Last updated: 21 May 2003

Manual Autoguider Simulator for 909 APM

Sent:	Wednesday, May 30, 2001 9:32:33 (corrected 20 May 2003)
From:	rseymour@wolfenet.com (richard seymour)
IF you'd like to play with the CCD functions of a 909 APM,
but don't have an Autoguider, nor wish to (immediately) pay
for one, here's a substitute:

It's merely a set of buttons which feed the CCD port of the APM,
and provide finer guidance than the normal slew keys on the 
Autostar are capable of.

When you push any button, the Autostar's CCD programming applies
 about a 2/3rds sidereal adjustment in the direction of the button.

I mounted the 4 buttons in  a diamond pattern, like  the Slew keys,
 and, as a personal preference, i ran the wires out the -top- 
 (north/up) end of the box.  I usually notch the edge of the box,
 rather than drill a hole through it, for the wires, since that 
 allows complete removal of the cover without the box still being
  stuck on the wires. (it also prevents -forgetting- to thread the
  wires through the hole during construction)(don't ask).

Parts List:   (RadioShack part numbers)
  4 Normally-Open push buttons  (275-1547  four for $2.99)
  1 6-pin plusg (279-421 for package of ten  $3.99)
     *or* buy a 6-pin cable (279-422  $7.99) and cut it in half.
        Which saves buying/borrowing the tool required for the plug
  1 box, similar to (RSU 11907698) suitable for holding the buttons.
If you don't take the "chop-cable-in-half" method, you'll need wire
 that'll fit in the connector.  (278-874  $19.99 for 100 feet (30m))

www.digikey.com is another parts source, or any electronics hobby store.

  +----- -------------->  6    Left (CCW)
  |    _v_
  +----- -------------->  5    Up
  |    _v_
  +----- -------------->  4    Down 
  |    _v_
  +----- -------------->  3    Right (CW)
  +-------------------->  2    ground

Looking into the *hole* on the 909APM, the pinnage is:
 (this would also be looking into the end you'd slide the wires into
  in the plug)
               | 1 2 3 4 5 6 | 
               +----+   +----+

1  "NC contact" (not used)(an LX200gps has +12v here)
2 - Ground
3 - Right (CW)
4 - Down
5 - Up
6 - Left (CCW)

 All signals are pulled low (to ground) to assert.

If you intend to make the wire longer than may 6 feet (2 m), you
may need a 4.5 volt battery and "pull-up resistors" on each 
signal lead to guarantee proper operation.  
I just recommend a shorter than 3 foot (1 meter) cord.

happy tracking

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Copyright ©1999-2001, 2003 Michael L. Weasner / etx@me.com
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