This circuit was found in a 90s Popular Electronics. It uses an LS3404 melody chip that has several recorded melodies and that is uncommon nowadays.
The relay of this circuit closes when the position set in P2 is reached by the sensor...
In this circuit the output voltage is given by xx. The L series circuits are for a maximum current of...
This circuit consists of an electrostatic sensor that can check if a cable is energized by simply...