This is a simple circuit for an electronic switch – I’d designed this for an external footswitch module but also with a duplicate button panel mounted. There are enough gates spare to easily make a dual version.
Output – 0v to +V Gate (switchable Mom or Tog), plus trigger signal (c. 1ms pulse) each time the button is switched.
The input should be a momentary (normally open) switch to ground.
Source : http://www.bugbrand.co.uk/pages/electronics.htm