How to rig a capacitive touch to a usb keyboard (or gamepad)?
I need to make a touch sensitive (capacitive) button that triggers a key. I got a capacitive demo board from qprox that should be fine...I touch it and I can hook it up to an LED that gets lit. But if I try to put the wires from a button on a gamepad to the out of the demo board, the button is constantly in the "Down" state. I think I remember reading somewhere about a polarity reverser or something so that it reverses the On and Off state, but not sure what I need.
Also, the demo board is powered via a small watch battery which is perhaps conflicting with the power from the USB? I'm not quite sure the best way to do this. I think I can power the demo board using the USB power rather than the battery.
I also would like some advice on creating the Capacitor to a 3" button surface are that goes through 1/4" glass. I've got a resistor that upped the Qs so that it works through glass, but not sure how to make it fit to a desired "button" shape.