We found this circuit in the May 1990 issue of Radio Electronics magazine. The circuit is powered by the relay used and uses both normally open and normally closed sensors.
To use the instrument for AC measurement, the tips are A and B. For CC use tips A or B for...
The interesting circuit shown in the figure, can have its gain digitally controlled and present two...
This simple MW radio was found in a 1975 publication, but it can be mounted with BC548...