can st-i autoguider port be used directly with an old AP Quartz controller

Discussion in 'Specialty Cameras SG-4, AllSky, ST-I' started by Rick, Mar 29, 2016.

  1. Rick

    Rick Standard User

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    had been using an old ST-4 with the e-m relays
    wanted a newer, more sensitive and finer pixel, guide camera so bought an st-I
    the HDA Quartz controller had a 9 pin DB input, which a cable can be crafted to mate to RJ11
    with proper pinout, is there a circuitry problem which would stop me from directly connecting?
    has anyone done this?
    I know there exists a relay box, but the sti does not provide power to RJ11 pin 6 as some cameras have the option to do, at least I do not see mention of it in the ops manual
    Rick
     
  2. Doug

    Doug Staff Member

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    The ST-I wouldn't have the power to run a relay box.

    I don't know the design of your controller, but if it doesn't have an RJ-11 input then it almost certainly needs a relay box.

    You could use an SBIG relay box but you would have to rig up power for it.
     
  3. Rick

    Rick Standard User

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    Oct 11, 2014
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    Doug;
    as I stated, I have run autoguiding on this mount using a venerable ST-4 where the relays basically acted as push buttons, where I assumed they closed circuits by allowing current to flow, either to power supply thru a pullup resistor, or to ground. In the Quartz controller, these are TTL level logic gates run on +5V

    the DB9 connector was just a Astro-Physics choice, but used the same DB15 output from the ST4 controller, and was just another cable pinout mapping, vs the RJ11 terminated cable which I used on a Losmandy G11

    It seems, based on the ST-I specs, that the solid state switches on the guide port output RJ11, would perform the same function. 25V seems more than enough voltage tolerance, and the 25mA is about the max an open circuit TTL device can source.

    Hence I am asking for confirmation on these spec values, and if indeed the design is intended to be a substitute for the electro-mechanical relays such as used in the ST-4?
    Rick
     
  4. Doug

    Doug Staff Member

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    I obviously can't guarantee the compatibility of your controller, as I don't have full technical details.

    I can tell you that the autoguider output driver for the ST-I is an optoisolator, CEL part number PS2801-4.
     

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