This 80's Exar circuit has a carrier detector for frequencies up to 500 kHz. The circuit uses a company 567 which is still a common component.
Found in Mallory documentation from 1968 this circuit uses an integrated circuit from that time. The...
This electronic Morse key was found in a Popular Electronics from the 90's. The components are common,...
Found on an 80's Radio Electronics, this two-section circuit is designed to pass the frequency...