We found this circuit in documentation from the 1980s. It is an input stage for a digital frequency meter. The circuit can operate with signals up to a few tens of megahertz.
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...