[Quark (Trevor)]

Originally Posted by iceman

Hey! DP out of the woodwork, how 'bout that!

Agree with the others, Trevor. You've done a great mod there and it should serve you well into the winter months. Just remember to let the air settle for 15-30 minutes after switching the cooling off (and before you start imaging).

At the moment, I use a power-point timer to turn the unit on and off. Eventually you might want to get tricky like Anthony, and have the temperature sensors feed back into a computer to control the switching on and off of the unit, so you can leave it running all night and know that when you get up at 4am the mirror is at ambient.

Once I left mine on too long and when I got up, the mirror was all dewed up from cooling to 2 deg below ambient.

I had to get the hairdryer out to get rid of the dew/fogging up until the mirror warmed up a bit

Thanks Mike, at the moment I can adjust the voltage to the Peltier's and switch the power supply on and off from my computer table beside the scope. I have found that, due to the thermal mass of the aluminium cold plate, even after switching off the Peltier power supply all together, the mirror temp continues to drop. Last night after switching off the Peltier's and then the cooling fans in stages, the mirror remained at or below ambient for about an hour. There are still some further trials that I want to perform and log the temp data to try and understand precisely what is happening and what procedure works best.

Originally Posted by davidpretorius

THat is a top piece of work.

I look at my birds nest of a cooling system and compare to yours, pauls and birds and I have to laugh

It really is worth the effort. If you can get the mirror to +/- .5 degrees of ambient and the seeing is great, then you will have a GREAT night of imaging. Simple as that.

Well done again.

Thanks David, the initial results seem very promising. I am able to bring the mirror down to ambient surprisingly quickly and ounce it is down to .5 of a degree C below ambient, due to the thermal mass of a 16" primary, the mirror temp remains stable for a considerable time, at least it does in the mild conditions that I have had for my trials thus far.

Originally Posted by Paul Haese

well done on joining the peltier club Trevor. The applications for these units is just about every telescope design. Many are still unconvinced of the merits but in time will be swayed by the body of evidence.

Well done.

Thanks Paul, I suppose this is just the next step as an amateur planetary imager to strive for better results. I really do enjoy the ATM side of amateur astronomy and I have designed and built most of my equipment. In the past I have been stuck in that rut of spending the majority of my time building stuff instead of using it but fiddling with this cooling system and comparing results with various settings is most satisfying. It definitely has made a difference to my imaging.