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

I studied this at uni a while ago and wondering if it’s still used ? Thanks for any help !

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?

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?

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!

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,

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 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?!

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.

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 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!

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

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

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.

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? ?

hi everyone, I'm working on a conductometric sensor that needs to be integrated into a flexible PCB cartridge, and I'm looking for advice on making reliable electrical connections without soldering.

The sensor is placed inside the cartridge, and the flexible PCB flaps are folded over it. We need to electrically connect the plated vias on the FPCB to the contact pads on the sensor.

my challenge:

The sensor is temperature-sensitive, so soldering or high-temperature curing isn't an option.

We've tried using conductive silver epoxy, but the application was messy and difficult to control and since the contact areas are quite small, excess epoxy also cause short circuits between adjacent contacts.

We're considering using a low-viscosity, room-temperature-curing silver epoxy and dispensing it directly through the vias with a fine hypodermic syringe.

A few questions:

1. Can anyone recommend a conductive silver epoxy or paste that flows through a fine dispensing needle and cures at room temperature?
2. Would dispensing epoxy through the vias onto the underlying sensor pads provide a reliable electrical connection?
3. Is there a cleaner or more reliable alternative that doesn't require heat?

Ideally, we're looking for something that provides low and stable contact resistance, precise application, and good mechanical reliability without damaging the sensor.

For copyright reasons I cannot attach pictures showing the device.

Any suggestions or experience with similar applications would be greatly appreciated. Thanks for your time!

I'm working with the WCH CH569W-EVT-R0-1V0 development board and would appreciate some advice on its USB 3.0 interface circuitry.

The CH569W supports USB 3.0 host and device modes, but this particular evaluation board exposes the SuperSpeed interface through a USB Type-A female connector (J3).

I need to operate the board as a self-powered USB 3.0 device connected to a PC.

Looking at the board schematic, J3's VBUS appears to be connected to the board's 5 V supply through fuse F2. I'm concerned about possible VBUS backfeeding when the board and PC are powered independently.

My questions:

1. What circuit arrangement would allow this board to operate safely as a self-powered USB 3.0 device?
2. Should J3's VBUS path through F2 be disconnected or modified?
3. How should upstream VBUS detection and USB attach/detach be handled? Does the CH569W provide a suitable internal mechanism?
4. Would I need external USB 3.0 signal switching, or could correct VBUS isolation and controller configuration be sufficient?
5. Does the CH569W ROM USB ISP bootloader have different connection requirements from application firmware?

I'm specifically looking for advice based on the CH569W-EVT board schematic or experience using this board in USB device mode.

I haven't connected or modified the hardware yet.

Any pointers to a tested reference circuit or relevant documentation would be appreciated.

Reference: https://github.com/openwch/ch569

Trying to decide whether I should learn to clean it or get a new one.

Any alternatives for them? I have custom power LEDs which I control with those (+transistors ofc) but I want to have the slave PCB much smaller. Ideas?

I purchased this 4 inch CRT online as a project to turn it into an oscilloscope. I hooked it up to 12V DC power as it called for and soldered in two pots for contrast and brightness, 1k and 50k ohms respectively (top left of board in blue). As far as I understand, turning on a CRT with no input should give some sort of visible raster lines or a dot in the center, but all I can manage is an extremely faint glow. I can hear the 15khz whine while it's on. What could this issue be? Is this normal and I'm tripping? The display is identical with the deflection coils both plugged into and unplugged from the board.

If there is a better subreddit to post this please let me know

Hi, I'm looking for AD75019 for my project. I have no idea where to look for it. It's available in eBay but it's overseas so I can't pay for the tariff. I wondering if I can salvage components but I have no idea which

I'm replacing this pot and for the life of me I can't get solder to stick to this terminal. Tried flux, flux cored solder, filed slightly, alcohol clean... nothing. Any clues as to what I am doing wrong? Iron set to 400.

I dug out my old weller gun and 100w got it done. Thanks guys!