How do you power your shutter?

[purgitoria]

So, i'm currently working on my new observatory design and am basing it on a Pulsar 2.7m. It will not use however the Rigel automation system but a version of the ScopeDome automation. I will also not be using the rubber support and guide rollers but am having a custom curvilinear rail system made to support the dome as i wish to make the dome fully robotic and unattended (i work overseas a lot and it would be great to be able to use it securely when not at home). This presents me with several issues when it comes to redundancy and reliability for powering the shutter. My optimal solution would be to use something like a Quint UPS module as the 12V battery backup that can be fed from a mains supply that would be the primary source of power (the shutter control system can take both 240V and 12V supplies) and would be fed off a main 240V UPS supplying the obs. The trouble is how i get the power up to the rotating part of the dome?

What does everyone else use?

Does anyone use home position contacts? What brand and what are they like?

Does anyone use a slipring system? What brand and what is it like?

[steppenwolf]

The simplest solution is to use a lead acid 12v battery installed in the dome section on the 'shelf' and a solar panel for re-charging. I used this system with great success on my Pulsar 2.2m Observatory.

A 12v lead acid battery has a large reserve capacity to cater for dull days reducing the charging rate from the solar panel.

[sloz1664]

I'm investigating automating my Pulsar Dome and powering the shutter is Phase Two of my project. I'm going down the route of battery/Solar Panel. I have six 12v 12 amp/hour batteries. I will use two batteries, one each side of the shutter. The remaining batteries held in reserve for the many, many dark and dismal days we have in the UK.

Unfortunately I have a major task modifying the existing shutter prior to automating it. 

Steve

[skybadger]

Any views on the shutter mechs either of you are using ?

I have explored using wire rope and cable guides but ca get enough tension for the 'winch' bobbin to bite in the endless loop.  So will likely be using a 12v winch modified to wind on and wind out at the same time from either side of the bobbin.

I also have a pulsar 2.7m, either early version or copy...

Mike

[purgitoria]

6 minutes ago, skybadger said:

Any views on the shutter mechs either of you are using ?

I have explored using wire rope and cable guides but ca get enough tension for the 'winch' bobbin to bite in the endless loop.  So will likely be using a 12v winch modified to wind on and wind out at the same time from either side of the bobbin.

I also have a pulsar 2.7m, either early version or copy...

Mike

My intention is to use a timing belt and pulley wheel system such as the open ended belts here http://www.davall.co.uk/dsg-power-transmission/catalogue/toothed-belts/ Effectively wheel would be fixed at the top of the dome and the other would be on the drive motor at the bottom with one of the clamping plates attached to a bracket on the shutter and a series of guide rollers to align and tension the belt (this is much the same way as the Rigel system works with it's chain drive). The only problem i would see is if it were one of the older pulsar domes that had the dual shutter consisting of the upper sliding part and the lower flap in which case i would use a similar timing belt/chain method combines with a small linear drive on a bracket attached to the lower flap.

 

1 hour ago, sloz1664 said:

I'm investigating automating my Pulsar Dome and powering the shutter is Phase Two of my project. I'm going down the route of battery/Solar Panel. I have six 12v 12 amp/hour batteries. I will use two batteries, one each side of the shutter. The remaining batteries held in reserve for the many, many dark and dismal days we have in the UK.

Unfortunately I have a major task modifying the existing shutter prior to automating it. 

Steve

My hope was to keep away from being fully battery powered as i want the redundancy and i also have concerns about just how long a 12V battery would power the shutter controller along with the heaters for the electronics and motor when it gets cold. I don't mind having battery as a backup to control the shutter when out from home position such as on a weather alarm and to keep the electronics powered during an imaging session but really wonder how big of a solar panel i would need and how many Ah i would need in battery power if i did not have a mains connection.

[sloz1664]

Hopefully, I will be using a 12v drill motor and nylon chain to drive my Shutter movement.

Mike, the winch bobbin you used was it a single grove variety or multi grooved variety?

