#21  
Old 03-10-2014, 06:32 PM
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ZeroID (Brent)
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OK, I now have a modded KM 7D camera. Opened her up and removed the IR cut window from the sensor, got it back together and it worked first time. Everything is PINK !
I'll reduce all the pix I took and post up a 'How to' in case anyone else wants to try it. Generically speaking if you download the Service Manual for any modern camera so you know where to find all the tiny wee screws it is not all that hard to do. The real trick is the miniature ribbon cable connectors which can be a bit fiddly but they all seem to have some form of release mechanism so be patient and have a poke round.
Story to come later.
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  #22  
Old 03-10-2014, 09:29 PM
PeterEde (Peter)
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I have a 40D I'm considering modding
Shouldn't be too hard for an avionics tech
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  #23  
Old 04-10-2014, 01:03 PM
julianh72 (Julian)
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Even though my CPU cooler came with a fan, I was hoping to get away with running it without a fan to avoid vibrations etc. However, even though I've been running the TEC at only 6 volts, I've noticed that sometimes the camera sensor temperature will stabilize at a Delta-T of about 12 degrees Celsius below ambient, but will sometimes then climb back again almost to ambient after a while, especially in warmer ambient air.

It looks like my CPU cooler without a fan can pump the heat from the TEC running at 6 volts effectively as a passive device (no fan), with ambient temperatures of up to about 24 Celsius or so, maintaining a Delta-T on the camera sensor of around 10 to 12 degrees. However, at a certain critical heat load and / or critical ambient temperature, the fan-less CPU cooler can no longer shift the heat without the cold side of the TEC warming up again.

Since we are quickly approaching summer in Brisbane, and evening temperatures can stay at 24 degrees or more, I need to do something to maintain effective cooling - so I thought I'd put the fan on and see what happens. The fan is rated at 12 volts, but since I'm running my TEC at only 6 volts, I thought I'd run the fan at 6 volts as well.

And the results?

Wow!

The fan runs more slowly than it does at 12 volts (no surprise there!), but importantly, it runs silently, and apparently free of vibrations (which is good!)

Secondly, the top radiator and copper heat pipes go from feeling warm-to-hot without a fan, to feeling quite cool to the touch - barely warmer than ambient -so the fan forcing is REALLY helping!

And with ambient temperature of 28 degrees, the camera temperature sensor dropped quickly from around 15 degrees (which was about the best I could do without a fan) down to just 2 degrees Celsius - and it stays there! That's a Delta-T of 24 degrees Celsius, compared to a (sometimes-unstable) 10 to 12 degrees that I was getting before!

I'll definitely be trying the fan-forced cooler outside next chance I get!
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  #24  
Old 05-10-2014, 08:32 AM
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ZeroID (Brent)
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I can see a fan in my system happening real soon. The 6 volts to the fan is good idea, I already use 5v and 12v to the fans on the Newt.
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  #25  
Old 05-10-2014, 09:09 AM
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ZeroID (Brent)
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Thanks for that Steve, had a quick read through to see what problems you ran into and any solutions. Looks like we've got a ways to go yet. The small size and construction of the ZWO makes it an easy candidate for a cooling mod. Haven't even considered control so far.
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  #26  
Old 05-10-2014, 11:03 AM
julianh72 (Julian)
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Quote:
Originally Posted by kinetic View Post
Hi Brent, Julian,

feel free to have a look through this thread of mine about peltier cooling:
http://www.iceinspace.com.au/forum/s...ad.php?t=52855
and another on how I tackled dew:
http://www.iceinspace.com.au/forum/s...ad.php?t=88572

I have my fan running at a lower voltage for the same reasons that
Julian mentions. Great work fellas.

Steve
Thanks for the links Steve - lots of reading there, and I'm a great believer in learning from the successes of others!

As ZeroID says - the ZWO cameras are an ideal candidate for this sort of hack - the aluminium body makes a great thermal interface between the sensor and the cold face of the TEC. Also, since they ship with an IR-cut filter (on the colour cameras, or clear glass on the monos), the sensor is inside an almost sealed enclosure, so I'm hoping there is very little risk of "frying" the electronics with unwanted moisture, but I'll put a silica desiccant pack inside anyway. I've had lots of dew dripping from my camera's body, but none on the sensor or IR-cut filter (so far).

