This approach alarm circuit was found in the September 1970 Radio Electronics issue. The 1 mH coil is wound on a ferrite rod. The relay is 12 V sensitive.
This simple MW radio was found in a 1975 publication, but it can be mounted with BC548...
This circuit is basically the same as the previous configuration (CB15616E) with a power stage with...
This experimental receiver works with alternative sources of energy or a single cell of any type....