off boards that won’t work that they sent off to china because “might as well get 100 and I can sell the extra 99 etsy” because they saw some washed-up zoomer youtube channel doing it because they bought a vic 20 off ebay for $5000 opened it up and saw silk screening on it.

[Anonymous No.2702566]

you vs. the guy she tells you not to worry about

[Anonymous No.2702571]

>>2702566
memes aside I just want a small diode with a low turn-on voltage for signal clipping, and jlcpcb doesn't have any ones lower than that massive schottky which is kind of cringe
the VCA I'm using has a -33 mV/dB gain response so it needs to be quite low if I don't want the thing to amplify, but having biasing circuitry would be quite cumbersome to reduce the gap

[Anonymous No.2702617]

>>2702566
1N5819WS

[Anonymous No.2702619]

>>2702456
why do you need silk screen in a 3d model? if its to show where the components are so you can extrude their bounding boxes, thats fucking retarded as you can just make 3d models attached to all your pcb footprints

[Anonymous No.2702671]

>>2702619
see >>2702505

[Anonymous No.2702740]

>>2702428
So I went ahead and tried to start it with 6.5v like the ecu then 12v and the drain was not opening. No trace of current consumption on the lab source. - on source + on gate, tried reverse too.

[Anonymous No.2702766]

Does anyone know if this is basically ANENG?
Do these cheap knock offs of cheap brands have any issues?

https://www.amazon.com/Ranging-Digital-Multimeter-Battery-Alligator/dp/B07R47RYPW?th=1

[Anonymous No.2702769]

>>2701128
JST PH series, 2mm pitch. The other side of these cables are typically XH.


An update from a couple threads ago:
After:
>replacing fuse (low voltage side, inline with main battery charge terminals)
>blowing fuse (high voltage side)
>replacing fuse (high voltage side), measuring 0v on any of the low voltage side, and replacing TOP255EN flyback switcher
>blowing fuse (high voltage side)
>measuring failed diodes in the rectifier bridge, replacing those and the fuse (high voltage side) again
>replacing a couple suspect looking caps just in case

I now have this. 5V going to the controller, 22V on what I believe should be 12V going to the battery, and the controller seems to be functioning with correct LED indicators. It loops attempting to charge, then I believe overcurrent or overtemperature kicks in and shuts off the charging circuit. But I believe the 22V is an error and I should be getting 12V on that rail instead. I've got a new charger that I'm not using, so I guess my next step is to open that one up and find out exactly what voltages should be where, but I doubt it's the same PCBA given the 4-5 year gap between buying the old one and the new. Still, I should be able to verify what voltage the battery terminals should be at while charging.

[Anonymous No.2702783]

>>2702769
Is the clamping zener diode ok?

[Anonymous No.2702794]

>>2702740
No, the MOSFET works. I think the current needed is supplied too fast for my lab bench to catch but doing a code test I can clearly see it opens once voltage is applied to the gate.

[Anonymous No.2702809]

What is the most visualy interesting SMD component you know?
It's for some art project so purpose is secondary, but if I can integrate a function I'll go for it.
Currently I'm looking at photodiodes.

[Anonymous No.2702812]

>>2702809
>>2702809
Go buy/borrow a copy.of this and flip through it

[Anonymous No.2702814]

>>2702809
I've seen bi-colour LEDs in a clear SOT23 package, they were pretty neat

[Anonymous No.2702842]

>>2701116
using paper as a silkscreen is quite a risky solution. paper attracts moisture, and becomes quite conductive over time. soaking the paper with a non-conductive lacquer or coating it with something similar would be a must for longevity

[Anonymous No.2702843]

>>2702809
i like the look of electrolytic capacitors, box capacitors and inductors the most.

there are some very very small 7 segment displays on the market as well.

[Anonymous No.2702873]

>>2701938
>>2701946
So the batteries do indeed clamp the solar cells down to 5 V almost on the nose. So I’ll just put the thing into Vin.
Also, bought a set of these ratcheting connector pliers along with Dupont connector kit. Wish I bought this thing years ago. Makes putting disconnects in the circuits 100 times easier.

[Anonymous No.2702879]

>>2702873
> Vin
Meant 5v

[Anonymous No.2702885]

>>2702766
> $40 on AMZ
Don't know, but I'd buy it elsewhere.
Interested in answers; autoranging would be neat.

[Anonymous No.2702903]

Where do I get the most efficient SMALL solar panel? I'm talking gameboy sized, 6-12v.
It feels like you can only get sorta reliable numbers on those huge ass roof panels but literally every fucking small panel datasheet seems to be FULL OF SHIT and you never get what you order.
Are there certain brands that usually deliver what they advertise in terms of (realistic average weather) output?

[Anonymous No.2702905]

>>2702903
ALSO, you hear about
>wowwww solarpanels have improved SO MUCH in the last 20 years!!!!!
And then you want to get a small panel and they all have the same output like they did in 2005. WHERE THE FUCK ARE THOSE IMPROVEMENTS?

[Anonymous No.2702911]

>>2702809
If there’s an SMD quartz window EPROM then I’d say that. PLCCs are kinda cool too. MELFs are cool looking too, both resistors and glass diodes.

>>2702842
Yeah I guess paper is probably bad for leakage current unless I soak it in oil or whatever. It was mainly just to make assembling it easier. I’ll have to revise the circuit anyhow, so I’ll likely rip it off.

>>2702843
Ooh, the ones with bubble lenses are cool. There may be some neat displays of other types, maybe VFDs, but I don’t know if those are SMD.

>>2702905
There’s just little market for a panel of that size. You get like 1-2W for that size of panel, and that’s fuck-all at 12V. But in the realm of USB solar chargers you can get decently compact shit, if you’re ok with 5V stuff.

[Anonymous No.2702919]

>>2702911
>SMD quartz window EPROM

and when you find that, see if you can get some nice SMD vacuum tubes; the glowing filament will be awesome.

[Anonymous No.2702924]

>>2702905
>WHERE THE FUCK ARE THOSE IMPROVEMENTS?
the cost

[Anonymous No.2702960]

>>2702903
Be the change you want to see in the world.

[Anonymous No.2702969]

>>2702919
https://www.industrialalchemy.org/articleview.php?item=1031
Also there are surface Mount vacuum tube sockets, but I can’t see any SMD tubes themselves. I guess they need the long leads to not overheat the glass joint when soldering, which defeats the purpose of SMT.

[Anonymous No.2703003]

>>2702905
> solar panel efficiency
They came up against the laws of physics years ago. Theoretical maximum is 30% and you’re well into the law of diminishing returns at 25% efficiency.

Just like microprocessors and cores/frequency. I think AMD is selling processors with chiplets (reached economically feasible die sizes) and like 128 cores (reached theoretical max frequency years ago).
Now they’re stacking them.

[Anonymous No.2703005]

>>2702766
At some point, it is worth looking at the chinese flukes, 15b+/17b+/18b+.

[Anonymous No.2703010]

>>2702885
Don’t get one with a fucking 9v battery.
Also, depending on how old you are, get one of the ones that looks like it’s a LED display. I think they’re probably reverse-masked, backlit LCD displays nowadays, but I can’t see shit on my fluke most of the time. Unless your a linesman in austrailia or something. I work indoors mostly.
And if you’re working on electronic projects, you probably don’t need fake CAT MCMXIV ratings for measuring lightning or the output of your tesla coil and or MOT.

[Anonymous No.2703011]

>>2702911
> mini LED 7 segment displays
> Ooh, the ones with bubble lenses are cool
Yeah, TI invented that shit, popular in the 70s. Guess what? Mine are STILL WORKING, unlike a lot of that bullshit VFD nonsense… cripes that was a scourge on society.

[Anonymous No.2703045]

Can anyone help a retard identify what type of temperature sensors these are? They're pulled from a diesel exhaust system, (2012 peterbilt 386)the SCR portion to be specific. Model number is 2894876.

I'm guessing they're some sort of NTC thermistors, however, measured resistance at room temperature is around 17.7 Kohms. When i squeeze it with my hand, the resistance dips down to around 14Kohm.
The closest rating I can see for typical thermistors near this is 20k, which doesn't seem to be the case.

One thing also bothering me, is thermistors have a small range, up to like 250 degrees celsius max for some, but where these probes are placed in the exhaust system temperatures are typically reaching as high as 400 degrees celsius

Wiring diagrams aren't helpful at all, and all product pages for this model number don't provide anything as to what the fuck these are exactly. I can't replace them, I need to read them as they are directly

[Anonymous No.2703060]

>>2703011
VFDs can be quite long-lasting, so long as the filament isn't overdriven and they aren't given any whacks. The glass sandwich is pretty robust and the filament is spring-loaded, makes a nice ring when stricken. Importantly for stereo sets and the like, they have a very wide viewing angle, so regardless of how tall you are and what position the stereo is in, you'll be able to read it. Those LED bubbles have a particularly narrow effective viewing angle.

>>2703045
Is it possible they're thermocouples, and you were just getting funny values in ohms mode by receiving their voltage? Flip the probes and check the resistance again. Thermocouples are typically rated for much higher temperatures than NTC thermistors. So are platinum wire thermistors, but they're PTC and have a rather shallow slope.

[Anonymous No.2703074]

>>2703060
Thanks for the reply anon. I tried with two different multimeters, maybe they're 20k thermistors with too much use/wear? Going based off of that, how can I interface it with an input card capable of 4-20 ma, 0-20 ma,0-5V, and 0-10V? Do i need another resistor that will equal 4 ma when added to 20k ohms?

At room temperature, this should be 20k ohms, with 5V supplied, i should get 0.25 ma right? I dont even know how it would scale at high temps. Would I be able to convert it to 0-5?


I've considered other type K thermocouples, however these SCR temp probes have a 12m thread size, which I can't find for any common thermocouple

[Anonymous No.2703089]

>>2703074
>maybe they're 20k thermistors with too much use/wear
They could well have drifted strangely considering the extreme environment they're in.

>input card
Is this some sort of an ADC-based voltage measurement unit? The simplest method is to just use another resistor to make a voltage divider. Using a 20k resistor or so will give you the most range, if you use a really low resistor or a really high resistor, you'll get less significant voltage changes when the thermistor changes temperature. Somewhat more noise immune would be to use a wheatstone bridge to make differential measurements to a fixed voltage divider on the same local power rails, though this is more important with something like a PT1000 where you need to amplify a weak signal. Both of these have the intrinsic issue that they're not quite linear; the voltage never goes down to 0 or goes up to 5 (assuming its power rails are 0V and 5V), it will taper on either end like a sigmoid curve. If you do want perfect linearity, you'd be best off using a constant-current source of some sort. It may also be necessary to use an amplifier with a bit of gain, since most current sources won't work close to at least one rail.

But ideally you can do linearisation and scaling in software, and just ensure your signal is noise-free enough. Plot some circuits in falstad to see what a varying resistance looks like in terms of output voltage.

Also consider using a known good temperature sensor and using it to characterise the thermistor (ice water, boiling water, hot oil, molten solder, etc.) that way it doesn't really matter what sensor you have.

[Anonymous No.2703105]

>>2703045
>>2703060
Those are 100pct thermocouples.

[Anonymous No.2703108]

>>2703010
What's the issue w 9v battery? Saw you converting yours but didn't see reason.

[Anonymous No.2703162]

explain how right isn't just dead circuit

[Anonymous No.2703168]

>>2703162
both the mosfet and diode have a forward voltage, this forward voltage must be exceeded before it starts to conduct. the diode has kind of a hard threshold for beginning to conduct while the mosfet has a curve between blocking and conducting current. it makes for somewhat soft clipping of signals.

cheers

[Anonymous No.2703171]

>>2703162
>>2703168
edit: with the MOSFETs connected like that, they act through their body diodes, behaving like normal diodes, the Uth would be about 1.2 to 1.4 volt in each direction

[Anonymous No.2703182]

>>2702783
I haven't found one t hat doesn't appear to be functioning correctly But that's a possibility. There's an important looking schottky in the 12V current path coming from the transformer as well. Should have some time to look into that today

[Anonymous No.2703246]

>>2703105
Do you mean pt100 RTD?

