KronTalk
Chronos => Chronos User Discussion => Topic started by: Nikon1 on November 02, 2020, 09:01:12 AM
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Has anyone yet messed around with the Cooling solution on the Sensor? 1.4 or 2.1?
I am currently thinking about Replacing the Stock Aluminum Sensor Heatsink with Copper on my 2.1, which should allow for noticeable better Cooling performance on the Sensor itself.
Would be interresting to see if that would help with noise.
Allready took all the needed Measurements for the Heatsink block today, and also managed to get some 30x10 Copper Bar Stock.
So, anyone got any ideas about this whole thing? Things to test to figure out performance differences or details to keep in mind for a project like this?
If anyone from the Krontech team, who has access to the Blueprints and actuall Measurements could confirm if my measurements are about correct, would be also very nice.
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Peltier module coupled to the heat sink 8) ?
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Peltier module coupled to the heat sink 8) ?
Also had that idea, but there isnt really space for that, sadly.Backside of the Heatsink will cool the Main processor, front side of the Heatsink block will cool the Sensor (the 9x12,5mm Surface and the Pad), so there is 4mm of space in between there, and Heat coming from both sides, so peltier wouldnt really work. Best thing you could do is propably Heatpipes and attatch some more beefy cooling solution elsewhere, somewhere where more space is inside there. But Heatpipes are quite a bit of effort, and i never messed around with custom heatpipe Cooling untill now. Copper i can do...
Also allready thought about Making it better and adding More surface area to have contact with the Moving air or even Water cooling, but that will add a ton of work...
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on this flange focal distance drawing you can see a cross-Section of the Heatsink, its just in between the Circut boards there. There isnt really that much space, sadly...
https://www.krontech.ca/wp-content/uploads/2020/02/Flange-Focal-Distance-Chronos-2.1-HD.pdf
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Peltier module coupled to the heat sink 8) ?
Had to think about this a bunch more, and think, Watercooling would propably be the easiest and most effective way to go beyond the Current, basically Passive Sensor Cooling.
Tricky bit is to get some very tiny tubes in there. Also pretty scary to have water runing around inside the Camera, but i guess no risk, no fun. Idea is to basically just drill a 2mm hole across the short side of the 4mm "base" of the Cooler and Solder on some 4x2mm Copper or Brass tube, and run water through there. with an 2mm Inside Diameter, there wont be that much volume of water moving trough anyways, unless you put a lot of pressure, so i would go with nice Cool water straight from the Tap, should give about the best cooling performance i can think of right now without a ton of effort or actually Hardcore Modding The Chronos, which i am not willing to do. This kind of cooler can still be swapped back to the Stock one.
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Well I wouldn't go for water cooling, although switching the aluminum passive cooler for a copper one, with proper sanding and polishing on the contact surface and a proper thermal paste (it's an adhesive right now, need to study better options for that part) should be the best option for a passive cooler.
I'm not very familiar with the inner parts of the camera yet, but passive coolers get hot really fast, so, unless there's a good air flow inside the camera, switching for copper won't be so beneficial. Assuming a good airflow it shoud drop the sensor temperature on a few degrees celsius.
I would love to see the technical drawings for the cooler, I'd get it done.
Sorry for my English :)
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Well I wouldn't go for water cooling, although switching the aluminum passive cooler for a copper one, with proper sanding and polishing on the contact surface and a proper thermal paste (it's an adhesive right now, need to study better options for that part) should be the best option for a passive cooler.
I'm not very familiar with the inner parts of the camera yet, but passive coolers get hot really fast, so, unless there's a good air flow inside the camera, switching for copper won't be so beneficial. Assuming a good airflow it shoud drop the sensor temperature on a few degrees celsius.
I would love to see the technical drawings for the cooler, I'd get it done.
Sorry for my English :)
I posted my measurements above, those should be reasonably accurate.
It also isnt really Thermal Adhesive, its a pretty thick thermal pad.
