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 circuit activates a water pump when the sensors detect lack of humidity in a vessel, for...
This circuit was obtained from an Electronics World of 1969. General-purpose transistors can be...
This circuit was found in many record players with crystal phono pickups. The output power is 800...