Hi, I initially posted this question on another forum, but I wanted to get a second opinion. I think I have bugged them too much ;) I have an aluminium block the size of a house brick that will have the inside milled out to leave around 5mm-10mm wall thickness. I want to design a circuit that will sense when the block has been touched. I want the user to be able to put their hand anywhere on the block and have it picked up by the circuit. The brick will have a 12V input via a mains transformer. What kind of system would be most effective at allowing me to do this? The current suggestions I have so far is: IC555 based "hum" based system, picking up the body's mains hum
A high frequency capacitor charge and discharge circuit - sensing the body's capacitance Please can I have your input on this, as I find it extremely confusing.