L/Exp & Peltier cooling - Modifying my ToUcam

[omaroo]

I thought I'd just take the plunge and perform these mods on my ToUcam as described on Ash's Astro Pages, and then provide (hopefully) better images describing the process than I've been able to: 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

Pic 2: The CCD removed and pins straightened.

Pic 3: Extension ribbon attached to CCD

Pic 4: CCD on peltier next to heatsink and fan assembly.

Pic 5: The board sans CCD

[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.

Pic 2: CCD positioning...

Pic 3: Peltier (will have aluminium "finger" laid prior to this in final assembly)...

Pic 4: Heatsink & fan positioned on standoffs...

Pic 6: Mogg adapter screwed in...

Pic 7: Back of unit with switch, leds & heatsink/fan assembly poking through...

[Grant]

Wow! Really impressive stuff Omaroo, I'd love to have the knowledge and skills required to do something like this!

Looking forward to see the completed project!

Best of luck,

Grant

[Cloudgazer]

Neat bit of modding Chris 8).. Look forward to seeing how you get on with the long exposure mod.

Scott

[Whippy]

Nice handiwork there mate, I wish my hands were as steady for delicate soldering job like that!

Tony..

[geppetto]

Nice one, thanks for taking the time to publish pictures and details.

Moved it here as it rightly deserves to be in the astro workshop 8)

Done four LX mods up to now but non with cooling.

What i'm interested to see, is weather the ribbon cables on the CCD introduce

noise (stripes on the image) as it's a sensitive liitle beast.

Great project mate, watching with interest

[beamish]

If successful, I'm sure it will be, any chance of listing parts reqd and suppliers, eg the peltier device.

cheers Karlo

[mpeniak]

Great job and thanks for sharing the photos!

Martin

[Saso]

You make an excellent modification on your camera. Well done.

Saso

[barkis]

Excellent piece of work there.

I hope you have the success you deserve for your effort.

Ron.

[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 of 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

[beamish]

With your admission to just limited tools ,'ave to say I am very impressed , well done. I'll be bookmarking this for use in the future!

Karlo

[Kaptain Klevtsov]

Really impressive stuff Omaroo, lovely engineering job. I really hope it works better than my bodgy modifications as you deserve a result after all your hard work.

Kaptain Klevtsov

[George]

Excellent piece of work, Ive got all the bits here todo the same mod but I keep putting off as i really dont think my hands are steady enough

BTW I was thinking of using a butchered hard disk ribbon for the wireing as this is shielded cable.

[omaroo]

Excellent piece of work, Ive got all the bits here todo the same mod but I keep putting off as i really dont think my hands are steady enough

BTW I was thinking of using a butchered hard disk ribbon for the wireing as this is shielded cable.

Thanks everyone - and upgrader - I think that your idea re; disk ribbon cable has plenty of merit. I'll investigate......

Cheers

Chris

[geppetto]

Wonderful..

Cold fingers crossed mate 8)

[Cloudgazer]

Looking good 8)..

Hope it works after all that effort

[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.

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

[Kaptain Klevtsov]

Superb Chris. I don't understand what you are cooling if not the CCD, I thought that the idea behind cooling was to chill the CCD to keep the thermal noise down?

Kaptain Klevtsov

[omaroo]

Superb Chris. I don't understand what you are cooling if not the CCD, I thought that the idea behind cooling was to chill the CCD to keep the thermal noise down?

Kaptain Klevtsov

Kaptain - 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. The beauty of using cork where I have is tht the CCD is now lightly clamped upwards without severe crushing because the cork has some give in it. It also seals the front face of the CCD off from the condensation (hopefully).

This should explain it a bit better:

Cheers

Chris

[geppetto]

Chris

If you get chance when the camera is finished, I would be

grateful if you would do a same time long exposure with and

without the peltier powered up for noise comparison.

I think that although the peltier will be the ultimate way of cooling,

the cold finger/heatsink and fan alone will be streets ahead of the

CCD in fresh air as per the origional board but less prone to dewing.

[omaroo]

Chris

If you get chance when the camera is finished, I would be

grateful if you would do a same time long exposure with and

without the peltier powered up for noise comparison.

I think that although the peltier will be the ultimate way of cooling,

the cold finger/heatsink and fan alone will be streets ahead of the

CCD in fresh air as per the origional board but less prone to dewing.

Absolutely Philip. 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. 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.

Say - I didn't realise that you were another Nikon D40 user..... and W/O 66mm Petzval owner.

Cheers

Chris

[Kaptain Klevtsov]

Thanks for the diagram Chris. Its all clear now.

Kaptain Klevtsov

[barkis]

May I echo all the plaudits you've had for this project Chris. It will be a success, your effort deserves it.

It is great to see something created in pictorial steps, it is always an inspiration to others who have the ability, but perhaps lack that little bit of confidence. Top marks for an excellent presentation and description.

Ron.

[omaroo]

Thanks Ron. I really appreciate the interest that these sort of projects generate. I love to make things and like nothing more than to share my ideas with those that see some merit in them - it they are useful to them.

Thanks again Ron

Cheers

Chris