[Anonymous No.2703309]

>>2703108
> 9v battery issues
They’re insanely expensive, don’t last very long, hard to find… i just went to 3 stores looking for 9v alkalines Because my fire alarm was chirping all night and I have to change it in free-air on a 30ft vaulted ceiling. None to be found. Yes, I checked wall mart, I don’t live in the middle of Negev desert.
Almost nothing uses 9v anymore. Only other thing is my wireless kareoke mic, and that’s been shelved for 10years.
And don’t get anything with AAA batteries either. Those are next on my hit list. AA will be the last battery left standing.

In fact, screw all that, get yourself a used LED benchtop meter you can plug into the wall. I have a hand-held fluke, and I used it away from the bench like one or twice in the last 30 years or so. I’ve got a kill-a-watt clone that tells me the ac voltage and current which I use for mains voltage situations anyway.

[Anonymous No.2703316]

>>2703060
> vfds are good?
I agree with everything you said, but I have several VFDs on plug-in devices with soft-on power switches that always have some of the VFD elements activated when sleeping.
Those elements are used for other things and they’re so dim now that it effectively reads the wong digit… it’s missing segments.
I’m advocating leds, not necessarily those bubble displays, but at least they still work despite my TI calculator being left on and plugged into the wall for 20 years showing ‘0’ typically and continuously.
So don’t buy any ebay test equipment from a lab with a vfd display, because 100% they left it on and the display is done for.

The problem is the VFD isn’t even-wear it’s just the stuff on the right hand side that’s unreadable. I probably could have boosted the cathode voltage but that will degrade it even faster, but the left side would be way too bright.

They used to make these TV tube refreshers for your CRT but Those have the same problem, they’d fix it for a while. It’s like spraying a noisy potentiometer with contact cleaner-fixes it long enough to re-sell it on ebay.

[Anonymous No.2703323]

>>2703089
Thanks anon. I'm working with a 16 bit 0-5V input card. I may go your route and use a voltage divider and measure the 0-5V range (or whatever I get with a 20k resistor).

I tested the thermistor with boiling water, so at 100 degrees celsius I got a rating of 4.05, it seems like this may be its base point, very close to 4 and is some sort of high temperature thermistor. Most thermistor charts show 20 or even 100k thermistor resistance dropping to the hundreds in ohms or low thousands at 100 C, so the range on this thing is definitely higher. I emailed a company that makes aftermarket models, hoping for a data sheet.

All I need is the Beta value to get some sort of semi accurate reading for scaling, I'm still not sure how I'll model it in the PLC (maybe some sort of polynomial?)


I'm not sure how I'll get accurate test values without investing in a known probe. So far I have

Room temperature - 18k ohms
Body temperature- 14k ohms
Boiling water - 4k ohms

[Anonymous No.2703324]

>>2703316
… vfd rand continued
They also use a bunch of crazy voltages, I have one that needs 70v. Fun. It’s got tons of special segment driver chips with no markings on them.

> just replace the vfd with a new one.
LOOOL… VFDs are all custom, one-off unobtainium.
With a LED display, i just need to know if it’s comon anode or common cathode and buy a new one, or get a cheap alarm clock at goodwill and use that.
But I never will have to do that because they never ever burn out.

I think I’m going to convert the VFDs to LED. I can probably just pull out the vacuum tube drivers and use the TTL source signal directly. Even if I have to use a ribbon cable and put the display on the top in a separate case. Thanks for helping me talk myself through this.

[Anonymous No.2703325]

>>2703323
> body temperature
I don’t want to know where you put the probe to measure body temperature.

Next you need to make this slushy ice water. Didn’t every high schooler do this experimental procedure, I still remember it somewhat.

[Anonymous No.2703354]

Now I'm trying to figure out this dofferential pressure sensor.

-5 V supply
-2 signals (for inlet and outlet)
-1.8 Kohm at atmospheric pressure


This has to be a 0-5 V reading right? It's hooking up to a diesel truck Electronic control module. These only use analog voltage signals right? Never current? (Like 4-20mA).

What do I need to get an accurate range/reading for this? Some sort of pressurizer? I will use a voltage divider to read a 0-5V signal

[Anonymous No.2703459]

>>2703309
Where I live every single supermarket has them, though not that cheaply. Where I work we sell them for 4.80USD each, less if you buy them in packs of six. We even sell lithium primary 9Vs and NiMH 9Vs.

Also the chad method is to just pop an 18650 into the back of everything.

>>2703324
Huh, my VFDs work on 12V.

[Anonymous No.2703529]

>>2703459
> $4.80 for a 9v battery
I got a whole multimeter with current clamp and with batteries for $5.00 CAD from princess auto.
Uses lithium button cells, still on first set of batteries after almost 10 years now.

[Anonymous No.2703605]

I want to switch an inductor to make an arc discharge (for EDM purposes). I'll probably spec my main transistor somewhere like 500V, but in the event the breakdown voltage of the system is higher than that, what methods can I take to prevent it from killing my FET? If I tune a snubber to absorb the full inductor's energy at ~480V, that snubber will be eating a lot of power and wasting energy that I'd rather not have to deal with, so I'll have to go with some sort of clipping. I know MOVs only have a limited number of energy blocking events, and TVS diodes are probably too small for me. Gas discharge tubes? PCB spark gaps? I could try to make a voltage sensing circuit that turns the FET back on again if the voltage rises too high, which might be feasible if I can delay the rise somewhat using a snubber/capacitor. Then I could just use a MOV as a fallback.

Thoughts?

[Anonymous No.2703611]

>>2703605
> thoughts
Use a more robust 1000 V SCR instead of a transistor.
Don’t try and switch 480 V directly. Send pulses through an isolated transformer to step them up.

[Anonymous No.2703617]

>>2703611
>SCR
I want to be able to turn it off. I will consider IGBTs, but honestly there are some bloody good MOSFETs out there these days. I can get the ASW65R072EFD for $2.90 each, which is a 700V FET with 72mΩ on resistance, and is capable of 162A pulsed. I have no qualms with designing a 10A gate driver.

>Don’t try and switch 480 V directly
I'm not. I'll be storing energy as a constant current in an inductor (something in the ballpark of 10A) using a half-bridge (Q1/Q2) while keeping the power transistor Q3 turned on. Then turning Q3 off will cause the current to spike and arc to the workpiece. Pic related, haven't worked out most of the details, the inductor could be anywhere from 100µH to 1mH. The initial power source is a 12V ATX PSU.
I'm copying the idea from this:
>https://tenebryo.github.io/posts/2021-04-07-edm-power-supply.html
He uses a full-bridge to get bipolar arcs, but I'm not really interested in that. He also uses rectified mains as his power supply, which feels overkill because resistor+capacitor methods work when they only run at 60-100VDC anyhow. It also seems kinda dangerous.

[Anonymous No.2703618]

>>2703617
> turn it off
This is going to sound crazy, but we turn them off with another SCR. That’s some old-school shit right there. Still needs some snubbers, but the whole thing, while not efficient should be very robust.
> IGBT
Those were invented after I stopped learning new things.

[Anonymous No.2703626]

>>2702497
Just do it a lot

[Anonymous No.2703627]

>>2702566
Nigga you really gotta make them pads bigger.
Nobody's gonna be able to fix that shit if it gets loose.

[Anonymous No.2703629]

>>2702812
https://archive.org/details/windell-oskay-eric-schlaepfer-open-circuits-the-inner-beauty-of-electronic-compo
NTA, but this book is really pretty, thanks anon.

[Anonymous No.2703794]

>>2701116
Does anyone have any recs for good in-depth resources/textbooks for learning RADAR concepts/design?

[Anonymous No.2703806]

>>2703794
This website is pretty good but the English is a bit shit: https://www.radartutorial.eu/
Other than that, go to you local university library. They usually have a ton of good radar books.

[Anonymous No.2703832]

>>2703794
https://youtu.be/PNbAM9IhfBE

[Anonymous No.2703873]

does there exist a switch for electronics that functions like a four-way switch used in electrical wiring? something with four pins which connects 1 to 2 and 3 to 4, but when pressed 1 to 3 and 2 to 4?

[Anonymous No.2703883]

>>2703873
it occurs to me that the same result could be achieved by shorting some pins on a 5 or 6 pin DPDT

[Anonymous No.2703920]

>>2703873
>>2703883
you talking about a reversing switch?

[Anonymous No.2703951]

>>2703920
yeah, that would do it. something electromechanical. looks like they're usually 3 position momentary where i want 2 position maintained. i found this 4 pin rocker switch on ebay and funnily enough it looks like it's just a modified 6 pin DPDT with shorted pins.

[Anonymous No.2703963]

>>2703951
>looks like they're usually 3 position momentary where i want 2 position maintained.

usually? no.
the 2PDT two-position toggle switch is the most common type, by far.
but having a third position (center-off) is often a good idea, for when you want the world to stop so you can take a piss.

[Anonymous No.2703997]

>>2703951
>those fucking clearances
Fuckin a

[Anonymous No.2704107]

I have these toroidal cores that I want to know the maximum amp-turns of, pic related. They're 35OD x 21ID x 13H (mm) toroids. The webpage refers to the ferrite material as "Toroid L8". The chinglish datasheet's only reference to magnetic field is this "Bms" value, with 2500 (gauss?) and 20Oe values.

20 oersted is 1592 amperes per metre, while 2500 gauss is 0.25 tesla. I think this oersted / amps per metre value is what I want, as it's the H field you put into the core as opposed to the B field you get out. But this H field strength and the magneto-motive-force F I want are related to one another with the equation F = H*L, where L is the effective length of the solenoid. The effective length of this toroid is probably 88mm or 0.088m, so F = 1592 * 0.088 = 140 amp turns. This sounds sensible I guess, but the fact that this depends on the length of the toroid but not the cross-sectional area feels really wrong to me.

Does anyone here understand magnetics enough to tell me what the fuck I'm doing wrong?

[Anonymous No.2704119]

>>2704107
>This sounds sensible I guess, but the fact that this depends on the length of the toroid but not the cross-sectional area feels really wrong to me.
That's because you're only calculating magnetic flux density - this quantity is normalized per unit area. To get actual total flux inside your core you still need to integrate magnetic flux density over cross-sectional area. And with that total flux you can then calculate inductance which is determined by geometry of the core. Magnetic flux density only gives you normalized values, it will be the same for thin or thick toroid of same radius.

[Anonymous No.2704144]

bump for spooky theme

[Anonymous No.2704176]

>>2704119
I assume you’re you’re going to make a choke or transformer. If you can do that, you should also be able to test them. Which you should do anyway to make sure your calculations are accurate, and that those shady looking specs are accurate.

[Anonymous No.2704179]

Im looking at CMOS gates...
How tf they don't short the power rail when applied voltage isn't logical 1 or 0,

[Anonymous No.2704184]

>>2704179
They’re not very linear devices like BJTs are.
They do make MOSFETS with larger linear regions, though, but not for CMOS digital ogic processes.

[Anonymous No.2704287]

Bear with me, I'm an electrical noob but I'm learning.
I've got an air pump connected to a pressure switch. The pressure switch breaks the circuit at a certain PSI to turn off the pump.
I'm trying to rig a simple LED to light up when the pressure switch shuts off the pump (signifying the pressure is ready).
What can I use that gives power to the LED only when the pressure switch has shut the pump off (power a circuit in absence of power to another)? My first guess is some type of relay? What specifically should I be searching for?

[Anonymous No.2704291]

>>2704287
Yes a relay would be appropriate. You want a SPDT relay. Connect LED to NC (normally closed) contact which will be on when relay is not energized. When pump is on pressure switch will be closed and relay energized turning the LED off. Once pressure switch turns of it will be back to de-energized state and LED will be on.

