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.
This circuit allows the use of the multimeter to measure the dwell meter, a feature used in the...
This circuit controls the temperature of heating elements, which may be lamps covered with...
This circuit can be powered by a voltage of only 2.5 V. Next to the diagram we have the formulas...