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.
This circuit can be used as a noise canceller for communication receivers or even common ones. The...
We found this circuit in an old American publication from the 1980s. Transistors can be...
This circuit is part of a synthesizer that was published in parts in several issues of Radio...