This circuit activates a relay after a time given by C1 and R1. The circuit is from a Radio Electronics from December 1974. The relay voltage is the same as that used in the power supply.
This circuit transmits beeps to receivers tuned in a wide range of frequencies placed nearby. The...
After starting, this circuit turns off the relay in a time that depends on the 4020 pulse-count. This...
This simple circuit can use general purpose transistors and SCRs like the TIC106. The warning...