SCT Cooler part I

davidpretorius · #1 18-04-2006, 03:42 PM

Ok

Moving from reflector cooling to sct cooling via peltiers and seriously looking at the lymax / cat coolers / asi industrrial home brand being peltier cooled.

Ok, my learned SCT and MCT and XXXCT owners, how much does this design of telescope suffer from "tube currents" so to speak?

I can only presume that if you take your sct out of a room that was 20 degrees and plonk it outside at 10 degrees, then the internal air cavity will continue to warm the front lens and hence set up "currents" on the outside of the scope but in direct line of where you are looking.

They always say that a reflector is more prone to having to be "cooled", but how much do you sct guys actually cool your scopes?

davidpretorius · #2 18-04-2006, 04:50 PM

Ok, here is a cad cam version. Thanks Bird for agreeing to be my model for the day.

air needs to be cooled = peltier
air needs to be clean = lymax filters
air needs to sirculate = lymax exhaust vents
everything is 12 volt
air goes up tube and is directed backwards to help circulate. buying a dual temp sensor so that one end goes up and attaches near the top so it measures older circulating air. Once inside cavity reaches ambient, woo hoo!

It should be very easy I would think (ASI???) to enclose current fan end of lymax cooler and then attach the d1ck smith peltier system to refridgerate that enclosed area.

Bird, would you need to recirculate the exhuasted air or have some vent holes near the peltier to draw in cooler ambient air??.

Further mods, desicants could be added along the way to get rid of moisture, but generally, the cold air will be quite dry.

davidpretorius · #3 18-04-2006, 05:04 PM

also, once the inside air may be at ambient, so no currents from the front glass to the outside, the mirror will still have to be ambient the internal air as well.

so, a temp sensor on the back of the mirror may still be needed. The internal air my need to go below ambient to get mirror to ambient and then let them settle for 1/2 hour similiar to bird does.

ok, enough thoughts for now, feel free to rip it to pieces if i have overlooked anything

[1ponders] (Paul) · #4 18-04-2006, 11:01 PM

How are you going to attach the sensors to the mirror and keep them there when the mirror moves up and down during focusing? Have a small coil of able inside the OTA?

[1ponders] (Paul) · #5 18-04-2006, 11:05 PM

Also if you have humid air inside as soon as you start to cool the inner air temp won't you start to get condensation forming? Especially if the colder air is blowing back towards the mirror?

asimov (John) · #6 18-04-2006, 11:15 PM

Fairly easy to build I would suggest.

davidpretorius · #7 19-04-2006, 07:49 AM

Quote:

Originally Posted by [1ponders]

How are you going to attach the sensors to the mirror and keep them there when the mirror moves up and down during focusing? Have a small coil of able inside the OTA?

how far would it travel from fully in to fully out?

thermal paste would attach the sensor to the back i would assume. That is the way bird and I have attahced them for the reflector