We found this circuit in the July 1992 issue of Radio Electronics magazine. An optical system produces the light beam that, when interrupted, triggers the alarm. The sensitivity is adjusted by R4.
This simple circuit for switching RF signals was found in an RF Design from the 90s. The circuit...
I found this circuit in a Popular Electronics from 1992. The circuit can be easily implemented with BC549...
This circuit was found in a 90s EDN. Its purpose is to increase the efficiency of operational...