Modifying my ToUcam - L/Exp as well as Peltier cooling

[omaroo]

I thought I'd just take the plunge and perform these mods on my ToUcam as described on Ash's Astro Pages: http://astro.ai-software.com/index.php?page=articles/cheap-o_astrocam_III/toucam2.html

All images taken start on the following page on my website: http://www.omaroo.net/index.php?set_albumName=album34&option=com_gallery&Itemid=40&include=view_album.php&page=5

It's a two-step process whereby I've firstly removed the CCD array from the camera's circuit board and will attach it to a heat-sunk and fanned peltier device. I've chosen a 30watt unit which should draw around 4 amps when running. Eek! Big battery required. Second phase will be to carry out the long exposure mod. I plan to re-case the whole shebang in a new plastic waterproof case (images in next post).

First I've removed the CCD array. Applying quick heat to the pins and a sharp knife I was able to gently pry up each leg and straighten it.

Holding it gingerly in a clamp edge-on, I attached 7-core ribbon to each side so that it can then connect back to the board remotely - allowing me to locate the CCD where the back of it can be cooled - on the peltier device.

Pic 1: Lifting pins
http://www.omaroo.net/albums/album34/DSC_05140001.sized.jpg
Pic 2: The CCD removed and pins straightened.
http://www.omaroo.net/albums/album34/DSC_05170001.sized.jpg
Pic 3: Extension ribbon attached to CCD
http://www.omaroo.net/albums/album34/DSC_05260001.sized.jpg
Pic 4: CCD on peltier next to heatsink and fan assembly.
http://www.omaroo.net/albums/album34/DSC_05320001.sized.jpg
Pic 5: The board sans CCD
http://www.omaroo.net/albums/album34/DSC_05390001.sized.jpg

[omaroo]

The case.

I thought I'd start on the case now as well. I bought a plastic jiffy case that is 115mm long by 65mm wide by 40mm thick. It has a grometted seal and the two halves are held together by 4 recessed stainless screws.

I drilled a hole in the base - just off centre (to allow for the placement of the CCD) and screwed in my Mogg adapter, which made its own thread. Great fit and very sturdy. Secondly I carved out a square hole to accomodate the fan and heatsink assembly. It protrudes through the case for better cooling. I plan to drill a few neat holes top and bottom to allow for condensation to escape if it can. This is why the switch gear and electronics will remain set up high in the case.

I placed a SPDT switch above the fan to allow me to switch between normal (AVI) and long exposure. I've yet to fit the 25-pin male parallel plug and I'm also going to fit a female USB port so that I can do away with the ToUcam's permanently attached cable.

Tomorrow I'll do the L/E mod wiring - for which I bought a small roll of the old "wire-wrap" wire - which is brilliant for this task. It's very thin, single core and insulated by a very thin and flexible sheath. Can't wait!

Looking OK so far....

Pic 1: Base half with hole drilled and Mogg fitted.
http://www.omaroo.net/albums/album34/DSC_05470001.sized.jpg

Pic 2: CCD positioning...
http://www.omaroo.net/albums/album34/DSC_05480002.sized.jpg

Pic 3: Peltier (will have aluminium "finger" laid prior to this in final assembly)...
http://www.omaroo.net/albums/album34/DSC_05500004.sized.jpg

Pic 4: Heatsink & fan positioned on standoffs...
http://www.omaroo.net/albums/album34/DSC_05520006.sized.jpg

Pic 6: Mogg adapter screwed in...
http://www.omaroo.net/albums/album34/DSC_05340001.sized.jpg

Pic 7: Back of unit with switch, leds & heatsink/fan assembly poking through...
http://www.omaroo.net/albums/album34/DSC_05540001.sized.jpg

[phoenix]

Hey omaroo.

What a excellent and professional job. How much are they, I'll have one.:Chessy_Smile:




Cheers Jason.:pipethinker:

[AstroTasmania]

Hi Omaroo,

Very nice indeed, I did something similat to a StellaCam EX video camera, using the same Peltier device. I also put a home made watercooled heatsink on the hot side to a speed controlled pump. I built a contrller also for the Peltier so I could ramp the Amps from nothing up to what I wanted,

I used a temp probe near the CCD to see what the inside/outside temp was. Too cold & I had frost on the front of the CCD window. I found about 10 degrees C below ambient was all I needed, and whan finished just ramped the Amps down slowly so not to shock the CCD.

