(meteorobs) Heat required to prevent dew in a box for allsky camera

[James Beauchamp]

The fan does a good job of moving the air, but they fail about every six months in mine, resulting in uneven heating.  Before reducing the heat, the natural convection in a failed fan situation caused it to melt the acrylic dome in two distinct spots.

I did send a recommendation to put the resistors in series, or increase their value to bring it down to 20 watts or so.

I bought a small lot of 2" fans from All Electronics and check it regularly.


Sent from my iPad

> On Nov 22, 2014, at 2:25 PM, Chris Peterson <clp at alumni.caltech.edu> wrote:
> 
> Well, like I said, the Sandia design isn't very good. Radiant heat is 
> not a very efficient way to raise the temperature of acrylic. Convection 
> is much more efficient, and therefore you need much less energy to get 
> the job done.
> 
> My camera design is operating all over the world, from the arctic to the 
> tropics. It simply doesn't dew up, under any conditions. The convective 
> heating system can always maintain the dome above the dew point, with 
> nothing more than the camera (and usually, it's power supply) providing 
> the heat.
> 
> Chris
> 
> *******************************
> Chris L Peterson
> Cloudbait Observatory
> http://www.cloudbait.com
> 
>> On 11/22/2014 12:55 PM, Ed Majden wrote:
>> Chris:
>>     Maybe where you live but on the WET Coast of Vancouver Island more heat
>> is required.  Even the Sandia All-sky can dew up here.
>> Ed
> 
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