This FM advertising suppressor (SCA) decoder circuit was suggested by Signetics in a 1980s documentation. The circuitry decodes the 67 kHz signal. The integrated circuit used is of the time.
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...