Published in an old Popular Electronics, this circuit makes use of components that are still current. The circuit must be powered with 9 V and eventually adapted to function as a shield.
Found in Electronics Now from the 1980s, this amplifier can also be seen in commercial amplifiers...
Found in a Popular Electronics from the 90s, this circuit uses a double 555 to emit beeps when the...
This circuit was found in the January 1992 issue of Radio Electronics magazine. The capacitor...