I bought a sewing machine recently and it came with a very sensitive pedal. They sell this other pedal which makes it possible to sew very slowly. £60 felt like a ridiculous price for this piece of plastic, but I'm not an electrician (I know some basics). Can someone please help me understand what the difference here is? Is it possible that I could achieve the same result by a simple modification? All I can see is the VR2 resistor missing in the new one.

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!

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

Kds9 2h1?

I’m guessing it’s a sensor of some sort but I have no clue and Google won’t tell me.

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!

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!

I have a Mantra chanting box. The main COB IC is damaged. Where can I get these type of COB ICs in retail (particularly in Kolkata) ?

So I've been using TVS diodes in all of my projects without really understanding how they protect the circuit, so I decided to do a few simulations

I got the ESD generator model from an article I simulated it and it worked correctly, but when I tried to apply the generator to a circuit I'm working on it didn't do anything?

What's the right way to do this? how do you guys simulate ESD events with accordance to IEC 61000-4-2??

I’m not to good with how computers work so I took a computer/networking class and they let me take some stuff from broken computers (speakers, power supplies, batteries, that kinda stuff) and something that caught my eye is a lot of them had a BJT attached to the outside of the front of the grounded case and whenever I looked up why it was there all I got is what a transistor is.the transistor is a 2n3904, my theory is it’s like temperature regulation or some other version of using a component to do something it wasn’t made for.

Hey folks,

I’m looking to source a part (or potentially compatible) for the attached motor. It powers a thermostatic valve on a shower (Vado Identity). Whilst the motor 49YTD seems to be pretty common, this configuration I’m struggling to find.

Is there a specific place/source I should be looking for this? Will alternatives with different RPM/uF potentially be suitable? I’m willing to try most things at this point as it’ll be a multiple thousand pound bill if I can’t find a replacement for this.

Alternatively, on the off chance anyone finds this and has a IDE-145C-CPU, broken or working they’d part with, I’d love to hear from you!

TLDR: part broken, no spares from vendor, no alternatives, powers a remote shower control, will need to replace entire bathroom if no suitable part found as tiles also discontinued 🙃

Hi, I am an EE student and I am trying to make a closed loop bldc motor controller so that I can learn more about power electronics and pcb design.

I was trying to find a bldc motor with hall sensors but many motors online don’t have datasheets and don’t tell you if it is a sensored motor. So I was wondering if anybody has advice about a motor to choose, I’m also open to maybe using a motor with an encoder instead. I’d appreciate any advice.

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?

Hello, as i said in the title I can't seem to find a site where i could order a load cell from that is high precision, i need it to measure the difference between euro coins.

So yeah if anyone could recommend a site that would be nice, thanks.(I live in slovakia btw).

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’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.

​

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!

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 want to integrate an OV2640 into an STM32 project and saw that it requires a specific power on sequence. However in terms of powering down, I could only find the commands to power it down from software/MCU.

Do I need to power down the camera in a specific order, or can it handle unexpected power loss (disconnecting main battery) fine by itself?

Relatively new to Ansys, I want to run the Q3D extractor for a PCB. Ansys has been extremely pissing off, I can either import step files and get a 3d model, or ipc and get the materials but I can't do both at the same time. Can anyone explain the exact process in a Q3D extraction, and how I can get my PCB up there?

Even when I did figure something out it threw a lot of errors and intersecting components. The PCB is just a github download that I was using to learn the process before using my pcb.

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?

Hi, I making a fan system with a led strip as a indicator. I am using a Buck convertor to step from 12v to 5v with a max of 10A to connect to a Raspberry PI Pico. The LED Strip I have also takes 5v. Could I Crimp the two wires together to power both device at the same time.