[Anonymous No.2704298]

>>2704291
Thanks for the suggestion anon.
Does my diagram look correct?

[Anonymous No.2704300]

>>2704298
Wait I found a problem. How does power get to the relay? Does it come in a different pin altogether?

[Anonymous No.2704302]

>>2704119
>you're only calculating magnetic flux density
Yeah that's what I thought. The entire equation F = H*L doesn't make a lick of sense to me, because it's suggesting that the mmf is only a function of flux density and solenoid length, it doesn't discriminate between a 1mm rod or a 1m rod.

But this image suggests that's the correct way of calculating it even for a toroid.

>>2704179
They do actually enter shoot-through states when transitioning states, just the current that flows isn't that significant.

[Anonymous No.2704318]

Ok I think I got it figured out.
Power goes through a master switch first, through the coil side of a relay, into the pressure switch. If pressure is low, switch is closed giving power to the air pump and opening the relay to kill the LED. If pressure is good, pressure switch is open, causing the LED side of the relay to close.

Did I do this right?

[Anonymous No.2704340]

Does anyone here know anything about hot air SMT soldering?
I managed to pick up a used hot air station for cheap but the wand didn't come with any of the nozzles. I'm looking to buy a nozzle but don't know what to go for. I've only ever used solder irons.

Can someone offer some advice what an all-round general-purpose nozzle is? I'm mostly interested in lifting off and replacing smaller ICs(say, 10-20mm wide). They sell so many type of nozzles in a variety of diameters.

Any advice is much appreciated!

[Anonymous No.2704347]

>>2704298
>Does my diagram look correct?

no.
here's an old trick invented by Michelangelo himself.
it's genius coz it requires no extra parts.
when you have a switch in series with a load, you can wire an indicator across the switch that lights up when the switch is off.

[Anonymous No.2704412]

>>2704340
>Does anyone here know anything about hot air SMT soldering?
No.
>wand didn't come with any of the nozzles.
Check diameter, get from usual suspects.
>Can someone offer some advice what an all-round general-purpose nozzle is?
Depends what you solder. Big ICs - big nozzle, long heat up time. Small nozzle - small component, fast heat up.

Nozzles are cheap, get couple of them.
I wouldn't go with real small ones, maybe 6 mm is smallest you should get.

Play around, get trash boards, try desoldering/soldering.

[Anonymous No.2704420]

>>2704176
So what's the method for measuring this? I don't think I can do it with a DC current, I'd have to make a sinusoidal current and measure the voltage. I'll probably just do that with a sinusoidal voltage source and a series power resistor. I have an audio amplifier I can probably use for it, though it's probably only ~1A capable. So I'll need like 140 turns, making it ~20mH. To get the 8Ω I think it should be, that's 64Hz. That's definitely doable, but man 140 turns is a lot for a hand-wound toroid. I can get much higher current by rewinding a microwave oven transformer, there the inductor can get away with only 24 turns. But those 24 turns will be eating like 50A. I hate it.

[Anonymous No.2704421]

>>2704420
Hang on, that's way more than 140 amp turns. So maybe I can just increase the sense resistor until it's only 6A, or better yet just decrease the number of windings.

[Anonymous No.2704429]

>>2704412
>I wouldn't go with real small ones, maybe 6 mm is smallest you should get.
Yeah, small nozzle == low airflow
>Play around, get trash boards, try desoldering/soldering.
Yep, that's what I'm gonna dial it on. I haven't found any good SMT tutorials online! Most of the "SMT tutorials" involve people using soldering irons to drag-solder chips.

Anyone have any opinions on these angled nozzles? Good idea?

[Anonymous No.2704430]

>>2704429
I dont have angled nozzles, but i think they are kinda better, easier to use.
>Yep, that's what I'm gonna dial it on. I haven't found any good SMT tutorials online! Most of the "SMT tutorials" involve people using soldering irons to drag-solder chips.
There isn't much to hot air.
a) temperature
b) time
c) flux
d) surface tension

[Anonymous No.2704459]

>>2704420
> 24 turns with 6 awg wire at 50 A.
Do you have any jumper cables for your car? Cheap ones for smaller cars are usually around 6 AWG. That should give you an idea of the practicality.

[Anonymous No.2704470]

>>2704459
I have a length of 8awg that's currently wrapped 16 times around my MOT core, producing ~8VAC when I plug the primary into the wall. I could fit four of its turns through my toroid, giving an inductance of 14µH, and an impedance at 50Hz of 4.4mΩ. Not easily measurable. I'd be better off just putting 24 turns of this 1.2mm magnet wire through it (512µH, 160mΩ) and just having one or two windings of the 8awg through the MOT and a 0.1-1Ω power resistor through which to measure the current.

[Anonymous No.2704473]

Any of you ham radio guys tried to make a pipe locator before?

[Anonymous No.2704495]

>>2704340
sounds like high maintenance sissy nonsense

[Anonymous No.2704564]

>>2704473
> 512 Hz to get through the ground.
You need a 150,000 meter antenna. Times two. You better start on that first. You can make it helical, so it won’t be so cumbersome, but both antennas need to be helical.
You can get together with the toroid guy and have a winding party.

[Anonymous No.2704568]

>>2704429
As >>2704430 says, there isn’t much to it. It’s hot air. I’d add distance and angle to that list. Just use or make a mid sized nozzle and control the other variables.
I use my butane iron, i can just pull off the tip and it shoots out hot air. There’s no flame, it’s a platinum catalyst.

[Anonymous No.2704590]

>>2704429
Those little hot air stations are only good for small SMD components and micros so don't go crazy thinking you're gonna be reballing GPUs and such. For that you need a preheater underneath and infrared top heat, with a proper jig to clamp the board so it doesn't warp.

[Anonymous No.2704646]

>>2704590
No, i reballed my ps3 with a hardware store hot air gun, an oven temperature probe and some tinfoil.
Not that hard.

[Anonymous No.2704650]

Can anybody glean how this dosing pump works?

I thought these used PWM to control a specific pressure for the outlet (typically like 120 PSI)

However, ignoring the pressure and temp readings, all there is is the 12V pump power (I'm guessing ON/OFF) and a return valve.

To maintain a specific pressure, is it possible the pump is always on and the return valve is an analog valve that adjusts how open it is?

Or could it be the pump always on, with the return valve turning open/close every few seconds as needed

[Anonymous No.2704671]

>>2704564
A magnetic antenna makes sense, but it could always be a short dipole with a high-Q filter for maximising its SNR despite a low gain.

Wonder if they picked 512Hz because anything higher (e.g. 2kHz) would be blocked too significantly by metal pipes?

[Anonymous No.2704673]

What is good flux?
I feel I've tried everything: flux pens, flux brushes, syringes with goop.
None of them work properly. The pens dry too quickly and have a tendency to get stuck when being pressed, expelling their entire contents over the board. The brushes I got a hold of were apparently a "wrong" kind of flux. The goop fucks up my lungs, gets everywhere and is impossible to clean up with alcohol, manually going through the board with a toothpick is annoying.
Everyone keeps going on about how flux is the best shit since sliced bread and every time I try it it just creates more problems than it solves. Thus far I'm always just falling back to applying fresh (leaded) solder when necessary and being patient with heating joints up. This gets me through most jobs, even boards with a load of 0402 components packed together.

Surely I must be doing something wrong, though, so I'm wondering:
What is good flux? What do anons here use? How do you clean the residue?

[Anonymous No.2704704]

>>2704673
I have a tub full of RMA paste that I use for large joints. Dissolving it in IPA and applying via squeeze bottle works well for smaller stuff. Though for SMTs I’d recommend whatever no clean flux Louis Rossmann uses.

[Anonymous No.2704707]

>>2704673
>I feel I've tried everything

sounds like you have yet to try any of the ones that say
made in the USA
made in Canada
made in Japan
made in Germany

flux is easy and fool-proof when it's made right.
when in doubt, buy Kester.

[Anonymous No.2704750]

>>2704707
Thanks, I was looking for specific brand names like that. I'll try that.

[Anonymous No.2704751]

>>2704750
MG Chemicals makes good flux and solder too.

[Anonymous No.2704789]

>>2704673
>Surely I must be doing something wrong,
no, you're doing it right
flux is a meme

[Anonymous No.2704812]

>>2704751
And to *remove* flux, chemtronics.
I just use 99% isopropyl alcohol (2-propanol) though for rosin fluxes. Works fine for me.

[Anonymous No.2704897]

>>2704673
sounds like a skill issue to me. a bad tradesman always blames his tools etc

[Anonymous No.2704935]

>>2704646
You need precise temp control, using heat gun is risky.
>>2704673
>What is good flux?
Define good.
What do you want from flux?
Tin really oxidized shit? -> Zinc chloride active flux + wash
Hand soldering fresh-ish parts -> Rosin flux, either pure rosin, alcohol diluted rosin. Any consistency.
Soldering clean shiny new stuff just fresh of the reel? -> Liquid flux. Either diluted rosin or flux pen.
Repairs and BGA? -> Proper bga flux paste, because rosin fluxes turn brown and you don't see shit.

Commercially made fluxes for electronics are some sort of rosin, with pinch of activators that make it better.
Proper fluxes are a bit easier to clean than rosin, because pine rosin contains some substances that aren't that well soluble in the alcohol, and factory made fluxes typically don't have non-soluble component to them.
>Thus far I'm always just falling back to applying fresh (leaded) solder when necessary and being patient with heating joints up.
Solder has solid rosin core. Try using pine rosin. You set iron cold-ish (<360C) dip tip in rosin, and quicky transfer to joint. With this metod you can even do rookie type of soldering where you just transfer snot of solder to joint, but with rosin it would actually work.
Rosin doesn't require clean up as it is non-conductive, and since you didn't dissolve it with alcohol, it won't stick.
> How do you clean the residue?
Alcohol, methanol works really good in particular. Mineral spirits.

[Anonymous No.2704954]

>>2704564
>>2704671
Well the reason I'm interested is I live in a condo building that lost the notes of where the landscaping irrigation lines were installed decades ago. Now we need to maintain them and paying a company to locate them would come out of all our condo fees. So I was wondering if I could find a cheaper DIY way to solve this and save me and my neighbors some money.

[Anonymous No.2704964]

>>2704954
>lost the notes of where the landscaping irrigation lines were installed decades ago.

you can do that manually by removing sod.
locate the water spouts, and dig a 6" wide trench following the pipe back to the source.
you're probably gonna need to replace some pipe anyway.
then, replace dirt and cut up some Home Depot sod into 6" wide pieces.
any radio methods are gonna give approximate results at best.

[Anonymous No.2704966]

>>2704954
Irrigation pipes might be quite narrow, getting the on-wire probe down the pipe might prove difficult beyond a metre or two. If you can flush it down using water flow it might be doable though, so long as the fishing line it's tied to doesn't get snagged and break.

If the pipe itself is metal then it's probably far easier to detect it with a more conventional metal detector, if not by connecting a signal generator to the pipe and using non-contact voltage sensing on a probe to detect it. It may be worth investing in making some sort of receiving antenna that's directional with respect to its sensitivity (think a really long thin metal detector coil pair, or mmultiple coil pairs like a humbucker), that way you can pick up the pipe's directionality. Directional sensing would make it a lot easier, and this may also be a feature you can build into an emitter+receiver setup.

For the antenna driver, you'll want to ensure that the driving circuit is resonant, that will minimise the energy loss and prolong the battery life. You can drive an inductive load quite easily by combining a half-bridge, a schmitt inverter, and a capacitor. The inductive antenna and capacitor form a low-pass LC filter, the half-bridge drives this, the inverter takes the output of the filter and feeds it back into the half-bridge driver's input. A resistor and some clipping diodes before the inverter is a good idea.

[Anonymous No.2705530]

26 hours without a bump. Shame.

[Anonymous No.2705534]

>>2704707
Does anyone else have trouble with the bottle dispenser for kester flux (top, second from right) leaking? It seems like the lid material is incompatible with the solvent in the flux.

