>>2868444
What in hell is this a video of

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Hello, I'm currently trying to make a AM transmitter.
I have a working prototype on a breadboard but it's dogshit, what can I do to make it better?

>>2868492
Looks like opening up a personal surveillance device.

>>2868495
If that's meant to be a schmitt trigger oscillator, the inverting and non-inverting inputs are backwards, unless the frequency you're operating at is fast enough that your phase offset is somehow that bad. A TL072 is also a strange choice, having a GBWP of only 3MHz.

That sort of unbalanced mixer isn't that linear looking, I'd see about making a diode or JFET mixer of some sort, though I've never tried to make such a transmitter myself. You could also try buffering the microphone's signal in your current mixer circuit.

>>2868497
>If that's meant to be a schmitt trigger oscillator, the inverting and non-inverting inputs are backwards,
Good catch, I'm used to reversed inverting/non-inverting pin locations in schematics/simulations so I made a mistake here, irl it's wired correctly.
>A TL072 is also a strange choice
It's what I have on hand ¯\_(ツ)_/¯
It seems to oscillate fine up to 700kHz~. anything more and it craps out.

>>2868444

garotte video, mate!

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>>2868495
> make it better
Change your construction technique.

> am transmitter
I’m used to seeing a tuneable tank circuit. I agree with >>2868497 that it’s a bit strange, but if it works, great.

>>2868504
>Change your construction technique.
What do you mean by that? Solder it to a pcb instead of breadboard? Add decoupling caps?

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>>2868495
>make it better?

use a crystal

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>>2868506
Most RF projects that are hacked together look something like picrel.

>>2868495
ground plane

>>2868492
>What in hell is this a video of
That's how I make $250 every couple of days.

I want to make and code an automatic roller for a blind that uses a chain to lower and raise. What do?

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is this oscillator any good? I just need to work with a quartz clock and maybe multiples of it. 120mhz would suffice for me, I think
https://www.aliexpress.com/item/1005006145916861.html

>>2868587
Use a motor and gear with limit switches or a rotary encoder. Drive it with a h-bridge controlled by either infrared or RF remote (maybe a wireless relay module), and wire hard switches for manual control in case you lose the remote.

>>2868593
Ta

>>2868587
Use an old RC car and remote.

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>>2868591
>is this oscillator any good? I just need to work with a quartz clock and maybe multiples of it. 120mhz would suffice for me, I think
Sure. But note the limitation. Only once channel can do 120MHz. Given the price, that's expected.
Looks like a decent rugged scope suitable for industrial use.

>>2868605
Thanks. I usually lurk /g/ so I'm not yet knowledgeable about EM/RF stuff.
as for 60MHz, that is to be expected for this price but 60mMHz still plenty good

>>2868610
Yeah, if you're not an EE working on some high-end products, you won't need 120MHz. And especially not 2 channels of it. For hobby, fixing, car stuff... 60MHz and 1 channel 120MHz is more than sufficient.

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Stuck on a problem. If Vin = 0V. How does Va = 0.7V and totally omit the last resistor as voltage drop?

I can see if Vin is 12V the diode is not conducting and each resistor drops 6V so Va would be 6V.

>>2868444
Anyone got time to help a retard out? Im trying to bypass a circuit board integrated into a 14.4v cell. Some componenet was bad and power wasn't passing to a 5 pin connector. This battery is for a robot vacuum that will not power on without being connected to the charging port. It goes into low voltage protection mode shortly after being connected to the charger.
To verify, it was a faulty battery board causing the issue, I'm straight wiring the cells direct to the 5 pin connector. This battery will not go back onto the charger.

The cheap connector plates broke on disassembly, so now I've got two 7v cells. I'm limited to tools at the moment and have wire nuts, scotch locks, and phone wire. How do I wire the components pictured back to the 14.4v cell connected to the 5 pin connector.
The blue wire was for the thermistors and probably doesn't need to be wired in if im reading the circuit board correctly. I can post the board if needed.

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>>2868753
Pic

>>2868753
>trying to bypass a circuit board

seems obvious that the gadget needs to communicate with the board that you removed
if you wanna bypass that, you have to make your connections AFTER the section that talks with the board
which means you need more documentation, more tools, more experience
unless you can find someone who did it and documented it, your only hope is to buy a replacement battery module

>>2868732
>How does Va = 0.7V

the diode provides a low resistance path to 0V, so all the electrons go that way instead of the formidable path thru the lower 10k

>>2868784
I disagree. The 5-pin connector looks like a conventional JST balance plug, and it's a 4S pack, so 5 terminals checks out.

That said, running it without the board that was presumably a BMS is asking for trouble, especially if the tool/appliance itself has no low voltage cutoff. Charging should be fine, I guess.

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>>2868492
crystal window mod its a new fashion trend
the paint layer behind the clear plastic is being dissolved with temperature and microwave vibrations, when its done you can see-through and the circuit board becomes visible
sort of like the clear see through cases for tvs phones and personal computers (see picture attached) in the early 2000's

>>2868807
That doesn't show up on Google, crystal window mod..

None of that makes sense
You said microwave?

>>2868755
>>2868753
Probably under ikt protection that is abused to prematurely kill your battery.
You haven't even said what the battery cell types even are

If you know what a thermistir is them you should know how to get 14v from two 7s

Go make a mot spot-welder..
You're gonna burn your house down with that tape and wire nuts

If I can't tie my shoes should I try to get into electronics? I'm a transgirl

>>2868807
>clear see through cases for tvs phones and personal computers (see picture attached) in the early 2000's
those were prison products, that were sold as a novelty.

>>2868813
>You haven't even said what the battery cell types even are
>18650's NOT being lithium ion
are you that retarded?

>>2868855
>I'm a transgirl
does that mean you were a girl and now pretend to be a guy?, or you were a guy and now pretend to be a girl?

>>2868980
It obviously means xxe was a guy/girl pretending to be a girl/guy but pretending to be a guy/girl.

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Can I get some advice on this
>>>/g/103074865
>>>/g/103074968
I was thinking of getting a small heatpipe like pic related off aliexpress, and glue it down (making sure it makes as much contact with the main heatpipe, of course) to improve things a bit. What I do not know is what kind of glue is ideal for what I want to do, there is a thing called "heatsink plaster", there are thermal epoxies, there is also copper tape with adhesive (but I think it is for other use cases). In the second post I linked you can see in the picture, above where the black rubber thing is, that there is another vent. Lenovo sold different versions of this, one (the one that I have) has the small vent on the back blocked and there are no fins attached to it, the other version is functional because it's both unblocked and has fins inside. I could purchase a small set of copper fins and try glueing it or maybe even soldering it (will probably damage the rest of the heatsink tho). I wonder if heat conductivity would be worth it.

>inb4 e-waste get rid of it
Not yet, I will only upgrade when 12th gen and over laptops come down in price, in practice there is not even that much difference because older systems had even worse thermals thanks to trying to copy Apple.

>>2868998

I have ho idea if you even have room to do that, laptop cases being tight as they are, but you want definitely a thermal epoxy. Ideally, you want as absolutely thin layer as you can get at the point of contact, which obviates any kind of tape (those are generally for fairly low-performance applications, anyway). There are single-part thermal adhesives, too, but they don't generally bond as well. Performance is roughly the same, assuming similar bond layer thickness.

Soldering is better than both, but not trivially easy. You need an extremely powerful heat source, both to actually heat up a chunk of copper that large, and to enable you to do it while keeping the ends cool enough that you don't damage too much of the working fluid (or, worst extreme case, cause an explosion). That's assuming it uses a fiberglass wick in the first place, since thermoplastic ones would be destroyed by the heat no matter what you do.

>>2868980
I'm pretty sure it means he gets away with personal fouls against women and children in sports, academia, employment, public libraries, and criminal court. That's just what I heard.

>>2868786
I guess the key word here is formidable, I just figured like in a parallel resistor even if ones greater it still conducts and has a voltage. Is there a formula that clears this up? I was told voltage divider but not sure how to set it up.

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>>2869004
There is just enough room for it, this is an old computer so nothing is glued or made to extreme tolerances plus the top-end version using the same frame (almost same heatsink with different anchor points) has a discrete gpu but mine (base version) has empty space there.

>You need an extremely powerful heat source, both to actually heat up a chunk of copper that large, and to enable you to do it while keeping the ends cool enough that you don't damage too much of the working fluid (or, worst extreme case, cause an explosion).
I see, I feared that would be the case. A 60w iron probably won't cut it, this is more like spot welding level of heat and quickness.

Thermal epoxy would be the only reasonable option left then. Do you or any anon reading this have any suggestion? I'm not seeing many options here, there is a 'thermal epoxy' sold by Arctic (the thermal paste company) but it's a bit on the pricier side and hard to find. There are some kinda crazy DIY 'recipees' that consist of mixing regular epoxy of any kind with either thermal paste or some other form of heat conduction (aluminium powder or graphite). I wonder if anyone here has tried that, of course I'd make sure nothing that can be shorted is touching them.

