This circuit is from an old Japanese publication of 1962. The circuit uses two batteries, one for the filaments of the tubes and the other one of high voltage for the plate circuits.
This circuit can be used as a shield for the control of stepper motors from microcontrollers. The...
This circuit was found in a 1960s Motorola documentation. Transistors are types of the time and...
In the figure we have two possible configurations for multivibrators with relay. The idea comes...