QT100 Touch LED

[Shur23]

Hi guys,

I've got a 12V touch-activated LED light:

Pin 2 of U2 is GND, and 4 goes to the sensor contacts via a cap, so it looks like it's a QT100A:

It works a treat, however my problem is that when I hook it up, the LED stays off until it's touched, whereas I need it to be ON by default, so that when I flicked a physical switch it would come on, and then I could switch it off via touch. Any way I can achieve that with some reasonable mod?

Appreciate your help.

 

[Diver300]

You could use a transistor or a single inverter to invert the output state of the QT100A. Then the low level output of the QT100A, the state it defaults to, would make the light turn on.

You could use a 74AHC1G04 for the inverter. You would have to cut the track that goes from pin 1, the output, of the QT100A, and connect the output of the QT100A to the input of the 74AHC1G04. The output of the 74AHC1G04 would connect to whatever the QT100A used to connect to.

Power and ground of the 74AHC1G04 would connect to power and ground of the QT100A

 

[Shur23]

Brilliant, thanks mate, I've ordered the part.