>>2868966
To be fair they’re occasionally LiFePO4. Which is plausible if it’s for a long-lifespan appliance like a mini power station. The new sodium ion chemistry is also being put in 18650 cells.

>>2869017
With 0V on the diode it’s basically in parallel with the low-side resistor. Shitty simplification ahead: a diode acts like a resistor whose resistance is dependant on voltage. It’s really high below 0.7V, and really low above 0.7V. See the schockley diode equation graph. With two parallel resistances, the smaller resistance dominates over the larger one. With 11.3V across the top resistor, it lets 1.13mA through it. There is then left 0.7V across the diode and other resistor, the resistor takes 70μA, while the remaining 1.06mA go through the diode.

>>2869041
Ok that makes sense, so it does have measurements, its just negligible at that point.

>>2868444
I'd start with resistors.. dem stripey boyz

Don't know if this is the right place or not, but is it ok to have Ethernet cables in the same plastic flex tubes (whatever they're called in English) as my mains power (EU, 230V), or is it safer to have them in their own tubes? I live in a 90 year old house with two stories + basement, and would like to avoid having cables running along all walls.

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how exactly does this microohm meter achieve any accuracy? it supplies a 1ma pulse current. the first stage gain amplifier (AD8228) has an input offset voltage of 50uv. they show this device as being capable of microohms, but assume 1 milliohm * 1 milliamp = 1 microvolt. the input offset voltage of the FIRST STAGE is 50x that. are they implicitly trimming the offsets by hand or with software?

also i get that they're using an AC or pulsed waveform to negate the Seebeck effect, which then has to be rectified back to DC. the AD630 performs this rectification but it's also really fucking expensive, $40 per chip on mouser/digikey. why wouldn't they just use a "precision op amp rectifier" configuration for a much, much, much lower cost?


>http://kripton2035.free.fr/Resources/Complete,%20low-cost,%20software%20programmable%20ohmmeter%20measures%20micro-ohms.pdf

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Aspiring automation technician here. 12 weeks into a 4 year education. Do I belong here?

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>>2869221

get 2 pairs of largish tweezers without sharp corners
wire everything using neat 90-degree angles
lay down runs of wires like a multi-lane highway
if you're fast and neat, your professors, coworkers, bosses and customers will venerate you, and call you 'doctor', sir, or daddy
based on that pic, they probably now call you 'sloppy joe'

>>2869192
The insulation on the outside of mains flex is rated to be touched by human hands, and ethernet cables are isolated by transformers on each end device anyhow. There's no practical reason for it to be an issue to have them in the same conduit, but there may still be regulations against it.

>>2869206
The AC coupling at the output of the AD8228 means it doesn't measure the net DC at all, it just measures the amplitude of the chopped square wave, which should eliminate any offset voltage. Don't know why they wouldn't just use a proper chopper amp, be it monolithic or discrete. Using a 74HC04 instead of a 74HC14 for the oscillator is strange too.
>microohm meter
>operating at 1mA
That seems ridiculous. The milliohm meter I made has three current settings: 10mA, 100mA, and 1A.

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do you guys have a storage bag or something for field repairs? or some way to move shit easily while staying organized?
i need to think how to organize a mobile workshop, i move a lot, also help neighbors often and i will like some inspiration

Is a piezo-electric transducer the best way to measure vibrations in steel? Will my output from that be very similar to a sound wave?
I need something with a read rate of over 3kHz.

>>2869304
Piezo is what I'd use. Maybe just a piezo disc as a pickup stuck directly to the steel. Or something that's intended to be used as a contact-microphone or surface pickup. An air-coupled transducer like you find on the arduino distance sensors wouldn't work very well.

let's say i want to make an ad-hoc LoRa mesh network that sends sensor data from each node to ALL nodes in the network (so each one has a copy of all the data to improve the chances of recovery). i'm only expecting like 3MB of data from each node (and around 10 nodes), but i still want something relatively efficient so that the airtime spent on networking is minimal
what kind of networking protocol/library would i use for this? would i just be stuck making my own custom thing?

>>2869307
Cool. That's what I'll do then. Thanks.

>>2869322
> 3M x 10 nodes = 30 MB
Over what time period?
LoRa is for things that ping every 30+rand(10) minutes with binary GPS coordinates. 30 MB is ridiculous. What format is it in? Yaml or something? Ughh…

>>2869304
You can pick up vibrations with a photo diode and a handheld laser pointer (and/or a focused LED).
You might be able to adapt a CD/DVD/BD-DVD read head for such a purpose.
First thing I would try is give the photo diode some turn-on voltage then send the output through a capacitor and into a preamp so you could hear it.

>>2869354
Any advantages to doing it that way over piezo? It does sound like a cool project but it also sounds like more work that I can't see the reason for, and this is just one component of my overall project.

>>2868998
Heatpipes are sealed, cant you just solder copper to copper.

>>2869348
the total amount of data isnt really fixed (3MB is highly, highly optimistic), it's more-so as much as i can get out before these things hit the ground and lose line of sight (these are air dropped probes). if all probes get a copy of the data, only one of them has to get a lock with a sim tower to upload everything
i'm using LoRa because it's the only RF family with good enough sensitivity for stupid long range (30+ miles) data transfer and solid library support
i've looked around at things like LoRaMesher and they seem almost perfect, but they all seem to be geared around sending packets to specific nodes rather than to all of the nodes at once with some networking to relay packets and make sure that all nodes get a copy
it'd let me use a higher lower datarate (and thereby lower sensitivity & range) rather than lazily broadcasting point to point with no mesh relaying at all and hoping that all the probes are within range.

>>2869361
> hermetically sealed pipe. filled with water. heated to 300 ℃ for soldering.
== pipe_bomb;

>>2869240
How the fuck are you supposed to do clean angles with 0.75mm2 soft wire?

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>>2869397
I use pliers.
You can acquire some good ones from you wife’s beading supplies.

>>2869398
That is beautiful autism, but no one here cares. We just use cable trays.

>>2869398
the anon is using stranded wire
it doesn't hold its shape

>>2869248
>The insulation on the outside of mains flex is rated to be touched by human hands, and ethernet cables are isolated by transformers on each end device anyhow. There's no practical reason for it to be an issue to have them in the same conduit, but there may still be regulations against it.
Alright, thanks! I'll find an electrician to ask about the legality of things.

>>2869356
> photo diode advantages over piezo?
I find piezos are a pain in the ass. I have a few, but I often have difficulties soldering wires to the discs and determining their electrical properties. They’re basicall weird capacitors. You have to find the right frequency, and there is a “best” or resonant frequency where it’s most sensitive.

Photo diodes have none of that bullshit.
Plus, you can get them anywhere… your old remote to your standard def plasma TV you never parted with even though you sent it out to e-waste over a decade ago.
Higher frequencies are also possible. In fact, you can even use a solar cell and bounce the light into that… I’ve seen them used to measure the switching frequency of electronic ballasts.
The NSA/CIA (or whatever) listens to people’s conversations in rooms across the street by bouncing a laser off the glass and picking it up on a photodiode, turning the glass vibrations into sound again.

>>2869240
>>2869398
trick to neat gear layouts with stranded wire is use a billion cable ties to tie everything together. aim for a kind of freestanding structure where the cable bundle/bus snakes around allowing short straight runs for each wire to where it needs to end up.
or just label both ends and chuck it in

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I want to connect my electric guitar to my computer. Output will be coming from electromagnetic pickups; about 8Kohm. Fairly high output voltage compared to a piezo element / pickup used on acoustics.

I'm reading two things:
> You need to buy an audio interface (~$100) or cable ($20, 1/4" to USB lol)
> You can just connect it to the 3/32" computer microphone input

In my mind there should be some sort of decoupling between the guitar and PC for option 2, probably a transformer of some sort to go from low to high impedance, a simple circuit, but I can't find a diagram anywhere.

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>>2869444
>some sort of decoupling

small transformers exist for this express purpose

>>2869444
its not going to explode from trying it out, its a guitar not a vandegraff generator, if a couple of hundred millivolts from a guitar pickip could kill a microphone input it would melt on a dry day by itself just from static

>>2869458
>its not going to explode from trying it out
Agree; at worst it would sound like trash. I'm just trying to be intentional.
>>2869454
Is that a 1:1 audio transformer?

>>2869444
>an audio interface (~$100)
Behringer interface is more like $30
>probably a transformer of some sort to go from low to high impedance
Audio transformers are chunky af, better off with that soundcard/scope mod

>>2869398
Do you just throw all those jumpers away when you're done, or buy new breadboards and leave those ones permanently populated?

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>>2869460
>1:1 audio transformer?

si mi caballero
just like this thing: https://www.farralane.com/art-pro-audio-t8-8-channel-hum-eliminator-with-xlr-1-4-inch-and-rca-inputs-outputs.html

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>>2869304
> best way
An accellerometer is the "best" and correct way to measure vibration in steel, or anything else. It's basically a piezo with mass attached, and calibrated.
https://en.wikipedia.org/wiki/Accelerometer
Lab ones are expensive, even in single axis, and no idea where you'd source it. Then FFT the output.
Piezo will work as well; iirc they're better at high frequency than low.
> t former noise and vibration engineer

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>>2869471
Once it’s working you can by those FR4 green PCBs with breadboard layouts and transfer the wires. Looks as good as an etched PCB in my opinion.

