This is from the service manual of a Pioneer SX-9000 receiver I'm working on. Have I just been working on this too long, or is there a legit mistake in the schematic? I feel like the C+ and C- labels are incorrect for the bottom going towards the push switch unit, but my overthinking is really thwarting me here.

It reads A810 and its like a SOT23-6 but some sites say it could be XC9208A103M but that component has SOT23-5.

This are the connections I could recreate.

Does anyone sell a non-conductive, esd-safe tool for flipping switches in small surface mount DIP switches? Something with a small hook and a poking point?

I’m using a screwdriver to flip switches on a powered, expensive device during testing procedures, and it makes me a little nervous that I might accidentally short something etc. (I’m using a wrist strap, esd jacket, and esd shoes already)

Can anyone help me build this logic circuit in multisim? A logic circuit subtracts two signed four bit numbers A = A3A2A1A0 and B = B3B2B1B0 by calculating A-B. The circuit has two outputs (Y and Z) and operates as follows: a. If A = B, output Z = 0 otherwise it is one. b. If A < B, output Y = 0 c. If A > B output Y = 1. Using the 74LS83, design and implement the circuit in MultiSim. The 74LS83 is a 4- bit binary adder. I've done up to this far, but then I realised that there needs to be two outputs only.

ok so basically i have this membrane keyboard from razer (razer ornata v3 x) and i raged a little too hard and hit my desk using my keyboard. after that it stopped responding to my clicks but the rgb still works. i was wondering on how i can fix it and what is currently wrong with it? ill add a couple of pics i took

or is that the capacitance is much greater than the frequency at that point

So I am working with a board with this kind of heatsink on a chip but it was glued with a white epoxy glue which I have never used. Now the board is OK I need to get this glued again but I tried with UV resin and it just doesn't work.

I'm looking to have a hardware shutoff for a MIPI-CSI device. In this case it's a IMX415 camera module. If I just cut power to it, will these be any potential damage to the device, or should I look to have a full MIPI switch to also make sure the data lines are disconnected? By cutting power is there any potential to damage the device? Then re-enabling power should theoretically also power it back on? Any risk of the initialization going wrong?

Can anyone show me a recreation of this on a mini bread board and in Tinker-cad. Please I'm a design student I don't know what any of this means 😭

Pointing to things that would help me understand would also be appreciated

Iv just bought this solder radio kit and I can’t get any radio stations to come up if anyone could help please im new to electronics and would like some guidance thank you

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Theres no marking next to this component. Unsure exactly what it is ? Any ideas ?

Cheers.

2 damaged pins where do we connect each pin?dose multimeter test work here?its for r2 side i think

My son's toy walkie-talkie set came with a faulty speaker. The first photo shows it in-place - it's marked 8 Ohm, 0.25 W, and I measured the diameter as 29 mm.

I bought a replacement from AliExpress here, matching the impedance, power rating and physical size - as shown in the second photo (sorry it's blurry). But when I connected it up, the sound output was *much* quieter than the original.

Have I just bought a poor-quality speaker? Should I try one from a more reputable source, such as this one from DigiKey? Or maybe step up to a 0.5W speaker? How else might I increase the volume to match the original? Thanks!

Markings: B500K

Shaft: D type, 6mm dia, 11mm length. Push stroke 4mm, approximately 270 degree rotation

Bushing/mounting threads: 9.6mm diameter, 1mm pitch, length 10.5mm

Switch type: Push lock

I'm having no luck on mouser!

Not sure if this is the correct sub but I have this light that turns on with a button but shuts off after a few seconds. I would like to make it stay on until I disconnect it from power via usb or plug?

We use a BMD-340 (nRF52840) module on a small wristwatch board, 4 layers and 0.8 mm thick. The antenna end of the module faces the board edge, and we kept the antenna keep-out from the data sheet on all copper layers. It is the red dashed box in the images.

The display FPC connector (Hirose FH34SRJ-10S) has two metal hold-down tabs. One of them, MP1, has no net and sits inside the corner of the keep-out:

- about 0.85 to 1.25 mm in from the side edge of the keep-out

- about 0.25 to 1.05 mm in from the top edge of the keep-out

- about 1.3 mm to the side of the module itself

The pad is 0.4 x 0.8 mm, and the metal tab on the connector is about the same size. The watch has a plastic case.

