Glen. I have been a little forgetful on this point, and you are correct. Rather than pull it all down I will leave the sacrificial patch. The system does 28C so I'm not overly concerned about the losses.
A few more pics to come with the heatsink and battery grip controller housing installed.
What I really want to do, is 3D print a shroud to fit between the back of the heatsink and the body. That would be a nice finishing touch. Brent has inspired me with his 3D pressure plate.
Glen. I modified the side panel to fit around the CF, both sides. It fits nicely still using the original screws. The rubber cover got a workover to light seal the USB and video ports.
It was getting late and I'll post some pics tomorrow. Only downside is reprofiling the cooling curve. Strangely it's a little different to the 1000D. But it might just be the power supply I used this evening.
Thanks for those latest pix Rowland. Starting to give me some confidence about modding the 450D. Still like to get another camera, 450D or 1100D so I can continue to image when the clouds cooperate of course.
I also have my water damaged SONY A77 which still works but has a weird pattern occurring in long exposures. It's ok to use for normal daylight stuff and moon pix and movies but anything longer than a few seconds and I get coloured dot trails wandering across the frame. At 24 megapixels and high ISO it would be fun to have available. An IR mod on that could be fun but it is still useful as a backup to it's replacement in an emergency. Or it still does good movies.
Back to TradeMe to watch for bargains, hobby fund has recovered somewhat after my lathe\mill buy.
No worries, Brent. The most sensitive component is the main board - use gloves.
A few more pics. Reconfiguring the cooling curve. It's a little different to the 1000D and needs more energy to achieve setpoint.
Decoding the OLED output most of which is for troubleshooting and of no value otherwise.
TMP - the analog value of the cold finger, which should match the TGT. Higher resolution than Celcius.
AIR -Celcius
SET - Celcius
CF - cold finger Celcius
DIFF - analog difference TMP and TGT
LO - TEC power off milliseconds
HI - TEC power on milliseconds
>T< on setpoint, otherwise UP> or <DN handy for aging eyes
You guys do a sensational job of making me believe this is achievable but I honestly don't know if my ham fisted approach will work for this mod. As much as I want to cool my 450D I think I'm going to have to really really think before I act in haste. I am certain I could make a cooling box but quite uncertain about this. Hahah. Maybe I'm just being a sook.
Alex. The camera is quite basic and the same precautions observed as for spectrum mods.
As for the rest - many hours getting it right. Don't be in a hurry. The electronics package integrates a number of features into the battery grip without the need for a lot of external bits and pieces, but you don't necessarily need to do that.
Yeah I thought the battery grip was a particularly good idea for housing electronics.
My biggest worry at this stage is
A. Making the cold finger. I'm good at making things but this is slitting into some pretty tight spots.
B. Stopping the sensor from frosting over.
If I only want an absolute sensor temp of say 3 or 4c will I have to seal the camera or will a nichrome or resistor warmer on the sensor be enough?
Alex I have not found frosting the sensor to be a problem. The sensor generates some heat, which the cold finger removes. Condensation is more likely on the front anti-alysing filter if you have left it in place, or any clear replacement that fits the holder frame - like the Astronomics ones. Rowland has heated his to control that, and I use Argon to control it in mine - either way can work. I am no where near Rowland's electronic and software capability so I rely on simpler external control system that anyone can put together and it requires no software. If you follow Rowland's cold finger template it will fit. Nothng ventured nothing gained - or lost in relation to heat. 'You can do it Bennant' to quote Arnie. We're here to help as well.
Alex. If you aim for 5C it is possible to stay out of the condensation/icing range, unless the humidity is particularly high. A degree or two makes a big difference. I found 7C a good compromise on dewy nights with an earlier prototype.
With 10C and 5C as presets or ball park depending on humidity, the results will be quite OK. No need for complex power scheduling to a heater. Having said that an argon bag will let you go subzero, no problems. I just find the heater convenient for the time being.
Perhaps we should write up a detailed step by step. I have some rough notes. Guidance - pick what you want out of it. Glen may want to add to the pool and suggest improvements. This should get you started.
I have no filters in front of the sensor so that's handled I guess. I was considering using a clip in ha filter... Is it likely that the clip filter would condensate? If so I wonder how I would control that. It would be hard to heat that... I might be able to use the drop in filter on my lens fr a 36mm ha filter but that might only move the problem into a trickier spot.
Possibly if I heat the rear end of the lens body to add warmth to those internal elements.
If you keep the cold finger temp around 5C or more you wont need heating. In which case the clip-in wont be affected. If you are concerned about condensation you could reinstall the sensor filter frame and sit a kapton wrapped resistance heater on that.
How are your dark frame tests? I've read online sensor temps between 7 and 3c show little difference in thermal noise and at 3C apparently the dark frame was essentially the same as a bias frame..
I'm not concerned about a little bit of noise, as long as it's manageable and I can replicate temps and build a dark library.
This is the latest update to the electronics. I noticed some very fine switching lines in images not present in the prototype, which had large copper planes on all the pwm pins and mosfet gates
Scaling down to fit the battery grip seems to have reintroduced interference. To be doubly sure, I added a decoupling capacitor and a pull down resistor to the mosfet gates (1nf, 1M) as well as a decoupling capacitor to each microprocessor pwm pin, which in the prototype wasn't required - no more lines. This was all tested with a circuit simulator and bread board, and seems fairly close to the simulation.
EDIT: added a 3D IDF created using simplifiedsolutions online program. Not exact but close. Had go with closest size match on a few parts here and there. The top right "I" shaped protrusion is snapped off and mounted perpendicular to the main board to connect camera power.
Added the schematic - sorry, it's not up to professional standards.
Summer waits for no man....so it's time for me to embark on my voyage of camera modification
My 1100D seems to give me pretty clean subs at ambient temps of 5 or less, so I think for v1 I'm going to attempt that range and see if I can avoid creating a condensation issue.
One design thought I've got bouncing around is that the rear screen is essentially redundant these days as the camera is always tethered to my laptop, so is there any sensing logic in the camera that makes it non-functional if the screen isn't there?
What I'm thinking is that if I remove the screen then a large hole suddenly appears in the back of the camera, and I can get away with a smaller cold finger, just a U-shape from the sensor and bending where necessary to present itself at the screen-free aperture at the rear. The TEC and heatsink/fan can then be attached there.
Dunk there is a guy in Singapore that stripped a bunch of stuff out of his camera in order to squeeze it into a cooler box, and the back was removed. I believe the CentralDS guys have some cameras where the internals have been moved into a small cooled case and they are PC control only. You would lose all the button controls on the back but not sure if that's a problem.
Thanks Glen, I've no use for the buttons when it's under computer control. I use APT and it is pretty obedient I would of course keep any parts I removed in case I needed them...
The first thing I need to do is to open it up and see how much of this golden information is translatable to the 1100D. With any luck, it won't be all that different.
