Touch Switch - Need help with Mosfet Specs

Hey Guys,

Noobie here ... Looking to build a touch switch for a project I am working on. I plan to use this schematic but I need help figuring out the correct MOSFET and Resistor to use: Assuming the resistor should be at least 20k+ ohms on MOSFET used so float doesn't take place. Any help would be GREATLY appreciated! Thanks!

Application:
* Running 4v or Running 6/7v
* Draw rate it up to 10A (roughly)
* On = Finger Pressing. Off = Finger not pressing

Schematic:
**broken link removed**

There area a couple of problems with that circuit. Firstly, it's quite easy for the MOSFET only turn on a bit, which will make it get hot. To deal with that you should have some sort of schmitt trigger. You could use a 74HC14.

Secondly, it's very easy to pick up electrical noise when there is an input impedance high enough to read the current through your finger. You will get large voltages at mains frequency any where near mains voltage wiring. That can easily lead to the load turning on and off at main frequency, even though there is no main connection. You can use an RC low pass filter to remove the mains signals.

Thirdly, it's easy for static electricity to zap the MOSFET's gate so some protection diodes need to be added.

Thanks for the reply guys! What about Resistance touch switches? Just using two transistors? Would something like that work better?

You could just use a couple of MOSFETs.