The thing that got me onto this experimentation path is the drastic drop in price over the last year or so to acquire an entry-level astro-camera set-up. My total outlay so far:

. US$299 for the camera (ZWO ASI120MC) shipped to Brisbane, running off freeware software (once I finalize on a preferred software chain, I'll make a small donation to the developers of my preferred apps)
. AU$1.91 for the Peltier TEC (including postage)
. AU$29.00 for the GPU cooler

I already owned the 12 volt SLA battery that I'm using to power it, and everything else (cable connectors and cable ties, etc) came out of my "box of bits".

At those prices, I could easily afford to buy the camera, and even take a bit of a risk in tinkering with it.
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  #27  
Old 05-10-2014, 12:30 PM
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ZeroID (Brent)
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Hmmm, forgot about the IR cut filter on the front. Must take note next time I'm using it. I'd like to keep the chip sealed and I haven't got a clear window for it. I can probably fit a CLS or 80A to the nosepiece as an option.
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  #28  
Old 05-10-2014, 01:52 PM
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Peter Ward
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You are not trying hard enough

Here's my twin-peltier + twin-turbo PGR mod
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  #29  
Old 05-10-2014, 02:31 PM
julianh72 (Julian)
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Quote:
Originally Posted by Peter Ward View Post

Here's my twin-peltier + twin-turbo PGR mod
I guess that's why you have the Ferrari prancing horse as your avatar!
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  #30  
Old 05-10-2014, 04:24 PM
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Quote:
Originally Posted by julianh72 View Post
I guess that's why you have the Ferrari prancing horse as your avatar!
Err...not quite...picture of real reason attached
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  #31  
Old 06-10-2014, 10:57 PM
sharpiel (Les)
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Quote:
Originally Posted by Peter Ward View Post
You are not trying hard enough

Here's my twin-peltier + twin-turbo PGR mod

Is that to reverse global warming?
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  #32  
Old 07-10-2014, 01:14 AM
Poita (Peter)
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Quote:
Originally Posted by Peter Ward View Post
You are not trying hard enough

Here's my twin-peltier + twin-turbo PGR mod
What sort of temperature drop do you get with that setup? I've modded my PGR with passive cooling but have been considering a peltier/fan setup for solar imaging.
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  #33  
Old 07-10-2014, 07:39 PM
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OK, clouds killed any viewing tonight but I ran up the Peltier with a fan both on 5v on the end of the Lunt. Got down to a reasonably stable 1.2*, ambient was 15*. I did experience some fluctuations up to 3.5* and down to .2*. Not sure why this happens
Camera was in double neoprene sleeve, you can only just feel the cold through that. Radiator array was hardly even warm.
But I will need to add some silica or similar, definitely some fine dew on the window. But there isn't much room down there for even the small packets I thought would fit. I'll give this some thought.

Was hoping to have a go at Siding Springs comet but there was high thin cloud to start with and then it got worse.

Here's a few pix of my setup. Please ignore the crude temporary ( honestly !! ) wiring.
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  #34  
Old 08-10-2014, 02:24 PM
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Quote:
Originally Posted by Poita View Post
What sort of temperature drop do you get with that setup? I've modded my PGR with passive cooling but have been considering a peltier/fan setup for solar imaging.
Unaided, my camera will typically warm up to 60 degrees C . With the coolers active the internal temp drops to around 20-24 C.
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  #35  
Old 28-10-2014, 11:27 AM
julianh72 (Julian)
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Quote:
Originally Posted by julianh72 View Post
I've had lots of dew dripping from my camera's body, but none on the sensor or IR-cut filter (so far).
I spoke to soon!

Brisbane's summer humidity has really kicked in over the last few nights, and I've had massive amounts of condensation on the IR filter the last few days (but none on the sensor itself, as far as I can see).

Looks like I'll be running un-cooled, until I can get a dew-heater mod added to the front of the camera.

