We found this circuit in an Electronics Now from the 1990s. The circuit crashes when light strikes the sensor. Instead of the alarm a relay can be used to drive higher power devices.
The circuit shown in the figure uses a programmable unijunction transistor (PUT) of the BRY39 type...
This circuit was sent by reader and collaborator Adriano Muniz Moura from Pirapora – MG. The...
This remote control for resistive loads using a triac appears elsewhere on this site. The circuit...