8.6  Autoguider Port 

IMPORTANT:

 There are two different versions of the Gemini Autoguider port 

hardware.  The versions can be distinguished by the type of connectors used for the motor 

cables.  The older Gemini version uses RJ 45 modular connectors, and the newer version 

uses 6 pin DIN connectors.  The primary difference between the versions is that the older 

version does not directly support autoguiders with TTL output, but the newer version 

does. 

Both versions of the Gemini Autoguider port are plug compatible with SBIG model ST 4 

and STV autoguiders.  

8.6.1  Connecting Autoguiders with TTL Outputs to Older Gemini 

Systems 

SBIG ST 237/ST 7/ST 8/ST 9/ST 10/ST 2000 series cameras with TTL outputs must be 

connected using the SBIG Relay Box, the optional Losmandy Optocoupler or equivalent 

when using an older version of Gemini. 

IMPORTANT NOTICE (Older Gemini only):

(1) Never connect TTL output stages to the hand controller or autoguider ports 

directly!  Severe damage may occur to the connected devices!  Use a Relay Box 

(as provided by SBIG) or the optional Losmandy Optocoupler unit instead.  By so 

doing, you get the additional advantage of providing electrical protection to these 

sensitive units. 

(2) The use of two separate power supplies without a coupler unit is strongly 

discouraged. To do so would connect the ground of one system to the supply 

voltage of the other system, causing the two grounds to be at different potentials.   

If the grounds of the two systems are then connected, severe damage is likely to 

occur. 

To connect cameras with TTL output, you will need the following: 

Gemini Users Manual 

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