Cooling The ASI range: Page 2

Cooling The ASI range

murison

Sam wrote:
the temperature is read from the sensor

the sensor itself provide such function

so that's the real temp of the sensor

Thanks! That is quite useful.

murison

In reference to my previous post (http://zwoug.org/viewtopic.php?p=2925#p2925), my replacement cooling fan arrived. I attached it to the heat sink already mounted to my ASI120MM, then started up FireCapture running continuous 10-second dark frame exposures (1280x960 in 8-bit mode) with the gain set at 100. After the camera had a chance to warm up, I turned on the TEC.

Um . . . holy moly. The temperature reported by the sensor on the CMOS chip dropped by 33.4 degrees C (60 deg. F) in five minutes! The mean noise reported by FireCapture's histogram function dropped from 54 to 1.02 counts (that is not a typo!). Ambient was about 23C (74F). When I turned on the TEC the CMOS chip was reporting 24.2C, and it subsequently went down to -9.2C. See the attached plot.

Flagstaff has a dry climate, but with that kind of temperature drop I may need to add a desiccant, similar to what ags did (http://zwoug.org/viewtopic.php?p=2782#p2782).

figure_1.png

chripell

This is the setup that I'm using. The problem is that I cannot afford to have the TEC working at a power higher than 6-7W without a bigger fan and dissipator, it just heats both the sides. So I use the step-down that is visible in picture. To control dew I use a W&W heater bought for < 20€ on ebay. All the stuff together drains 1.3-1.4A from 12V. I see a drop of 12°C. It's not much but it's just amazing how hot pixels fade and many of them disappear in long exposures. I'm a bit disappointed with the cold-finger concept, I tried various bolts but they just do nothing and I'm considering to fill the hole as described above (but it's a pity to loose the possibility to easily attach the ASI to a tripod (I'm using the ASI120MM with an IR filter and an adaptor for Nikon lenses for daily IR photography for example)).

I'm really looking forward for a cooled ASI Camera from ZWO (my dream would be something like the ASI120MM cooled and with a built-in filter wheel). I would buy it immediately. :-)

PS I'm more of a software than hardware guy, so any advice would be really appreciated

chripell

murison wrote:
my replacement cooling fan arrived

Hi, if I'm not asking to much: may you post some photos how you manage to put such a big fan (92mm diameter) on the ASICamera and your telescope? I would like to try something like you made but I'm in doubt if it will be usable (and the monorail focuser will handle it without vibrations). Many thanks!

marcos

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chripell

MarcoS wrote:
Good day,

can you please post a link to the W&W heather?

Hi,

of course: http://www.ebay.it/itm/191224846528?ssPageName=STRK&_trksid=p3984.m1439.l2649

marcos

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