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New heating pad for my primary mirror

Discussion in 'All Other Observing Equipment' started by Nebula, Oct 10, 2022.

New heating pad for my primary mirror

Started by Nebula on Oct 10, 2022 at 12:27 PM

19 Replies 796 Views 2 Likes

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  1. Nebula

    Nebula Well-Known Member

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    Today I built a heating pad for my 12" mirror, for when it's time to get freezing telescope inside of the house during winter, this gentle heater will slowly reheat the mirror for an hour while the telescope is resting in it's bag, this will prevent dew formation on the mirror.

    It's 2.49w total, very gentle but also very effective for slow heating.

    [​IMG]
    [​IMG]
    [​IMG]
     
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  2. Ed D

    Ed D Well-Known Member

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    Very resourceful and impressive solution. :)

    Ed
     
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  3. Mak the Night

    Mak the Night Well-Known Member

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    Looks pretty ingenious Neb. I've noticed that even my small refractors can sometimes take up to 24 hours to become totally dew free in storage. On the 11th of July 2020 I'd planned to take my 80ED out again. I'd had an early morning session with it the night before. That July seemed a bit humid though, more like early September. As a consequence when I was checking out the 80ED on the 11th I noticed the objective was still dewed over. So I took the 72ED out.

    neo.jpg

    I did get to see Neowise though. I never saw it the same again as it had lost a couple of magnitudes. It's the best comet I've seen for some years. I even got to use my Lumicon comet filter lol.
     
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  4. Orion25

    Orion25 Well-Known Member

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    That's a great idea, Neb. Winter is a'comin':eek::eek:
     
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  5. Nebula

    Nebula Well-Known Member

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    @Ed D and @Orion25 It's working well, the pad is a bit small for the size of the mirror but it looks like it's heating the glass plate enough to cover the whole mirror over time. Unless the exterior of the telescope is all wet, or if there is ice formation inside of the tube then I might need a bit more watts on the mirror. I'ts possible to fabricate another pad easily to cover the bottom of the mirror. My DIY dew heater has 4 output connectors.

    My 8" I can get it inside of the house from -20 Celsius, leave it in the sealed bag with the primary heater, it takes about 30 minutes, I open the bag and the mirror is at room temperature, no dew. The coating of my telescopes should last forever!

    it's very cold during winter here.. i regularly do observation at -10, -15, -18, celsius it happened at +- -27 on a couple of occasions, it's hard for the focuser and the mount at these temperatures.
     
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  6. Nebula

    Nebula Well-Known Member

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    @Mak the Night I fear the dew a lot, it's causing mushrooms and premature wear of the coating...

    Shit I remember Neowise, that was AWESOME!!! at the dark sky the target was very bright naked eye, I have 2 or 3 sketches of it. Great great memories. :D

    The Comet filter, Dave In Vermont liked that one I think.
     
  7. Mak the Night

    Mak the Night Well-Known Member

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    I'm glad I got to use my comet filter on Neowise lol.
     
  8. Nebula

    Nebula Well-Known Member

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    @Mak the Night I bet!

    I wonder if I'll see another comet like that one one day, as bright.
     
  9. Mak the Night

    Mak the Night Well-Known Member

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    It's a possibility. If I remember rightly Neowise wasn't initially predicted to be visible with the naked eye. Apparently comets are associated with plagues/pandemics, so not seeing one may be good too. lol
     
  10. Nebula

    Nebula Well-Known Member

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    @Mak the Night yeah I read that, panspermia, virus and bacteria seeded on earth by comets, it makes sense.
     
  11. Nebula

    Nebula Well-Known Member

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    My concept is not working... 1 Pad is not enough to keep the mirror from dew formation.. Well after 1 hour, 1/2 of the mirror has dew and not the other side, the mirror needs 2 heat pads , minimum, double the watts.
     
  12. Nebula

    Nebula Well-Known Member

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    Another upgrade for my secondary heater.

    [​IMG]
    [​IMG]
    [​IMG]

    And this is the look of the telescope when I get it inside of the house during cold winter, only the wires come out of the bag. This should work fine for the secondary! Works well with my 8"
    [​IMG]
     
  13. Nebula

    Nebula Well-Known Member

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    I am unstoppable, I decided to upgrade my heating system again and this time it's 90% over.

    A third mirror heater, 2 of them was not powerful enough to have the mirror stabilized in less then 1 hour.
    [​IMG]

    A custom wire holder
    [​IMG]

    Then yesterday I decided to replace the 12v 7AH battery with a 12v 2.67A MAX transformer, that way it's possible to use a common 120v timer to shut the power off so i can leave the heater for 2 hours and go to sleep, the timer will toggle off automatically. (The battery still can be used if required)
    [​IMG]

    The whole system with the new AC and the multimeter calculating the total Amps.
    [​IMG]

    The whole system will draw only 0.6 amps @ 12v, it's very gentle heating.
    [​IMG]

    :)
     
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  14. Orion25

    Orion25 Well-Known Member

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    Magnifique, Neb! Exquisite craftsmanship. Have you tried it out yet? Inquiring astronomers want to know! :D
     
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  15. Nebula

    Nebula Well-Known Member

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    @Orion25 I have not tested the system yet, because of VERY bad weather, gray skies and some energy draining difficulties at the job. The job situation is stabilized right now so I can resume with astronomy observation and think about something else.

    :D

    My final upgrade for the system, I made these wires extensions to hook up the controller to the pads. These wires are quite soft, I think they are used for trailer lights, automotive exterior wires. Hopefully they will remain softer during cold weather then my previous wires. The RCA connectors are all welded and tested, they work fine. Aesthetically it's also much better because they all are of the same length, except for the one from the secondary mirror which is longer, they all arrive at the controller at the same place, mostly aesthetics but better wires in the cold.

    [​IMG]
     
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  16. Orion25

    Orion25 Well-Known Member

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    Looks great, Neb. Bravo!
     
  17. Nebula

    Nebula Well-Known Member

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    @Orion25 It worked well yesterday when I brought the telescope into the house, it's nice that I don't have to bother about a battery life no more, after 30 minutes of heating I removed the cap from the telescope and the mirrors were 100% free of dew.

    I am happy with the results!
     
  18. Orion25

    Orion25 Well-Known Member

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    Great! And WHEN you get the ASI224mc I'll be glad to share any tips about planetary imaging :)
     
  19. Nebula

    Nebula Well-Known Member

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    @Orion25 The camera yess, but I can't buy it right now, it will be a project for 2023, can,t do it now. :(
     
  20. Orion25

    Orion25 Well-Known Member

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    You'll have something nice to look forward to :)
     

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