Scope Temp Measuring

[Wombat_In_Space]

Well after reading all the treads on measuring the temp of your mirror rate of cooling I thought I would build a unit to read the temps of the mirror,tube and ambient air.

Here is the unit finished and ready to be mounted to the 12".

[davidpretorius]

lovely looking piece of gear!!

[ballaratdragons]

Cool Darren! (no pun intended)

Be interesting to read the results.

[asimov]

Nice looking piece of equipment Darren! You don't muck about do you! Wish I had more electronic knowledge.

[Wombat_In_Space]

OK all the sensors are fitted to the scope :prey: for some good weather to run some test. Here are the photos of the finished and mounted to the scope.

[iceman]

Very nice Darren..

I might have to consign you to make me one of those!!

Look forward to seeing your results! Can you make one that interfaces to a computer via serial port?

[Exfso]

Are these basically thermistors? top idea, necessity is definitely the mother of invention. Looks like stuff one could get from DSE or Tandy.

[Wombat_In_Space]

This unit does three things interfaces to the pc, displays on a LCD at the scope and saves the readings to its internal memory for later download.
At the moment I haven't got the LCD so when it does I will post the image.:)

[iceman]

Sounds great, and even more so I'll consign you to make one for me! :)

[Wombat_In_Space]

The sensors are made by dallas semi conductors I owe the idear to BIRD as it was his post that gave me the idear to use the hardware I did. See his post here http://www.iceinspace.com.au/forum/showthread.php?t=5276.

[rochler]

I too am impressed. You could probably get a nice little sideline going here - custom temperature sensing gear for scopes!

This would probably be very handy for astrophotographers, since they could keep an eye on what is happening & how it affects their results. Also useful for accurately recording conditions that affect 'seeing' etc.

Wish I had the brains to do stuff like that... :nerd:

[bird]

Well done Darren - looks like you've done a nice job putting it all together. You got the emails I sent?

Bird

[Wombat_In_Space]

Here is the parts list for this unit for those that would like to build it.:confuse3:

I also have the code for the pixaxe unit written so if anyone does build it I am happy to supply the code, the code will be an on going process of improving it to do other features as well ie: display the current time on the screen and read humidity. :computer:

All later versions of the code will be email out to those that have already got it in their units.:)

[Wombat_In_Space]

Yes I have I am about to go through them.:thumbsup:

[rochler]

This would a *great* project to add to the Projects, Articles & DYI section (hint hint!) once you've tested it all out & tweaked it etc. I'm sure that there would be a lot of interest....:thumbsup:

P.S. I'd be happy to get a copy of the code - I need a project to keep me busy...

[davidpretorius]

very neat and tidy compared to my wires everywhere solution!!

well done darren

[slice of heaven]

Looks great Darren , give us a good run down when you test it.

[Wombat_In_Space]

It's 11:30pm and just bought the scope outside temps to start with Ambient Temp:17.62 Tube temp:19.62 Mirror temp:21.44. I have the fan running and the scope is at 45 deg angle.

12:05pm Ambient: 13.31 Tube: 14.50 Mirror: 15.44

[bird]

Looking good Houston. Seeing tonight seems much better than last night, fingers crossed.

Bird

[Starkler]

Just had an idea.

If we only really care about the differential between mirror temp and ambient temp, a simple bridge circuit with a small meter or an single op amp could do the trick.

edit - nevermind its not an analogue device .

[davidpretorius]

this is true!!!

[Wombat_In_Space]

Ok temps are starting to stablize it been 45 minute since bring the scope out and thes are the readings.
12:15 am Ambient: 13.25 Tube: 14.44 Mirror: 15.12

[Wombat_In_Space]

Ok one hour up and here are the figures.
12:30am Ambient: 13.37 Tube: 14.31 Mirror: 14.81

[Wombat_In_Space]

Now at 2 hours and here are the temps.
1:30am Ambient: 13.75 Tube: 14.44 Mirror: 14.44

[Wombat_In_Space]

1:40am turned cooling fan off these are the temps.

Ambient: 13.81 Tube: 14.31 Mirror: 14.31

[Wombat_In_Space]

3 hours into testing here are the readings, 50 minutes since swtching the fan off.

2:30am Ambient: 14.12 Tube: 14.12 Mirror: 14.00

[Wombat_In_Space]

5 hours of testing and still going strong here at the temps.

4:30 am Ambient: 15.19 Tube: 15.25 Mirror: 14.50.

Now to go have a good look at saturn.

[bird]

Saturn looks nice at the moment :-)

Bird

[iceman]

Nothing but bad seeing up here last night. And clouds this morning.

[Wombat_In_Space]

Well it's test night no.2 and I am set up for an all night test scope bought out at 9:45 pm and here are the starting temps.

Ambient:, 10.81 ,Tube:, 12.87 ,Mirror:, 17.00

[Wombat_In_Space]

Ok one hour in to tonights test here are the temps.

Ambient:,9.94 ,Tube:, 11.00 ,Mirror:, 11.94 looking good:thumbsup:

[bird]

Wow, you dropped the mirror 6 degrees in 1 hour! That's pretty impressive, what have you got hooked up to the scope??

regards, Bird

[Wombat_In_Space]

I have a feeling there was a error in the sensor for that starting temp as it dropped way to quick compared witht the other night, I think I might have a faulty 3.5mm phono plug because I lost the readdings from the mirror for about 20 mins or so in the 3 hour so it's off to Jay*** monday morning to by some new plugs.

[astrodave]

What sensors are you using? I have used Dallas DS1820s for years (for domestic,but not astro related temperature measurement) and found them a wonderful device, but their accuracy not as good as claimed. I've had to run calibration tests on them and apply corrections in software. If you are using the 1820 series - are you running them in the high precision mode?

[Wombat_In_Space]

I am using the Dallas DS18B20 sensor it is the newer version of the ones you are use to using, I am still fine tuning the software for the microcontoller to get it to do every thing I want it to do, I am running the sensord in high precision mode but I am looking to drop the back to a +/- 0.1°C reading setting as that is all I need accuracy wise.:thumbsup: