On 9/24/2016 8:19 PM, drlegendre . wrote: > Can't you use a common $25.00 optical (laser) tachometer? Like this: <http://www.ebay.com/itm/322094942979> > Do the simple laser tachs lack sufficient accuracy or resolution for > the job? No, they are plenty accurate enough. -- Jeff-1.0 wa6fwi http://www.foxsmercantile.com