Temp control success

davidpretorius · #1 19-11-2005, 09:57 PM

Hi all,

after Birds fantastic introduction to temp control for us all, I went looking for a temp monitor we had from when our 5yr was a baby.

I found it and it was as I remembered it. It has two sensors, for outside and inside. The theory being you stick one sensor to the window for outside temp and the main display has its own sensor for inside.

Guess what, the outside sensor still had the sticker on it, so it is now proudly stuck to the side of the mirror. This sensor has about 1.5 m of cable back to the main sensor/display and it also has a stcky back. It is now mounted next to the eyepiece holder.

I can now monitor the temp of the mirror and the ambient temp.

I will visit the chemist where we bought it 5 yrs ago and try and find a price for you guys.

As you can tell, i am very happy!!!!

asimov (John) · #2 19-11-2005, 09:59 PM

Sounds cool Davo!!

davidpretorius · #3 19-11-2005, 10:03 PM

yup have the scope outside cooling as we speak. I have adjusted the primary screws and collimated with my cheshire. I will star test to finish off and even if it is raining, i will image saturn at 4am after the alarm wakes me at 3.29am.

Does anyone want to know the tempertaure, they started off at 18.5 and 18.5 about 10mins ago!!!!

davidpretorius · #4 19-11-2005, 10:06 PM

mirror 15.5
ambient 12.5

after 15mins

asimov (John) · #5 19-11-2005, 10:16 PM

Yes! This is what happens...the mirror can't keep up with the falling air temp. Once the air temp stabilises, I'll be REAL interested to know how long the mirror takes to catch up! I'll give my eye teeth for one of those sensor units toooooo!

davidpretorius · #6 19-11-2005, 10:19 PM

i know you can go silly with the first born and spend heaps, but I would like too think it was not a lot of $$$ I will check tomorrow!

janoskiss (Steve H) · #7 19-11-2005, 10:20 PM

Wow Dave, that is too easy! Please let us know how it goes. I'm very interested.

asimov (John) · #8 19-11-2005, 10:20 PM

Do you use a fan Dave or do U have to wait for the mirror to reach ambient 'naturally'?

davidpretorius · #9 19-11-2005, 10:21 PM

right on the 1/2 hr

mirror 15.0
ambient 14.3

davidpretorius · #10 19-11-2005, 10:23 PM

Quote:

Originally Posted by asimov

Do you use a fan Dave or do U have to wait for the mirror to reach ambient 'naturally'?

i prefer the natural method.

actually, the 10" from andrews went to including a fan about 2 hrs after mine left his shop!!!

davidpretorius · #11 19-11-2005, 10:43 PM

50 minutes

mirror 14.2
ambient 12.9

slice of heaven · #12 19-11-2005, 10:47 PM

Good one Dave

RAJAH235 · #13 19-11-2005, 10:56 PM

I can see a fan being installed.

L.

davidpretorius · #14 19-11-2005, 11:09 PM

80 mins

mirror 12.3
ambient 11.5

bird (Anthony Wesley) · #15 19-11-2005, 11:22 PM

Nice one DP.

Something to be careful of - you need to insulate the back of the sensor on the mirror so that it doesn't come in contact with the air, otherwise it'll end up reading part mirror and part air temp.

It's easy to do - just find some waste styrofoam from a parcel and cut out a cap to stick over the mirror sensor.

Weather looks clear here too, and I have my alarm set for 3am, maybe we'll be imaging at the same time ?

Bird

janoskiss (Steve H) · #16 19-11-2005, 11:28 PM

Davo, your numbers so far are telling a similar story to Bird's detailed graphs. The temperature is dropping and the mirror just cannot keep up; lagging by around 1 degree.

davidpretorius · #17 19-11-2005, 11:39 PM

100 minutes

mirror 12.3
ambient 9.5

davidpretorius · #18 19-11-2005, 11:41 PM

Quote:

Originally Posted by bird

otherwise it'll end up reading part mirror and part air temp.

It's easy to do - just find some waste styrofoam from a parcel and cut out a cap to stick over the mirror sensor.

Weather looks clear here too, and I have my alarm set for 3am, maybe we'll be imaging at the same time ?

Bird

if i only have two sensors, is it a good thing to try and measure mirror and tube air temps???

or should i just stick to purely mirror?

bird (Anthony Wesley) · #19 19-11-2005, 11:52 PM

Buy another baby monitor, then you'll have the 4 sensors :-)

You'll find the difference between tube temp and air temp very amusing, and you really do need 2 sensors on the mirror to get an accurate picture of what it's doing, one in the middle of the back and the other on the side up close to the aluminised front surface.

Bird

bird (Anthony Wesley) · #20 19-11-2005, 11:55 PM

Interesting to watch your temps - ambient dropped 2 degrees in the 20 mins from 80 to 100, but the mirror stayed at 12.5

If you're near the scope, watch out that you're not warming up one of the sensors. I've done that a few times by accident.

Bird