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Posts posted by Gina

  1. The 60mm fan sends a lot of air through the cooling fins and I'm not sure whether I want all that air directed up to the dome, one side could go straight out to the environment with just a hood to keep rain out.

  2. The first test got down to -2°C now on the second with more fins but lower ones and it seems to be about done at 0.7°C.   Looks like the new cooler wins contrary to expectations.  Maybe the bigger air space helps cooling.  I'll go with the new taller cooler then and design the ASC casing and air ducts to suit.

  3. Now testing with the new cooler replacing the waterblock in the ASC.  The camera temperature is slowly coming down.  The fan is pretty noisy run from the full 12v.  I could do with rigging up some digital thermometer chips for reading temperatures with this sort of testing.  With the aluminium adapter ring for the lens and no warm air blowing over the lens it has steamed up.  Camera image sensor has not yet got down to freezing - still a degree or so above.

  4. The CPU cooler I ordered arrived today but the fins are further apart and fewer than I thought but deeper.  Whether this is as good, better or not as good as the one I already had I don't really know.  I guess totalling up the surface areas of the fins should tell me.  Base is the same size.

    Here's a photo of them both - new one on left. 



  5. I think I shall go for the simplest approach to this and try a sealed chamber for the camera again.  I can use a 3D printed plastic adapter ring for the lens to thermally insulate it from the cold camera body and hopefully this may let the lens warm up above dew point.  I've concluded that a standard axial fan should not fail from damp air as the motor part will be warmed by the current flowing through the motor coils and the air RH will probably be above dew point anyway. 

    A standard CPU cooler on the hot side of the Peltier TEC may produce enough cooling whilst the warmed air can be fed up into the dome.  Clearly this will be less efficient than water cooling but may be sufficient.  It's worth a try.  If the 60x65mm CPU cooler is not enough I have a heat pipe type with larger fan and cooling fins.

  6. This is proving problematic and I'm wondering whether to separate the dehumidifier from the camera cooling.

    The only part that actually needs dry air is the camera, the lens and dome can have warm air blown over them to prevent condensation.  Maybe I should go back to the idea of sealing the camera and including desiccant like the cooled astro cameras do.

  7. I have the larger heatsink on top of the big TEC on the plate and the two small heatsinks underneath.  Then, just for testing, I have a 50mm axial fan blowing through both heatsinks.  There is not enough cooling of the hot side of the TEC to get the cold side down below the dew point so it needs more air blown through it.

  8. Taken the camera out of the bottom of the casing and sat it horizontally on the table and the temperature has decreased a couple more degrees so maybe the casing wasn't helping airflow into the camera.  The inlet was a lot bigger than the fan and shouldn't have affected the air flow.  However, I can easily give the camera an open mounting bracket.

    I've also tried focussing and think I may have it a bit better.

  9. Now running a test to see if the routing of air from the camera cooler up to the lens affects the cooling.  I ran the cooling for a while with the casing on with the unit indoors and then with the top of the casing removed so that the air was free to escape straight out.  There is a slight difference but it's only about 0.3°C - from -14.7°C to -15.0°C.  It is a warm day and the indoor temperature is around 22°C so the cooling may be struggling anyway.

    EDIT - the camera temperature reading has now risen to -14.5°C so that small difference noted earlier is not significant - the ambient temperature is varying a lot more than that.

    The cooling performance of this ASI 1600MM-Cool camera has definitely deteriorated then :eek: - I can get down to -20°C with the cooling system in my ASC with the DIY cooled ASI 178MC.  Maybe I would be better using the same system as in my ASC except with the mono version of the camera (ASI 178MM).

  10. To get enough cooling from a TEC-12706 it needs an efficient heatsink - the 40mm ones aren't sufficient so I shall use the 60mm x 65mm one.  For the condenser I'm not sure but the same size would seem logical (with the same air capacity) so I've ordered another of these CPU coolers.  Due to arrive tomorrow.  At least that gives me another option to try.

  11. I'm going to try stacking.  This means that I've had to change the ROI to exclude ground based lights so that the stacking routine can use stars for alignment.  I have reduced exposure to 90s to avoid star trailing.  Maybe if I can get a dozen or two frames it might show the hydrogen clouds better.  I think the test so far shows promise.


  12. If I can improve the cooling on the camera and increase the gain I think this technique may reveal the hydrogen gas clouds (nebulae).

    I think it possible that directing the warm air from the camera up to the lens may be restricting it and reducing the amount of cooling available.  Maybe vent the air straight out and use some other way to stop dew on the lens.

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