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 found in an 80's Electronic Engineering. The circuit uses operatives of the time...
The selected circuit was obtained in a Texas Instruments opto-electronics manual. The transistors can be...
In short wave receivers or in the recovery of signals from scratched discs this circuit can be...