troeger@sequoia.tti.com (Jeff Troeger) (12/27/90)
I have a friend that is doing some astrophotography as a hobby, and he has a question that I can't answer. Any help or pointers would be appreciated. His question follows. E-Mail responses would be great, but I'll also monitor the groups I posted this to in case e-mail is a problem. ----------------------------------------------------------------------------- I've been doing some astrophotography and I learned some interesting things about camera batteries and how they don't work in freezing weather. Anyway, I'm thinking of re-working my clock drive, as the current stepper motors aren't as smooth as they could be. The tracking error fuzzes up my pictures. Can you recommend any application notes in the data books or text books on writing device drivers for stepper motors (pulse duration, waveforms, etc.)? I know the manufacturer's data books are full of them, but I can't remember where. The current circuit has no current regulation, no torque adjustment, no electronic clutch, and no electronic dampening. It just rattles along. Literally. I know how to do the analog circuitry, how to design the ring counters, and how to get the bits in the ports to switch the transistors. I just don't remember what the wave forms are s'posed to look like, and how often they change.
jfbn@cbnewsl.att.com (james.f.burnell) (12/29/90)
In article <22158@ttidca.TTI.COM>, troeger@sequoia.tti.com (Jeff Troeger) writes: > fuzzes up my pictures. Can you recommend any application notes in > the data books or text books on writing device drivers for stepper > motors (pulse duration, waveforms, etc.)? I know the manufacturer's > data books are full of them, but I can't remember where. > > I know how to do the analog circuitry, how to design the ring counters, > and how to get the bits in the ports to switch the transistors. I > just don't remember what the wave forms are s'posed to look like, > and how often they change. Motorola makes a really nice stepper motor driver chip, the MC3479. The Linear and Interface data book shows the stepper waveforms. I was given a crate of about 30 really nice stepper motors a couple of years ago, and recently I started playing with them with the intent of designing a 2-axis stepper motor drive for a telescope. I would be interested in hearing what advice people offer regarding a stepper drive design. Would anybody who has any thoughts please post your replies. Thanks Jim Burnell AT&T Bell Labs