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 light meter can be mounted with equivalent integrated circuit. The power is made by a single...
This circuit uses NOR ports to generate signals up to 10 MHz, depending on the crystal. The supply...
We found this circuit in GE's 1977 transistors manual. Transistors admit equivalents according to the...