This is a physical strobe disc and protractor tool that will be mailed to you.
Speeds visible under 50Hz lighting:
33.33 rpm
45.45 rpm
78 rpm
Speeds visible under 60Hz (USA) lighting:
50Hz vs. 60Hz power, location details.
33.33 rpm
45.00 rpm
78 rpm
Mount on center spindle.
Start player.
Pattern appears motionless *if* player reaches desired speed under 50 or 60hz standard lighting. Probably won't work very well under CFL lighting but please let us know if it does. We have a customer report that Christmas LED lights work very well. (presumably the white variety)
