Jump to content

Banner.jpg.b83b14cd4142fe10848741bb2a14c66b.jpg

1100D cold finger sensor cooling with TEC and water cooling

Gina

By Gina
in DIY Astronomer

Recommended Posts

Gina

Gina

Posted
  • Author
Posted
Not sure there would be much difference. Makes me think moving the the LCD screen out of the way or removing it all together would deliver some significant improvements from close in TECs.
Removing the screen would also leave a convenient cooler sized hole

This was my original plan but it seemed I needed the display. However, since then I have found ways round this. Also, there are commercial mods that dispense with the display so it must be possible. Maybe it's time to look at this option again - if I did it this way and found a problem I could change it to no.3 or no.4 above.

Link to comment
Share on other sites
  • Replies 388
  • Created
  • Last Reply
Gina

Gina

Posted
  • Author
Posted
If you needed access to a screen, can't you plug a screen into the dslr? I think my 450d will output to a composite screen, pretty sure it had all the controls on it that you normally get on the lcd.
It has an mini HDMI output but I haven't checked what comes out of it. Maybe I'll get a mini HDMI cable and check.
Link to comment
Share on other sites
Gina

Gina

Posted
  • Author
Posted

I'm going for the "all in camera Peltiers" option. This is how I see the arrangement, though I shall need to see how the clamping is going to work out.

Key :-

  • Cold finger in blue
  • Hot side in red
  • Copper sheet in dark red
  • Circuit boards in green
  • Ribbon cable in orange
  • Semi round shapes with a T are digital temperature sensors

post-25795-133877775976_thumb.png

Link to comment
Share on other sites
Starlight 1

Starlight 1

Posted
Posted
It has an mini HDMI output but I haven't checked what comes out of it. Maybe I'll get a mini HDMI cable and check.

I got a HDMI cable for my 1100d try puting it to a laptop but not a thing ,

so it look like the camera is out only and the laptop the same.

Link to comment
Share on other sites
Gina

Gina

Posted
  • Author
Posted
I got a HDMI cable for my 1100d try puting it to a laptop but not a thing ,

so it look like the camera is out only and the laptop the same.

AFAIK HDMI are output only on cameras and computers. You'd need an HDMI equipped TV set to feed it to.
Link to comment
Share on other sites
Gina

Gina

Posted
  • Author
Posted
These are too powerful. You would need to get rid of over 300W of heat. It would be hard to find a heatsink that can cool the hot side sufficiently.
Absolutely! I found the lower wattage Peltiers were much more suitable. I'm using 5v 20W and 12v 50W and I think they may be more than optimum. I can easily get rid of the heat from that combination with water cooling. But I think with even lower power ones it might be possible to use air cooling.
Link to comment
Share on other sites
Reggie

Reggie

Posted
Posted

you know you lot are going to an awful lot of trouble, I just wonder if something like this would be more practical?

http://www.ebay.co.uk/itm/Mini-USB-PC-Laptop-Refrigerator-Fridge-Beverage-Drink-Can-Cooler-Warmer-Red-/380431767586?pt=UK_Computing_Other_Computing_Networking&hash=item5893801822

Don't get me wrong, it's a fantasic idea with the coldfinger and it could still be used, I just wonder if the goal should be to get as cold as possible or to be able to cool your sensor enough with controllable repeatable levels?

Back to the soda can fridge, I wonder what other sizes they do, whether there would be something suitably camera sized? Or whether it could be attached to a different type of box, or whether it's big enough for a camera to fit in? Would most certainly be very very easy to put a philips webcam into one of those fridges :) Also makes me wonder whether it's controllable via usb, if not, a small amount of electronics could turn one of these into a cooler for just about any small camera setup.

BTW. Gina, how are you running that peltier? Are you running it flat out or pwming it? I read that running them via pwm is way more efficient than running them flat out, something about thermal properties that means that someone could run it almost efficiently pwm'd at 12v 6amps vs straight dc 12v 1amp.

Link to comment
Share on other sites
Gina

Gina

Posted
  • Author
Posted

I will be using PWM control but I'm testing at 5v and 12v which is a bit below the max voltage. I have the MOSFETs for the power control and also bits to make the control circuit. What I'm not quite sure of is how to control the 2 TECs relative to each other to obtain the required set point temperature. ie. run one or other at nominal voltage and control the other or control both proportionally. Controlling both from the same PWM generator so they share the control would seem the obvious way to go.

I've found a lower power TEC on eBay - 3.5v 10W which I could run from the 3.3v supply. http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=170696055358

Link to comment
Share on other sites
Gina

Gina

Posted
  • Author
Posted

Disassembled the camera, swapped imaging assemblies, put it back together (except the back) and tested it - all fine :) Now ready to put Peltiers in camera. Here's a photo.

Coldfinger-12.jpg

Link to comment
Share on other sites
Gina

Gina

Posted
  • Author
Posted

More photos :-

  1. Back in place showing the cold finger through the hole where the display was.
  2. 25mm Peltier TEC on cold finger
  3. 40mm on top
  4. Water cooler on top of Peltiers

Coldfinger-13.jpg

Coldfinger-14.jpg

Coldfinger-15.jpg

Coldfinger-16.jpg

Link to comment
Share on other sites
Gina

Gina

Posted
  • Author
Posted
Looking good Gina,
Thank you :)
a few questions.....

What's the grey stuff

The grey stuff is thermal paste - conducts heat but guaranteed electrically non-conducting so safe to cover electronic components. It keeps possible condensation from shorting anything out.
and how are you holding everything in place?

Tony.

I'm still thinking about that.
Link to comment
Share on other sites
Gina

Gina

Posted
  • Author
Posted
Not sure I entirely understand the need for 2 peltier units in there?
Two Peltiers seem to be needed to give enough temperature differential. However, having reduced the thermal resistance from Peltier to sensor it may be that just the one (smaller one) will be sufficient. I need to allow for a heat wave in the summer (if we get one) and still manage -10C at the sensor. That could be 40 degrees C temperature difference - a lot for one Peltier TEC. The cooled CCD astro cameras use stacked Peltiers I'm told.
Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.