This voltage-controlled oscillator was found in a 1965 Electronic Design. Transistors are from the time, and modern equivalents can be tested.
The accuracy of this 3-digit digital capacitor meter depends on the tolerance of the components used and...
This circuit was found in the March 1997 Electronics Now magazine. It uses a common analog...
This is a diagram of a 1958 commercial receiver. The circuit was found in documentation at the...