Touch the sensor of the alarm with your finger and it starts beeping, goes on for some time and then stops. Touching it again, and it goes again! This little and flexible circuit consists of a touch ...

Here are two circuits from Discover Circuits - a site created by David Johnson, P.E. I urge you to visit his site and check out his library! The italicized text has been reproduced from his site.

General purpose circuit of the simple pressure sensor alarm is built around a couple of readily available cheap components. Working of this circuit is straight forward and self-explanatory. When the ...