Timer IC555 gives timing output pulse depends on triggering input applied at the terminal 2 (trigger input) and the duration of pulse depends on timing resistor and capacitor connected between terminal 7 and terminal 6.
Here we can convert IC555 into On / Off touch switch by removing timing capacitor this will avoid pulse duration limits at output.
Make touch metal piece for on / off control, and then place with trigger (pin2) input and Threshold (pin6). Placing Ground supply plate near to trigger pin makes On switch and placing Positive supply plate near to threshold pin makes Off switch.
|5.||Small metal piece
(for touch switch)