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.

Pulse Width Multiplier (CB6349E)
This circuit is intended to increase the width of a pulse. The circuit is TTL and can be used as a...
Sequential with triac (CB7200E)
This sequential circuit appears in other versions on this site. This is from American...
PWM speed control (CB7173E)
Suggested by Motorola documentation from the 1980s, this circuit can be implemented with...