We found this circuit in an article that describes several alarms that are in the sequence in our section. The article is from the Radio Electronics magazine of May 1971.
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....