Without regulation, this basic circuit has the output current, and voltage determined by the transformer. The input can be 110 V and 220 V if the transformer used is of the indicated type.
Found in a 90’s Popular Electronics, this circuit uses a component that can be difficult to obtain...
This VCO makes use of components from the 1980s. The circuit can be implemented with modern...
This circuit is intended to measure the Idss current of a junction FET under test. The limiting...