Thought I'd better do my own thread on this rather than hijack other peoples.
Been working on a build for the KM 7D, my expendable camera with the IR Mod done. My original plan was to mount a copper slab in behind the sensor with more copper down to a TEC beneath. Fail, not enough room between the steel frame and the rear control\LCD panel.
So decided to come in from the side and under the steel frame instead. Also decided as I wasn't going to attempt sub zero results I'd use aluminium as the finger instead. After copper it is the most conductive element around apparently.
So hacked a huge hole in the steel frame and case and patterned a finger to slide in through that. Good old Duct tape gives some isolation of the components and even secures it within the frame.. Then created a sandwich of the heat sink, TEC, finger and clamp and some Styrofoam insulation. Added a small fan to assist air flow.
I trimmed the rear protruding pins of the sensor from the back of the board to give a bit more space and I'll add the silicon slab as a heat transfer medium, electrical isolation and moisture excluder. It will be ready tomorrow.
Unfortunately this camera does not communicate and I don't know if temp is shown on the EXIF data even but at 5 volts I should be able to knock 10* or better off the internal temp and kill the amp glow in one corner and prove operation.
Pics should give you an idea of the build. The securing bolt goes through an oversized hole in the finger and is shielded inside a plastic tube.
Nice work Brent, I would only make a couple of suggestions. The use of nylon screws and nuts on cold finger attachment points and for through bolting to your bracket will prevent thermal transfer between the cold and warm side , ie improve cooling efficency. Every degree of efficiency helps.
There are plenty of cheap digitial temperature sensors that you could insert onto the finger near the camera sensor, much easier than trying to find exif file data and you can view it in real-time. Finding space for it internally can be a challenge but usually it can be done.
No screws at all in mine Glen, the steel frame and case holds it all in place quite well and there is insulation between the finger and chassis, minimal as there is not much room.
I have yet to add the silicon pad, just received it and that should secure it even further.
Depending on size of the sensor it should be easy enough to get a probe in there. Any suggestion for a suitable model ?
I've tried fitting a TMP36 sensor to mine which are pretty small but it's too large to fit between the sensor and its circuit board, as I'm prototyping I'm reluctant to glue it down.
I have access to the top edge of the sensor\finger as I removed the viewfinder frame earlier to make dismantling easier. Should be able to get some kind of indication from there
But... the camera is being recalcitrant and not starting. It's been hacked around quite a bit so I'm not surprised it may have finally given up the fight. dammitt
I'll shift my focus (ha ha) to the 450D anyway. Having worked on the 7D I feel a bit more confident with an IR mod and Cold Finger. I'll try with Aluminium again but may use that as a template for copper later if it warrants the effort.
I've also picked up a slimmer lighter copper tubed & finned heat sink that looks ideal for mounting off the DSLR. As the company is about to shift to new premises and move the servers to a hosted environment there are all sorts of spare parts no longer needed so I am watching the chuck out bin for resources.
FWIW, while the 450D seems to have a generous gap, the 1100D for example seems tighter. I'm using 0.7mm for my experiment and it's a little tight even with just one layer of insulation tape on the circuit board side.
Brent said he was shifting his efforts to the 450D which is why I offered the 1.2mm copper. I have no experience with the other models so can't comment.
Cheers Glen, I haven't had time to look locally for coppper, my job mostly precludes any extra business time excursions off site.
The copper would be appreciated if you can spare a bit, I'll PM you my address.
From the other thread Dunk is working from the right side of the camera which is something I'm contemplating. I'll probably start with an alum finger as I have heaps of that and then use that as a template for copper. The 7D is still working except for the fact that the connector on the back of the sensor has broken, it has suffered too many of my DIY actions. So it is out of the scene experimentally but has been a good learning tool.
The 450D is now in bits and the IR Mod has been done. Gary Honis's instructions are invaluable especially now that others have offered extra tips. I butchered ... err modified the case in two places to get access to buried screws. A left side screw that holds an earthing strap and the top screw for the sensor assembly hidden behind the viewfinder. Pix marked with arrows for anyone who wants to think about doing the mod. I broke the IR glass (as Gary did). It is very thin and won't be used obviously. Just be careful to clean up as you go, dust, chips of glass, finger prints etc.
Biggest problem is it is full of connectors, heaps of them all over the place. There are connectors under connectors and some are quite short and are hidden up under the top case. Reassembly will have to be taken very carefully and I can see why the left side cold finger access method is about the only really viable option.
Looking good Brent. FYI there is a note in Gary's instructions about drilling out the plastic near the eye piece to gain access to the top sensor frame screw, everyone has to do that. Those thin metal straps are a real pain, esecially that one at the bottom which has some sort of threadlocker in it. Re the ribbon cables, did you draw a line across them with a fine point marker before you removed them? This helps ensure that when you put them back they are properly seated before you flip the locking tab. If you didn't its not a real issue just make sure they are centred and even before locking. Btw, putting those ribbons back on is the hard part, especially the ones at the top tucked up under the body top. A box of toothpicks is a necessity.
Watch the shims don't fall off the posts. The sensor is aligned with those shims so they have to stay on the posts that they originally occupied.
Congratulations, your an expert now, well once you get it back together and power it up!
Shims ..? Oh, ok, I see them, still in place.
OK, so here is the first iteration of the finger in Aluminium. It's longer so I can bend as suits for access etc. I'll mill the holes out one evening, have to set up a base jig to hold it all down, it's only .9mm thick but I see what you mean, there ain't much room in there. Could have done with a few lateral dimensions on the drawing, had to guesstimate some of the hole offsets.
