Using the name of varactor this circuit was found in the Radio Electronics magazine of July 1982. Varicaps of any type can be used and the components selected according to the component.
This shield can be used both to interface TTL circuits and microcontrollers. The resistor in...
We found this circuit in a 1980s General Electric documentation. It appears from other sources in this...
Based on NXP 74HC logic, this circuit can be adapted for various uses. The circuit can also be...