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.

Timer 4049 (CB15094E)
This simple timer uses one of the six inverter ports on a CMOS integrated circuit. Rx and Cx...
Doorbell Tone Generator (CB18473E)
This circuit can be used as a residential doorbell. We found it in an English publication from...
Strobe 7400 (CB22418E)
In the old original version of this circuit from 1989, the LED is common (we recommend 330-ohm...