This circuit is for a siren that can be used with any of the above alarms and also other types. The circuit is from a Radio Electronics magazine from May 1975.
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...