Touch circuit help needed

[originator]

I am trying to find a circuit whereas you touch a piece of stainless steel and generate a 12 volt pulse that is sustained while the pad is being touched. I have circuits for one one touch and timed output, but I can't seem to find a circuit anywhere for what I described. Any help would be great. Thanks

 

[BrianG]

The harder part of this sort of application is deciding the circuit to interface to the stainless steel plate (e.g. doe it use "mains hum" pickup to trigger it, or change in d.c. leakage to ground using a VERY high input impedance amplifier).

If you say you have some similar circuits (which must provide the "front end") why can't you just omit the flip-flop stage in the push-on push-off circuit, or the timer in the timed output pulse circuit?

 

[originator]

I am using the typical 555 one shot circuits for other parts of the interface that don't require a "hold" feature for varying durations. I am not sure how to adapt the front end of that circuit to cause a stable output but I'll use that as a starting point. I am not aware of the other concepts you mentioned. Thanks for the ideas.

 

[itsmoked]

http://www.eepn.com/Locator/Products/ArticleID/31959/31959.html

http://www.touchsensor.com/faq.html

http://www.electronicsforu.com/EFYLinux/circuit/dec2003/CI-06-touch-dimmer.pdf

http://www.4qdtec.com/putpr.html

http://www.4qdtec.com/tchsw.html