We found this circuit in an American documentation from 1947. The circuit uses 5 tubes and has a feature to keep the tube filaments preheated.
In the figure we show a widely used configuration for the CA3140. The power of this circuit can be...
The circuit shown was found in a Japanese publication from the 1960s. Transistors can be...
This circuit was obtained in a Popular Electronics of the 90s. The circuit can be assembled with...