This high sensitivity circuit was found in the July 1992 Radio Electronics magazine. The circuit drives a buzzer, but a relay can be used to activate an external load.
We show an oscillator that produces rectangular TTL signals based on inverters. Inverters can also be...
I got this circuit from a magazine in 1967. The magazine no longer exists, but the circuit that...
This egg timer has been found in an English magazine that no longer exists in 1982. The...