Great Polaris Question
Posted 23 August 2012 - 08:02 AM
Posted 23 August 2012 - 04:52 PM
Just picked up a used EQ mount which I think is an older GP. It has encoders and motoros and clutches, but no hand control. The cables look to be 7 pin DIN. Anyone know what kind of hand control will work with this, e.g. DMD-1 or 2 or 3? If so, would anyone have a spare hand control? Thanks much -- Michael
Picture of the mount, to verify it is in fact a GP, and with a close up of the motors, is needed. Greg N
Posted 23 August 2012 - 06:25 PM
Posted 23 August 2012 - 06:36 PM
Posted 23 August 2012 - 06:54 PM
Actually, I made a mistake. The DIN plugs have 7 pins around most of a circle, plus one pin in the middle. I'm trying to add a photo... Thanks -- Michael
Sounds like the MT-1 motor. SD-1 (single) or DD-1 (dual) controller.
Posted 23 August 2012 - 09:49 PM
I bought a single axis EQ3 single axis motor drive from China for about US$60. I removed the internal parts from the old electric motor and fitted the internal electrical parts from the EQ3 reusing the old gears. My friend modified the electronics of the EQ3 control box a bit for me to suit the gear ratio. It works but I have to remember the 6-volt electrical supply has now to be center pin positive.
Here is this SP eq. mount adapted to fit onto a old Gitzo photo tripod and with a vintage Astro 3” f/18 achromatic refractor. This set up is a favorite at star parties.
K W TONG
C8+CG5 GT, TSA102+HEQ5 PRO, MK67+Voyager, NexStar 6SE, C5+Mizar K, WO ZS80FD+Kenko NES, Megrez 72FD+Kenko KDS, Mini Borg 50, PST
Posted 24 August 2012 - 12:03 AM
You could even sell the two MT-1's that you have (which are worthless without a DD-1) for $50 a pop. That would take you most of the way to an Orion drive.
Or if you are handy with an Arduino (or similar) you can make your own stepper controller for the MT-1's and add fancy stuff like ST-4 autoguiding and Periodic Error Correction. Google "starjar MT-1" for the pinouts. The motors are Nippon Pulse 48 pulse per rev, unipolar steppers, with a 120:1 gearbox. Dead-simple to drive, if you're anywhere handy with electronics.
Posted 24 August 2012 - 09:32 AM
Posted 24 August 2012 - 05:15 PM
On my SP mount, I put a bridge rectifier inside the hand controller. Using the wrong power lead was too high a risk for me. Now it's 12V like everything else and there was space to put a reasonable sized capacitor in there too.
It works but I have to remember the 6-volt electrical supply has now to be center pin positive.