Questions

1. Is a small floating tab like this likely to reduce the range or detune the antenna in a way we would notice?

2. Would it be better to connect the tab to ground, or to leave it floating as it is now?

3. Do you see anything else in the images that could hurt the radio performance?

Thanks for any help!

We are building a small research wristwatch with an nRF52840 module and an nPM1300 PMIC (nPM1300-CAAA-R7, WLCSP-35). We are about to build a few prototypes and would like a second opinion on the PMIC area. The images show only this area.

The board

- 4 layers, 0.8 mm. Layer 1 is the top, layer 2 is solid ground, layer 3 is the 2.0 V rail pour with some signals, and layer 4 is the bottom.

- U1 is on the bottom side. The images are seen from the top of the board, so they are not mirrored.

- BUCK1 is set to 2.0 V and BUCK2 to 3.0 V. Both use 2.2 uH, 2.0 x 1.2 mm inductors (L1 and L2) and 10 uF output caps (C7 and C8).

- PVDD is tied to VSYS and has two 10 uF caps (C2 and C3). VSYS has one more 10 uF cap (C4).

The land pattern

- 0.25 mm round NSMD lands, 0.30 mm mask openings, 0.25 mm paste apertures and a 0.10 mm stencil.

- Seven inner balls (B5, B6, C3, C6, D3, D4 and D6) have a 0.15 mm via in pad. The fab fills them with epoxy and caps them flat.

- Tracks neck down to 0.10 mm inside the mask openings.

- Nordic's reference layout uses 0.211 mm lands with 0.363 mm mask openings. We used 0.25 mm lands because that is the smallest land our fab can cap a via in.

Questions

1. Do you see any problem with this land pattern or the via in pad escape for reliable assembly?

2. Do the BUCK1 and BUCK2 loops look OK? That means the PVDD caps, the inductors, the output caps and their PVSS returns.

3. Would you add a small 10 to 100 nF cap on PVDD close to the ball, because the board also has Bluetooth?

4. Layer 3, right above U1, is a power pour and not ground. Is that a problem for the bucks?

Thanks for any help!

I am working on an old animated Santa for a customer and I am stumped. I would really appreciate any input y'all might have on this....

Here is the schematic as well as I was able to reverse engineer it - www.RobotsAndComputers.com/temp/Santa.pdf

OK... when I got it, the battery pack as disconnected, the switches were wired wrong and the S8550 transistors were shorted, as well as one of the H8050's. I fixed all of that and it kinda sorta works. D1 checks ok, as do all of the resistors and capacitors. The IC (which is an encapsulated blob) SEEMS to be working right, but... .

The way this is supposed to work is that when you press the button SW2, the front of his coat will open (M2). When that reaches it's limit (either TP12 or TP13, not sure which right off hand), that motor stops and the platter inside spins (M1) while the lights flash (P1) and it plays Christmas music (Q8 and the speaker). When that times out (if SW1 is in DEMO) or you press SW2 again, the front of his coat should close (M2) and everything stops.

As I have it now, the platter spins, the lights flicker and the music plays. What DOESN'T work is M2 - the doors (the front of his coat).

Without the motors connected, the voltages between R1 and R6 seem to be alternating correctly. They also seem to be alternating correctly between R1 and Q3 as well as R6 and Q3.

If I am understanding this circuit correctly, the Truth Table is as follows:

P2 on / P3 off / P4 on = M2 fwd P2 off / P3 on / P4 on = M1 rev P2 on / P3 off / P4 off = M1 and M2 fwd P2 off / P3 on / P4 off = M1 and M2 rev

I'll admit that H-bridges are not my forte, especially when you go throwing the middle connection in, so I may be completely off about that.

When I connect the motors back up, though, so long as the limit switch (P3) says that the doors are open, M2 doesn't spin and M1 spins (and the lights and sound work). When you press SW2, everything just stops. M2 doesn't reverse.

If P3 is open on both sides, SOMETIMES M2 will spin continuously, ignoring the limit switches.

If I measure M1, ohmwise, I am getting about 11.5Ω across M1 and 6.4Ω across M2.

I am wondering if the mixmatched resistance has anything to do with my issue? If not, can you see anything that I have missed or need to check? I am at my wits end and this is REALLY making me look bad!

