We found this circuit in a Popular Electronics from the 80s. This circuit eventually doesn't work with modern, higher speed controls. Experiments must be done.
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...