This circuit was obtained in a 1970 EEE and applies to almost any operational amplifier. The supply voltage depends on the operational amplifiers used.
Found in a 90s Popular Electronics, this circuit checks if a remote-control transmitter is...
This circuit for a decorative robot was found in the April 1988 Radio Electronics magazine. The...
This siren circuit was found in a Popular Electronics from March/April 1969. We can easily...