Found in a Hands On Electronics from the 80's, this circuit activates a relay with alternating touches on the push-button. The relay depends on the supply voltage.
This circuit for vehicular use is from an 80's American publication. The circuit has a light...
You can change the output voltage of a fixed 3-terminal regulator using a zener diode. The voltage of...
This circuit was found on a Radio Elettronica (Italy) from April 1974. The circuit can still be...