Measure My Turntable Speed

Given the relatively slow speed of a turntable, it may be difficult / expensive to find a tach that measures with enough resolution to give accurate readings. An alternative approach is to either buy or build a counter and measure the number of revolutions over a fixed, measured time - there are as many ways to do this as you can think of. Perusal of catalogs from companies like allied electronics will likely lead to an optical counter. If you can let the unit run for a measured extended time you will end up with an accurate average of the speed of the turntable. While this is a different measurement than the instantaneous result from a tach reading it is not necessarily a less informative result. Multiple tach readings and average readings would tell you more about the speed and stability of the unit. My guess is a little research will yield an inexpensive counter or the components to build one.