This circuit was obtained in an Electronics Now from the 90s. The circuit uses operational amplifiers from the time and the indicator is of the Sonalert type with internal oscillator.
This circuit generates some very interesting tone forms having been found in an American...
Found in an 1868 Mullard documentation this circuit has a dynamic range of 10 Hz to 25,000 Hz....
This circuit that generates a special sound was found in a Popular Electronics from the 90s. The...