motor spool up time?

[KA4HJH]

>If I take an electric motor and run it at 440 rpm, how
>long on average would it take to get it to ramp up to
>880 rpm or down to say, 200 rpm?

Depends on the angular momentum of the entire mechanism.

>is there a reliable
>way to conrol this?

This is a fundamental problem in automation/robotics. Everything has 
some momentum which makes stopping on a dime (or whatever) with 
minimal over/undershooting impossible without some fancy 
software--unless you've got plenty of time to wait.

I once saw a project where the height of a ping pong ball inside a 
clear plastic tube was controlled by varying the speed of the fan at 
the bottom (distance was measured ultrasonically). The approach that 
ultimately worked the best was fuzzy logic. It worked surprisingly 
well.

Terry Bowman, KA4HJH
"The Mac Doctor"

ICQ: 45652354