Better than this shit in picrel, eh?

>>2868444
Just splurged on Horowitz & Hill, quite expensive books, but I heard only good things about them.

Probably will take forever to go through them but it's gonna be an interesting journey.

>>2869485
I thought IMU might be overkill and a piezo would do, but I'll go with those since they are actually better. It isn't my money I'm spending anyway so price is not a big deal.
I'm looking at these on Adafruit, and they look like what I'm after:
https://www.adafruit.com/product/4502
https://www.adafruit.com/product/4517
Updates at 6.7kHz, which is probably what I actually need rather than 3kHz, because I'm comparing the vibrations at 2 points about one meter apart, speed of sound in this steel is ~3,200m/s, so having double the sample rate gives me my Nyquist frequency.

>>2868492
This is what is going on here.
https://xdaforums.com/t/mod-clear-back-glass-mod.3615367/
https://xdaforums.com/t/clear-back-glass-mod.3928135/
Looks pretty bad to me. Why would someone want the biggest visual feature on the back of their phone to be the battery's safety information?

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How can I possibly multiply the output of my 100MHz oscillator 32x? I am not particularly concerned about signal integrity so long as it bunches up at desired freq. Or is this more of a /ham/ question?

>>2869444
A simple voltage divider should be fine. Maybe you'd want to buffer it first, idk. Some microphone input sockets have a low bias voltage applied to them, so a DC-blocking capacitor after the voltage divider is a good idea. Along with some clipping diodes if you're paranoid.

>>2869494
If you had a significantly higher frequency you'd be able to capture more vertical edges. I'm not sure if aliasing will be a problem with those sensors, probably not, but it's hard to say what their anti-aliasing filter will do to your signal.

>>2869545
You want 3.2GHz? You'll likely need to buy a high-speed DDS IC. Maybe there are dedicated frequency multiplier ICs that have less of the extra stuff around the PLL, but I'd imagine they'd have smaller markets and hence be more expensive. With any luck you can browse Octopart or a vendor and filter by output and input frequencies.

Bleh, looks like I need to replace a USB port on something. I'm not very experienced and these joints look tiny but I'll make the attempt. Anyone have good how-to videos or suggested iron tips? I grabbed a SI012 Pro a while ago.

>>2869586
If it's USB A or B, no problem. If it's a micro or mini, then it's a bit of a pain but definitely doable with a small tip and flux. For a C port, doubly so. Ideally you want a dedicated desoldering iron for any through-holes, but a solder sucker can work. With surface mount pads you'll run into issues with them being easy to delaminate, so don't put yourself in a position where you're applying force to a component that still has connected surface mount pads. Your method will be to desolder or cut the through-hole pins, before trying to reflow any SMD pins all at once. It's technically an option to try to pry up any SMD pins as you reflow them, but USB connectors often have the pads go somewhat far underneath the connector.

Worst case scenario you have to completely destroy the old connector, but this is hard to do while not applying force to the SMD pads. When you do inevitably delaminate one of these, fixing it may be possible.

If it is a micro B connector that's only used for power, you can buy 2-pin micro B connectors that save you the hassle of trying to solder the other 3 pins.

>>2869545
Here’s what I’m thinking.
You take your output, and split it into 32 individual lines. Send it through an amplifier you stole from the cable guy first, though obviously.
Now take 32 lengths of your RJ59 cable. How long each length is depends on the cable. Mine is 1.2 ns/ft (0.85 c).
The total wavelength for 100 MHz at .85 c is 100.32 inches. Now divide that by 32 and get 3.135", and you’ll make 32 delay lines of 3.135", 6.27", … etc, adding 3.135" each time. Now put a small capacitor at the output end of each delay line (you can make them with RJ59 cable as well (it’s 16.2 pf/ft from conductor to shield) if you want) to remove any DC component and shrink the pulse and sum them (put them together through a resistor) and then, possibly amplify again.
There’s your 3.2 GHz.

No fancy PLLs, esoteric GaAs chips desoldered from falling skylab equipment, just stuff around your house (or your neighbour’s house).

>>2869587
Yeah, it's a mini. I forgot a desoldering tool, I'll grab one.

>>2869610
A desoldering iron or pump only really helps with through-hole pins. If the mounting holes are through-hole, then great, do that. But if they're surface-mount, no amount of pumping or wicking will loosen those pads without at least some mechanical force. It's possible to wick away extra solder from those mounting pads, before reflowing and lifting them up, but that force is going to run the risk of delaminating the smaller pads. I tried a steel feeler gauge once seperate the two, but solder sticks to steel. Might be possible with something sufficiently strong and thin, without conducting much heat and without wetting to solder. So, titanium?

The sensible method is hot air or a reflow plate.

>>2869613
>So, titanium?

stainless steel

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>>2869389
Should be fine if you do it quick, also it's not water inside but a liquid with a low vapor point.

>>2869613
>The sensible method is hot air or a reflow plate.
I'm too cheap for sense, the /diy/ way.

>>2869628

got car halogen bulb?
i dont but i have 500W floor lamp bulb
and 2000W projector bulb
https://www.youtube.com/watch?v=nl4EkIs8aIo

>>2868492
Some elaborate method to separate the glass from the plastic oled panel below.

>>2868807
>>2869498
That's the front of the phone not the back, notice the front cameras.

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Love the simplicity of old electric equipment.

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could i use secondary windings from MOTs to make a coilgun? i have never made a coilgun btw but i think it would be good to use them to save time winding coils and i already have several

>>2869494
So, if it's corporate money... you'll want to go a bit better. idk your situation, but this is a lab-grade accellerometer. Single axis are $300+, each. For 3000 hz you're correct that you need 6000+ hz, but that's the sampling rate... frankly not sure how this translate for the element, but I'd buy 2 rated at 10 kHz since that's what most are rated at. This is lab grade stuff.
https://www.ifm.com/us/en/product/VSP001

Back in the day, I used a 4 channel HP FFT scope. That can output amplitude and phase, and could keep up with the accellerometer (sample rate was something like 32kHz.) Phase will tell you what frequency your natural frequency's occuring at. These 4 channel HPs go for a few thousand now... but even when I did this stuff 20 years ago there were emerging data acq systems that could do same with software for $100.
https://www.ebay.com/itm/382213467416

LMK if more Qs. If not a corporate client, you could just go cheap arduino stuff and upgrade if it doesn't work. For comparison, I used to glue ~200 3-axis accels to car, shake the whole car with 50 lb force transducers, then run a 600+ channel data acq system to pull vibration data from the accels. You could do mode plots in software, all done to measure natural frequencies of full cars and car bodies.

Thoughts on how tarriffs will affect /ohm/?

Also 900 seconds is such fuking bullshit.
I am not sure I will continue posting here.
I start the timer and forget.

>>2869770
If Trump kills China-USA epacket (like he's threatened to before) the hobby market's going to jack up overnight. 2-3X price increases.
Otherwise it's a nothingburger.
> 900
I unironically moved on to reddit after something like 10 years here. Combination of the timer and getting softbanned for a month.

>>2869770
The timer has tripped for me exactly once, and I post almost every day. If your not getting banned all the time or swapping networks it's a nonissue.
>>2869772
Any good subreddits for this kind of stuff?

if i need a component/block with some arbitrary, tunable impedance for a circuit im designing, whats the best way to do that?

>>2869772
Wouldn't epacket just effect small packages? If you buy a hundred dollars worth of chinkshit in one package shouldn't be influenced.

As for the timer, I bought a pass. For the time I spend on /diy/ it's really not much to spend. YMMV.

>>2869802
What are your requirements? Q factor? Frequency? How many orders of magnitude do you want it to cover? How linear does it need to be? There are a lot of methods from vactrols to varactors and JFETs, to transconductance amplifiers and those coupled inductors.

>>2869821
>What are your requirements?
after some googling, i realize i shouldve just asked about impedance matching. and i literally mean matching the impedance, not the conjugate of the impedance. i have a frequency response that im trying to recreate exactly.
i think my first step is to just make a Bode plot and see what it looks like. if it's simple enough i can probably just use some resistors and varactors. thanks for the tips tho fren! <3

>>2869772
>China-USA epacket
>2-3X price increases.
but that's shipping not the cost of goods due to the tarriffs?

>>2869797
>If your not getting banned all the time or swapping networks it's a nonissue
I am probably swapping something, I do swap browsers from time to time, maybe that affects it. This is my 3rd post today after I got hit with the timeout, and it is not happening anymore now that I haven't switched browsers or machines.

>>2869829
I think he’s referring to the shipping cost of China is subsidized by other countries’ taxpayers (whether or not you buy stuff from china) because they continue to fraudulently keep china in a “developing nation” status in order to do so.

This will hurt American businesses because almost every non-food related business basically “drop-ships” everything from china and the executives pocket the profit and sell you at 4x their cost without producing anything.

Luckily, there’s so many chinese fakes out now (or perceived fakes) even many hobbyists buy components from reputable companies like digi-key.

