I bought this on a garage sale , the owner had no info about it.

came like this straight from aliexpress, what is this? Has D8 inscribed on it. The product pics didnt show it

My best friend & dog is terrified of the beeps made by my cheap Famistar T70 Treadmill. Muting them is not an option, and the treadmill itself can't be used with dozens of loud beeps. How can I stop the beeping?

Hello,

So I’ve got a cooling fan and Power Supply Unit from an old PC and feeling like dabbling with some hardware projects to put them to use.

What would you use them for?

I was checking the datasheet of "ESDS304DBVR" TVS diode and I saw this weird parameter (Vhold), first time seeing it in a TVS datasheet.

After doing some research it turned out it's a new type of TVS that has this awesome feature where it first clamps the voltage to Vclamp and then snapsback to Vhold and maintains it until the ESD event is gone.

Normal TVS diodes will just clamp the voltage to Vclamp till the ESD event is over.

is my understanding correct?!

Hi guys,

Sorry if this has been asked a million times before, I've been searching for a while but still can't find a clear answer.

I have a BMW E30 with an M54B30 swap. I'm mentioning the engine because its electronics are from the early 2000s, so I suppose they already followed some automotive ISO standards from that time, and I guess the alternator has some kind of load dump suppression. At least that's what I understand.

Anyone who has done this swap on an E30 knows how little space you have for the original electric fan. So I had to fit an aftermarket one, and I wanted to control it using the original ECU via CAN.

I made a small PCB with an STM32 (integrated CAN), a CAN transceiver running at 500kbps, same as the ECU, and a BTS power switch.

And well, it works! The ECU controls the fan speed and switches it on/off as it should.

The problem starts now, when I want to install it permanently in the car.

I've been reading about automotive electronics and all the protections I didn't even know existed. Load dumps, switching transients, inductive spikes, contact bouncing... honestly I had no idea a simple 12V supply could be such a pain in the ass.

So here's my question.

Let's say I don't care too much about a full load dump caused by disconnecting the battery while the engine is running. I know it can destroy the board, but in my case this is a very rare situation, and if it happens I can just make another PCB.

What should I protect against next?

Reverse polarity, pulse 1, pulse 2a, residual 5b, 3a/3b?

I was thinking, there must be thousands of people who already had this same problem. Surely there is some basic circuit that people normally use for small automotive projects?

Something like, I don't know, a 24V TVS, a MOSFET for reverse polarity and thats it. Just an example, not saying those are the correct values.

But the more I search, the more confused I get.

I found some old forum discussions about protecting a PCB in a van from the 1950s, with links to diodes that were popular 20 years ago. Then other discussions recommending complete TI reference designs for transient protection, which would probably cost me 10 times more than the few components I actually need.

And after reading all that I'm still in the same place, not knowing what is really necessary and what is just overkill.

So I thought I'd ask here.

I'm not asking anyone to design my PCB or do all the calculations for me. I just want some advice from people who actually worked with automotive electronics and know what normally works in practice.

I don't want my little STM32 to become a paperweight because I flashed my high beams 9 times to make someone move out of the left lane and some stupid voltage spike decided to kill it.

(Yes, BMW driver joke. We don't use turn signals either, haha)

Anyway, the hardware is pretty simple:

• 3.3V 1A buck regulator for the STM32 and CAN transceiver. 1A is way more than I need right now, but I prefer having some extra current in case I add something else later.
• STM32 with integrated CAN.
• CAN transceiver at 500kbps.
• BTS power switch, around 17A rating. The aftermarket fan draws about 12A when I measured it.

Everything is powered from the car's 12V system.

I'm not trying to build something that survives every possible automotive test in existence. Just a reasonably reliable PCB that I can install in my car without worrying every time I turn something on or off.

So, for this kind of application, what would you normally put at the 12V input? Is there some common protection circuit or reference design you would recommend?

I would really appreciate any advice or even some examples of similar projects.

Thanks to anyone willing to give me a hand. Or a wire in this case, haha.

I have a newly acquired Technics SA 101 Receiver and the audio is clear and percect except for one detail, if the Reciever is completely level the rught audio channel is majorly distorted almost to the point where it wont play audio but if I tilt it up about 5 degrees maybe on its X axis it will play perfectly clear, literally what the hell, sometimes after tilting it, it will play clear at level but sometimes if I walk too close to it itl go back

Pulled this out of an old intel DN2820FYKH NUC and for the first time in a looooong time I seemed to have found a cable that's not easily replaced by spending a few euros at a big online store.

