[amsat-bb] Re: inquiry about homebrew az-el systems
8p6sm at anjo.com
Thu Feb 28 21:29:51 PST 2013
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
-- 73, de Gus 8P6SM
Barbados, the easternmost isle.
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