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Old 01-10-2015, 08:38 AM
elken2004 (Australia)
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elken2004 is offline
 
Join Date: Jan 2015
Location: boronia
Posts: 35
ZWO asi 174mc TEC modifications

Hi just thought I would share info on adding TEC cooling to the ASI174mc CCD.

I added a Melcore TEC I bought about 20 years ago.
It is a 12volt 127 couples TEC
I added thermal paste to both sides of the TEC and used a Northbridge heatsink from a PC mother board, it had two mounting holes that matched perfectly the diagonal 39mm holes on the CCD.
Then I screwed a ball bearing type CPU (older style) fan to the heatsink fins
I dob of epoxy the screws to keep the fan in place, then added tape to ensure airflow was pulled thru the heatsink to maximize on cooling.
The fan pulls air from the heatsink and expels it out the rear.
My tests on the bench, were first at 5 volts approx 1 amp draw. This reduced the operating temp of chip from 37 degrees down to about 15 degrees.
I then increased the voltage to 12 volts which drew about 3 amps, this reduced the temp down to about 12 degrees.
However the potential fan vibration might cause a negative effect on imaging.
I found the optimal was about 8 volts with 2 amps drawn.
This also was the best as far as condensation and fan vibration.

Oh PS the ambient temp was approx 22 degrees during these tests

The heatsink performed perfectly not at all warm, however the gain of cooling at 1o volts might be good, condensation not with standing of course.
A reduced fan speed at this 10 volt level would be good, I will have to modify the feed circuit to do this, as at the moment the fan is connected using a 6 ohm resistor, (very basic).
I will test using Zener to reduce its voltage from a common 12 volt source, minimizing the connections to CCD, I think a voltage of 6 or so volts will give enough heatsink cooling with nil vibration.

Each pair of photos show the temp graph and resultant 30 secs image with black cap on CCD.

The test software was FireCapture

all of this is to see how it performs for deep sky objects.
It will also certainly improve planetary photos too, plus plus gain

The weight increase in not significant either still quite a light package overall and good for grab and go imaging.

to be continued..........
Attached Thumbnails
Click for full-size image (zwo test4.jpg)
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Click for full-size image (non cooled 33.4.jpg)
124.2 KB20 views
Click for full-size image (zwo test3.jpg)
143.5 KB19 views
Click for full-size image (cooled 13.2.jpg)
141.5 KB18 views
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