Power requirements

These are the measured currents that the equipment draws, mount without equipment mounted (bare mount). The 12V DC converter used, was a 3,7A AC/DC converter that originates from a Wii gaming console.

I measured the current required for the divers equipment I’m using:


Equipment or combination

Current in Ampere
Only stand-by LED’s from dew control and power distribution box0.03A
Switch on the EQ80.47A
Siderial rate on0.50A
Slew at rate 9 in RA2.05A
Slew at rate 9 in Declination2.00 A
Combined RA and Decl slew at rate 93.15A
Slew at rate 7 in RA1.7A
Slew at rate 7 in Declination1.7A
Slew at rate 3 in RA0.55A
Slew at rate 3 in Declination0.55A
EQ8 at siderial rate and dewcollar full charge of the C111.9A
Only Dewcollar C111.42A
Dew collar APO120mm only1.10A
Small dew collar for guiding scope 50mm0.52A
EQ8 siderial rate + dew collar APO2.04A
idem + slew in declination rate 93.44A

above + slew in RA rate 9 (as well as decl)4.6AConverter overloaded, halted
ASI184MM Pro cooler at 94%1.9A
above + EQ8 Siderial2.24A
above + slew in RA Decl rate 93.9AConverter overloaded, halted

Putting the QHY Polemaster beyond the pole

I have been working with the QHY Polemaster to do polar alignement on the EQ8. And it works great. But after alignement is done, the 350€ worth of equipment disappears back in its box.

Here is how I made it useful beyond the pole (click on the image to enlarge)

The Esprit 120mm with the ASI183MM at the focal plane, the 400mm telelens with the ASI290MM, and the QHY Polemaster mounted instead of the finder.

When finding an object, I usually use a red dot finder, or a classic 8×50 finder. However, when firing up Cartes du Ciel, and syncing on a first star to align telescope and CdC, these optical devices require you to step away from the laptop screen. And – because I’m not using a gamecontroller (wired or wireless) to move the telescope, I also need to step back to the laptop to press the arrows and make guestimate corrections (since at the laptop, I don’t see the target moving in the finderscope).

So I removed the finderscope and replaced it with the Polemaster. For polar alignement it does not matter where it is positioned on the scope, as long as it is able to see the pole, and as long as it rotates on RA that’s ok. Works great.

But now, since it is looking directly where the main scope is looking at, I can use the Polemaster as a finder. To do so, I don’t use Sharpcap or Firecapture (to many driver issues). I simply use the Polemaster software, but keep it at step 1 after connecting the camera. I set the gain and exposure to maximum. Yes, I do not have crosshairs, and no that doesnt matter. With any reasonably sized sensor at the 663mm F/5 focus of the Esprit, positioning the target more or less in the center is sufficient to make it appear on the main screen in Sequence Generator Pro or Sharpcap or equivalent. Then it’s only a matter of finetuning, and sync Cartes du Ciel.

The QHY5II is a Black-and white USB2 MicronMT9M001 cmos camera, with a resolution of 1.280 x 1.024 pixels (1,28Mp) with square pixels of 5,2µm. The chip measures 6,7 by 5.3 mm. The quantum efficiency is measured as 56%

Example of the view on Coma Berenice (click to enlarge)

The screenshot above gives an idea what the view looks like. This is Coma Berenice (next to Virgo) and it shows stars to about 8th magnitude.

In combination with the F 1.2 ; 25 mm CCTV lens this sensor gives an image of 921 x728 arc minutes or approximitely 15 x 12 degrees. The resolution is 42″ per pixel.

I’m happy with the solutions as there is no need to buy extra equipment, I put to use what I have and it works without hickhups (on a USB 3 hub); No need anymore to lie down on the ground or bend myself as a snake in awkward angles to look through the finder.

Positioning the view of the Polemaster is done with the two set screws of the “Witty” Alt/Az system I used to position the finderscope.

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