This circuit is from a 90s Radio Electronics. The resistors must be precision types and the transistor is a general-purpose type. The operational admits equivalent.
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...