This 1970 Electronic Design circuit uses a varactor or varicap. The circuit divides the frequency of a 150 MHz signal by 2. Similar versions appear on this site.
We find this circuit in the 80s used integrated circuit manual itself. The integrated circuit is not...
Found in a 1968 Electronic Design, this circuit makes use of an unusual ultrasonic delay line...
This setting appears multiple times on the site from different sources. This is from a 2000 manual...