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Hi everyone,

I'm an ECE undergraduate working on a research-oriented embedded systems project for the VLSID 2027 Design Contest, using the Renesas RA6E2 microcontroller.

The project explores detecting thermal sensor degradation while distinguishing it from legitimate changes in the physical process. The current concept uses two temperature sensors, physical-consistency checks, and controlled disturbances to evaluate whether sensor readings can be trusted.

Before committing further time, I want critical technical feedback from people experienced in embedded systems, instrumentation, control engineering, or industrial research.

Specifically:

1. What existing methods, papers, or patents already address this problem?

2. Is there a defensible research gap here, or would this mostly reproduce established sensor-fault diagnosis techniques?

3. What experiments and quantitative baselines would you expect to see before considering the contribution meaningful?

4. What are the biggest technical weaknesses in this experimental setup, particularly regarding two sensors, shared faults, and distinguishing sensor degradation from real process changes?

I'm looking for honest criticism rather than encouragement. If the core idea is insufficiently novel, I'd rather discover that now than after building the complete prototype.

Thank you!

Beginner here. Asked Grokbot to teach me a basic USB 5V to 3.3V power tree (AMS1117-3.3).

Looking at the pic — is VOUT shorted to GND? Or am I reading it wrong?

I’m working on a senior design project using an ESP32 Feather V2 and an Adafruit TLV320DAC3100 audio DAC for Bluetooth audio playback.

I keep running into an issue where the DAC appears to pull the I2C SDA line LOW whenever I start I2S. When I stop I2S and reinitialize I2C, everything works again. The SDA line only stops working when I2S is started.

What’s even stranger is that I’ve tried unsoldering and resoldering connections, moving wires to different GPIO pins, and even replacing the DAC board entirely. All of these fixes work initially, even through several power cycles. However, when I leave everything overnight and come back the next day, the exact same problem returns.

I’m genuinely at a loss as to what’s causing this. Has anyone experienced something similar or have any idea how to fix this?

I’m building a system using an ESP32, a relay module and a 5V solenoid.
The setup was previously working correctly, but now the solenoid doesn’t activate at all.
My setup:
ESP32 development board powered through USB.
Relay module with S (signal), V (power) and G (ground) connections.
5V solenoid connected through the relay.
Separate DC power supply for the solenoid.
Breadboard and jumper wires.
A web application built using Replit that sends activation commands to the ESP32.
The problem:
The solenoid doesn’t move.
The relay doesn’t make any clicking sound.
I’ve compared the wiring with photos of the previously working setup.
The wires appear to be connected securely.
I may have deleted the original Arduino source code, although I haven’t confirmed whether the firmware on the ESP32 was overwritten.
I haven’t measured the voltage or tested the relay independently yet.
What I need help with:
Can someone identify any obvious wiring mistakes from my photos?
I’m particularly interested in whether the relay is receiving power correctly, whether the ESP32 connections are correct, and what would cause the relay to stop clicking.
I’d appreciate specific troubleshooting steps to identify the actual fault rather than replacing components unnecessarily.
I’ve attached photos of the current wiring and the previously working setup.

looks like a resistor but the band colours (silver, grey, brown, gold) dont really match up with how resistor band colours are supposed to be ordered im pretty sure. this is on an applevision 1710 crt and is on the deflector board. saw sparks fly out the bottom while it was on and found that this component was charred on the bottom. i also recapped this board recently, so that might be related. am i stupid and reading the colours wrong? please help!

I bought an ESP32 with pre-soldered header pins, planning to connect everything using female jumper wires. Unfortunately, the space between the header pins and the battery below is pretty tight. I can technically fit the female connectors and get everything in place, but the wires have to bend pretty severely, and I'm worried they'll eventually break or lose connection. I cant use longer standoffs because its sized to a hole in the box for a usb-c.

I'm considering a couple options:

I could remove the header pins entirely by cutting off the plastic housing and desoldering each pin individually, then soldering wires directly to the board. However, I'm concerned about putting too much heat on the board and damaging it.

I could also solder wires directly onto the top of the existing header pins. This seems like the easiest solution, but the pins are pretty close together, so I'm worried about accidentally bridging two pins together.

Maybe just removing the pins that i need to use is best. im only connecting to GND, 3V, EN and a data pin.

Has anyone dealt with anything similar or has a recommendation?

Appreciate any advice!