This circuit for old analog telephones is from period documentation. It controls a relay that can be used to turn the extension on and off.
Found in Linear Technology documentation from the 90s, this circuit uses components from that...
This 500 MHz oscillator has an output power of 1 W when powered by a 20 V source. The circuit was...
This circuit is from 1987 when there were only analog TVs and stereo sound was still a novelty for this...