On 02/28/2013 11:24 PM, Lizeth Norman wrote:
A stepper still needs some sort of position feedback..
Steppers rotate a predictable amount with each step. To calibrate, the software only needs to count steps from one limit switch to the other. Then, by keeping track of step count (+/-), it will always know exactly how far round the turn it is. It can store last position in NV RAM or EEPROM, so as to avoid the need to recalibrate on every startup.
Unfortunately, I can't think of a common source for surplus steppers of useful size. And driving them is slightly more complicated than firing a relay to a DC motor.
OK, why do we have to use A multi-turn pot? Why not just an ordinary linear pot?
-- 73, de Gus 8P6SM Barbados, the easternmost isle.