|
All TECs are not created equal
As several people are working on cold finger cooled DSLRs I think a word about TECs is in order. They seem to be everywhere on ebay, and I used one of those initially (burnt it out pretty quick). I found that the Jaycar ones, while more expensive, are good quality and I have used the same one for over a year now without it missing a beat (PWM speaking). The one in my colour Canon is a 51W/6amp version, and I have a 68W/8.5 amp one as well which may go into my mono camera shortly.
The 51W/6amp TEC was good for a delta T of -25C for most of the year, but now that summer is approaching again it can struggle on warm nights to maintain -5C actual at the sensor. However, that's good enough and it's reasonably good on power consumption, and via the PWM can be dialed back on cold nights when all the cooling is not required. I am tempted to install the 68W/8.5amp version so that I have more 'low range' in summer, and can still dial it back on the PWM in winter. They are the same size (40x40mm) and same height. I have not done a performance comparison but when I get the mono camera completed that will be done.
It is possible to stack TECs to create 'two-stage' cooling, which some CCD cameras use, but the power consumption would make dark site use impossible but in a home/observatory setting it would work fine. If stacking you could go to lower rated TECs to reduce power consumption. As always with these things the heatsink/fan combo has alot to do with the ability to shed heat and if you aim at CPU type heatsinks/fans then the TEC will perform better. IMHO
I have attached a photo of the two Jaycar TECs I am using and the part # info is there as well.
|