New Pulsar Dome Design

[pmlogg]

There have been a number of postings previously about powered rotation systems for Pulsar domes.

For the 2.2 and 2.7m domes there was a Pulsar-supplied, dome-mounted,battery powered system. This, rather than a more conventional mains powered system attached to the dome walls, was a result of the way the dome rotated, using wall-mounted rollers riding on a rail attached to the non-rotating walls.

In June I asked Pulsar about the motor system as their website was showing a different version, which was mains powered. I couldn't understand how it could work with the dome I have, or the version that was still shown in the installation instuctions.

Today I looked again and there are new docoments in the download list for the installation of the dome and the motor rotation system. These make it clear that the design has changed quite significantly. The dome now sits on wheels attached to the non-rotating walls and a vertical surface is provided for a drive wheels to act on. How well it all works I don't know but it should make for much easier diy motorisation than the original design.

[dmahon]

I'm about to buy a dome (in the next week) so this is interesting news to me.

I was planning on copying one of the other member's setups to automate my dome. Can you take pictures of your dome and highlight the changes (so I can work out how I will need to adjust my plans if my new dome will be different to his)?

[dmahon]

Ah - I see the difference:

OLD

New

[pmlogg]

Essentially it means that if you don't want to spend nearly £900 for Pulsar's system you can make your own to apply rolling motion to that inside surface in a similar way, and even add your own computer control. The well-thought out systems for the domes like mine had to be dome mounted and therefore either run by battery or have a trailing cables. It also complicates computer control.

The old Pulsar dome design, barring ease of motorising, is good too but I've stuck to manual for the moment. If I attempt to motorise rotation I will probably go down the route taken by those other members as they seem to have cracked most of the problems.

[dmahon]

Old installation instructions:

http://www.pulsar-observatories.com/downloads/OBSERVATORY%20INSTALLATION.pdf

New installation instructions:

http://www.pulsar-observatories.com/downloads/OBSERVATORY%20INSTALLATION%20NEW.pdf

[Steve 1962]

That's interesting - I've just successfully motorised my "old" design by mounting the motor on the moving dome ... and would make a couple of observations / suggestions:

The new design clearly allows the drive motor to be mounted on the fixed wall rather than on the moving dome. My experience is that the fibreglass is fairly flexible, so I would suggest that the motor is fitted so that the drive wheel / cog of the motor bears on the dome directly in line with one of the "side thrust" wheels shown in the Pulsar instructions.

Also - if you want to slave the dome to your mount, you'll still need to monitor the azimuth of the dome - I use a magnetic sensor attached to the dome and a usb connected arduino which has a trailing lead - if this could be done wirelessly (or devise some form of wall mounted encoder), it would be possible to eliminate trailing leads altogether.

Looks like a good move by Pulsar.

HTH

Steve

[robin-m]

I would have thought that the majority of people who want to motorise their dome would want to go the distance and have it computer controlled. As with the previous incarnation this appears to fall short of that. If Pulsar offered a way to monitor azimuth and an ASCOM driver for the dome I could see many who don't want to go down the DIY route buying the system. As it is I don't see that it offers much over manually rotating the dome.

[dmahon]

They do. They sell a Shelyak controller, with ASCOM driver. This includes an absolute position sensor and a rotation encoder so Azimuth can be calculated.

The dome rotation motor is £900

The controller is £700 - it can also control the shutter too

(Shutter motor is another £900)