Besides, do you really need that 8000-piece smd resistor kit for $2.99 from aliexpress? Probably not.
Just buy the components you actually need.

>>2869552
>If you had a significantly higher frequency you'd be able to capture more vertical edges.
What are vertical edges? I guess from context those are sharp short duration peaks that would be "skipped" in a low sample rate sensor, and that's what you mean about how the anti-aliasing could capture that or might not. Is that close? I'm new to vibrations but I do have a little experience in audio signal processing.
>>2869754
Thanks for the recommendations. I appreciate it. It's research money from my funders so I'll start with the cheaper IMUs to see if my concept has legs and then if those aren't enough go for the lab accelerometers you've listed.

>>2869925
If you were trying to measure the amplitude and frequency of the vibrations inside the bar of steel, you'd only be able to see the fundamental harmonic as a sine wave. Any squarer edges to that wave, or any other harmonics, won't be visible. I'd want something far faster to see tens of harmonics.

Alpha Phoenix measured the speed of sound in a rod of steel using piezo discs and his oscilloscope IIRC.

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Anyone got one of those ESR meters? Looks pretty good judging by the description (supposedly can measure in-circuit, too), but I wonder about actual user experiences.


https://www.aliexpress.com/item/1005007857088790.html

>gradually have gotten better at electronics
>the fun and charm is gone, curiously has taken a backseat and everything is a "bother"
Another hobby gone

>>2869984
oh yeah? make a pid controlled vfd

>>2869985
That's exactly what I'm talking about
3 years ago i would've spent several nights making the best possible design out of sheer passion and cobbled together shit tier, but working code (yes, i prefer having MCUs) for it.
Now i will begrudgingly spend twice the time, not enjoying a second of it to come up with an even better design and write NASA tier code for it but i won't enjoy anything and my work will be well documented, commented with great engineering decisions but the soul... its gone

>>2869990
What about your non-hobby interests? Does everything feel soulless, or just electronics?

>>2869990
i'm kind of the same way except i'm incompetent and get analysis paralysis and just give up before physically making a project. i get more satisfaction out of understanding the general principals and vague details of how a circuit, device, etc. works than i do actually performing real world engineering. things like writing code, dealing with tolerances, dealing with inaccuracies/parasitics, etc. -- it drains my motivation.

>>2869829
If you live in the USA, you're not currently paying the true cost of shipping, per >>2869909. Items under 16 oz ship for about $1 from China to USA, tracked. USA direct. you can't do this for less than $4.50 or so. This dynamic sets an effective lower price floor on small, lightweight items.
Arduino boards are a good example. You can't buy a single nano board; they are sold in kits or multi-unit bundles, to get the price above $10. At a price of, $10, you ship ($5), pay Amazon ($1), leaving you $4 to buy the thing, pick and ship, and pocket the margin. If that seems really thin, it is. On the $4 left, recall you buy these in bulk from China, and they're shipped over at a freight cost higher than epacket. And you still have to fulfill from USA using USA based people.
Vs. AliExpress, which is more like $2 to ship, $1 for the part, and you're selling direct from factory. $10 on Amazon, $3 on Aliexpress. This is where my 3X comes from.
If epacket goes away, the whole dynamic changes.
If you buy bulk, or things over 1 lb, it doesn't matter, b/c you're out of the epacket market. But for hobby guys like me that buy 1 or 2 of something and can deal with Chinese stuff, I would just see the parts go up in price. It would be closer to 80s-90s catalog days, where you bought a lot at once so you could save on shipping. The economics of things have changed a lot since then, and cheap supplies of small qty from China is part of that.

>>2869982
It's not 4-wire sensing, so it probably won't be very good for low resistances.

>>2870081
>It's not 4-wire sensing
yeah I doubt I can find one this accurate within same budget though.

How about stuff like LCR-TC1 or LCR-T7 and similar testers, are their ESR readings reliable at all (within the realm of 2-wire accuracy)?

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>>2868444
Got a question here, as an electrical-let.
I've got one of these 500w spindle motors I want to manually control the RPM on.
I purchased the Speed Controller in my pic to handle that, I'll be using a 48V power supply to run things.
Should I be concerned about the component leads on the pcb? They are very long and nearly touching the aluminum shell being used as a heatsink.

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Looking to get a multimeter to start learning about electronics. Are the harbor freight ones any good or should I get one from Amazon? Budget is about $60. Also looking to get one of those pen tester thingies. Should I just buy a multimeter from ali express instead? Shipping time isn't an issue.

>>2870109
your pwm controler will burst into flames

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>>2870113
>multimeter to start learning about electronics

you want a combo DMM and scope
usually they also include frequency measurement
so it's 3 instruments in one
some even have a signal generator
and that's a complete lab setup
that fits in your underwear

>pen tester thingies

worthless and dangerous

>>2870109
>nearly touching the aluminum shell

majority of electronics is 1/16-inch away from complete disaster
but if you're a scared lil girl, just slide some acetate sheets between the two warring factions

>>2870089
Those cheap ones just use three different resistors and an AVR's internal ADC. Given that design, they work unreasonably well for measuring inductance and capacitance within sensible bounds (e.g. measuring 10µF but not 1nF), but when it comes to ESR below 10Ω I wouldn't trust them.

If you want to get an idea of ESR, you should consider making an in-circuit ring-tester like this:
https://danyk.cz/avr_ring2_en.html
It makes a resonant circuit with its own inductor or capacitor, and measures the number of oscillations. The oscillations themselves start off with a low amplitude (below 0.7V) so it can't influence any electronics it's connected to. I've got myself some PCBs made with a modified design on them, but I haven't built one yet. I should get on that.

>>2870197
did you improve the ring tester? i am planing on doing one myself one of these winter rainy days

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I cannot find Resistors with exactly these rings
Can someone help me?

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Is the resistor on the left I am planning to buy the same as the ones on the right?

>>2870216
why not desolder one and measure its resistance?

>>2869017
Yes. For parallel resistors the total resistance is 1/(1/Ra+1/Rb+...).

>>2870197
Huh. I guess I might build this eventyally, but I'd still like to get some dedicated ESR and/or LCR meter. Might just get the first chink one anyway and report back on it I guess.

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will learning electricitty and electronics turn me into an trans electric wizard?

>>2870312
Depends on your power level.

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why wouldnt this work?

>>2870319
It looks so burnt that some of the PCB might be carbonized and turned conductive.

>>2870323
Its a CRT psu
its shorted somewhere and I suspect right there

>>2870312
You're already a faggot so just cut your dick off and skip the electronics. Learn to code or play women's volleyball at Yale.
>>2870319
Did you try unplugging it and plugging it back in?

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>>2870323
These resistors are in series anyways.
Couldnt I skip the burned board completely and just solder them all together and only go from hole 1 to the end skipping the potencially cooked PCB?

>>2870325
Yeeeah the more I look, the more it seems like the PCB might be internally shorted through carbonization. You may try to scrape all the black stuff away and then try to reconnect the traces.

>>2870328
>Couldnt I skip the burned board completely

you cant skip it coz it's there and it exists
and if it's carbonized, it's adding a parallel resistance between various points
so you've have to physically remove it by drilling and filing
so before you do anything, poke some probes into the PCB and measure resistance

>>2868855
Why do the likes of you always have to make it about your mental illness?

>>2870319
Resistors typically serve a vital purpose; namely, ensuring that you aren't shoving too much current through a component. You run a good chance of blowing stuff up with it like that.
>>2870323
Also this, you'll want to clean/scrape off the burnt material before doing anything else.

>>2870329
surprisingly, multimeter measures totally fine and the issue might not be there at all

>>2870381
I am afraid the defect on the PSU wrecked something else inside the monitor
in which case GG because I do not trust myself to troubleshoot such a complicated device even with service manual

>>2870400
Would it be possible for you to link us to the service guide, or at least post photos of the pages?

>>2870404
https://elektrotanya.com/mitsubishi_diamond_pro-2060u_nsz2107sttuw_sm.pdf/download.html#dl

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>>2870319
>>2870400
>>2870437
All three are 22k, 2W, 1% metal film resistors. Get rid of the black shit and replace them.

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I'm dealing with a vintage technics amp that's stuff in protection mode.
There's a speaker circuit protection relay that doesn't close it's contacts 5 seconds after power on like it's supposed to, however, when I manually close the relays contacts (pictured) everything works and sounds great.

Could this mean the relay itself is faulty or should I consider the entire protection circuit?
Is it dumb as fuck to simply tape the contacts closed (I did this last night and used it for an hour with no problems)

>>2870474
Probe for voltage on the low side of the relay after powering on. If you read sufficient voltage then it's a bad relay. It's fine to bridge the high side of the relay in that case.

>>2870207
If I recall, I made it such that I could have both an internal capacitor and inductor, and have the ability to independently use either the internal or external component for any measurement. Maybe I made room for two or three different capacitors, idk. For the display stage, I think I used some ULN2003 chips to drive multiple 7-segment displays. I’m hoping to have it display both the number of cycles and the cycle frequency. If I could know the value of the reference component, I could also calculate the value of the test component, and the ESR, but we’ll see. Square roots on an 8-bit AVR seem difficult, especially across 9 orders of capacitance magnitude.

