The time of this timer depends on C1. The circuit was found in the July 1994 Electronics Now magazine. The supply voltage depends on the relay and can go up to 12 V.
This simple circuit for switching RF signals was found in an RF Design from the 90s. The circuit...
I found this circuit in a Popular Electronics from 1992. The circuit can be easily implemented with BC549...
This circuit was found in a 90s EDN. Its purpose is to increase the efficiency of operational...