If you’re into anything even vaguely mechanical on the broad hacking spectrum, you’ve come into contact with things that spin. Sometimes, it’s important to know precisely how fast they are spinning! When you’ve got the need to know angular speed, you need a device to measure it. That device is a tachometer. And the most useful tachometer is the non-contact photo-tachometer.
The basic principle of operation of a photo-tachometer is quite simple. The device contains a light source – typically a laser, which can create a focused, coherent beam of light. This beam of light is capable of bouncing off …read more http://pje.fyi/Nh9M3v