A very simple and lowcost touch switch

Hello

Here is a simple touch switch, with only 3 components: a darlington transistor (or 2 transistors), a 4.7uF capacitor and a 22k resistor It work find with the sketch "Button".

So, with a PCF8574, an ULN2803, a resistor array and capacitors, you have a real lowcost I²C touch pad ;)

PS: Sorry for my english, I haven't practiced for 8 years..