With this circuit it is possible to use a frequency meter as a tachometer. The circuit was found in American documentation from the 90s. The phototransistor can be of any type.
This circuit couples 600-ohm signals to a line of the same impedance consisting of an amplifier stage....
This circuit is suggested by RCA and is based on a dedicated integrated circuit that is the...
The power supply shown has protection against short circuits and can eventually be mounted with...