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 found this circuit in an English publication in 1982, but it can still be easily assembled by...
This circuit was obtained in a 1967 General Electric documentation. It alternately fires two xenon...
This is a traditional flasher configuration with two neon lamps. The frequency is given by the 100 nF...