This simple audio and RF signal tracker was found in a Japanese publication in 1967. The transistors are made of germanium and the headphone is made of crystal.
Found in a 1970 EEE, this circuit can be applied to TTL ports. The supply is 5 V and the...
This circuit is from a 90s Popular Electronics. The integrated circuit is from that time. The...
This automation control circuit uses two relays to control 4 loads using just one switch. The...