----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]---- I don't know where the article you saw was but I can tell you how it is done. Under florescent or even better, a mercury vapor yard light, the prop will appear to stop at 1800 rpm. It does this because the light pulsates with the 60 hz power it runs on and if you multiply 60 pulses per second by 60 seconds to get pulses per minute you get 3600. Now if you could run the engine up at 3600 rpm the prop would appear to stand still with the same blade in the same position each time. At 1800 rpm, the prop is actually being strobed twice each revolution and so you are looking at alternating blades as the prop gets caught twice each revolution. Various other rpms combine mathematically with the 60 per sec light pulsation to freeze the prop at different positions in it's rotation I.E. at 900 rpm you should see 4 blades. BTW the accuracy of line frequency is generally regarded to be .01%. Dick in NM
> Some time back I ran across an article describing how to use a florescent > light at night to verify accuracy of tachometer. Does anyone recall where > that article can be located? Thanks for the help... --------------------------------- to unsubscribe send mailto:[EMAIL PROTECTED] ___________________________________________________________ T O P I C A The Email You Want. http://www.topica.com/t/16 Newsletters, Tips and Discussions on Your Favorite Topics
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