[g__day (Matthew)]

So if someone was doing say ten of these at a time - how many hours would each unit take to produce? I basically thought about 4 hours effort * $50 an hour; else you are into diminishing returns - were the labour cost far outweighs materials consumed.

But I am slightly intrigued now - and may have a go at this myself, the results certainly look impressive. If high school kids can send a camera into near space and photograph the curvature of the Earth for under $100 and get all their gear back - well a functional unit should be well within my capabilities, it just won't look art deco!

So reading what one needs:

1. Peltier ($20 each from Jaycar for a 68 Watt unit), power supply ($25- $70), circuitry ($20), heat sink and two fans ($40)
2. 30cm square thin metal sheet to spread thermocouples' cooling effects (Aluminium would be fine) 12" * 12" ($12) 24" * 24" ($50)
3. Foam Insulation ($2)
4. Plastic shielding box ($5)

Tools and wiring, cable ties etc.

So for $140 - $200 in parts one could readily build a unit that should work and see how it helped their astrophotography...

Caution in all this thinking TEC's (Peltiers) love lots of tightly controlled current and nailed (regulated) voltages, the cooled side will condense any water in the air - so sealant and keeping air around things dry is critical, and the hot side needs efficent heat transfer (big radiator and high flow fans) to be most effective.