BartC wrote:
"The Natural Philosopher" wrote in message
...

andrew wrote:
I'm looking for the simplest monostable to provide a short pulse to


simplest is a resistor a capacitor and a pair of CMOS gates.

How about just a large capacitor? Normally connected to a power supply,
pressing the button (a changeover switch) connects one end to a relay
instead (the other end is common). Value and relay (and perhaps series
resistor) chosen to provide a long enough pulse.

This doesn't stop someone pressing repeatedly, but neither does a
monostable, unless you have a second monostable that stops you operating
the switch again for a longer period.

I think the condition to stop is jamming the button down.

You are right that a capacitor with a leaky resistor across it that is
connected in series with a relay wont hold the relay in for ever. If te
resistor is relatively large you will have to wait a fair time before it
works again, too.