Oh well - I always need something to do on those all-too-frequent cloudy nights!
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  #36  
Old 28-10-2014, 01:04 PM
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ZeroID (Brent)
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Plenty of 'Cloudy Nights' over here at present. Peltier experiments on hold at present while I get my guiding and control sorted. Added another PC and reduced cabling to pier but haven't had a chance to test the system live yet.
Once that is sorted I'll get back to the Peltier experiments and try and source a cheap Canon DSLR or similar to have another go at IR modding.
If I can find a way to manage dew in the ZWO ASI120 I will remove the IR cut filter on that and see how it works. Might order a clear glass window for it. ..... hmmm, that has just given me another idea.
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  #37  
Old 02-11-2014, 07:21 PM
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Getting back on track finally, except for clouds of course !!

Got the Toucam working through the 80mm f5 for guiding using Metaguide and GPUSB on the laptop.
Added my beam splitter from an earlier project into the optical chain which gives me a 12mm reticule EP at the same time.

Then got FireCapture working to the ASI120 from the desktop for imaging via the LUNT which meant I could put it back together with the TEC and fan\radiator. So I cannibalised the 5v\12v switching box from the Newt, mounted that to the pier and wired it separately to the TEC element and the fan so I can also switch those individually. It's all plug'n'play now.

Then to tidy up and minimise any interference possibilities I rerouted all power cabling to the east side of the pier and imaging cables (2) to the west. The only signalling cable to the west side is the ST4 guiding. The AC line goes to the scope heater, and the rest are DC anyway.

I can switch cameras between scopes easily target dependent and I can mount the SONY DSLR to any as well.

Just wish I could manage the weather as easily ..
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  #38  
Old 05-11-2014, 06:24 AM
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Weather is still #@%*##!!! so I'm still fiddling. Managed some sky time on Monday night for a bit of testing through cloud gaps.
Discovered I'd put the TEC element in backwards (DOH!!) so it was warming the camera. Scratch that test for the evening.

Ran some longer exposures in avi on 47Tuc, 8 secs per frame. Gave me some video to stack which was interesting despite the poor seeing. But camera definitely needs the Peltier going as noise really gets obvious otherwise. TEC is now fixed.

The Beam splitter idea introduces too much aberation and reduces light to the guider so that is now gone. 45* Diag in place instead to get focal length correct and the Toucam is so light I don't see any flexure issues. All cables are supported at the mount head and top mounting plate so very little strain on the optical train.

Weather is looking hopeful for later this week although the moon is not !
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  #39  
Old 09-11-2014, 01:47 PM
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ZeroID (Brent)
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Weather is brilliant today so tried some solar imaging. haven't processed it yet but also tested the Peltier and AS!120 combo.
Ambient was 16.2* about 10 am, at 5v to TEC and fan I got to 8.8* within 10 mins and it held there. So switched to 12v and within 15 mins I was at 2* and still sinking. About 20 mins later I had -4* and ice film forming on the sensor (I'd taken the IR filter out ). By this time ambient was at 20* so 24* delta no problem. Ice\Dew is now the problem !!
How the heck do you manage that ?
How do the professional Astro cameras manage it ?
I've fitted the IR window back on to seal the sensor off but I may have to give the camera a gentle warm up to dry it right out and reseal it. Then the problem becomes how to keep dew\ice off the window ?
I'm contemplating using a wee tube to blow a fraction of the warmed air from the fan on the heat sink onto the window. Possibly a light draft might just keep it clear.

Hopefully the weather will hold this evening and I'll have a go with guiding and the DSLR with a CLS filter in front.

Better go and process some solar for now, if it's any good I'll post something up of the big sunspot currently visible.
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  #40  
Old 10-11-2014, 05:15 PM
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Quote:
Originally Posted by ZeroID View Post
WIce\Dew is now the problem !!
How the heck do you manage that ?
How do the professional Astro cameras manage it ?
Just like a cold can of XXXX on a warm summer's day, too high a delta-T will always cause condensation (and eventually icing).

Pro cameras, such as SBIG, have sealed chambers with desiccating plugs, plus the chamber window is heated.

Further, the CCD chamber temperature is stabilised to 1/100th of a degree to allow accurate dark frame calibration.

Sure, lowering the camera temperature helps....but there are limits on unsealed systems.
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