This circuit was found in a Motorola documentation from the 70s. The integrated circuit is from the time, an operational power amplifier according to the controlled motor.
This circuit with unijunction transistors was found in a documentation from the 80's. The trigger...
In this circuit of an old American documentation, the input impedance is the same as the output...
In the figure we have the way to obtain a voltage of 18 V from a 6.3 V transformer with central...