This simple optical alarm circuit was found in the 1991 Electronics Experimenter Handbook. The circuit uses a lamp as the emitter but can use LEDs.
This circuit was obtained in the publication 101 Electronics Projects of 1979. The circuit can be...
This control was obtained in an old publication from 1985 and uses a triac, which today can be of...
This is the traditional configuration of an unregulated bridge rectified power source. The circuit...