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 car alarm was obtained in a Signetics documentation from the 1980s. The circuit uses the 555...
The frequency of this circuit can be varied from zero. The circuit uses the CMOS 4046 and was...
This simple binary counter triggers two LEDs according to the number of pulses applied to the...