This wired intercom circuit was found in an English publication from the 80's. The integrated circuit can be replaced by an equivalent, just like the transistor which is a general-purpose type.
This basic oscillator with tunnel diode generates a 100 kHz signal with 1 uW output power. The...
This windshield wiper interval switch was found in the April 1990 issue of Radio Electronics...
This circuit is from General Electric from the 80s, using a relay with high current contacts (20...