From: Milton Aupperle <milton@outcastsoft.com>
Date: August 3, 2012 1:21:41 PM MDT
To: Astro_IIDC@yahoogroups.com
Subject: Re: [Astro_IIDC] Cooling Fins
Hi Dave;
Nice design.
In summer time - especially when I am out at the lake - the outside of my camera would drip with water when cooled. To combat that I would wrap the camera in saran wrap (i.e. vapor barrier) before attaching it to the Cooler with straps, which kept it dry. Eventually, I wound up using flexible foam packing as insulation around the camera, which not only keeps it dry, it also helped trap the cooling too.
The other thing I do now is to leave the cooler off and then run the camera for about 10 minutes so that it gets warm / hot. That dries out any moisture in the camera and the filter wheel area etc. I do this about an hour before I start imaging, and then 30 or 40 minutes before I want to start, I start the cooler back up to cool the camera down. Also I cool it down with the camera not powered up, so it cools off faster.
As far as a CCD chamber, if your using a 1.25" nose piece you can probably thread an clear glass filter in it, which will add dead air space in front of the CCD. I have a 2" LPR filter in front of my FilterWheel which helps seal the camera off from the outside air.
HTH..
MIlton Aupperle
On 2-Aug-12, at 7:44 PM, Dave Goodyear wrote:
Hi Guys. Seeing Milton’s cooler made me cool my GrassHopper Express 2.8mp. During solar my camera would easily hit 135-140F. With the dual cooler my camera now shows through AstroIIDC as around 74.2F. I just finished this mod yesterday. Just like Milton, different voltages and amps vary the cooling. I have found that 8v is the ideal voltage for the dual coolers. @12v it pulls 5 amps @14 it pulls 6amps. At 8volts its pulls around 2.5/3 amps. One amp for the fans.
Now I do know that the coolers are cooling the case way below ambient temp and the dew point. I live next to the ocean in southern California and my humidity is always very high. Especially at night. The case will start to form a lot of water. My plan is to either wrap the camera more, add a timing circuit, or seal the camera in a box except for the nosepiece and fill with Scuba air (Scuba air’s dew point is -56F) Scuba air works very well when the front glass of a camera dews up. I can use a ccd chamber sealer and seal the front of the CCD with scuba air and the ccd sealer.
I was able to pick up ten 30mm x 30mm peltier coolers with heat sinks on ebay for $20 and six maglev 40mm x 40mm x 28mm fans for $15. I use Anderson Powerpoles exclusively with my tele power as well as other areas so I have extra “poles”.
The Reflective insulation was something I added a little bit ago without testing.
Here are a few links to pics. The second one is not in focus all that well:
http://ns1.kb2networks.com/GHXPeltier1.jpg
http://ns1.kb2networks.com/GHXPeltier2.jpg
Dave Goodyear
KB2 Networks Inc.
214 Main St. #318
El Segundo, CA 90245
310-933-2436
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