I posted this circuit to the ‘net a long time ago, and it hung around on various forums or websites for a long time. I had it in watsonseblog but that’s no longer available. So here it is, along with a few more touch switch type circuits.
It’s a flip-flop that it toggled by the absence or presence of charge on C1 when the P.B. pushbutton switch is pressed. The C1 is slowly charged or discharged through R2 so you can press the button quickly and C1 will not yet be charged or dischaged and the circuit will not toggle.
The Q3 PNP transistor can deliver a hundred or so milliamps, enough to drive a relay. If you use a relay, make sure to put a 1N4002 rectifier across the coil, with the cathode or banded end to the positive side. If you want more current, then a power transistor could be added to greatly increase the current.
Back to experimenting…