Unlike the previous circuit, the output of this one goes high in the window voltage range. The circuit is from Radio Electronics from June 1986 and is based on the CA3140.
This commercial circuit is from a Japanese magazine from 1967. It uses germanium transistors, and...
This circuit can be used to drive relays, solenoids, motors and other loads according the...
This circuit is based on the small keychain that responded to the sound of a whistle and were...