What you have is a stepper with an optical track 0 sensor (gear drive, sounds
 like an old MiniScribe).

Mark

-----Original Message-----
From:   Neil Cherry [SMTP:ncherry@WORLDNET.ATT.NET]
Sent:   Friday, September 12, 1997 10:52 AM
To:     PICLIST@MITVMA.MIT.EDU
Subject:        Re: Servos questions

Cliff Rogers wrote:

> G'day, give this a go, it has links to more as well.
> http://werple.net.au/~tonymerc/steptheo/steptheo.htm
> Cliff Rogers   (Computer Technician)  email  cliffrogers@usa.net
> Absolute Computers Pty. Ltd. Cairns, Queensland, Australia.
>

Actually it's a very interesting page and I enjoyed it. But it's not about
servos it about steppers. BUt traversing the links gave me ideas for an
excite search and I've refound the Seattle Robotic goupand other useful
links. (I really have to back up my bookmarks).

What I have is a motor from a hard disk, the motor controlled the head
position via a gear drive. It has 4 wires which enter the motor and 4 wires
which go th a light emitter and detector (2 wires for each). What I'm trying
to discover is what wire do what for the motor. There has to be power (most
likely 12v) and ground. Then there are the other 2, I suspect this motor is a
servo and one is the signal in and the other signal out(???). Any ideas.