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 for signals up to 30 MHz can improve your reception in the medium and short-wave...
This circuit can be used as a shield for transmitting the temperature of a sensor. The circuit is from...
This astable multivibrator follows the traditional configuration for use as a signal injector, found in...