I was talking with another tech this morning about checking RPM. this brought up the subject of strobes. As we were discussing strobes it occurred to me someone had probably created an app with RPM already. Shazaaam!!! Here's a app that will allow you to test RPM on fans. You can also test motor rpm, if, you place a mark on the shaft. https://itunes.apple.com/us/app/strobe-light-tachometer-to/id708094321?mt=8 To check fan speed just dial it in till the fan appears to be not moving at all. That'll give you your RPM. Same with a motor if you mark the shaft. When the mark appears to no longer be moving you've got the RPM. I'm not really sure if this is the correct use of this Blog thingy, but, bet I'll find out sure enough!! Yeeehaw!!! Huh... I hope I wasn't the last person on earth to figure this out!