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 shield circuit in the SGS Integrated Circuits Manual of 1982. The circuit is...
This circuit with transistors and a crystal microphone appeared in Radio Electronics magazine in...
This circuit amplifies the signals in the UHF band starting at 470 MHz, reaching just over 900...