You will find that the CCD lasts a lot longer by ramping up and down slowly then turn the Peltier off and leave the camera on for a while to get to ambient and dry off.

Link to my video cam mods. http://picasaweb.google.com/AstroTasmania/AstroVideoCamersSCO

Good luck with the project &
Clear skies...
Shevill

[Radar]

Nice work Chris, be interesting to see a before and after image (of a DSO that is).

What exactly does the Peltier do?

Cheers

Ray

[omaroo]

Nice work Chris, be interesting to see a before and after image (of a DSO that is).

What exactly does the Peltier do?

Cheers

Ray

Thanks Ray. As soon as it's operational I'll try and get it mounted to a known good tracking scope within our club abd take some long exposures.

A peltier device is basically a "heat pump". It moves heat from one of its surfaces to the other. If you take a warm object and pump heat from it, it becomes cooler. With this device you have a heat sink on one side, and when energised correctly (it's pump effect is directional dependant on current direction) it literally pumps heat from one side to the other and into the heatsink. This leaves the other side of the device colder than the one being pumped to. You mount a "finger" of aluminium on the cold side, with the CCD attached to that, when you turn it on you get a cooling effect at the chip as heat is being pumped from it. Less heat, fewer excited pixels, better photographs :)

[Radar]

Less heat, fewer excited pixels, better photographs :)

Awesome mate. You are a DIY guru! :thumbsupmate:

I learn heaps by watching you DIY guys build stuff.

Cheers

Ray

[floreatfocuser]

Hi Omaroo,

I used a temp probe near the CCD to see what the inside/outside temp was. Too cold & I had frost on the front of the CCD window. I found about 10 degrees C below ambient was all I needed, and whan finished just ramped the Amps down slowly so not to shock the CCD.

Shevill

I have built a peltier cooler and controller for my dsi Pro. Was wondering where you got your temp probe from/ how you buil it, as I would like to put one near my ccd.

Thanks for your help

Andy

[omaroo]

Thanks so much, everyone, for your kind words of encouragement thus far! :)

I continue-on with what I though was going to be the hardest to get right - the mounting of all the cooling hardware. I don't have access to milling machines, lathes or fancy drill presses. All I use are electric hand-held tools, a hacksaw and a flat file.

I've used 4mm aluminium strip sheet to fabricate the bottom mounting plate, CCD tunnel as well as the top finger plate that presses against the peltier. The peltier sits on top of the finger and is clamped down snugly by the heatsink - which I've drilled and tapped so that the four screws from underneath can screw up through the set of plates and into the heatsink. The bottom plate has a countersunk (45 degree-bevelled) hole in it through which the CCD pokes. I've painted it the whole plate matte black so that there is nowhere for stray light to bounce around in. The plate sits on the four threaded sleeves in the bottom case of the jiffy box.

With the 30w peltier running, the first test proved that the heatsink got very warm without the fan and stayed cooler with the fan running. The cold finger and CCD tunnel was VERY cold.... and without humidity in the air it remained dry. To the touch it filt like it was almost about to freeze. Yay!

I bought two peltier devices - one 30w and another rated at 60w. I'll do some experimentation in realistic conditions when I've finished this project to determine which I'll stay with. I can swap them over fairly quickly, so it's almost easy enough to do in the field.

Next - the wiring-up. I'll get that done over the next couple of days - stay tuned :)

http://www.omaroo.net/albums/album34/DSC_0599.sized.jpg


http://www.omaroo.net/albums/album34/DSC_0603.sized.jpg


http://www.omaroo.net/albums/album34/DSC_0604.sized.jpg


http://www.omaroo.net/albums/album34/DSC_0605.sized.jpg


http://www.omaroo.net/albums/album34/DSC_0606.sized.jpg


http://www.omaroo.net/albums/album34/DSC_0608.sized.jpg

[Radar]

Looks awesome Chris. Did you have some images taken with this ccd prior to the mods?

Cheers

Ray

[omaroo]

Thanks Ray :)

The only thing that I've used it for (see image) so far is lunar. I haven't had the opportunity of having the long exposure mod alreay done to tackle DSO's... which is what I desperately want to try with it.