>>2870474
It could be that the relay is the problem, but it could also be some other part of the soft-start circuit. I’d suspect the relay isn’t as low of a potential failure vector as relays often are because the making and breaking current will be pretty low. If it’s the charging resistor that the relay is in parallel with, then bypassing the relay will just cause the inrush spike that the circuit is there to prevent. Post schematic or start measuring the nearby components. As the other anon says, check if the relay is even getting sent voltage that could turn it on.

>>2870474
Also, make sure you don't have a mute switch engaged, if there is one.

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I have an old ISP provided cable-modem router, it heats like crazy and I am sure the heat causes it to slowdown and perform poorly in general. It is designed to be positioned vertically because it has really tiny air vents on the top and bottom, but due to space constraints it is sitting horizontally. I took it apart, noticed it has a heatsink and repasted it. It still heats up, naturally because hot air is getting trapped. The normal solution here would be to either drill a few extra holes or put it in the correct position but I don't want to do either for reasons.

Instead I noticed there is enough space for a couple fans in various positions, this would simulate the natural air draft to cool it down. It has an internal usb3.0 port. So how trivial is it to power and control it from there? I could put either 1 50mm fan or 2 40mm ones. I just need a way to power them from the usb port and ideally control their speed (don't need that to be wireless or anything fancy, a simple knob is cool with me).

I found this stuff on aliexpress, has anyone used them? Do they work how I think they work? like you just plug them in and adjust the knob? Some guys on stackexchange say that if I were to power the fan directly from the usb port I'd need several extra components for safety and stuff. That's another reason I want to use that "usb controller".

Thoughts or advices?

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>>2870491
And this is the fan I'd be using, a generic chinkshit 40mm or 50mm. I don't know if they're pwm or not, most likely they're whatever is cheapest. I'm also looking for the simplest, cheapest solution here. Don't need a large airflow, any airflow at all is better than zero.

I'm not sure how fan speed is controlled, but my guess is through either changing the input voltage or through PWM, or both. Some fans come in 2 pins and others in 4 pins (I think the 3rd and 4th pins are for feedback, for software controlled fans). Dunno what I'd need for this. Don't know if either a 5v or a 12v would work.

Also sorry for asking so much, normally I'd do my homework before expecting to be spoonfed but 11.11 sale is coming and I want to save money.

>>2870491
>>2870492
A 5V fan is more than enough, and PWM control is easiest. You could accomplish the same thing by pointing a desk fan at the modem.

>>2870190
Woah I didn't even know about these things. I just downloaded a bunch of electronics ebooks and bought some of those beginners kits to get a head start before starting trade school for electrical work soon, are there any other things or specific devices or models you recommend if money isn't an issue or even an aliexpress alternative before I buy an American made one?

What is it with displays and being pains in the ass? This is the second time now that I've worked on a device and managed to somehow cause the solder joints for the display to break.

>>2870492
>>2870491
Just buy a USB fan. It won't do anything anyway.
Some brushless fans work on lower voltage than rated, e.g. a 12v computer fan will run at 5v because the controller tolerates it. A 5v fan doesn't leave a lot of headroom to reduce before it stops working entirely.
Someone told you need protection, so what? The controller hasprotection? Probably not it's cheap shit. Also it says 4-12v so what does that mean? Boost? Or auxiliary voltage in? Pwm fans are normally 4 pin, certainly not 2 pin brushless.

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Is this a good SMD component tester? Anything else I should look at?

>>2870544
It sort of looks like my capacitor tester, kek. As for other components, I just tend to use my bench multi-meter.

>>2870551
I've been reading reviews of all this shit. This one is cheap af and apparently works well. It can test a lot of SMD components in circuit.
I have a decent DMM but the probes are too chunky and for whatever reason, it cannot reliably test stuff that's in circuit. I don't know how these SMD component testers work but they do have a mode to test stuff in circuit.
If anyone can explain how this works, I'm all ears.

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Do you trust wall adapters like this or is it a gimmick? Sounds tempting to reduce clutter and eliminate external chargers, but I am not sure if it is a good replacement for an OEM USB charger from Apple. It says "USB A up to 2.4A/5V per port, USB C up to 3A/5V max".

>>2870560
I wouldn't trust one of those that doesn't have a built-in 10A circuit breaker. They also look awfully flimsy. And if the USB shit breaks, then you have to throw the whole thing out. And all the weight of the plugs in it could easily pull the thing out of the wall.

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>>2870495
>if money isn't an issue

if you're doing electrical, as opposed to electronics work, then you must keep safety top of mind
so you wanna buy brand name stuff that protects itself and you
fluke meters, for example, wont blow up if you try to measure resistance across a live wire
and a clamp meter is essential, so you can measure current without cutting wires
a clamp meter is enough for most jobs, but a desk meter adds accuracy and resolution, so buy 2

>>2870565
>built-in 10A circuit breaker
Why? For the convenience of not having to walk all the way to the garage to reset the tripped breaker?

>>2870191
That's an interesting point. So is driving. I periodically wonder how our brain is able to completely filter this out. We find ourselves literally inches from a head-on collision and a sure death every single day. I am sometimes watching a 50 ton tractor trailer speeding at me at 70mph and thinking that what if I or the other driver accidentally (or intentionally) veer just a little bit. And yet people are more afraid of flying.

>>2870756
lol 10A DC

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>>2870560
If you're going to do that, use pic related and replace outlet, or get a power strip with a USB built in. No reason to cover the outlet.
I was on fence about the usefulness of these things (or that they'd burn up the USB side.) They've been fine in placed I've installed them. probably helps that they're UL listed (and thus throughly tested) in the US, so the electronics are actually solid.

>>2870610
Brymen are as good and as safe, without the Fluke markup.

>>2870756
Because the breaker in the box isn’t a 10A one, it’s a 25A or so. There’s nothing stopping you from drawing 20A through the dinky wires inside that splitter box and causing a fire. Where I live all power strips have a built in breaker, but 1-2 splitters lack this.

>>2870832
The USB quick power charging standard has advanced to version 3.188.05, please upgrade your obsolete wall outlets before the 8th of November 2024.

>>2868492
Removing the screen glass of a Galaxy S10+ with a some thin wire, without removing the OLED while more likely than not still fucking up the OLED and still having to remove the back to actually connect a new one. I have no idea.

>>2868998
>What I do not know is what kind of glue is ideal for what I want to do
For heatpipes? Solder.
>there is a thing called "heatsink plaster"
That's 1W/mK or in other terms ever so slightly better than Soviet thermal paste for transistors KPT-8.
>T520
Just buy the dGPU heatsink, wait for a cheap one to show up.

>>2870491
>fucking with ISP equipment
you do not own it, give it back jamal
anyway just wire any scrap pc fan and plug it into the usb, tape it to the vents

>differential amplifier
>common-mode input impedance: 233
>single-ended input impedance: 58.3
how do i terminate these both to 50?

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>>2870479
>>2870480
>>2870480
Here's the relay on the circuit diagram for the amp. When I measure resistance across the coil on my tester, I get overlimit.

There's 40v DC between each leg of the coil and each leg of each contacter.

When I manually close the relay and test the output, there's a low ac voltage.

I'm unsure if this means the coil is munted and therefore the issue is the resistor?

I can't seem to link a schematic but it's a technics SU-V3.

>>2870982
>resistance across the coil on my tester, I get overlimit

that's all you need to know
the coil is burnt so the relay is dead and unfix-able by all but gods
if you wanna sell it as a vintage-working, then you gotta find a replacement and someone to replace it
otherwise just keep using it as is, in hackered condition
you can use rubber tubing or heat-shrink to keep contacts closed; it's better than messy tape

>>2870992
I'm gonna try replace it myself I think. Will practice on old circuit boards from work for a bit first since I've only ever had to do very rough soldering. Previously soldering on a similar error turntable I melted the fuckin copper off the pcb. Is this skill issue or too-hot shitty cheap soldering iron?

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>>2870982
>Technics SU-V3
Found the schematic here:
Looks like it's a muting (and anti-pop) circuit, not a soft-start circuit.

>There's 40v DC between each leg of the coil
So it is giving it the right voltage, but it isn't turning on, so yeah it will be dead. It probably isn't a 40VDC rated relay coil, which would explain the series resistor R439, which should be a 2W 470Ω resistor. Or maybe 47Ω. It may be that this resistor drifted low under the heat, causing too much current to go through the relay coil, so double check that it's reading correctly.

Presumably you'll be swapping out the relay for another, in the event you can't find a perfect replacement you'll likely need to modify the value of that resistor anyhow to ensure the correct current flow. Some searches online for the SSY69 relay suggest that the original relay was 24V rated, so if that's a 470Ω resistor dropping 40-24=16V, then it consumed 34mA when turned on, with a coil resistance of 705Ω, give or take. If you can match that and the resistance is fine, then great. If not, I guess I'd prefer less current flow, that way both the resistor and relay would run cooler. These online searches suggest people buying different relays and bending their legs to repair Technics amps, since the SSY69 doesn't seem to be easily available anymore.