[Anonymous No.2705544]

Got an old digital piano I fixed up a few years ago, and now it's getting issues with the key contacts. Sometimes they get a bit dirty and it's no big deal, but it's become more frequent. Cleaned the contacts thoroughly like two weeks ago, then started getting loud notes (meaning the first contact didn't register so it sent max velocity) two days ago. Yesterday I cleaned it thoroughly again, and then later that evening had the same damn problem (different keys though).
So, what's the best way to clean these bastards?
Pic related for reference, the green rubber piece it's got two lines of graphite I guess embedded in it. Mine looks more or less fine, only very slightly marred where it makes contact with the circuit board, but no obvious gaps or deficiencies. I'm about to take it all apart again and try flipping it and hope it's slightly offset (where the plastic shields the strips) and see if that works.
Should I just go ahead and order a replacement though?

[Anonymous No.2705545]

>>2705544
Just realized that was kinda rambling should probably clarify my question.

Previously cleaning the contact strip would fix things for months, but now I've had to do it increasingly often. Am I just doing a shit job and could do it better (just a lint free cloth to wipe it down, haven't used chemicals or anything) or is the strip toast and I need a new one?

[Anonymous No.2705550]

>>2705534
I think it's the squeeze bottle that gets deformed around the threads. Try a brush applicator.
>>2705544
>>2705545
I'd replace the wear parts considering the symptoms are becoming more frequent.

[Anonymous No.2705560]

Are any of those 30V/10A switching power supplies on Amazon worth it? I hear they aren't terribly precise and noisy.

[Anonymous No.2705569]

>>2705550
>I'd replace the wear parts considering the symptoms are becoming more frequent.
Guess you're right. Just cleaned and flipped the thing around and already had one loud note plus a bunch that didn't register the first time I played them but would do so subsequently. Guess there are indeed bad spots in the strips.
Annoying that I have to spend the money and wait on shipping, but I suppose 30 years was a reasonable lifespan for a part like that, and I'm lucky enough that I can even still get parts considering the age lol.

[Anonymous No.2705583]

>>2705569
>I suppose 30 years was a reasonable lifespan for a part like that
That's a damn good run. Imagine an original NES controller working for 30 years. lmao

[Anonymous No.2705603]

>3 AAA batteries
>Measure their voltage
>All slightly over 1.5V
>Slot them in a headlamp that doesn't work
>Measure across them
>3V ... 2V ... 1V ...

what?

[Anonymous No.2705612]

>>2705603
Likely something is shorted and it's pulling so much current that the batteries can't keep their normal voltage.

[Anonymous No.2705634]

>>2705530
We’re trying to figure out how >>2704966 works.
HB is obviously an hbridge mosfet gate driver with simultaneous ‘on’ protection. Sinusoidal?

[Anonymous No.2705637]

>>2705603
See >>2702306

[Anonymous No.2705639]

>>2705637
So you're saying it's magic? I get ya

[Anonymous No.2705644]

>>2705634
>Sinusoidal?
I'm guessing pulsed DC square wave.

[Anonymous No.2705690]

>>2705634
>>2705644
The voltage waveform at the output of the half-bridge turns out to be about a 50% duty-cycle square wave, but the voltage waveform after the inductor is a higher voltage sine wave, 90 degrees out of phase with the input square wave.

And yes, shoot-through protection in the half-bridge driver IC is a must.

[Anonymous No.2705704]

Retard here again asking for more help. What kind of power consumption should I expect from this here DEF (diesel exhaust fluid) pump.

My 12V switching supplies keep faulting out/dying when I try to power this pump with them in parallel (rated 4.5 amps and 12.5 amp output in 12V and 120vac plug input)


Is it just that a diesel battey can supply such a high current? The wires leading to the connector are like 14-16 gauge, I can't imagine the current draw being much higher than what my two power supplies are providing (17 amps).

I tried measuring resistance across the two leads on the pump, shit starts at 0.2 MOhm and keeps climbing, I'm about to take this thing apart

[Anonymous No.2705724]

>>2705704
So I opened it up, and don't know what exactly is going wrong.

The 3 circled Pins have continuity at the points the lines run to.

Pin 9 is Battery Voltage + according to the harness schematic

Pin 8 is the return voltage

And 7 doesn't have any connections according to schematics.

However, there's a marking on the plastic that says
-24V 1+3
-12V 2

I have no idea what this refers to.

Applying 12V to pins 8&9 shuts off my power supply, when the dosing pump is tiny and no way using 10+amps

[Anonymous No.2705725]

>>2705724
These are the schematics, here is the picture of the inside pintout going to the pump.

[Anonymous No.2705726]

>>2705725
And here is the pump (3 pinout)

What exactly am i missing here? The drawings have V supply, and return, but nothing else regarding the pump

[Anonymous No.2705730]

>>2705726
Okay so after touching everything with a multimeter, it turns out pin 7 is grounded to the pump body, which doesn't run anywhere, but I'm guessing I need it grounded somewhere to resolve my issue

[Anonymous No.2705745]

>>2705730
>to resolve my issue

I don't know if this link will help; it's all way over my head.

https://www.picoauto.com/support/topic22772.html

[Anonymous No.2705758]

>>2705724
Looks like pins 9, 5, and 11 all get 12V from the battery. Then all the return lines are 0V (ground). Only the pressure sensor gets 5V.
>However, there's a marking on the plastic that says
>-24V 1+3
>-12V 2
>I have no idea what this refers to
It can be used in a 24V or 12V system depending on which pins are powered?

[Anonymous No.2705769]

>>2705745
Really hope I don't need PWM for this, would that explain why my 12V supply acts like it's shorting out when applied to the pins? Shouldnt a straight 12V just have it run at a constant speed?

>>2705758
Car/diesel batteries are 12V. Any idea why applying 12V to pins 8 and 9 should fault out my Power supply?

Touching wires to them makes a little spark and faults out the PS.

Even if it required PWM, shouldnt it at least still move when powered?

[Anonymous No.2705789]

>>2705769
So, after looking closely to the pump chip, it is indeed PWM. One terminal labeled PWM, another LB, and the third GND.

Ordering a 12V dc motor controller, hopefully solves the dying PS issue as well as running the damn thing.

[Anonymous No.2705796]

>>2705704
Not going to be more than 200W, probably. Inrush current for things that run off a lead acid battery can be bad though, especially motorised things like pumps. You may want to look into a soft-start circuit, this could be anything from a resistor+relay, a big LC filter, a series NTC thermistor, or a proper PWM circuit. Measure the DC resistance across the motor, if it’s so low you can’t get a good read on it compared to the meter’s ESR, chances are it’s an inrush current problem.

[Anonymous No.2705809]

>>2705796
It does weird things when i measure resistance

It starts at 200 Kohm, and keeps climbing fast, and slows down after a couple of minutes to like 350 Kohm. It's not a normal motor, it's got a lot of circuitry on its board.


I'm going to order a cheap 12V DC motor pwm speed controller and see if that gets me anywhere

[Anonymous No.2705813]

>>2705603
>>Measure their voltage
>>All slightly over 1.5V

these measurements are meaningless.
batteries must be measured only under load.
especially carbon batteries. unloaded, they'll show full voltage even when 99% dead.
see if your meter has battery settings (puts a load across, then measures voltage).

[Anonymous No.2705817]

>>2705809
>>2705796
For reference, I'm guessing the battery/components have something to dobwith changing resistance the longer I have it connected

[Anonymous No.2705831]

>>2705817
>changing resistance

it's pointless to be guessing about this.
let's assume the thing has electronic parts which control a relay or FETs to turn on the load.
your DMM likely isnt putting out enough voltage when it's measuring resistance to even turn on the voltage regulator.
so all these components are un-powered, or un-alive, which causes these high readings.

a better way to measure resistance --- not sure why, but whatever --- is to use 2 meters.
one measures voltage, one current, then you calculate R= V / I
calculate at various voltages, maybe draw a graph, maybe extrapolate.

[Anonymous No.2705854]

>>2705809
You’re measuring the input, not the motor itself. That’s the input capacitance you’re charging with your meter, which could itself be a source for inrush current. You want to put the meter directly on the wires coming from the internal motor.

By turning the speed controller up from zero you should basically get a soft start function anyhow.

[Anonymous No.2705863]

>>2701865
Niceee.

[Anonymous No.2705869]

I have a project I'd like to do for my (one day to be born) kids.
What software would be good to plan simple projects?
If anyone is interested in one of my ideas read on:
>be me
>I'm a noobie
I'll explain the idea in the simplest way I know how:
I'd like to build a set of red LED lights were when a dimmer is turned up it makes the lights go to their brightest, but I also want another set of blue or yellow lights to blink when the dimmer is on all the way. All powered by D batteries.

This would be for a prototype of an interactive playset I'd like to build.

[Anonymous No.2705920]

anyone have 2:1 mux recs? preferably all single channel and smd. hopefully fast as well. Designing an analog keyboard and need to mux keys into different adc channels. I have 25 channels and 45 keys to mux.

[Anonymous No.2705940]

>>2705920
I have a spreadsheet full of analogue switch ICs, pic related. The "seperate A/D" refers to whether they have seperate analogue and digital power rails, the rest should be self explanatory. I filtered them for having "N throws" = 2 already, whether two switches is counted as seperate switches or poles of the same switch is dependant on if they can be changed independently or not. I recommend the DG4xx and DG6xx series. They seem have the best effective open-to-closed impedance ratio so will minimise crosstalk (this is the spec the entire table is sorted by). Though for this case you can probably get away with bog-standard CD4053, that difference matters more for a sample+hold circuit.

What kind of analogue source is it, optical? Potentiometer? An oscillator of some kind?

[Anonymous No.2705978]

>>2705940
Using linear hall sensors as the source. Haven't picked out a specific one yet, but I was looking at AH49Es. I'm reconsidering though because I want to try to take all options into consideration. Thank you so much for the spreadsheet btw, you're genuinely a lifesaver <3

[Anonymous No.2706006]

>>2705978
>linear hall sensors
Ah, under each key, while the keys have magnets on them? Probably the most reliable method, but it would probably be more expensive than having LED+photodiode pairs under each key and using the reflectance of the key to figure out the distance. Personally I'm looking into using capacitive touch pads, where the resultant variable frequency of the RC oscillator is measured by the MCU and used to figure out the key press strength. But it's a real pain to measure frequency in software on so many pins, and having a hardware filter and peak detector on each key is a lot of components. Maybe optical is the way to go for me too, or maybe resistive through the body.

Anyhow, hall sensor outputs are buffered IIRC so it shouldn't really matter what analogue switch you go for.

You could also go for analogue switches that have a higher throw-count at the expense of having less poles/switches (e.g. DG406), because it would mean less total analogue switch ICs (and also less analogue inputs required). Might make wiring simpler. On the other hand you could just have one of those little 6-pin muxes for each pair of keys, and that would probably be pretty easy to do.

[Anonymous No.2706009]

>>2706006
>Personally I'm looking into using capacitive touch pads
NTA, but this is something I also looked into for a similar project. Basically what I came up with would be to use a single pin to charge a number of variable capacitors through a large resistor, and continuously sample the capacitors using shift registers. Drive pin -> Resistor -> Shift register input -> Capacitor -> Ground. Times x100.
The amount of time between the drive pin going high and the shift register reading high tells you how much each key is pressed, without needing ADCs. The disadvantage is that you only get as much resolution as the times you sample the registers, which does limit the sampling rate you can get if you have a lot of keys. Probably has other issues I don't know about since I haven't come up with an easy to make slider variable capacitor that would actually work.

[Anonymous No.2706020]

>>2704964
>>2704966
Yeah it's a small plastic pipe so I guess this isn't really feasible. I suppose I'll just volunteer to help dig a trench. Thanks for your replies frens.

