Measuring turntable speed

Optimize, in this life it helps to be realistic about things. Nobody I know is going to spend $50 large on a turntable and try to add mass to the platter.
Does a heavy platter reduce wow and flutter? Given the same motor probably but with a different more powerful motor maybe not. One thing I will guarantee is you will never be able to tell the difference. So all this is purely academic. In reality people do just fine with plain A/C synchronous motors and stepped pulleys. The only good reason to have adjustable speed is to match pitch which the vast majority of us do not need. 
I do have a SOTA cosmos with all the fixins and one of the nicest things about it is you can set it and forget about it. I'm not going to add mass to the platter and risk burning out the motor and I do not care about the wow and flutter spec because I can't hear it. Don not burn your brain out mental masturbating about less than trivial issues.  

Optimize, I know of no turntable were you can adjust wow and flutter. I know a bunch were you can adjust the speed. Thus a device measuring 3150 times a second is no more useful in adjusting speed than one measuring every revolution. It is revolutions per minute after all.

Got it. It is called the DT-2234+ digital tachometer. Comes in a little blue soft case with 3 10" strips of reflective tape and a 9 volt battery.
Accuracy is said to be +- 0.1 RPM. Works as advertised and sure beats messing around with strobe lights plus you can measure with the record playing.

Cousinbilly, you are absolutely right. You have to be able to measure the speed with the record playing which big_greg's device will do. I have the Road Runner on my SOTA so I can compare big_greg's device to that and use it to check the SME. Hard to go wrong for $15.00.
As an aside, is turntable speed all that important. I think not as important as speed variations like wow and flutter. The absolute speed could be off 1 or 2% and most of us myself included would not know. The only time I ever noticed it was when I was synchronizing the turntable with the computer to compare digital vs analog versions of the same record.  

big_greg, great find! for $16 does the same thing a Timeline does for $400. I ordered one and will report back.