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.
This high Q “rejector” or notch filter rejects signals whose frequencies are in the range...
This circuit was found in documentation from the 90's, having an LC compensation network. The...
This two-transistor circuit was found in the January 1994 issue of Electronics Now magazine....