This circuit was obtained in a 1975 documentation. The maximum frequency depends on the diodes and the FET. Type 1N34 diodes and a FET BF245 can be used for frequencies up to 100 MHz.
We found this circuit in an internet documentation. The circuit uses a 1 mA instrument, and the...
This circuit can be used to measure the frequency of a low frequency square signal. The signal can be...
This circuit is from 1985 documentation. The integrated circuit used is not very common today, but...