I tried to use the cap sense setup with some LED strips in aluminum channels I have installed under the kitchen cabinets, and it just didn't work. After digging around I found another fellow with similar problems, but no solutions:
Is there any other sort of touch sensing technology that might work for this sort of thing?
Previously I used the channel by itself as a touch sensor to drive some little halogen puck lights, and there was an analog circuit that did the sensing via an IC that was purpose built for that sort of thing. It was only about 80% reliable though, so my wife complained a lot.
Maybe I could just lay some foil tape out under the counter and use that as the sensor instead of the aluminum?
Thanks for jumping in with some help Larry - I need all that I can get on this one!
I should have been more clear in my first post, in that I do have the CapSense library working on the Arduino and was using it to run a relay module perfectly, using a big piece of foil tape as a sensor.
But when I hook the same circuit up to the aluminum channel with the LEDs in it, it won't work. I've tried all kinds of different resistances, no help there.
In the link I posted they cited three reasons that it won't work:
The LED strip adds significant capacitance to ground,
The PWM drive adds a bunch of noise (although in my case I'm using a wall wort, which wouldn't be PWM from what I understand)
A long sensing wire from the sensor to the circuit will act as an antenna to pick up noise from the LED strip
The aluminium channel will act as the other plate of the sensor, making it quite insensitive to hand touches.
It may help to drill holes into the channel, filled by the isolated sensor material, but then you can use resistive sensing as well (finger contact between channel and isolated sensor plate).