[Anonymous No.2706057]

>>2706020
https://www.kwipped.com/rentals/environmental-testing/ground-penetrating-radar/428
What hurts more?
A: Digging trenches
B: Spending $250

[Anonymous No.2706058]

I'm a noob for electronics but I got a couple schematics going and good sim results, so I'm getting ready to build a prototype. However, I need:
1- Some kind of cheap piezoactuator
2- Some kind of threaded stage with corse (micrometer or so) approach capability, hopefully motorized
For 1, I can use a unimoprh disk in a pickle, but I'd like to go with a piezotube if I can. However, I haven't been able to locate reasonable sellers anywhere. Any idea? Best I can find is $100 a tube, except alibaba where they're more reasonably priced, but repeatability is important here so I don't think that's a real option.
For 2, any recommendations? I want to keep the stage within 50. I nead linear (vertical) movement. Coarse control is OK but can't be too coarse. Was looking into brushless, but again the only reasonably priced ones are either alibaba or for haptic feedback, and so as far as I could understand, not suitable for this. I can use a mechanical approach instead (just use a screw and manually screw tighter to move the stage), but I'd like something more. Also, I'm not sure what kind of treading mechanism to use. Any thoughts?

[Anonymous No.2706059]

>>2706058
>cheap piezoactuator
Don't know.
>hreaded stage with corse (micrometer or so) approach capability, hopefully motorized
pic related

[Anonymous No.2706060]

>>2706059
Posting the pic would probably be more helpful.

[Anonymous No.2706061]

>>2706060
Awesome, that's exactly what I need. Thanks! Can't find any under $200 but I'll look around.
I'm hoping I can built the whole finaly thing (including pcb) for less than $500 or so, and this would go right above budget, but I'm sure I can find another way.

[Anonymous No.2706063]

>>2706061
How heavy is the stage that you're moving? Could you use a hydraulic or pneumatic system?

[Anonymous No.2706067]

>>2706063
It's pretty light, 100g top and that's for the first prototype. I can reduce this to about 30g max easily enough, and more like 1-2g if I try harder.

[Anonymous No.2706073]

>>2706067
I'm thinking about using an old CD-ROM drive disc tray with PWM control.

[Anonymous No.2706076]

>>2706073
Yeah, that's a good hack, akin to what I might have to do with the piezoactuator.

[Anonymous No.2706197]

I bought a creality k1 3d printer, and they provide a jst connector, I think 1.0 based on the measurements, to attach their camera, but I want to see ifI can use my logitech webcam.
>pic related

the jst connector on the 3d printer is 5 pin, looks like two grounds, but continuity test shows they are connected.

My webcam appears to have something like that as well, a splice ground, but what confuses me is that when I disconnect the jst, and do a continuity between the jst connect pcb pin and the J1 soldered pad still shows continuity, why would they splice and solder a wire if its still connected via pcb? I am wanting to save money by just depinning the 4 pin connector and 5 pin, and put the 4 pin on the wires on the printer. Is that possible or will I need to buy a connector kit and make a 5 to 4 pin wiring adapter?

[Anonymous No.2706204]

>>2706197
The extra black wire is the cable shield and it's connected with 0V.

[Anonymous No.2706208]

>>2706204

It seems to be necessary, be easier to buy connector kit and crimp connectors that I need. Thanks.

[Anonymous No.2706227]

I need something small/light to hold a wire vertically (the device must hold the wire as if the wire was a drillbit and the holder was the drill's jaw), wire being 30 AWG.
In fact I know there are standalone mechanisms just like a drill jaw specialized for these dimensions but I don't remember what this is called.
Ring a bell to anyone? Or anything else I could use instead?

[Anonymous No.2706231]

>>2706227
why? just wrap the end around something and cut off the excess
or use a vice

[Anonymous No.2706233]

>>2706227
I mean I bought drill chucks, like these small ones here, but these are adapters to use on a 1/4 shank. "drill chuck" is probably what you want.
https://www.amazon.com/gp/product/B086JK6VDL

[Anonymous No.2706235]

>>2706061
>Can't find any under $200 but I'll look around
or just use a normal $20 stepper with an 8mm worm screw coupled to its shaft, like a cheap 3d printer

>>2706227
Collet chuck?

[Anonymous No.2706238]

>>2706231
The wire is used as a cheap nanometric needle and the feedback is detected by a piezo above whatever is holding it in place. It has to be as perpendicular as possible, but also be easy to replace so glue is not ideal and wrapping it is not viable at all.

[Anonymous No.2706240]

>>2706235
>>2706233
>Collet
That's the one, thanks!

>or just use a normal $20 stepper with an 8mm worm screw
Yeah, that's what I ended up getting. Stepper, driver, adapter, rod, plates, standoffs and rod nuts. Total cost per unit about 50 for this part.

[Anonymous No.2706256]

>>2706240
Looks like what I'm looking for is actually a collet nut, but I can't find small enough ones. Regular collets get there but I don't know about the dims/weight of the shank.

[Anonymous No.2706259]

>>2706256
Try "dremel collet set"

[Anonymous No.2706260]

>>2706259
A lot of these do come with a nut, that should do the trick. Now to figure out how to handle the total weight.

[Anonymous No.2706329]

Hey guys, I'm not sure if this is the right place to ask but I have a quick question about stepper motors, mainly having to do with microstepping. If you are trying to achieve a position that is normally not achieveable through a stepper motor's normal step angle of 0.9 or 1.8 degrees, can you use microstepping to get to and hold that position? I can't really seem to find this info by searching online, so I'm leaning towards a servo over a stepper.

[Anonymous No.2706335]

>>2706329
>can you use microstepping to get to and hold that position?
Yes.

[Anonymous No.2706342]

>>2706073
>CD-ROM drive disc tray

you must mean the laser transport mechanism, as it has much much higher precision.

[Anonymous No.2706348]

>>2706342
Don't they use piezoelectrically actuated suspensions with passive damping these days? Not quite the same use-case.

[Anonymous No.2706405]

I have a button that was used to turn traction control on and off in a car. The button clicks and immediately returns to its original position. I checked continuity and it seems to be unchanged before and after clicking the button. Clicking the button breaks the circuit momentarily.
Is this some kind of momentarily open rocker switch?
What can I pair this with so that clicking the switch (momentarily breaking the circuit) can alternate from one circuit to another? Some type of electrically controlled switch?

[Anonymous No.2706427]

>>2706405
I think it's an NC momentary switch.
Not sure how to toggle between circuits, maybe someone else can help with that.

[Anonymous No.2706461]

>>2706405
>>2706427
Sounds like you want a circuit with a mechanically latching relay. It will stay in the position it was set to even without power, and a momentary pushbutton can be used to toggle it.

[Anonymous No.2706556]

Forgot to set the clock back so I lost an hour of sleep. Daylight losings time.

[Anonymous No.2706573]

>>2706461
Thanks anon for the suggestion, I think this is on the right track. So the break in current as the button is pushed prepares the relay, and the current suddenly resuming is what causes it to change circuits?

[Anonymous No.2706661]

I've got 2 pairs of chinesium turn signals for a bike but they don't come with integrated flasher circuits and I'm too lazy to mess around with flasher relay. What's the easiest way to make 12 volt flasher circuits using transistors, 555s and NOT relays?

[Anonymous No.2706667]

>>2706661
https://www.circuits-diy.com/simple-relay-flasher-circuit-with-ne555-timer/

[Anonymous No.2706684]

>>2706661
Adding a flasher relay isn't that difficult...

[Anonymous No.2706725]

What is a good way to test a solar panel for maximum wattage?

When I connect this panel to a motor it seems I'm getting 30 watts but when I attached it to a big 3 ohm resistor the voltage drops to 6 volts and I'm reading only 2 amps which would be like 12 watts. With the motor as a load the voltage stays around the rated 34 volts.

[Anonymous No.2706728]

>>2706573
If you’re actually trying to fix your traction control, the relay might need replacing. Or, perhaps, the switch toggle mechanism is bad (e.g. latching spring is broken).
If you’re just using the switch for another project, and the switch is OK, you’d need a latching relay to make it hold the connection—a non-latching relay will let go of the connection when the power is gone since it needs a continuously powered electromagnet to hold the contact. All this is using older automobile technology to implement the latch. Modern stuff goes into some random computers.

[Anonymous No.2706729]

>>2706725
The maximum-power voltage is usually 80% of the open-circuit voltage. The maximum-power current is usually 90% of the short-circuit current. But those are for new silicon panels, it may be different for older panels or different types of panels.

[Anonymous No.2706731]

>>2706725
The motor is an inductive load. You will be unable to measure the wattage accurately with what you’ve got there because the windings back-feed (what will appear to be random) AC into your test setup.

The resistor will be accurate if you set your meter to DC assuming it’s not going through an inverter or other motor control.

[Anonymous No.2706732]

>>2706731
Is a DC motor though.

[Anonymous No.2706734]

>>2706732
> DC motor
So? It still has coils of wires and will backfeed AC emf through the commutator. Measuring static inductive loads is non-trivial, motors even less so.

[Anonymous No.2706736]

Car speakers do not work. No sound at all from any speaker including static. The radio itself functions, meaning I can turn it on and change stations and volume but no sound. I pulled one speaker and tested the resistance. Back said 4 ohms and the multimeter read 4.1. Used a 9v battery and some clips and the speaker moved back and forth. Odd thing was when I tested the resistance the reading occasionally got very jumpy and I could hear some static.

Where do I go from here as far as testing? I assume the connector that plugs into the radio itself should be tested? Do I use a multimeter for that?

[Anonymous No.2706738]

>>2706736
Is the wiring harness in good condition? Are the connectors dirty or broken? Are the wires broken? You could pull the radio and hook it up to an ATX power supply on your bench to know for sure.

[Anonymous No.2706743]

>>2706736
> jumpy resistance reading on speaker.
Maybe developed a short to ground and burned out the driver transistors on the amp.
Yeah you could use a multimeter for testing the connectors, but it’s easier if you have an extra home amp that can do 4 ohms and an extra speaker (8 ohms is fine for that)

[Anonymous No.2706745]

>>2706731
>>2706734

You are correct that a motor has inductance, but a brushed DC motor does not "backfeed AC" at all. It spins up and presents a DC back EMF which is why it does not overload the solar panel like the heavy load of a 3 ohm resistor. If he stalled the motor it would overload the panel the same way.

Anyway, this will spiral out of control so I'm out, and you may go back to being the expert. Have a nice day. (Think for a moment how DC generators work - they are basically a back-driven DC motor).

[Anonymous No.2706750]

>>2706738
The radio is pulled and all the pins look fine. I have access to a 12v battery and clips but not sure how to test specific parts.
>>2706743
I don't even think my system has an amp. It's stock early 00s.

I don't really understand this electrical stuff, just been copying youtube vids. Here is my wiring diagram if that helps.

[Anonymous No.2706755]

>>2706745
> some mumbling about motors
The commutator makes and breaks connections on the inductors on a brushed DC motor in accordance with the rotation of the shaft. That’s AC for sure… and a lot of it. On cheap motors there’s a nice beefy spark, so it induces AC and high-frequency AC into the surrounding environment you can hear on the radio. With the collapsing field of the coil, it can also be quite a high voltage.

Anyway, that’s some motors “101” … don’t forget to hook a motor up to an oscope and verify it for yourself.

[Anonymous No.2706763]

>>2706750
Twist the green+purple and black+pink together and connect them to 12V. Make sure the volume is turned all the way down and connect at least two 4-ohm speakers before you power on.

[Anonymous No.2706766]

>>2706763
>connect them to 12V
+12V, and the solid black wire to the negative battery terminal. The black+pink wire comes from the ignition switch to toggle the radio power.

[Anonymous No.2706782]

I've been starting to do more with soldered boards, and had Qs about veroboard / strip board like pic related.
What's the best way to break a trace? I typically scrape it away with a knife.
Is there a veroboard "layout" or some such in Kicad? Ran through a tutorial to see the workflow (at suggestion here) but not interested in having board printed yet, just enhancing design. Is there a veroboard underlay that can be put into Kicad when placing components?