>>2871004
The key to soldering is getting good thermal contact. From there you heat up joints quickly, without giving time for heat to spread and damage the board or components, and without giving the flux time to burn away and the solder to turn all grey and gluggy. RMA flux is in most modern solder.
Cheap non-temp-controlled small irons shouldn't easily damage PCBs if you're quick, but they do drift hot over time, and they have conical tips which aren't ideal for getting good thermal contact with both the PCB and the component at once. You kinda have to use them on a shallow angle, which is really inconvenient. See if you can get a screwdriver tip for your iron.

>>2870832
Hmm, thats a good idea. I hate external splitters / adapters especially the generic 3-way $2 a piece from Menards. Some of them don't fit well and sag under weight when there's lots of cords attached to them so I have to push them back in once in a while and that's annoying.

I have an old guitar effects pedal (zoom 505ii) that doesn't turn on. I had thought that it could be the barrel jack for the power cord was corroded inside (it was visibly somewhat corroded) and i cleaned it up and still it wouldn't turn on. Then I desoldered the jack from the board and tried directly supplying power and still nothing. I am unsure where to go from here with troubleshooting. the capacitors all look visibly alright.

>>2871081
Disassemble it entirely and scrub any corroded areas including the battery terminals with a toothbrush and white vinegar. Let it sit for 5 minutes and rinse the vinegar with isopropyl alcohol. You'll probably have to replace corroded components so keep an eye out. Touch up any solder joints that look questionable while you're in there.

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Hello, extreme electronics beginner here.
I'm working on a homebrew device based on a Pi Pico and got some of these 4-pin USB-C sockets from Aliexpress to route the USB 2.0 wire to an external USB-C socket.
I soldered the wires like described here: https://blog.4dcu.be/diy/2023/12/03/pi-pico-usb-c.html

Problem is I can't seem to get it to work.. Initially I thought my solder job was shoddy but I redid both sides multiple times without success.

I can't even get any voltage reading when plugging a connected USB-C cable into the socket and checking between the V and G pins.

So now I'm wondering if there's something wrong with the socket boards..
There's this empty solder point marked R1 that looks like it should hold a resistor but doesn't. Could that resistor be necessary so that a USB-C host recognizes this as a USB 2.0 device and provides 5V voltage?

>>2871133
https://community.infineon.com/t5/Knowledge-Base-Articles/USB-Type-C-connector-Rp-Rd-and-Ra-termination-resistors/ta-p/253544#.

>>2871140
Right, shit. Guess I'll have to order new connectors and double check they have the right resistors then.

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>>2870610
> desk meter
> poleman meter
> buy both.

No need. It’s already been done. It’s also over for other meters. I will look back and tell my grandchildren I had the first generation design of what al meters look like nowadays.

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>>2871140
>>2871141
Welp, that worked. That's what the big pad next to the R1 pads was for I guess.

>>2871174
Congrats. It looks like shit, but if it works then it's fine I guess. I do wonder how sturdy those soldered panel-mount USB C sockets are.

>>2871174

impressive: someone trained their pet gorilla to solder

>>2871010
>So it's giving the right voltage

>The original relay was 24v voltage

Anon I'm confused

So the resistor should be lowering the voltage from 24 to 16? But then resistor is reading at 40

Is the resistor before or after the relay in the circuit?

Should I be reading 24 on those measurements where I was getting 40?

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>>2871277
Should the resistor not be dropping the voltage or does it drop the current instead? Because of the triangle

>>2871277
https://www.manualslib.com/manual/690398/Technics-Su-V3.html?page=7#manual
SVITA7317P

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>>2871284
Thank you, I checked that out and got the following readings... They don't seem to align with any of the described relay off examples in the manual.


I did find that if I short 4 and 5, the relay contacts, so apprantly not a faulty relay.

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>>2871277
>40VDC
>a 24V relay has constant resistance in steady-state, and hence wants a certain current
>need to drop 16V across resistor so relay sees 24V instead of 40V
>calculate required resistance based off relay's current such that the resistor drops that 16V
do you understand

>>2871296
That is a strange symptom, but it's also a strange chip. Looks like the chip is also known as just the "TA7317", which has one or two more datasheets available, but it's still slim pickings.

>>2868444
>desktop computer power supplies from even decent manufacturers use UC384x as their main control IC
Is it truly that good? Or is all the magic in the flyback transformers?

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Does anyone here have experience or resources on fixing a Vectrex? I have the test cartridge but I think this needs more than that basic calibration.

I believe it was also re-capped recently since the caps look pretty new, so it's possible one of the solder joints is no good, I just don't know where to start looking

>>2871450
Start by checking the power supply for stable voltage output. Look for discolored or burnt component on the board and test/replace them. Reflow all solder joints where plugs are inserted into connectors, as well as the flyback transformer pins and big caps. Clean the connectors, plugs, and adjustment pots with contact cleaner. Pay close attention to the neck board connections. Use a bright light and magnification or take pictures and examine them on your phone.

So with dielectric grease, you can fill up electrical connections before plugging them together, and they still make electrical contact. Is this the case with any other non-conducting grease?

>>2868885
no?
early gameboys and shit were like that
the 90s was a time of tech enthusiasts.
prisons didn't even have this shit in them.

>>2869498
>>2869712
you should be able to accomplish this at commercial scale with a laser

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>>2868444
I was trying a different PSU on my old PC, because on the old 3.3V rail was low.
PC was working fine, sometimes under load it would reboot which is why i started looking.
So I left the old PSU in the case while I attached the new PSU like an octopus.
Not unlike pic related.

Removing the 24 pin connector was very difficult, the pcb was flexing.
I attached the new PSU and everything was working proper.
I turned off the PC and left to eat dinner.
Returning I powered the PC and heard small pop sound but the PC kept working.
But it did not want to boot to desktop.
Turned it off again and tried to clear cmos and all that, now the PC wont post.
Fans spin,drives seek,everything fine but wont show the post screen.

So I removed the motherboard to inspect it.
Turning the motherboard upside down to check what the hell happened,
I revealed one ceramic capacitor on the north bridge has blown.
The north bridge chip is near the 24 pin connector.
I very likely cracked the capacitor while pulling and after it blew up.

That said I have no caps on hand.
Since its a capacitor immediately near the chip it is most likely a filtering capacitor.
Can i just bypass it with a soldier blob?
Please can someone advise me how to proceeded.

>>2871768
Do not bridge. Remove the cap and post pics of that area of the PCB. You might be able to get by without it, but you should salvage a cap from something and install it if you still can't boot. Start with 0.1uF, then 1uF.

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>>2871784
The area in question with the yellow arrow.
Here is a link to high quality picture (6MB) of that area.
>https://theretroweb.com/motherboard/image/asrock-p4v88-back-64d9fc210bd95701346126.jpg
As you can see the thing is gone.
I'm pretty bummed.
Solved one thing broke another.

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Is there a record of historical chip pricing?
Want to know if the 200% price inflation is a temporary thing or a steady and stable increase likely to not change much soon.

>>2871806
It's up 200% because of inflation and supply chain crunch. This is the new normal

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>>2871806
The pricing heavily depends on what secret contracts your bigcorp has with the suppliers.

>>2870216
They appear to be the same value (22k). Make sure their sizes are the same because that is what determines power rating. Also watch out for voltage rating because resistors can blow up due to voltage overload even if they are not dissipating much power or getting hot. You appear to have a high voltage board judging by the capacitor behind the resistors (450v) so I'd get 500v rated resistors or even 750v just to be safe

>>2871793
>>2871784
>Start with 0.1uF, then 1uF

that's most likely a 10uF MLCC
hopefully you have some dead gadget: mouse, wifi stick, USB drive, keyboard, etc, that you can salvage one from

>>2871793
There are probably broken solder joints from the board flexing when you were unplugging the 24p connector. A hot air station would help immensely, but the board might still have other problems.

>>2871806
why would prices EVER come down? sudden hikes like this are a sign that they're here to stay
at least, until the next chink supplier comes in and undercuts everything

>>2871869
Every single thing you buy is affected by the price of energy, i.e. gasoline and diesel fuel.

>>2871810
>holding the iron by the metal
>trying to apply solder to the top of the chip
Can the idiots taking these pictures be bothered to do even a few minutes of research first?

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>>2871888
What else can one say? The children are naturally drawn to irons with small tip-to-grip distances. The passively radiating iron will go the way of the dodo, as will their default conical tips. Negative feedback irons with screwdriver tips shall rule the world.

>>2871863
>>2871866
Alright thanks anons.
I will see what can i dig out.
Fingers crossed its the only thing that's broken.

>>2871465
Cool thanks. I'm like halfway through and nothing seems off so far. I'm getting access to an oscilloscope this weekend so I can check the power rails and some signals from the service manual

I'm gonna start working on/restoring an old tube ham radio. Do I really need a VTVM, or will a 1GHz scope + RF probe work fine? I'm looking at a $15 one from Ukraine on ebay

>use 50 ohm setting on oscilloscope
>signal is only 15% of what it should be
>check DC resistance of probe while unconnected
>315 ohms
the fuck? is this normal? do i have to buy special probes to use the 50 ohm setting?

