This circuit is from a March 1978 Radio Electronics magazine article that showed how to build it. The circuit is TTL based and is powered. The components used can still be found.
This configuration was found in a 1976 publication. The outputs of the logic circuits are applied to...
With this circuit it is possible to measure frequencies up to about 500 kHz using a common...
The very high-input impedance of the CMOS gate allows this kind of device to be used as a...