This circuit for frequencies of 20 to 2 kHz was obtained in English documentation from 1966. The transistor can be any general purpose and powered by batteries.
This circuit was obtained from Popular Electronics from March 1967. The transistor used is from...
The purpose of this circuit is to control the high and low light of a car, detecting when a...
This circuit triggers three incandescent light bulbs following the audio signal applied to its...