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.
The battery charger suggested in the figure has its current limited by resistor R1. This component may...
This interesting 80's EDN circuit divides the input pulse frequency by a number given by n...
This circuit was found in a 1969 CQ magazine. It is intended for coupling telephones to radio...