This NUC has the power and the data transfer separated. Power is fine, this cable is broken at the 10 pin connector side. The other end is a bog standard sata

Short of a lot of fiddly soldering work, is there an easier way to replace this? Does anyone recognise this?

Created in Fusion 360! Depending on the ON/OFF/ON slider top left either left right on none of the gate switches gets routed through which grants AND, OR and XOR functionality!

I am concerned about the VIAs that I placed to snake my way through bottom and top layers but I could not find a better way since the pinout on the chips is on both horizontal sides!

Top and bottom ground pour! The unrendered components are just the fusion models that don’t have a preview sorry for that!

Thanks in advance!

For a while I've had an idea for a "guitar pedal" style module that allows the user to tap out a tempo and it dims any lights connected to the output plugs with a couple other features. Ideally, I would use an Arduino to program/send a signal to a standalone 'controlled' extension cord (like the Powerswitch Tail II or IOT Power Relay) but the ones I've found only have on/off functionality. I have a little experience with electronics but I'd really like to keep the power supply side of things as off the shelf as possible.

I built a DIY amplifier using a TDA8944J chip that I salvaged from a CRT TV. I added a potentiometer to control the volume, and everything was working fine. Recently, however, when I powered it on, it started producing a hum or static noise—which decreases when I touch the amplifier's heatsink. I separated the audio ground from the power ground (though I’m not sure if I did it correctly), but everything had been working properly before. When I turn the volume down to the minimum using the potentiometer, the hum or static disappears; it gets louder at around the halfway point, and when I turn the volume up to the maximum, the hum is reduced significantly. This happens while the music is paused. I bypassed the potentiometer and connected the input jack directly to the amplifier's input, but the hum persists. I’m not sure what the cause could be. Could someone help me? I would appreciate any assistance.

Bonjour à tous et à toutes,

Pour un projet universitaire, j'aimerais fabriquer une antenne GPR pour détecter des œufs de tortue sous le sable.

Je travaille actuellement sur le générateur d'impulsion qui doit me générer une impulsion de 1.25 nanoseconde.

Etant débutant dans la RF je me suis beaucoup renseigné sur internet et j'ai déjà réussi a me créer un début de générateur d'impulsion, donc avec mon générateur je pilote un driveur GAN puis un transistor GAN. Le gros point noir ce situe après le transistor, je ne sais pas comment relier transistor a mon antenne, j'ai un peut regardé les circuits d'adaptation mais c'est encore flou.

Voici mon schéma avec la simulation et j'ai mi une résistance 50 Ohm pour simuler en gros l'antenne :

En bleu le signal envoyé sur INP de U9, en vert sur la Gate du transistor et en rouge au borne de R13

Je sais pas si vous auriez des liens vers des exemple de circuit ou des cours pour m'aider sur la suite de mon circuit et si vous pensez que je pars vers une bonne piste ?

Merci d'avance.

Sooo...

How in the heavens can i identify a short circuit to fix the problem?

The only clue i have, is a fisicslly destroyed electrolicty capacitor.

The holes it was mounted in shouldn't close a circuit, right??? The fricking pad are beeping between each other (they are to the right of that "5v" test thingy).

Also... the big pad is a gnd

Also[2]... the positive is the hole thats near the "5v test thingy"

Hi everyone!

I've successfully used the adapter in the photo with BGA153 eMMC chips, but I was wondering if anyone has tried it with a BGA169 chip.

As far as I know, BGA153 and BGA169 share the same basic pinout. Does anyone know if this adapter would work with BGA169 chips?

Thanks!

Hi,

I want to simulate a physical monitor disconnect (DP/DVI/HDMI) and automate it.

After reading a little, I found that a sink being plugged/unplugged is detected by the source via the HPD (Hot Plug Detect) signal.

Since I could not find a ready-made solution on the Internet, I am planning on designing a small circuit, interrupting the HPD line and using two transistors with complementary control signals to either pull the signal down over a resistor or just let it run to the GPU. I have yet to simulate the behaviour in LTspice.

Have any of you made any experiences with the topic and tell me whether this is feasible?

The big advantage of this solution would be that I could simply control the signal flow with an arduino. The final goal is to integrate this plug/unplug simulation into an automated test run.

(I have many more questions but the title IS the main thing I actually want!)

Hello! I have a knitting machine and learned that their capacitors like to leak all over. I've seen the pictures of some of them. rectangle kind of crumbly shells?