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>>2871906
>$15 one from Ukraine

for VTVM?

anyway, you dont need a vintage voltmeter to fix a vintage radio
a cheap modern DMM will be way better
with an expensive scope, you'd need to take care about overly-high voltages and possibly shorting out the radio thru grounding
https://www.electro-tech-online.com/threads/oscilloscope-and-grounding.15623/

>>2871941
how is that going to fix a series resistance?

>>2871942
>fix a series resistance?

it doesnt, but knowing the resistance of all concerned components, you can calculate a finagle factor, X
take whatever values you measure and multiply/divide by X

>>2871946
well yea, of course i could do that, but theres obviously a reason i want the impedance of the probe to be specifically 50 ohms.

>>2871948

this should work
- add pass-thru 50ohm termination at the generator, or whatever source
- set scope input to high-Z so probe resistance is irrelevant

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>>2871952
nope, the characteristic impedance of the probe isn't 50, and in fact its not even real. i could try to match the non-real impedance of the probe... or i could just buy some probes that dont have this problem.
the reason im asking about it here is because the datasheet for my probes doesnt mention any sort of DC resistance, so im wondering what the exact type of probe i need to buy is so this doesnt happen.

>>2871955
>nope, the characteristic impedance of the probe isn't 50
actually im assuming the resistance is all along the cable. if its right at the probe then i suppose i could just manually account for the attenuation but that still sucks.

>>2871955
>just buy some probes that dont have this problem

far as i know, they're all like that
usual way to get around it is to use 10x setting to make the effect almost disappear

>>2871957
>far as i know, they're all like that
if all probes had this problem i would seriously question the purpose of the 50 ohm on most oscilloscopes.
>usual way to get around it is to use 10x setting to make the effect almost disappear
that would make the reflections 10x smaller, while also making your signal 10x smaller. except the 10x switch assumes a 1Meg impedance at the oscilloscope, so it would actually be 180000x smaller, or -105 dB.

>>2871938
Would that be due to their high input impedance? They're typically in the near GOhm range I suppose. How does their bandwidth effect the potential measurement tho? I'm potentially gonna be up to the ~30MHz range

>>2871936
Yeah, normal probes have impedances in them to compensate for transmission line bullshit. There's an EEVblog episode on it. If you just use a BNC-to-BNC cable with a BNC socket on the device under test that's the easiest way. Those BNC to alligator cables will probably also work, lmao.

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>>2871962
yea, switching to a BNC alligator cable fixed the singal up right quick. i just... i just dont understand why probes arent 50 ohm. why does a shitty alligator clip have better functionality than fancy probes? there must be something im missing.
i have half a mind to solder some jfets and a BNC header to a perfboard and make my own active probe. save me a thousand bucks.

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do power bricks produce Electromagnetic interference? I'm using a power brick to step down 220V AC down to 53.5V DC at 0.8 Amps.

I'm using it near an unshielded lines. a critical communication line.

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>>2871968
>Electromagnetic interference?

>>2871810
Sure, a new technology finding use of some chip might bottleneck the supply even before the new thing has reached the headlines. (?)
After looking around $20 does not seem out of the ordinary for high performing in-amps.
I guess the cost comes down to production costs (low success rate of meeting the specs) and handling of less popular products.
The chip in question is from a failed company and is at a couple producers later by now, profits from acquisitions probably adds to the cost as well

>>2871962
>>2871967
Here's a playlist of EEVblog videos on oscilloscope probes:
https://youtube.com/playlist?list=PLvOlSehNtuHvIDfW3x2p4BY6l4RYgfBJE&si=oj-J4oAPDK-CP9Y1
It's probably got the one that will explain why 1x probes aren't just straight-through wires like the shitty alligator probes are.

>>2871968
Yes, though it depends on the brick. SMPSs with a ground/PE connection will emit less electric field noise than simple two-pin SMPSs. You can make any supply better by adding a layer of shielding around the entire supply and tying this shielding to ground/PE. Depending on what you're doing, you should usually tie the negative/middle rail of the supply to ground/PE as well. Magnetic field noise would prefer an iron shield over a simple copper or aluminium shield.

What communication line are you worried about? Is it twisted-pair or otherwise a differential signal? Can it be? Is it isolated at one or both ends? What protocol? Any long-range comms line should be in a robust enough format to resist common, ethernet and RS422/485 and CAN should all be fine around common SMPSs. Though if you're doing high-speed RS232, or long-range I2C for some ungodly reason, you may have a problem.

You can get around this problem by using an iron core transformer as your power supply, though at 43W plus headroom for linear regulation it won't be a compact one.

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So my pickup came in today
I've only had really bad experience with soldering so i'm kind of scared the fuck out to mess shit up or leave a mark on the body but i recently got a pinecil so i have higher hopes
I only have shitty leadless solder, is that a problem or should i get something better?

>>2872088
Use leaded 63/37 with a rosin core (non-chinkshit), and get some RMA flux or you'll hate yourself. Load the new tip with solder and let it heat for a couple minutes to season it before use. Keep it clean with brass wool or a barely dampened sponge as you work, and keep the tip tinned. When you're finished, clean the tip and load it with a blob of fresh solder before you turn it off. Don't try to use the tip as a lever to bend or lift component legs as you'll gouge the plating and hasten the demise of the tip. The plating protects the core of the tip so it doesn't dissolve in the molten solder alloy. Clean up any flux residue with isopropyl alcohol and cotton swabs or toothbrush. Use tweezers to hold wires while you heat them. When soldering multiple wires to one point, secure them in place mechanically (tape, hot glue, wire ties, etc.) before joining them. Tin the wires and the solder tabs before each joint to reduce dwell time and make a solid connection.

Cover your geetar with paper and Scotch tape to protect it and always keep the iron in its holster when you aren't using it.

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>>2872116
well fuck, there's no way i can get that at my local hardware store
i'll get what you recommended
>keep the iron in its holster
yeah that's a problem because i have no holster for it
what about this sort of thing? i think it'd be pretty useful

>>2872088
Lead free solder is usable if you turn your temps up a bit and use extra flux. You might have an easier time getting yourself some bismuth solder, which is even easier than leaded solder to work with, though it’s not as strong.

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I want to map what every panel switch powers what outlet. Is it possible to do this without having to plug something into every outlet by only turning one panel switch one by one?

What tools do I need to do this if I have access to every cable from my attic and access panel and know where every wire is going to?

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>>2872239
I fucked up the question. I want to map what ever panel switch and cable powers, what outlet, what light, fan switch, etc.

Is it possible to do this without having to plug something into every outlet by only turning one panel switch one by one? i've seen electricians use one of those devices that clip around a wire, could I use that to see if it's running electricity, etc?

What tools do I need to do this if I have access to every cable from my attic and access panel and know where every wire is going to?

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>>2872121
>because i have no holster for it

there's 100 diff ways to fake it, from a bit of bent metal, to an empty glass jar of imported honey

>>2872278
>devices that clip around a wire

that's a clamp meter, and it doesnt work if you clip a cable with 2+ wires
because you have current flowing in 2 opposite directions, the magnetic fields cancel out
for it to work, you'd have to split the 2 wires, and use the cock ring on only 1 of them

anyway, what you wanna do is best accomplished by 2 people on walkie talkies, or phones
one flips breakers and takes notes
the other plugs things in, and flicks light switches
make sure to use terms like affirmative, copy, roger, over, loud-and-clear, and ''10-4'' like some short-legged italian sparkie

>>2872239
Because circuit breakers contain solenoids, a non-contact wire tracer should work on one circuit but be blocked from the other circuits. You probably can’t find an easy way to actually inject the high frequency tracer signal into the wire while it’s on because it’s a really low impedance, but you could shut off all the breakers and figure it out to at way.

I'm at my wits end here. I want a decent fitness band but everything commercially available is shit. Bad battery life, massive fucking screens
Should I bite the bullet and design my own? I design low power BLE devices at my day job so it's the same exact skillset

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>>2868444
I have a question, most of you will probably find it stupid but I have no background on electronics.
recently I discover this game, Turing complete. it is about building circuits and realize I am a living dunning-kruger and severely retarded.
now, we have this thing called Not, which does the opposite. you give Not an input, you get no output.
you don't give Not an input, it does give an output.
and that's the question. if Not isn't gettin any signal, any power; how does it send an output? it doesn't have anything to output

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>>2872384

every gate has 2 extra wires going to them: ground and power
they're omitted for clarity
or drawn so small you need a microscope to see them
lemme zoom in on the pixels
yep, there's one
dim but visible
to straight people

>>2872384
It's an inverter. The logic is tied to a voltage rail and the output is 0 or 1. I suspect that you aren't seeing pull-up and pull-down resistors in your game.

https://www.electronics-tutorials dot ws/logic/logic_6.html
https://www.electronics-tutorials dot ws/logic/pull-up-resistor.html

>>2872384
In real circuits, all logic gates have a power and ground wire alongside signal wires. Most logic simulators don't bother showing them, as they aren't concerned about the electrical side of things and just clutter the screen.
https://en.wikipedia.org/wiki/Inverter_(logic_gate)#Electronic_implementation

>>2872402
>every gate has 2 extra wires going to them: ground and power
>they're omitted for clarity
>>2872403
>>2872404
I understand now, thanks.

