Crystal oscillator with a 6A6 (T437E)

We found this circuit with the 6A6 double triode in a 1938 Radio Handbook. The power source is not provided.

2-transistor LC oscillator (CB22388E)
This circuit was found in English documentation from the 90's. Transistors are general purpose types....
Precision Rectifier (CB24972E)
This instrumentation circuit is from the June 1986 issue of Radio Electronics magazine. Equivalent...
Audio Remote Control (CB24138E)
This is an interesting idea that we found in the May 1971 issue of Radio Electronics magazine. It can...