This circuit was found ina 90s Popular Electronics. It is intended for switching analog video signals, indicated components that are still common today.
This circuit locks when the sensors are opened. The relay can be 6 or 12 V depending on the power...
Found on an 80's Elektor, this circuit uses common components, being the diode a general purpose...
This circuit can either directly supply a piezoelectric transducer (BZ) or a stage with a...