[Anonymous No.2706783]

I've been starting to do more with soldered boards, and had Qs about veroboard / strip board (pic related.)
What's the best way to break a trace? I typically scrape it away with a knife.
Is there a veroboard "layout" or some such in Kicad? Ran through a tutorial to see the workflow (at suggestion here) but not interested in having board printed yet, just enhancing design. Is there a veroboard underlay that can be put into Kicad when placing components?

[Anonymous No.2706786]

>>2706783
keyword: perfboard

[Anonymous No.2706812]

>>2706750
Okay so I verified the speakers are all functional with a multimeter. Resistance was about 4.7 for each set of wires. Used a 9v battery and clips/leads to touch each pair of wires and all the speakers could be heard moving. This was all in the car.

Not really sure where to go from here. The head unit is out but I don't know how I find the disconnect between the head unit and the connectors that would cause the speakers to not make any sound

[Anonymous No.2706819]

>>2706786
I prefer using strip boards for the pre-made traces.

[Anonymous No.2706856]

>>2706783
I use a knife. You can get spot-cutters for them, they’re basically a tiny counter-sinking bit that clears the copper from around a hole. Some sense designs require the cut to be between adjacent holes, so you have to use a knife here either way.

I just use KiCAD without any special settings other than a 2.54mm grid size. The cuts are done in edge-cuts, the strips are done on B.Cu (if the parts are on the front) and the jumper wires are done in F.Cu. I made such a design a week or so ago, see the OP pic and the last post or two in the previous general.

>>2706812
I’m guessing the amp is dead, though it could be anything in the signal path, maybe high-pass caps after the amp or the speaker wires. You can test the amp output by playing a 50 or 60Hz test tone from your phone and measuring on the output connector with your DMM’s ACV setting. You can then follow that signal from the input to the amp to see where it stops.

>>2706819
It really is the most convenient prototyping method, unless you have a CNC router.

[Anonymous No.2706858]

>>2706783
you can buy a tool which is a 3? 5? mm drill bit with a handle that you twist in a hole.
the problem is then you lose the hole.
the better way is with a sharp knife carefully cut at a slight angle once from each side in between two holes to create a V valley break.
the benefit is you do not lose any holes and can make much more compact design.

personally for complicated things i have used a program called diylc, designed i believe originally for guitar pedals? or something. but its JUST for laying out, there is no circuit, net, rules, tools etc. its just for laying out to find an optimum positioning for size, or making a record of it etc. but i think its a lot easier than something like kicad for prototyping on proto boards.
use solid core wire and a comfortable set of round nose pliers to make jumper wires with lots of 90 degree ish turns and straight lines, makes it a lot neater and easier to follow.

[Anonymous No.2706881]

>>2706856
>most convenient prototyping method
Wire-wrapping was king back in the good ol' days.

[Anonymous No.2706884]

So it sounds like I need to break out the xacto knife, vs. the lockblade I was using.
>>2706856
>the strips are done on B.Cu (if the parts are on the front) and the jumper wires are done in F.Cu.
OK, that makes sense. Then you just lay out the copper line, and move componets and jumper around until it works.
>>2706858
>solid core wire and a comfortable set of round nose pliers
Yep, have been doing that, though hadn't considered making 90def bends on the board to work around things.

[Anonymous No.2706886]

>>2706881
I still have my Radio Shack wirewrapping wire and tool from the 1980s.
I don't care for it from a troubleshooting perspective; it's too hard to find where the design went wrong. I prefer breadboards for prototype and veroboards for anything I plan to keep around awhile.
What wirewrapping wire (and lesser extent the tool) was really good for was fixing broken traces on circuit boards. You could quickly point to point wire the soldered ends of through-hole parts and work past breaks.

[Anonymous No.2706959]

Any DYI options for GPS shoes for Alzheimer wanderers? It should be able to send an alarm when the wearer wanders too far away from a safe perimeter of when no motion within a perimeter is detected (a potential fall). It should be small enough to fit into a shoe. I am not sure how much power it is going to consume and how long it would be able to run on a single battery. A bracelet is probably not a very good option because the wearer could lose it or take it off or break it etc.

[Anonymous No.2706971]

>>2706728
You are correct, I'm trying to repurpose the switch. Really I should just use a rocker switch and call it a day, but I'm a masochist and this is a good opportunity to learn electronics better.

When I researched latching relays I found there are three types: magnetic, mechanical, and impulse.
For my particular case it seems like impulse is what I need, but when I searched for them they seem to make no differentiation between impulse and mechanical latching. Any idea why?

[Anonymous No.2706977]

>>2706959
Get them to commit some kind of nonviolent crime, have them placed under house arrest with an ankle monitor, and the government will provide the monitoring services for free. Who said we don’t have free health care?

[Anonymous No.2706980]

>>2706886
> wirewrapping sucks
I agree totally. I used to have a job where I manually tested wirewrapped back planes (which is where I think wirewrapping started, and the only thing that makes much sense, imho) with a DMM from a connection list and I can tell you this job is cruel inhuman torture. You can only do it for about 20 or 30 minutes at a time, longer than that and all the gold pins start to go blurry and you have to start shaking off the focus fatigue every few minutes or so. It changed me.

Although I can now keep all my color banded resistors in a single big unsorted box, and I can just immediately pick out the values I need instantly from the haystack.

[Anonymous No.2706983]

>>2706731
The AC averages out to 0, so all he'll measure will be the DC portion, which will be indicative of the real value (voltage or current) for calculating power. Assuming the DMM's DC measurement mode has a sufficiently good filter to block the noise, which it almost certainly will be. Might be a tad RMS skewed or whatever, but it's more than good enough for a couple significant figures.

>>2706858
>there is no circuit, net, rules, tools etc.
I wouldn't be able to do that easily. Having the netlist to ensure that my connections are correct is a hard requirement for anything with more than ~25 parts. Especially for dense layouts.

>>2706959
Any reason not to use something like an airtag or tile? There may be methods of setting up alerts with those.

>>2706980
Wonder when the first automated testing jigs with the moving probes came around? Surely even when they first came out they'd be cheaper than employing someone full-time.

[Anonymous No.2706995]

>>2706783
>Is there a veroboard "layout" or some such in Kicad?

10 seconds on google.
there are others, BTW, but i only had 10 secs to waste on you.

[Anonymous No.2707019]

>>2706783
>>2706786
All garbage. Horrible for prototyping, nearly impossible to desolder. Unnecessary expense. Horrible grounding.
Get a roll of copper tape, lay some across some heavy cardstack, and solder your components point-to-point. Desoldering is literally just melting two blobs and moving. +Free ground plane.

[Anonymous No.2707032]

>>2706983
> automated test robots
I think in, like, 1983 that was something we’d never even conceived of—stuff you’d see in ‘omni’ magazine. We were a small group, and we’d only be able to produce 2 or 3 of these things a year. The backplanes were enormous, they were actually the back connection ends of the edge card holders where the wire wrap pins come out. Back then I got less than $10/hour.
When completed, these things would be populated with cards, tested, and forklifted into white, unmarked vans and driven out to the middle of nowhere, hooked up to ground sensors, and they’d set off explosions and collect the data to build a 3d picture (eventually) of what’s under the ground.
No DSPs, no microprocessors, just seas of TTL logic and memory chips.

[Anonymous No.2707036]

>>2706971
> relays
Yeah, these things are ‘barely’ electronics, there’s a lot of terminology/naming differences. In electrical work they call relays “contactors” for some reason.
I’m sure some autist will come out of the woodwork and explain to me the difference.

[Anonymous No.2707038]

>>2707019
Point-to-point is a mess for dense designs. Easy to rework, but hard to troubleshoot and design in the first place.

>>2707032
>we’d only be able to produce 2 or 3 of these things a year
I guess that shifts the economics somewhat.
>off explosions and collect the data to build a 3d picture (eventually) of what’s under the ground
That's really damn cool sounding. DIY lidar, radar, sonar, etc. for mapping surroundings or just calculating position is something I'd like to get involved in, but the sensor arrays seem expensive and the software side is daunting.

[Anonymous No.2707092]

>>2707038
>Point-to-point is a mess for dense designs
False. It is extremely dense if you bend the leads right.

[Anonymous No.2707102]

>>2707092
>reading comprehension
I'm not saying it can't be dense, but it's a mess of wires when it is. Very difficult to trace a complex circuit, which you want to do not only for troubleshooting but for assembly and modification also. And your ground plane isn't that valuable for noise immunity if you don't eliminate crosstalk. It's good for simple analogue circuits, but doesn't scale well, especially with significantly interconnected circuits.

[Anonymous No.2707127]

>>2706995
Actually prefer to stay in a more complex tool (Kicad) as I can then transfer learnings over into more complex / custom layouts.
But that tool's interesting b/c it's so specialized for the one thing, and appears workflows are similar. I'll check it out.

[Anonymous No.2707192]

love ali shops and their creativity.

[Anonymous No.2707203]

>>2701116
Guise let’s say i need a comb filter as part of a diy project, how would i go about creating this out pf electrical components? I need to be able to control the operating frequencies and resonance levels with simple analog inputs such as piezos or variable resistor

[Anonymous No.2707212]

>>2707203
You don’t need any components if you have the digitized waveform you’re trying to filter, you just do it on a computer.

What frequency range and signal level are we talking about? Generally you’re gonna have to buy some ferrite cores and magnet wire. Or litz wire.
Possibly some pin diodes and or rotary capacitors.

[Anonymous No.2707217]

I work at an electrical assembly type place where there are all sorts of wires and cables stocked. I need some speaker wire for an upcoming surround setup, what should I use? Something shielded? Twisted pair?

[Anonymous No.2707221]

>>2707217
For speakers, it’s generally under 60 V, so you can use almost anything. No need for shielding unless they are powered speakers driven by a “line out”
Usually anywhere aroud 18 AWG is good, thicker for higher wattage.
Generally speaker wire is the same shit that a household table lamp with a lamp shade would use.
I prefer the clear insulation (also common on lamps)

[Anonymous No.2707223]

>>2707221
>clear insulation
Don't think we have that, but I'll tuck it away as much as possible.

One pair may have to run underneath a refrigerator though, should I consider shielded for that?

[Anonymous No.2707227]

>>2707221
not him but what about special silver / or deoxidized copper for better frequency response? i read that it has something to do with intrinsic electron spin moment and its interplay with the cable's inertial characteristics.

[Anonymous No.2707228]

>>2707227
sounds like audiophile faggotry

[Anonymous No.2707234]

>>2707228
could be. but all of them can't be crazy? i read numerous theories how when electrons move through a copper wire, their spin and momentum interact with the cable's molecular structure and as a result, the cable develops a unique "sonic fingerprint" or something.

[Anonymous No.2707241]

>>2707234
No, they can all be crazy. Sounds like it's rubbing off on you.

[Anonymous No.2707254]

>>2707227
>for better frequency response?
>>2707234
>a unique "sonic fingerprint"
Untrue and homosexual. The only two things that matter in speaker wire are:
Resistance, the more power you waste the quieter your speakers will be. If the wire looks thick enough, it's probably more than needed.
And quality of the connections. This is what actually separates good setups from garbage. If you're twisting wires together or use screw/spring terminals with bare copper wire it will either come loose or oxidize and not make a good connection. I know that because none of the speakers I spliced worked properly after a few years and I had to redo them all.

[Anonymous No.2707312]

>>2707203
Make it with BBDs, they're fun.

>>2707254
I just tin-plated the ends of my cable and put it back into the binding posts. Could probably swap to banana plugs but eh it works fine.

[Anonymous No.2707313]

>>2707227
>special silver / or deoxidized copper for better frequency response? i read that it has something to do with intrinsic electron spin moment [more garbage]
Holy shit. I was trained / worked as an acoustics engineer. This kind of audiophile nonsense makes my head hurt to even read.
LIke others have said: make sure wire is proper gauge and has a good connnection, is the important thing for wires.

