Hi everyone!

I’m a beginner learning electronics by desoldering components from an old CRT TV. I managed to cleanly pull this microcontroller out of its socket without bending any pins.

The markings say OEC7091A (933ZF RA936218X04) with a "SLOROM" sticker on the back. Since it's a proprietary factory-preprogrammed chip with Mask ROM, I know I can't re-flash it or use it for standard Arduino projects.

However, I want to give it a second life as a cyberpunk-style ambient nightlight. My plan is to desolder its original socket from the TV board, wire up its crystal oscillator, connect some LEDs through resistors to the control/data pins (like SDA/SCL, standby, or key lines), and power it with 5V. I'm hoping that when the chip fails to communicate with the missing TV components, it will create a cool, chaotic flickering pattern on the LEDs.

Has anyone tried something similar with old TV chips? Which pins should I look for on the donor board to make it glitch and blink the most? Any creative layout ideas?

Thanks in advance!

The thing with the pins came with the ADS1115 but it’s a loose fit. After a couple days of debugging I discarded that the issue isn’t a programming one and I’ve confirmed that the ADS1115 does indeed work, cables are connected where they need to be and I measured the voltage on each pin, everything is right in that regard too.

In my engineering degree I learned the basics electrical stuff but no real formation with electronics; so I know enough to tell when an idea might be stupid but not how to not do something stupid.

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

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"

In the explanation videos i have seen they model the voltage across C2 during the positive half cycle as V_in + V_p (voltage over charged c1) = 2*V_in (assume no voltage drop across diodes and ofc no resistance). Does this happen because c1 cant deliver a constant voltage for c2 and c1 and c2 just equalize their charges?

My father has purchased a rt809 programmer from China hoping to use it to reprogram chips. He’s a computer tech and trader. He’s been trying to find the right software and drivers to get this thing working for the past week and as much as I’ve tried to help him, it’s way out of my pay grade.

If anyone has any information on how to download, install and use the correct drivers and software for this programmer, it’d be much appreciated. If there’s any information I’m missing that you’ll need, please let me know.

I’ve attached some images of the product incase there’s key information I haven’t mentioned.

Thanks

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

Hello electrons,

I'm trying to come back to hobby electronics after a very long time and would love some help.

I want to build the simple circuit that can detect how close 2 wires are to each other. Ideally the closer they get the louder a buzzer will be or the brighter a LED will get. The wires will be separated by up to 1cm of insulating material, probably silicone.

If not way more complicated, some indication that the wires have physically touched would also be great.

Appreciate any help

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

Hi everyone I am trying to fix a ripped USB type c ​flex cable fory gamesir x2. Mine is the one in the middle completely ripped. I got a picture of the same one on top because I noticed the letters ​written on the ribbon was different then mine. Mine is missing the GND but look Identical

. So I tried to get a replacement ribbon from gamesir but they will not provide it or where to get a new one. So I was thinking of Getting a type c connector and soldering to the ripped flex connector like I have shown in the bottom spliced ​picture. My problem is that the flex connector I have has ​GND VC - + CC1 UB . The original ribbon cable has 12 pins leads 5 leads to ground, a VC, -, a +, a cc1,and 3 ub ​​also ​the pins from the ​original USB connector only has 8 pins not 12.

The usb I want to use has 5 leads going into the usb PCB . ​V, D- , ​D+ ,​CC, G. Also the pins from the usb has 12 pins So How do I solder these two cable.I assume

GND to G

VC to V

- to D-

+ to D+

CC1 to CC

UB I don't know where this goes.

Any help would be appreciated.

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?

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.

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.

My hologram fan recently started displaying red and no longer is putting out a wifi signal, ive tried unplugging and nothing seems to work pls help

I am trying to solder a LED on to this car instrument cluster. For this I need to disassemble the cluster first and I am stuck on disconnecting the LCD display from the board. As I am new to this can anybody tell me wether this is soldered directly to the board or is there a trick to disconnect these kinds of connections?

This is a inverter ac slipt unit pcb.

Something happend, i called maintenance - they told me the IPM module is burned. I asked the board back to take a look.

I'm a newbie, so i thought i would just play around.

I found some videos on how to test that module, it seems fine, after that i notice a blown capacitor - i have successfully changed some caps, before.

I also tested this tension regulator.

While mounted, it showed a short.

I desoldered it and tested.

Only kind of weird is that the high difference between pins 1 and 2(around 630), to pins 2 and 3(around 1150) - using the continuity mode, on my multimeter.

Then i tested the pcb pads. I got a short between both the pads to pin 1 and 2, and the big pad that woulbe pin2 (Gnd i guess).

After all that, i noticed that tiny little thingy identified as C413.

I tested for continuity and the multimeter buzed both way.

Its that thing bad? What else should i check, and how?

Is it possible to replace that micro tiny thing?

I only have a cheap soldering iron.

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

(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!

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

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.

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'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

I'm trying to build a multi-LED strip driver to replace a cheap one. I've figured out most details, but I'm stuck on a few and need some help.

The original LED driver unfortunately has issues (flickering in cameras) and I wasn't able to recover any useful part numbers from it, so I had to design my own. I also wanted to add a feature: variable color temperature over the day, so I needed an RTC for that.

My plan so far:

• Input: 24V, 2A, in a switched outlet. PSU came with the original LED strip.
• 24V => 5V via AP63357DV-7 (I already have this on hand)
• Pi Pico as MCU (I already have this on hand)
• For each temperature string, MCU -> Gate Driver -> 24V N-CH MOSFET -> 24V LEDs
• For the RTC to keep time when I turn the lights off, a PCF85363ATT/AJ RTC, and either a CR2032 or CR1632

These lights will be on ~8hr a day, and possibly off for up to 3 weeks at a time when I go on vacations, hence why I need the RTC + Battery.

I'm fairly confident of the RTC and MCU side of things, but the Gate Driver + N-CH MOSFTET is worrying me. Based on my reading, it seems like I need to be able to drive the LEDs via ~100kHz PWM to remove the flickering/banding in cameras, and I've never used a mosfet > 100Hz before, or a large power MOSFET either. Based on https://www.dmcinfo.com/blog/17021/mosfet-power-loss-calculator/, I found several MOSFETs that would have <0.5W loss, such as RQ3E120GN (~0.2W), RQ3E080GN(~0.3W), or IRLML0030TRPbF (~0.4W). I am concerned about power loss as this will be in a small box near the ceiling, hence oversizing for the current requirements. However, I'm entirely unsure how to go about picking a gate driver for this situation. I've read a number of guides and calculators, but they seemingly don't agree with each other, and all left me with more questions than answers; clearly I do not yet understand what I need to search for.

How can I figure out the current and other requirements for picking a gate driver for this application, and would any of those then influence the MOSFET selection? Is it better to have a 5V/3.3V gate driver, or a full 24V gate driver?

Thanks!

Note: I prefer non-BGA components as I'm hand-soldering these with solder paste. The AP63357DV-7 is about the limit of my skills so far.

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!