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.

Sonic Switch (CB11000E)
This circuit is from a 1997 English magazine, but it is very current due to the components it...
AP7380 Regulators ULDO
July 2017 - Diodes Incorporated's ultra low voltage drop voltage (ULDO) AP7380 regulators can now...
Digital Control Oscillator (CB18246E)
This oscillator can be controlled by digital or binary signals from another digital circuit or...