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.
We found this 4.5 MHz amplifier for video signals from old analog TVs in the June 1992 issue of...
This circuit was found in the 1990 Motorola Dataar Linear. We can mount it with more modern...
The oscillator shown in the figure can generate signals between 3 and 15 MHz approximately, depending...