We found this circuit in an English publication from the 60's. The transistors are of germanium of the time and the headphones must be high impedance magnetic.
The transistors in this 1978 circuit can be BC548 and 1N4148 diodes. The electrolytic capacitors can be...
This circuit was obtained in the 1994 National Linear Application Handbook. The circuit admits other...
This is the basic version of a gain 20 amplifier with the LM386 providing a few hundred...