A delay of a few seconds to a few tens of seconds can be achieved with this circuit found in a 1980 publication. The transistor can be the BC548 and the diode 1N4148. The delay is adjusted in the 50 k (47 k) potentiometer and larger capacitors can be used to increase the time. The circuit also works with 6 V reed relays, simply changing the supply voltage.

 


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