[Anonymous No.2707318]

>>2707312
>I just tin-plated the ends of my cable
That's what I did too. Solder doesn't oxidize as far as I know, so it's more than good enough for low-voltage, low-power applications like this.

[Anonymous No.2707319]

Is there a good quick connect terminal that's heat resistant?

I want something to quickly shove small heating coils in without it melting.

[Anonymous No.2707320]

>>2707318
I chemically tinned them. It's probably fine to tin via soldering iron if you get that really thin solder wicking into the strands, but a blob could well deform and make a loose connection over time.

[Anonymous No.2707321]

>>2707320
>but a blob could well deform and make a loose connection over time.
The terminals were spring-loaded, just like in the pic of >>2707319, so no such problems.
Even then I'd prefer a blob that slowly deforms than bare stranded wire that comes loose a couple years in a screw terminal.

[Anonymous No.2707323]

>>2707319
Ceramic terminal block?

[Anonymous No.2707328]

>>2707323
Screw terminals would be annoying.

I want to push a coil in for 10 seconds, pull it out, put the next one, and so on.
It doesn't need to be a very stable connection.

[Anonymous No.2707329]

>>2707328
Put some alligator clips in the terminal block.

[Anonymous No.2707331]

Mystery of Chinese solder is solved.
It is 40% Tin 60% Lead or similar.
>40/60 solder
>big ass solidus-liquidus gap (183 - 238C)
check
>dull color
check

[Anonymous No.2707335]

if I have a 4 layer PCB, with stackup of
>Signal/Power
>Ground
>Ground
>Signal/Power
how bad is it to occasionally route the power on the ground layers

[Anonymous No.2707339]

>>2707331
thats just flux residue.
wash it with 99% IPA to see the true color of solder.
and the best way to test the composition is to heat it to a specific temp and see when it melts.

[Anonymous No.2707349]

I was in the middle of making a "flashbang" but just a flash using a camera flash and it's capacitor, however I need to make something that charges the capacitor fast enough, is it a stupid idea?Can i make the charger from scratch? Capacitor is 330v 90uF if it matters

[Anonymous No.2707355]

>>2707349
working on something similar currently
basically a boost converter without the load

[Anonymous No.2707357]

>>2707339
>thats just flux residue.
Nope. I've cleaned it a bit.
You can also see crystals like on galvanized steel.
>and the best way to test the composition is to heat it to a specific temp and see when it melts.
Yes. But my iron has analog knob and I've no thermometer.
So it is 30/70 or 40/60 solder.

[Anonymous No.2707361]

>>2707203
two PT2399's running in parallel

[Anonymous No.2707364]

>>2707102
>it's a mess of wires when it is.
False.
>Very difficult to trace a complex circuit,
False.
>And your ground plane isn't that valuable for noise immunity if you don't eliminate crosstalk.
Autistic nitpicking
>but doesn't scale well,
Name one prototype that does retard
>especially with significantly interconnected circuits.
False.

[Anonymous No.2707386]

>>2707349
>Can i make the charger from scratch? Capacitor is 330v 90uF if it matters

you want a fast charge? that's easy, nigger.
put a 24V zener in series so you dont go over the max.

[Anonymous No.2707388]

>>2707386
good one

[Anonymous No.2707390]

>>2707364
>False.
>False.
>False.

this has gotta be a troll.
no sane person who's ever built a lot of circuits would defend such a stupendously bad idea.

[Anonymous No.2707395]

>>2707390
It's some retrophile hard for old radios using vacuum and whatnot. The LE cool idiot aura points to someone inspired by the roadie having soldered hundreds of deadly amplifiers with nothing but a nail in a stick and a zippo lighter using pine sap and whisky for flux while smoking a marijuana cigarette high on LSD acid...

[Anonymous No.2707406]

>>2707102
>Very difficult to trace a complex circuit,
incorrect, as someone who has worked on more than 60 point to point wired devices, it is extraordinarily easy to trace things. way easier than any double sided circuit board.

[Anonymous No.2707407]

>>2707357
>You can also see crystals like on galvanized steel
Maybe antimony.

[Anonymous No.2707411]

>>2707390
this is extremely simple to trace.
everything is visible, everything is identifiable,

[Anonymous No.2707418]

>>2707407
antimony is expensive, so probably lead.
It also sticks good to steel, and IIRC all solder alloys with tin<50% are designed for soldering steels

[Anonymous No.2707444]

>>2707390
Retarded organization is the fault of the user. Component networks can easily be free-wired into compact modules (Hint: twist the leads together), and then tacked down in an organized manner.

>>2707395
>hundreds of deadly amplifiers
What part of "prototype" are you failing to comprehend?

[Anonymous No.2707453]

>>2707335
why ground in the middle instead of the outsides?

[Anonymous No.2707458]

>>2707411
That's like 20% density at best. I was talking about actually dense designs like you can get with protoboards. If you had a good diagram showing which component was where then your pic would be easy to trace. Without such a diagram, dense or not, if you want to figure out what voltage is across R15 then you're first gonna have to figure out which resistor that is.

[Anonymous No.2707464]

>>2707453
https://youtu.be/ySuUZEjARPY?t=2996
daddy hartley recommended the stackup in a video and it seems to fit my use case
I guess ground-signal-signal-ground would work as well

[Anonymous No.2707571]

>>2707395
That beautiful sentence reminds me of the good ol days.

[Anonymous No.2707605]

>>2707458
Ah yes... pulling shit out of your ass.

[Anonymous No.2707655]

>>2707605
That reminds me of the time Bobby Brown reached into Whitney Houston's poop chute and wrenched a hefty bum clot from her sore arse because of the opioid-induced constipation after decades of horse riding.

[Anonymous No.2707659]

If i cut 2 piezos the same size, play a sound through one and use the other as a microphone and then push them together, this would effectively create a highpass resonant filter right?

[Anonymous No.2707687]

>>2707659
more or less yeah
you could always find the impulse response to be sure

[Anonymous No.2707691]

>>2707687
So if i cut a circle out of it, the diameter will be the wavelength that gets receives the most gain?

[Anonymous No.2707705]

>>2707691
it would definitely play a part in it for sure. I'd argue that the response would be more akin to a bandpass filter with a lower roll-off on the highs than on the lows

at this point it might be worthwhile to either find the transfer function/differential equation for a generic piezoelectric buzzer, or try to derive it yourself. That would offer a huge amount of insight.

[Anonymous No.2707882]

So I converted a 2 HP, 3 phase 220 hydraulic pump to single phase 220 with a VFD as in pic rel. It runs a few minutes and the trip on the start coil pack pops. Draws steady 1800W or so. Jumping over start coils causes error on VFD and no start. Can I move the VFD between the contactor and the start coils so they're between the VFD and the motor? Or did I do something else wrong anyone can spot? Is there too much current now that 2 legs of 120 are passing through the start coils instead of 3 legs of 220? Do they need upgraded? Why does the VFD seem to need them in the first place? Ideas?

[Anonymous No.2707890]

>>2707659
you can cut piezos? I figured they'd shatter like glass

[Anonymous No.2707933]

>>2707890
Not him but yes, it's a common trick to make 4-way piezoactuators on the cheap: you take a unimorph disk, cut it in quarters, depolarize and glue some wires with silver glue to avoid heat deforms.

[Anonymous No.2707969]

>>2707882
I suspect it's fine to have it the other way around. But I don't actually understand what these start coils are doing.

[Anonymous No.2707982]

>>2707969
This is a pic of a similar unit. The top is the contactor, the bottom is the starter coils.

[Anonymous No.2708000]

>>2707882
>Can I move the VFD between the contactor and the start coils

well, that would make sense.
right now the starter coils are running at line frequency, and running coils are running at VFD frequency.
they have to be in sync: at the same frequency, and at the same phase angle.
the purpose of the start coils is to give the motor a boost to overcome inertia.
so the two sets of coils must work in unison. not at random.

[Anonymous No.2708011]

rate my >20A 24V power supply, it's got 6x 18awg wires for +12V and GND rails from (non-modular) PSUs, using EC5 bananas as connectors. had to add nylon washers beneath one of the pcbs to isolate its gnd rail from protective earth

with that barrel jack on there I doubt I'll be able to handle more than 10A but that's just to plug into this snapmaker 3d printer

[Anonymous No.2708025]

>>2708011
>rate

2 out of 10.
- wires sticking thru metal w/o a grommet
- a switch flapping in the breeze. should be mounted on the chassis
- two wires on switch using dupont-type connector. should be soldered or use a locking connector
- 3V and 5V power output using male banana jacks. should always use female for safety
- and mounted on case for extra safety
- only 1 supply made floating. should be both to make sure. unsolder IEC ground pins and isolate PCBs from case
- heat shrink color does not match wire color. that's gauche
- overly long fuse wires are messy and cause power loss
- for longevity and power savings, power switch shoulda been used on 120V lines instead

[Anonymous No.2708031]

>>2708025
>wires sticking thru metal w/o a grommet
that's how the non-modular psu was originally, can't be that bad
>a switch flapping in the breeze. should be mounted on the chassis
i'll make some sort of face-plate for the whole thing eventually
>two wires on switch using dupont-type connector. should be soldered or use a locking connector
well it's meant to be separable from one of the supplies, don't see a particular reason to use a locking connector considering the friction of the dupont pins feels solid enough for an environment without vibration
>should always use female for safety
all the males are GND
>mounted on the case
no case yet, and chassis-mounted ec5s don't exist. i don't really trust conventional 4mm banana plugs for the ~50A these psus are capable of
>only 1 supply made floating. should be both to make sure
i want the whole thing grounded for safety reasons, there's a fuse between the psus so there's not really a risk
>heat shrink color does not match wire color
they reflect rail color, yellow for 3.3v and 12v, red for 5v, black for ground. the all-black supply would mean all the heat-shrinks would be black and that's not helpful at all. ideally i'd open the supplies up and replace all the wires with custom wires, maybe some nice chassis-mount connectors too, but high-current chassis-mount connectors are hard to find and kinda expensive.
>overly long fuse wires are messy and cause power loss
that's a 30a fuse holder for a particular implementation that's only going to eat 5-10a, like the barrel jack it's not an issue for now and i'll upgrade it for a beefier fuse if/when i set it up for a higher-power circuit.
>power switch shoulda been used on 120V lines instead
it's just a switch that connects the power-on pin to ground for both the psus at the same time, no significant current goes through it. i guess it's fine to leave the power-on pins constantly grounded, i'll consider that change.

[Anonymous No.2708035]

>>2708031
>no significant current goes through it.

that's not the concern.
unless you cut off 120V power, part of the supply will be hot, and waste maybe 4W all the time.
plus that circuit will be live so the components are wasting away their life expectancy.

>i'll make some sort of face-plate

you already have 2 cases than can be drilled for switches, jacks, even fuse-holders.

[Anonymous No.2708055]

>>2708000
Thanks, I'll move it over and see what happens. I was afraid the VFD might experience some weird feedback from the start coils but since obviously they need to be in there somewhere it makes the most sense to put them where they belong, especially in light of the frequency issue you bring up. I'll give it a whirl!

[Anonymous No.2708068]

>>2705869
notepad, unironically

[Anonymous No.2708071]

>>2707453
Because then there's no crosstalk between the traces on the two signal layers.

[Anonymous No.2708125]

>>2705869
Don't limit yourself with simple document based specifications. For your project only acceptable solution is to use enterprise grade MBSE software like capella.
>https://mbse-capella.org/

[Anonymous No.2708214]

>>2701128
that's JST PH not XH. had a similar issue a while ago.

[Anonymous No.2708452]

>>2706208
>>2705545
YouTuber "My Mate Vince" fixes the graphite contact pads underneath the drum button-membrane of a Yamaha keyboard.
See 22:40 of this video https://www.youtube.com/watch?v=oVkdpMC3-ds&t=1361

I believe he uses copper tape in the end because the graphite keeps flaking off.