Cheers
Chris

http://www.omaroo.net/albums/album36/MOON_010507.jpg

[omaroo]

Thanks guys - cheers and thanks for that.

I've added a new layer of 2mm cork between the tunnel edges and the front mounting plate. The CCD pokes through a hole on the cork. I reckon that this will at least shield the front plate, and therefore the CCD face from the cold. I'll investigate covering the rest somehow soon. I've just screwed it all together for good, and so have applied the thermal grease to all plate surfaces as well as the back & sides of the CCD at this point (now that I know it all fits together.

Cheers
Chris

Pic 1: 2mm cork gasket between the tunnel fingers and the front plate to hopefully stop the front surface of the CCD from getting too cold, and to keep the front plate from generating it's share of condensation.

http://www.omaroo.net/albums/album34/DSC_0614.sized.jpg

Pic 2: The front plate painted black, and now you can see the CCD through the aperture.

http://www.omaroo.net/albums/album34/DSC_0613.sized.jpg

[Radar]

So the cork is used for stopping the ccd from dewing up? If so what about using a dessicant ring?

Great project mate.

Ray

[omaroo]

So the cork is used for stopping the ccd from dewing up? If so what about using a dessicant ring?

Great project mate.

Ray

Ray - the back and sides of the CCD are still in direct contact with the aluminium "finger" above it. The front plate is in front of the CCD, so I've isolated that plate with the cork. The little piece of cork that you see over the ribbon cable is just a small piece I've used at either end of the tunnel to clamp the wires down.


This should explain it a bit better:

http://www.omaroo.net/albums/album34/CCD_cooling.jpg

Cheers
Chris

[Radar]

Okay, that makes sense. I wasn't sure how the cork was going to work in there. Woops.

Ray

[omaroo]

I built a contrller also for the Peltier so I could ramp the Amps from nothing up to what I wanted,

I used a temp probe near the CCD to see what the inside/outside temp was. Too cold & I had frost on the front of the CCD window. I found about 10 degrees C below ambient was all I needed, and whan finished just ramped the Amps down slowly so not to shock the CCD.

You will find that the CCD lasts a lot longer by ramping up and down slowly then turn the Peltier off and leave the camera on for a while to get to ambient and dry off.

Shevill - I have built a variable pulse width controller for my dew heaters which will easily supply the current required to run the 30w peltier. Only thing is that it is, of course, a variable on-off-on-off stop/start type of supply versus a linearly variable, constantly on supply. Would it still, in your opinion. work? I'm guessing that it wouldn't hurt to try it. I would still want to run the fan constantly though.

Cheers
Chris

[omaroo]

Wow. My eyes are aching after doing this latest wiring. They weren't kidding when they said "small". The D16510 is a TINY surface-mount chip that I decided to left the legs on where needed, and soldered to both the lifted pins as well as the pads underneath rather than tracing the pads out to a via point.

The use of some old wire-wrap wire was fantastic as it is just so much thinner than a ribbon cable strand.

I've connected power and, after mounting the board properly, I've also connected the CCD back up again. Fiddly, fiddly, fiddly!

Next I have to complete the piggy back board, cut it out from the rest of the protoboard and wire it up...

It may just make first (or is that second) light tomorrow evening.

http://www.omaroo.net/albums/album34/DSC_06750001.jpg

http://www.omaroo.net/albums/album34/DSC_06820001.jpg

[Radar]

Nice job Chris. I know the pain that comes with surface mount soldering. It will be awesome to see second light from this unit over the next few nights. All the hard work will pay off I'm sure. Also please post a comparison of before and after images so we can see the diff.

Cheers

Ray

[omaroo]

Thanks Ray. That's exactly what I intend to do. I suspect that the heat dissipation is going to be markedly better by virtue of the fact the CCD is in contact with the upper finger and tunnel anyway - even without the peltier functioning. What I'd like to do is do a comparison of the 5 following scenarios:

1) All off (heatsink only)

2) Fan on

3) Peltier on

4) Peltier & fan controlled by my variable pulse-width dew heater controller (less thermal shock to the CCD)

5) Peltier & fan - full on

Should make for interesting discussion.

Cheers
Chris

[Radar]

Hey Chris,

Any new shots from this camera yet?

Regards

Ray