Weird Science

[Paul Bruening]

I was doing a little math on my new (read as: ancient, raggedy-a**) 24V DC motor that I snagged off of Ebay for dirt. It's for my Mitchell, NC projector head. It runs at 1800 rpm and gears down to 24 rpm. I have to rheostat it down to 23.976 rpm. When I did the math- 1800 / 23.976, I came up with 75.075075075075075075075075075075 on my MS XP calculator.

 

This doesn't really mean anything deep or cosmic. It's just that you don't often hit such patterns in ordinary calculations. The thing is, how do I rotary encode the rpm's for an endless string dividend? I guess I could put the sensor on the output shaft and read the 23.976 rpm instead of the motor shaft for 75.075-to-freakin'-infinity rpm.

 

I guess, since it is 1800/24=75, it should be calculated as 23.976*75=1798.2 rpm at the motor shaft. I guess that's readable by even a hand held tachometer. How's my thinking on this?