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 circuit was found in a 1960s General Electric unijunction transistor manual. The circuit can...
In the figure we have the configuration of a variable voltage regulator with two transistors and a...
This circuit was found in Raytheon's 1967 documentation. The circuit uses an operating of the era,...