 

Steve

 

[sloz1664]

8 minutes ago, purgitoria said:

My intention is to use a timing belt and pulley wheel system such as the open ended belts here http://www.davall.co.uk/dsg-power-transmission/catalogue/toothed-belts/ Effectively wheel would be fixed at the top of the dome and the other would be on the drive motor at the bottom with one of the clamping plates attached to a bracket on the shutter and a series of guide rollers to align and tension the belt (this is much the same way as the Rigel system works with it's chain drive). The only problem i would see is if it were one of the older pulsar domes that had the dual shutter consisting of the upper sliding part and the lower flap in which case i would use a similar timing belt/chain method combines with a small linear drive on a bracket attached to the lower flap.

 

My hope was to keep away from being fully battery powered as i want the redundancy and i also have concerns about just how long a 12V battery would power the shutter controller along with the heaters for the electronics and motor when it gets cold. I don't mind having battery as a backup to control the shutter when out from home position such as on a weather alarm and to keep the electronics powered during an imaging session but really wonder how big of a solar panel i would need and how many Ah i would need in battery power if i did not have a mains connection.

I assume you will only be opening and closing the shutter probably once an imaging session, less than 2 mins per session. That's not going to task the batteries too much. To aid solar charging you could always programme the dome to follow the sun during the day to maximise it's charging capabilities.

Steve

[purgitoria]

37 minutes ago, sloz1664 said:

I assume you will only be opening and closing the shutter probably once an imaging session, less than 2 mins per session. That's not going to task the batteries too much. To aid solar charging you could always programme the dome to follow the sun during the day to maximise it's charging capabilities.

Steve

My concern i not so much the powering of the motor as i know a battery will be more than capable of holding the charge to operate the shutter for a couple of cycles. I am more concerned about the powering of the electronics for long periods with the constant wireless broadcasting and also for all the heaters for the electronics and the motor, heaters always use quite a bit of power and it gets pretty cold in Scotland over the winter.

[sloz1664]

I see. I assumed you were powering the rest of your equipment from mains power, which is what I have done.

Steve

[skybadger]

On 02/08/2017 at 22:41, sloz1664 said:

Hopefully, I will be using a 12v drill motor and nylon chain to drive my Shutter movement.

Mike, the winch bobbin you used was it a single grove variety or multi grooved variety?

 

Steve

 

I have a single groove round section belt wheel and tried wrapping 3 turns around it, with offset in and out feeds, to minimise overlapping. Do you think if I turned a purpose made bobbin with multiple turns on it , that would work better ?

[sloz1664]

11 minutes ago, skybadger said:

I have a single groove round section belt wheel and tried wrapping 3 turns around it, with offset in and out feeds, to minimise overlapping. Do you think if I turned a purpose made bobbin with multiple turns on it , that would work better ?

Absolutely, the friction caused by wrapping, what is actually a 3 turn thread, will lock the wire rope and stop it slipping.

Steve

Edited August 4, 2017 by sloz1664

[skybadger]

I'll give that another go then. See what I can turn on the lathe.

The system I was planning to use is a wire rope over pulleys and returned back via cable guide . I was aiming at something with very low visual obstruction.

[timfrench14]

Hi,

Sorry to come a bit late in the conversion.

I’m close to finishing a longtime planned and 17 month build of a 12ft x12ft square to 10 ft wide DIY dome. The build is actually 18 ft in length as my “warm Room” is part of the overall build being 12 ft x 6 ft fully insulated with a picture window between the two. A standard 12 inch by 8 ft concrete pillar goes down into a 2 x 2 x 4 ft concrete filled foundation. When in operation the observatory will have Celestron C-14 edge hd on CGE - pro mount sitting on specially made (and too expensive!) plate.

After the snow disappears the dome will be installed on the top of the square telescope room. I want to get the shutter powered up before installation. Mains power is pretty much up and ready via a 100 ft long 2 ft deep trench with cabling ready to go. My electrical contractor who has very generously donated all equipment and his time for free will do the installation.

The shutter rolls very easily on the rails, weighs about 30lbs +/- 5lbs but I don’t know which type or where to find the 12V DC motor, geared to drive an exploradome type wheel plus track. Any ideas?  Also, how about the wire guides etc?

If you’re interested, this was my first serious telescope; University College London Observatory Observatory when I was doing Astronomy and Physics degree.................no, GO-TO no CCD or even digital cameras, no pc’s! Happy days!

Link www.ulo.ucl.ac.uk