We found this circuit in an English publication from the 1980s. The circuit uses current components and can be tuned for frequencies between 300 and 1500 Hz.
When the sensor X1 is opened, the relay is energized. When waiting, the current drained is very...
This circuit can also use other series operational amplifiers such as MC33172, MC33174, MC35171,...
This circuit was originally designed to power the CB18698's MSX interface, but it is suitable for...