Hi all, I've searched the forums and the web for this info without any definitive answer. I am constructing a basic 555 monostable circuit that when powered gives an output to a relay for 2 seconds, then go off and stay off until power is removed and then re-applied. I want the circuit to trigger automatically (ie when power is applied) and as such I don't want to have to physically push a switch to trigger the circuit. Is there a simple way of doing this ? I realise that a pullup resistor is to be used on Pin 2, and to trigger it Pin 2 must briefly go low. Can a simple capacitor between Pin 2 and ground be used ? If so can anyone attach a simple schematic to assist me. Many thanks in advance, Paul

 

Here you go. Change R1 to 18k for 1.98 seconds (give or take for component tolerances.)

 

Many thanks. Perfect response, and it works a treat !!!