i need to make a simple electronic circuit to do the following but stuck.
i have a momentary switch that is normally closed and when opened de-energises a lock that unlocks a door.
what i want to do i have a circuit that when you press the switch to open its contacts to take power away from the lock to allow the door top open, when you release the switch i want the lock to remain de-energised for around 10 seconds to give people time to open the door when they release the switch when they have got one hand.
how to do this??
Monostable multivibrator (one-shot) ICs can debounce and
extend a mechanical switch event. You'd likely find app notes
for this. Like use a 555 timer IC in that mode and let its fairly
fat output sink, drive a small relay (w/ catch-diode if you want
to preserve contact life).