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 was found in the December 1977 issue of Radio Electronics magazine. The circuit uses...
We obtained this circuit from an old Argentine magazine. The circuit originally uses germanium...
The 78XX series voltage regulator integrated circuits do not support an input voltage greater than...