The frequency of this circuit can be varied from zero. The circuit uses the CMOS 4046 and was found in the November 1984 issue of Radio Electronics magazine. The base frequency is given by C1.
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....