| Joined: | Mon Apr 2nd, 2012 |
| Location: | South Lakeland, UK |
| Posts: | 4066 |
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My friend called after a few days and asked if I was interested in a motor which moved 15º every hour, the penny didn't drop but I'm always interested in anything mechanical so I agreed. Cutting long story short, I now have my own somewhat old, equatorial mount. The price? 50 used paving bricks. At first the mount wouldn't work, the motor drive lead was broken and the control unit wouldn't power up. I figured out the pinouts for the six core cable myself, little or no info on-line. The mount is a Vixen Optics Photo Guider, apparently good for a 15 Lb payload, provided it's counterbalanced. What I didn't realise at first was the motor is a stepper motor, I was expecting a synchronised DC motor regulated by a timer circuit. These devices sell for between £500 and £10,000, depending on size and power.
Eventually I discovered the reason why the controller wouldn't work, somebody had reversed the polarity of the voltage regulator inside the controller.
I now have it running beside me as I type. I started it at 10:00pm last night, I am interested what it will say at 10:00pm tonight, it has clock calibrations on the head which you use to help with tracking. It has a polar scope which has to be aligned with Polaris with an offset because as well as spinning, we are drifting in space compared with Polaris.
I need to create a red LED illuminator to illuminate the polar scope, the calibration markings are clearly visible in daylight but not in the dark. I am considering a fibre optic bonded with a small red LED in shrink sleeving, with a small button cell battery and switch, it's only needed when setting up the tripod at the beginning or after making adjustments to the setup.
I am hoping it will handle my 300mm f/2.8 lens on the D800. As soon as I get a clear sky I will try it out.
This was the battery pack:
This is the mount, with the Nikkor 300mm f/2.8 and D800 mounted.
I am investigating various forms of power supply, the controller will handle from about 6Volts to 30Volts but the higher the voltage the more heat it dissipates, so I am working on a maximum of 12 nominal. I do have ideas for using EN-EL4 D3 batteries which are nominal 10.8Volt, 2600mAh or perhaps some racing pack batteries.
It's been a very interesting few days.
I need to make a new 'wedge' mount to adjust the elevation, the one which was fitted wasn't fit for purpose, too small and seized up. I intend to craft one from solid aluminium bar, with a fine tune adjustment for Polaris alignment. I also need to create a counterbalance bar so I can slide a weight into the correct position to counter the weight of the camera and lens.
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Robert.