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is there an easy way to generate a -2.5V reference relative to ground from a bipolar +/-12V power supply? i tried using a TL431 until i realized that i'm stupid and a tl431 generates -2.5V relative to my negative voltage rail... i need -2.5V relative to ground.

>>2872410
oh wait never mind, i am a RETARD and breadboarded it wrong. IT WORKS.

Where the hell can I buy a normally-on GaN MOSFET? All the ones I can find are using a cascode with a silicon MOSFET to make them normally-off.

Any other high-power high-voltage depletion mode FET would be fine too I guess.

>>2872360
Fucking do it. Give it a headphone jack so it can be a bluetooth DAC.

>>2870494
>>2870502
Thanks for replying anons, turns out that PWM control emits considerable EMI but a typical brushless fan by itself has no such drawback, and the USB standard should already include any "filtering" and other considerations when powering any device, so I settled for regular 5v (according to the manufacturer) 40mm fans.

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I've got an AC desk fan that seems very slow on speed setting 1; it used to be faster before. Curiously, it seems to speed up to normal speed if I tilt it forward, and slows down if I tilt it backward. Wtf is going on?

>>2872648
>Wtf is going on?

it needs oil on both bearings, front and back
one way you tell it needs oil is that it stops a little abruptly when you switch off
when properly lubricated, it slows down super evenly

>wake up
>get an idea about a cool device that i can make
>don't want to start because it will take me multiple days or months of work to get it done
>drop the idea
Reliance on instant gratification has fucked me up

>>2872673
What’s the idea?

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>>2872676
I want to make a device to profile batteries, their internal resistance and transient response (it can become sluggish on some chemistry types if high current drains are done repeatedly). The final aim is to let the device+computer software be able to spit out a first order battery model (pic rel) so that you can plug that into simulations in any spice program
I want such a device because I work with low power IoT devices which run on coin cells and other high impedance primary cells

https://www.youtube.com/watch?v=FzrZoVKT8gM

>>2868444
>live in 3rd world shithole
>can't buy anything better than OP07 from local stores
>can't buy 3S cell management ICs
>can't buy any sensor that isn't supported by Arduino
>can't buy gate drivers which work below 12V
I don't want to pay the digikey 9 gorillion dollars for a 0.1USD part because shipping costs a ton and digikey warehouse workers must be paid 6 figures to cut reels and put them in bags

Makes me want to go nuclear and design and replicate the behaviour of every single IC using 2n2222 and 358

>>2872709
buy in a chink digikey like LCSC.com

>>2872719
>order from LCSC
>customs employee having a bad day
>"you must pay 9000% import duty on this resistor. Yes even if the law says the duty is 0%. Pay up schmuck"
>"or we keep the part" (the customs employee throws it away or if it's fancy tech he takes it home)

>>2872723
do you live in North Korea?

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what is smallest buyable smd push button ?

>>2872755
I live in India anon. And I'm probably exaggerating a bit, its not that bad but customs agents and charges are indeed arbitrary and random, often losing your items entirely

>>2872723
Sounds like canada.

>>2872755
>do you live in North Korea?
Its actually very common in most counteries (at least 3rd and 2nd world) for customs folks to abuse their position to take home "unclaimed" or seized stuff like smartphones and other tech. They know the importer (usually an individual buyer) is not going to spend a penny more to legally challenge the import fee of their 150$ smartphone from china

>>2872678
That sounds interesting…. I remember when Nimh batteries came out it fried a bunch of things that relied on the high impedance of the cells to automatically limit current (like leds) or making battery-free adapters for low current zinc-air devices.
I was attempting to make a tiny low-power proximity detector that went off once per day by using a low-power microcontroller that would wake -up, charge a capacitor through a mosfet, then let out a high-power lora chirp from that capacitive charge, then go back to sleep. It was more work than I thought though.
If I were you I’d use a uart to hook up to a pc, use the d to a converters to have the pc control a load on the cell (mosfet), and use the a to d converter to measure the voltage and current and send it back to the pc through the uart.

>>2872723
not a problem in the eu, sorry man

is there a website or something where i can input any kind of periodic signal and it makes me hear how it would sound if it was given as an input to an amplifier? Im trying to get into sound synthesys and I want to build an intuition for how different signals sound

>>2872673
Autistically design the circuit board, then put it off until you have enough board layouts to make a big order from a fab house.

>>2872678
The hard part there is the code. I’d just do a series of tests, then send the raw test data to a python or matlab script on a computer and do the model calculation there.

>>2872723
LCSC already does import duties, I’d hope that that’s enough to dissuade any hostage taking. You could also try having it mailed to your workplace, with the business name as the recipient, to make it look like you aren’t a low hanging fruit. Also Digi-Key really isn’t that expensive.

>>2872763
Maybe those little tactile discs that use a pad on the PCB as one of their two contacts.

>>2872840
An amplifier should be linear, so it shouldn’t make a difference besides the gain (just turn up your headphone volume). There are sine generator or function generator webpages, though you can also use python plugins like sounddevice to output a data array as audio. This makes it easy to modify a simple waveform in all sorts of ways (clipping, filtering, Fourier, etc.), or even take a sample waveform from a .wav file to test effects on.

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What is the name of this tool used to simulate circuits?

>>2872878
>name

falstad
it means ''Dagnabbit!" in swedish

>>2872890
>falstad
ty! I came across it long time ago but lost the link. saw some guy use it in a yt video so he reminded me of it.
looks useful. kinda like LTspice.

>>2872894

circuitlab is better
and a native computer app like multisim is best

>>2872896
thanks! Didn't hear of any of these. will look them up.
I also need to search my Linux distro app catalog to see what they have in there too.

>>2872903
Based KiCAD has a simulator in it. If you use it anyhow, it may be worth learning to use it as a simulator too. Looks like some people are doing EM analysis of PCBs with KiCAD and FreeCAD too, which is cool.

>>2872840
VCV rack is a free modular synth app that lets you generate arbitrary signals

>>2872285
i'd rather get something comfy
not really sure what its called though i dont get many results looking up soldering stand and station brings up whole stations

>>2872872
>The hard part there is the code. I’d just do a series of tests, then send the raw test data to a python or matlab script on a computer and do the model calculation there.
Yeah its definitely the "hardest" part but the project in itself is pretty straightforward I think. I've interfaced a lot of projects with python and written UIs for them and also worked with numpy so its fine for me

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Any idea how to remove spot welds from a coin battery? Just pry it off?

>>2873014
https://www.amazon.com/soldering-iron-stand/s?k=soldering+iron+stand
https://www.amazon.com/Liyafy-Soldering-Holder-Solder-Cleaner/dp/B07Y32S4PL
>>2873025
Grab the tab right up against the battery with needle nose pliers and roll it like you're forming a coil.

>>2872767
Is it possible to make friends with the local customs? Give them things they want in exchange for looking the other way?
If they don't respect the law, then the current state becomes the actual street law. Use the actual street law, then, as that is acceptable.

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>>2872410
is that how youre supposed to use a 431 with negative voltage? ive been doing it like this...

>>2873075
Your circuit makes a voltage that's X volts above the negative-most rail. The other anon's circuit makes a voltage that's X volts below the central ground rail. I'd say his method is better, since signals should be referenced to ground, but if your rails are constant and noise-free it doesn't matter much.

>>2873048
Thanks, Ill give that a try

>>2870319
it's butt ugly but if your intention is to jumper the pads then yeah no problemo

>>2870557
>I have a decent DMM but the probes are too chunky and for whatever reason, it cannot reliably test stuff that's in circuit.

you can always make your own with some wire. Keep in mind that when components are in circuit, there's not just the path between both leads of the component going through it, but also through any common (ex ground) paths on either end of the component. This WILL fugg up your measurements regardless of what tool you use to measure.

Also, if you're looking at an op-amps output you'll want some impedance on the probe or else you'll fuck with the output. Solder a 1k resistor on the output in parallel and clamp your probe on to that (or just have a probe with a 1k in series)

>>2870557
>I don't know how these SMD component testers work but they do have a mode to test stuff in circuit.
ok tbf it might be doing something fancy but I wouldn't know what

>>2872384
power and signal are sperate - AA's keep the controller on, button pushes send a signal yeah? NOT sends the opposite signal of what it gets - "no signal" is code word for the signal is 0, "there is signal" means the signal is 1. If the NOT gate gets a 0, it sends a 1. If it gets a 1, it sends a 0

>>2873098
ahh i see, ty ty <3

>>2868444
Where's the roll image for project ideas

>>2873808
https://github.com/Rocheez/4chan-electronics-challenges/blob/master/list-of-challenges.png
It's in the OP github, alongside the project list by categories:
https://github.com/74HC14/ohmOP/blob/main/ProjectCategories.md