This circuit is from an American documentation from the 90's. The SCR can be of any type and the diodes must have current according to the controlled motor.
This high voltage stage has a behavior like to a 12AU7 tube according to the 1975 publication. The transistors...
In the figure we have the way to obtain a voltage of 18 V from a 6.3 V transformer with central...
This oscillator was found in a book on transistors from 1954. The transistor is from the time, and...