Based on the CA3140 IC, this circuit was found in the June 1986 issue of Radio Electronics. Sensitivity adjustment is made using a trimpot in series with the sensor.
At dusk this circuit triggers a relay switching lamps. The circuit can be powered from 6 to 12 V...
This circuit uses a 455 kHz crystal or for close frequencies. We found it in documentation from...
The oscillator in the figure has its frequency determined by the crystal. The indicated value is...