This circuit was obtained from an 80's Electronic Engineering. The circuit detects ice formation by triggering a warning light. The operational amplifier is of the time.
This circuit was obtained in a 90s documentation. However, it can be developed with modern...
This circuit uses a 455 kHz crystal or for close frequencies. We found it in documentation from...
This circuit turns off after a time that depends on C1. The circuit is from an Electronics Now...