This circuit from a March 1971 Radio Electronics uses a transistor to stabilize the bias current of the output transistors. The circuit is médium power.
In the figure we have an improved method of varying the voltage of a 7812 regulator. The circuit is...
This 5-range current measurement circuit was found in the September 1989 issue of Radio...
Found in an old English publication this circuit uses a dual gate MOSFET. Coils not specified....