this post was submitted on 27 Sep 2025
22 points (95.8% liked)

Ask Electronics

3869 readers
1 users here now

For questions about component-level electronic circuits, tools and equipment.

Rules

1: Be nice.

2: Be on-topic (eg: Electronic, not electrical).

3: No commercial stuff, buying, selling or valuations.

4: Be safe.


founded 2 years ago
MODERATORS
 

Can anyone help me identify this touch sensor module from a UK home bathroom light switch?

The IC is a QT113 charge transfer touch sensor, the only writing on the board is SAT 02.

I'd like to know enough about it to order replacements.

https://sopuli.xyz/pictrs/image/256ab3e9-90b3-4e38-affe-5c716332cbc3.webp

top 4 comments
sorted by: hot top controversial new old
[–] SW42@lemmy.world 1 points 2 days ago

It looks to me like the through-hole Plating is gone. Could be worth soldering a wire from the top pad, through the hole directly to the “grid” on the back side. Need to scratch a bit of solder mask off the grid fill first.

[–] Tolstoy@lemmy.world 4 points 3 weeks ago (1 children)

Easier way is to measure the voltage and get a new sensor... Afaik this qt113 runs at 5V

[–] Sadbutdru@sopuli.xyz 3 points 3 weeks ago (1 children)

I have the datasheet for the qt113, it indeed uses 2.5-5 V. But I don't know what wide is going on there.

Is that other black component a transistor, and that's what's doing the switching for the lights based on the sensor output? Or is this whole board sending a digital signal to something else that switches the lights?

[–] Tolstoy@lemmy.world 2 points 3 weeks ago

It's way out of my knowledge but it looks like the electrode for the touch is missing. It should be on the left corner where the "02" is printed on.

As you guessed the black thing is a transistor and should switch a led or probably a 5V relay. But please be careful since I'm guessing too xD