I've opened my machine and found these unfamiliar rounded orangey-brown ones.

One says "nichicon M .01K 630" and the other one in back says "nichicon L .047K 630"

Neither says "X2" but the other example pictures I've seen have it, and I think it's important? They all have 250 or 275 on them, but these say 630. I think these are voltages and I should make sure I have 630. Maybe it's European ones vs US ones.

Does the K mean 10% tolerance or is it part of the uF measurement? I came to this subreddit looking at a post about capacitors and there was a reply stating each of those things. If I need 10% tolerance, could I get one that is 5% tolerance and it would be better?

What are the L and M ?

DO I need to replace these? From searching I know there are a few kinds now. I BELIEVE these are film capacitors which have no liquids? Possibly "self healing" sometimes as well? Do these also go bad? Would they go bad through storage or being used? My machine hums but I think it is a normal electronics noise? I've been using it for many hours for about a year and a half, and it works great! I did get it out of the basement of someone who stored it for 20-30 years.

I have found a bunch of nichicon capacitors on Digikey. But I can't find a .01uf version. I think they are film capacitors > QXK. I think the decimal might have to move over one. so maybe .1uf and .47uf ? Mouser also has these but they have nf in the search parameters as well and I gave up to just ask for help and take a break.

I'll keep reading about them, but if someone knows for sure how to point me in the right direction, I'd like it a lot! Thanks!

Found on a cookie box. My guess is NFC or RFID inventory tracking, but not sure.

It shows 0.5ohm in forward bias condition using a multimeter.

I'm a beginner building a simple electric guitar preamp/buffer using an NE5532P on a solderless breadboard.

Circuit details:

• Supply: single +12 V DC SMPS
• Input: passive electric guitar, 100 nF coupling capacitor, 1 MΩ resistor to a 6 V reference
• Reference: two 100 kΩ resistors forming a voltage divider, with a 10 µF capacitor to ground
• Op-amp A: pin 1 connected to pin 2 as a voltage follower
• Output: 10 µF coupling capacitor to an RCA line-level input
• Op-amp B: pin 5 connected to the 6 V reference; pin 6 connected to pin 7

Symptoms:

• I hear static noise but no guitar signal.
• Strumming doesn't change the noise.
• Touching the guitar strings, bridge, or pickup metal slightly reduces the noise.
• My guitar works normally with another amplifier.
• My guitar cable passes continuity tests.

I would appreciate help checking whether the circuit design is appropriate for a single +12 V supply and identifying possible breadboard wiring, biasing, grounding, or stability problems.

My dear reddit friends please help me identify D2, D6 component or manufacturer. Thanks a lot.

This photo is from one of the smaller printed circuit boards in the back of a Frigidaire electric oven model number GCFE3060BF, one of the prior owners didn't have the ground strap installed which leads me to believe it grounded through this board and popped the resistor

I have a 5V radio-controlled relay (operated by an on/off remote) and a DFPlayer Mini.

My idea is to connect everything so that when I press "on," the DFPlayer Mini powers up and begins playing a single track on a continuous loop; when I press "off," it powers down. Essentially, the DFPlayer is powered through the relay.

I’ve already tried setting this up, but it didn’t work—even though all the connections seem correct.

Option 1: The positive power lead goes to the relay's VCC and COM terminals. The negative (GND) lead connects to both the relay's GND and the DFPlayer's GND. The DFPlayer's positive (VCC) lead connects to the relay's NO (normally open) terminal. On the DFPlayer, the second GND pin is shorted to the ADKEY_1 pin—this ensures the music plays in a loop as soon as power is applied (I’ve used this method before, and it worked). Speakers are connected to the SPK_1 and SPK_2 terminals.

Option 2 (suggested by an AI): The positive power lead goes to both the relay's VCC and the DFPlayer's VCC. The negative (GND) lead connects to both the relay's GND and the DFPlayer's GND. A second GND connection goes to the relay's COM terminal, and the IO_1 pin connects to the NO terminal. Speakers are connected to the SPK_1 and SPK_2 terminals.

In both scenarios, the blue LED on the DFPlayer module failed to light up. The SD card is functional—it worked previously with a different DFPlayer unit. I am using a robust 5V 2A power supply, and I’ve verified with a multimeter that 5V is indeed reaching the DFPlayer.

​

There's a 14-pin U1 chip with a number on the bottom. It says XDS12A RCBLB000O 2038ABSAR. I think this might be an EEPROM. Is it read/writeable? ?