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.

Digital Clock Alarm (CB24421E)
This 555-based circuit was found in the August 1976 issue of Radio Electronics magazine. The tone...
50W Inverter (CB21485E)
This circuit for a frequency of 40 kHz was found in an old Electronic Design. There were no...
6-Channel Sequential (CB16306E)
This system of sequential lights for shop windows, discotheques, stores, does not use integrated...