[Anonymous No.2708485]

>>2708452

did you click my post number by accident? >>2706208

[Anonymous No.2708503]

>>2708485
Yes sorry

[Anonymous No.2708534]

What's the smallest readable silkscreen on JLCPCB?

[Anonymous No.2708538]

>>2708534
>To make the silkscreen clear on the board, the width of the texts (filled lines) and the space between letters need to be no less than 0.15 mm with a height no less than 1 mm. The preferred ratio of width to height is 1:6
Jul 24, 2023
https://jlcpcb.com/help/article/14-Instructions-for-ordering

[Anonymous No.2708638]

>>2708534
Readable by who? Boomers without their glasses?

[Anonymous No.2708642]

>>2708638
Girl, you'll be a boomer soon.

[Anonymous No.2708742]

I'm trying to figure out how the circuit for a coffee mixer works. It is pretty similar to this:
>https://www.amazon.com/dp/B089K8SG2R/ref=sbl_dpx_kitchen-coffee-appliances_B0C2T4FDTG_0
It basically controls the speed of a DC motor andI know the voltage going to it stays the same no matter the speed, I assume the MCU controls via resistance as the current going though the motor changes with the selected speed. It's all controlled with a single push button that cycles between 3 speeds and if held down for one second or so, shuts it off completely. There's a sole MCU with 8 pins that I think does all the work but everything is completely unlabelled.
If kept on, it automatically switches off after 10 minutes or so and I want to modify it so that I can keep it running for as long as I want or till the battery dies. Does anyone has any idea how that could be done?

[Anonymous No.2708745]

>>2708742
>It basically controls the speed of a DC motor andI know the voltage going to it stays the same no matter the speed
PWM (pulse-width modulation)
>I want to modify it so that I can keep it running for as long as I want or till the battery dies.
If it's only going to be used at one speed then you could just connect a hard switch between the motor and power supply/battery, bypassing the MCU.

[Anonymous No.2708747]

I used a plugin in kicad to generate the files I need for JLCPCB manufacturing. Problem is, when I upload the BoM and placement files, I get this error.
How big of an issue is this? Intuition tells me that if they can't associate the parts with the placements, there's probably going to be an issue. But, intuition tells me these tools probably suck and there really isn't too much of a problem.

Has anyone gotten this before? Should I just press on and see what happens?

[Anonymous No.2708748]

>>2708745
>PWM
Shouldn't I see an oscilation at the current measured by the multimeter if it were that? It pretty much stays bang on at 166 mA. Maybe the meter just isn't fast enough?
>connecting it straight to the battery
Yeah, I thought of doing that and right now I think that's what I'm gonna do, I just wanted to see if I could remove just the automatic shutdown timer without doing that, controlling the speed isn't that important but it's still nice.

[Anonymous No.2708752]

>>2708748
>Maybe the meter just isn't fast enough?
This. Scope it for an accurate reading.
>controlling the speed isn't that important but it's still nice.
You could use a tarduino or attiny and make your own PWM controller, or buy one off-the-shelf from scamazon.

[Anonymous No.2708753]

>>2708752
or a 555
lmao

[Anonymous No.2708757]

>>2708752
How bad would it be if I just slapped a couple of resistors to it and a switch to change between them? I know it would be wasteful but it would allow for some speed control.

[Anonymous No.2708762]

>>2708757
Do what >>2708753 said, easiest speed control you could ask for.

[Anonymous No.2708798]

Asked this on mcg but might be more of a ohm Q, bc issue I assume is in the power supply.
Powering an arduino nano project. I've set up a power supply that's putting out 5.2V and rated ~300mA, sending power to the 5V pin as well as the other stuff connected to it. It's a salvaged Nintendo GBA wall wart. Should be more than enough current for everything.
Had zero issues running it from battery, but when I switched to the AC supply, the OLED screen fuzzed out, and it started randomly firing the relays attached to it. Trying to run from USB, it was dead. Reprogrammed it and now it's fine.
Ideas on what's going on?

[Anonymous No.2708802]

>>2708798
Pic of supply. Wondering how this thing is regulated…

[Anonymous No.2708804]

>>2708802
>>2708798
have you tried to power it from a known-working power supply of similar caliber

[Anonymous No.2708806]

>>2708798
>5.2V and rated ~300mA
>Should be more than enough current for everything
>OLED screen
>relays
You need a better power supply.

[Anonymous No.2708812]

>>2708804
I’ve run it off 3xAA on 5v pin, and from usb.
>>2708806
The AC ps is putting out 5.5v and stays stable. The relays are in optically, isolated and don’t draw much power. Pic related.

[Anonymous No.2708817]

>>2708806
>>2708812
Checked with relays. Marginal but probably ok.
Any rate this AC PS is bugging out the Arduino without the relays attached. And that draws nothing.

[Anonymous No.2708819]

>>2708747
Contact JLC about the files and see if they can work with them or not. If you dive in they’ll probably contact you about it anyhow.

>>2708812
AA bats can handle like 3A peak. Most USBs these days can provide 2A. It may also be an issue of power supply ripple, add a bunch of extra capacitance and see if that fixes it.

[Anonymous No.2708821]

>>2708819
>power supply ripple, add a bunch of extra capacitance
Add some electrolytics across +/- rails of the AC PS?
Also, does someone need to bake a new thread?

[Anonymous No.2708824]

>>2708802
Check the flip side for shit joints and replace the electrolytics.
>>2708821
>does someone need to bake a new thread?
This board is so slow that there's another 36 hours at least before the thread gets archived.

[Anonymous No.2708942]

I got a chink bluepill. Couldn't find any information on it online at all. The markings I see say "STM32F103C8T6" and "DevEBox", seemingly no other information. Just messing around, not sure what I'm doing. I'm trying to connect to it by gdb using openocd, but no matter how I mess with the config I can't seem to get anything but "Error: open failed". Also the board isn't visible at all as a usb device. There are 2 leds on when plugged in, one led labeled d2 is blinking while the other (d1) stays on.
Any ideas?
Or maybe /mcg/ would know better?

[Anonymous No.2708949]

>>2708942
it most likely uses an SWD connection for your debugger not gdb. any jlink should work with it. if it doesnt then its a chink stm32 and you should probably avoid it. some of the stm32 series have usb dfu which can be activated by resetting the cpu under specific conditions

[Anonymous No.2708985]

>>2707969
>>2708000
Followup: Moved VFD between Contactor and Start Coils, SUCCESS. Likewise, to whomever engineered that 5532 Op Amp circuit to bring a 5V control signal to -10V to +10V, should you be watching, that was a success as well. THANK YOU!

[Anonymous No.2708989]

>>2708949
openocd does swd, it can bridge gdb for the device. But it's failing to connect at all. It's a devboard with an inbuilt debugger that I'm connecting to, but 0 documentation anywhere, not even in chinkrunes. There's no dfu support for the stm32f103.

[Anonymous No.2708991]

>>2708989
Check the regulator and clock.

[Anonymous No.2708996]

>>2708989
its probably a built in stlink v2 clone

[Anonymous No.2708998]

>>2708996
Yeah, that's what I assumed, No go so far though.

[Anonymous No.2708999]

>>2708998
you could try putting the chip manually into bootloader mode with the boot0 pin, and inject the binary over the uart interface - if its a good chink clone that is

[Anonymous No.2709013]

what do you guys do when you want to solder something but its too cold outside? dont want to do soldering with my windows closed but its already pretty cold where i live.

[Anonymous No.2709077]

>>2709013
Fart on it. Go ahead. Give it a little toot.

[Anonymous No.2709081]

>>2709077
It sounds like he's afraid of the buildup of deadly solder fumes. If you add fart gas to that equation he may well drop dead within seconds, rather than the slow agonizing death over days that solder fumes cause! I'd recommend putting on a nice Covid mask, known to protect humanity from any concievable threat, THEN fart on it.

[Anonymous No.2709091]

>>2709081
Good thinking, Anon. Safety first.

[Anonymous No.2709137]

Hello Anons. I'm interested in making an FM transmitter like in the kits >>2702130 posted. I've looked into the different designs out there and decided to go for a single transistor design, like these:
https://www.circuitstoday.com/miniature-fm-transmitter
https://www.buildcircuit.com/simplest-and-cheapest-fm-transmitter-do-it-yourselfdiy-kit-for-amateurs/
My question is, what transistor can I actually use for this? Every design I found uses a different one, and I don't understand what makes one better than another. I do have a set of transistors already, so using one of those would be ideal. The set contains BC 327, 337, 517, 547 to 550, and 556 to 558. I looked at their datasheets but I'm a complete noob when it comes to analog electronics so I have no idea what anything means. I can probably figure the rest of the circuit out, but would I need to change any of the other components if I use a different transistor than it was designed for?

[Anonymous No.2709155]

>>2709137
Probably the very high switching speed of the 9018 under high gain.

[Anonymous No.2709158]

>>2709013
What’s your guys take on lead solder for hobby level exposure? Like, a few hours a month.
Had a friend flip out re lead solder I typically use, and have been for years.

[Anonymous No.2709159]

>>2708942
Maybe you need to set fuses first? Check the datasheet I guess.

[Anonymous No.2709160]

>>2709155
That's what the schematic has already. My question is whether any of the ones I have on hand could also work.
>The set contains BC 327, 337, 517, 547 to 550, and 556 to 558.
If not, then I'm probably better off buying an actual kit.

[Anonymous No.2709161]

>>2709137
>what transistor can I actually use for this?

Elektor magazine would often uses the names TUN and TUP when specifying a transistor.
it means, ''use whatever general transistors are popular in your country'' in NPN and PNP.
for an FM transmitter, that'll be more than sufficient.
something like a 2N3904 or 2N2222 in N America or a BC547 in Yurop.
however, a single transistor transmitter wont work very well. i'd go for a 2 or 3-transistor design.
(well, not really, coz i have a bunch of car FM transmitters I got for a couple bucks each).

[Anonymous No.2709165]

>>2709161
Thank you, I thought that would be the case. I guess I'll use the BC550 then. As for how well it works with just one transistor, it doesn't matter too much to me. I'll probably make a better version after I figure out this one.

[Anonymous No.2709221]

>>2709013
Huff that flux.
>>2709158
Minimal. Because lead doesn't boil until it is like 2000C.

[Anonymous No.2709223]

>>2709137
2n2222, KT315, anything with Fc > 250 MHz.

[Anonymous No.2709277]

>>2709159
Yeah, problem is I have no datasheets. The package comes with nothing and I can't find anything online either.
I did find an old forum post suggesting I need to jumper boot0 high, but the followup posts included people having the same issues as me (usb not even detected) which makes this not the right solution.

[Anonymous No.2709284]

>>2709277
https://www.st.com/resource/en/datasheet/stm32f103cb.pdf

[Anonymous No.2709323]

>>2709277
I mean the datasheet of the actual STM32F103C8T6. If your chip doesn’t follow the real one in its fuses and debug hardware then it won’t help, but generally fakes of STM32s are like 99% as good as the real ones. There’s even some fakes that fix a hardware bug that the originals have. Though it’s also possible that they skimped you on specs or even sold you a dead chip, but chances are if you can program it it’s good.

Might also need to read an additional document about how debugging works on STM32 chips.

[Anonymous No.2709375]

>>2709158
wash your hands, never let the joints go dull and it'll never produce dust
>>2709013
I've given up on pc fans and window bullshit completely. I just solder with a respirator now

[Anonymous No.2709491]

>>2709490
>>2709490
>>2709490
NEW THREAD

[Anonymous No.2709499]

>>2709158
Just be smart about it and nothing bad will happen.
Wash your hands after touching lead solder, avoid eating/drinking in the middle of it, avoid touching your eyes/mouth/face/whatever. Pick up any bits that splatter if you care about the workspace.

[Anonymous No.2709795]

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