This interesting circuit in which the LED display is circular imitating a common clock appeared in the Radio Electronics magazine of May 1977. The power supply is included.
This circuit includes a high voltage inverter to power a Geiger tube. We found it in an American...
This circuit generates a signal up to a few megahertz depending only on the LC resonant circuit...
With the CMOS circuit shown, rectangular signals up to a few megahertz can have their frequency divided...