This 4-tube amplifier with 6W of output was found in an American manual from 1947. The sound quality is excellent.
The four gates of a 40111 IC are used in thes two-out circuit. The output chages their state in a...
This circuit was found in a 1980 publication. It uses only 3 easily obtainable transistors. It is a...
This circuit operates at a voltage of 1.3 V from a single mercury cell. We found in an old...