The first and most important question to ask is “Do you Only Want to Check RPM?” If the answer is yes, then maybe you should buy an optical tachometer.
If your user cannot shutdown the rotating equipment to attach a piece of reflective tape for the tachometer, then they must use a stroboscope to read RPM while the device is running.
Many times users want to "stop or freeze” the motion for diagnostic inspection with a stroboscope to view what is happening at that particular RPM or Flashes Per Minute (FPM).
Checking RPM of a rotating device with a stroboscope is more complicated and takes practice as compared to using an optical tachometer. A stroboscope will give the user more than one stop-motion RPM readings and these are called harmonics. Harmonics are multiple single, double, triple, etc. stopped-motion images at various RPM or FPM settings.
Does the application require a Contact Tachometer to read in RPM or linear speeds such as a conveyor belt or elevator speed in inches per minute, feet per minute or meters per minute?
