Crystal oscillator with the 42 tube (T436E)

In the figure we have a crystal oscillator with a 42 tube. The circuit is from a 1935 Radio Handbook. The high voltage source is not provided.

12,5W Amplifier with the741 (CB4023E)
This circuit is from the 1990 Motorola Data Databook. The circuit can be implemented with...
IR Receiver (CB875E)
This circuit can be used in alarms, data links or áudio links using IR radiation. The circuit is...
M204 Audio Preamplifier (CB849E)
This is a general purpose pramplifier launched in Brazil by Philips in the years 70. The BC549 is...