Found in an American publication from 1947, this 4-tube amplifier has excellent sound quality. Its source makes use of a transformer.
Using a sensor from the time, this circuit was found in the 1992 Radio Electronics Handbook...
This TTL oscillator uses a ceramic resonator as a frequency fixing element. The resonator is found...
The circuit below uses common JFET transistors, which can be the BF245 or MPF102 amplifying video...