From: "Milton Aupperle" <milton@outcastsoft.com>

Date: September 11, 2005 5:36:15 PM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Flea Camera Peltier Cooling Results

Hi Folks;

I finally picked up a digital probe thermometer today (accurate to

within +/-1°C) and then ran some tests on cooling the Flea Camera with

my home built Peltier Cooler (PeC for short) unit.

I stuck the sensor on top of the camera case, on the opposite side of

the PeC cold plate where the rubber bands are (look in the Files Other

folder for the Cooled_Flea_Front.jpg image). I also tried wrapping the

camera in a flexible styrofoam packing material "tent" which I thought

might help reduce heat gain from the surrounding environment.

For testing purposes, ambient room temperature was  24.5 to 25.5 °C in

the computer room. The PeC was powered by a 12 volt max 1.7amp DC

power source.

With the camera running at 60 fps, it is at a steady 31.1 deg C and at

1 frame every 10 seconds it's a steady 30.1 deg C. This is with no

active cooling at all. The faster you transmit frames, the faster it

heats up and stays hot. I let the camer achieve steady state

temperature before begining the cooling tests and grabbed single

frames periodically as it cooled down.

With the PeC powered up and the camera running at 1 frame every 10

seconds, it drops to  14 deg C.

With the PeC powered up and the camera not powered up, it drops to 

11.1 deg C.

With the PeC powered up and the camera un powered and the tent removed

it rose to  16.0 deg C.

So it looks like the PeC is dropping the temperature by about 15 deg C

or 33 deg F with the "tent". The total cool down period from 30 deg C

to 15 deg C took 14 minutes to achives steady state of +/1 deg C.

Visually there is a noticeable decrease in noise levels from single

frames grabbed at 30 deg C and at 14 deg C. To amplify the noise as

much as possible, I cranked the gain and the black level as high as

possible.

I think If I made a reasonably tight fitting insulated jacket around

the camera that closed off the back and front as much as possible and

leaves it with dead air space, then I could probably push it down even

further. Also using a conductive grease on the camera case / colde

side  peltier interface would probably help transfer more cold too.

TTYL..

Milton Aupperle