Xref: utzoo sci.astro:11026 comp.sys.ibm.pc.hardware:4066
Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!think.com!linus!philabs!ttidca!troeger@sequoia.tti.com
From: troeger@sequoia.tti.com (Jeff Troeger)
Newsgroups: sci.astro,comp.sys.ibm.pc.hardware
Subject: Device Drivers for Astro Photography
Message-ID: <22158@ttidca.TTI.COM>
Date: 26 Dec 90 19:12:37 GMT
Sender: troeger@ttidca.TTI.COM
Distribution: na
Organization: Citicorp/TTI, Santa Monica
Lines: 25

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.