Double button microphone preamp (T352E)

This circuit was obtained in the 1937 RCA tube manual. Tubes are well known types that can even be obtained today. The power source is not given.

Regenerative receiver (CB20513E)
We found this receiver in old documentation. The transistor is made of germanium and the...
Differential Phase Inverter (CB967E)
This circuit was found in and old documentation of 1958 and uses complementary germanium...
Transistor AM Radio (CB1389E)
The coil of this receiver consists of 100 turns of wire 38 to 30 in a ferrite rod and the...