RE: [APML] (OT?) got the STV, and questions about it & Losmandy

["k 50" <k010150@hotmail.com>]

The issue of current draw is certainly true and is a good
reason to not hook the STV (or your dew heaters) to the
Losmandy controller.  You also should be aware that the
Losmandy and STV use opposite polarity, but physically
similar power plugs!

The GM8 and G11 use virtually identical electronics boxes.
I believe a PROM is the only difference.  In both cases,
the "common" line to the hand controller is *not* connected
to ground (negative side of 12V input).  Consequently
connecting it to true ground via a typical CCD guider will
cause a current to flow, blowing something out (in one
case it was the 5V regulator on the Losmandy board).
However if the guider has isolated outputs as the ST4 and
STV do, then the connection between the two is avoided,
and there is no electrical problem.

Bottom line:

   - Make sure your STV power connection is the correct
     polarity.
   - Don't connect the STV power cable to the Losmandy
     electronics box.  Instead connect directly to your
     battery or 12V power supply via a separate power cable.
   - STV guider control lines can plug directly into the
     GM-8 or G11 because it has relay isolation.

If anyone knows why the Losmandy is designed this way, I'm
listening.  I haven't gone so far as to trace the circuitry
to figure out what is happening.




>I'm not an EE, but it is my understanding that the STV takes
>about 2 amps to operate.  There is a fused connection to the on-board 12v 
>supply from the losmandy.  If you draw the power through the controller, 
>you may blow fuses.
>Try a splitter from the battery with separate fuses, or separate 120v power 
>supplies.
>
>Regards,
>
>Paul Hunsberger
>http://www.paulandpeggy.com
>
>-----Original Message-----
>From: owner-astro-photo@seds.org [mailto:owner-astro-photo@seds.org]On
>Behalf Of dtlocke
>Sent: Monday, February 12, 2001 9:43 PM
>To: astro-photo@seds.org
>Subject: [APML] (OT?) got the STV, and questions about it & Losmandy
>
>
>All,
>
>Got my STV last week after a fairly short wait through Anacortes.  I was 
>able to get it running the first night despite zero guider/CCD experience.  
>The biggest
>problem was figuring out how to focus while dodging the clouds (with numb 
>hands).  Haven't tried it as a guider yet, and I haven't tried the efinder 
>thing
>as it is out of stock.
>
>I had a bit of panic when I found my hand controller didn't work.  I 
>realized that the splitter I bought for both the CCD input and the hand 
>controller
>input only had 4 wire; need 6.  Anybody got an extra six pin splitter???  
>Radio Shack didn't seem to have 'em either in stock or in their catalog.
>
>I'm getting conflicting info on this matter and I'd like comment from 
>anyone with first hand experience:  What's up with powering a GM8 & STV 
>from the
>same source?  One person told me he does it with no problem.  SBIG seems to 
>recommend their relay box be used, but I have an email into them with 
>specific
>questions.  Email to Scott hasn't been returned.
>
>The GM8 manual has the following:  "Can I plug my SBIG auto-guider into the 
>same power source as my drive system? Yes and no. The ST-4 and ST-5 can be
>plugged into the same power supply. The ST-6 and greater can NOT be. You 
>must have a
>different power source, they can NOT be tide together in anyway."
>
>Any EE's out there care to explain why this is an issue in the first place?
>;-)
>
>-Dick

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