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As i posted in an other Thread yesterday, i just replaced the Stock fan with an Noctua one, and am not yet done with Temperature testing, but from what i can tell from now, the 11% less airflow on paper for the Noctua will result in about 4 to 5°C increase in Temperature with partially blocked intakes and a little less difference with fully open intake holes. So the Static pressure of the Stock fan makes a bigger difference if something is in the Way of the Airflow. I am also planing on putting an 40x40x28 (Will need to be mounted outside the Camera Body) High RPM, High Static Pressure Server fan on there to test if MORE Airflow does actually help a lot with cooling. The one i found laying around has DOUBLE the Airflow compared to the Stock Fan of the Chronos, which should show some noticeable difference, if airflow had an huge influence on Sensor Temperature. The Noctua Fan Mod i did there is mainly because of the Noise. Now with the Noctua its so silent, i actually forgot that i had it just sitting there on my desk running while temp testing, which absolutely wont happen with the Stock fan...
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The Thing about the Watercooling is, i can easily force the sensor to below room Temperature, at a constant temperature. I will not go down below dew point, because for obvious reasons i dont want to deal with water condensating on the Outside of the Cooler, but just above that should be fine. Aiming for something like 15°C Heatsink Temp, which should work out to 20°C or well Below for the Sensor itself. Right now, sensor Temperature is sitting somewhere between 45 to 52°C for all the Testing i did at 21,5 to 25,5°C Room Temperature with the different Fans and sometimes partially blocket ventilation holes. Purpose of reaching such a low Sensor Temperature is to find out if Temperature will have a significant impact on Image Quality, more specifically Noise Levels and Dynamic range. Keep in mind, i could also run hot water through there, Turning it into a Water-Heating-Block. So i can easily test a huge Temperature Range with very stable temperatures.
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Actually using some kind of water-Cooling Setup in the Camera for Daily use isnt very practical and i also wouldnt reccomend that.
But the Copper Block is propably what i will end up using. I assume that just replacing the existing Aluminum Sensor Heatsink with Coper Material in the Same dimensions will proppably make back the few °C i lost with the Noctua, which would allready be huge, so same Temps as a Stock Chronos but Way more silent, without any crazy solution. Replacing a Fan and using a different Material for the Sensor heatsink isnt that crazy to do, and i can even realistically See Krontech maybe even doing this at some point in the Future for their cameras, if it turns out to be working well, isnt that mutch more Work/ effort to do.
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As of now the Cooling of the Sensor itself is technically actually partialy passive cooling (The Camera body itself takes away a lot of the Heat from the Sensor itself, which is of course somewhat cooled by the Fan. I think the Fan is mainly there to also make sure nothing else in there overheats.). This little Heatsink thing shown there is more or less just a "bridge" for the Heat to then go into the Metall body of the Camera. Of course A lot of airflow will lead to better cooling, since there is still a ton of surface on the Camera body itself and also a little bit on the Heatsink itself, and also on the Sensor and Circut boards. But there isnt really fins or something to really increasy the Surface Area to get the Heat away there more efficciently. Speaking about cameras overall, this is pretty much allready Way better Sensor cooling Than About any "usual" Video Camera or DSLR/DSLM has (Metall body with an Actual heatsink connected to the Sensor AND an fan!), but that Sensor in the Chronos is also doing way more serious work than most of those Sensors, and because of that also puts out a lot more Heat.
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I might even go as far as to Modify the current original design by Krontech for the Sensor Heatsink a bit and add fins (There Seems to be quite a bit of space for Fins or someting) or even Heatpipes (actually found some Heatpipes laying around in my pile of old Server cooling and got to play with them a bit, seems doable, but certainly tricky to do in such a small space, but would help a lot to get away the Heat FAST there) for my own Camera, but for sure no Watercooling of any sort. Not even I am that crazy to go with a Watercooled Chronos for Daily use....
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About Lapping the Heatsink, sure i could get that done or do it myself, but i think i would start at replacing the Fat Thermal Pad between there first, since with that in between there, this seems like a waste of time. Or at least replace it with a thinner one, if you want the best possible cooling solution. But that would in turn mean that you would need to Modify the Dimensions, which i dont want to do for the Contacting surfaces. An other Problem with getting good contact there is, that you dont have any kind of Spring Loaded Mounting there like you usualy have on an CPU/GPU-Style Cooler. This Little Heatsink Thing is Straight up bolted to the Camera body itself. So if you get anything just a little bit off or missaligned, bad things will happen. So the Thermal Pad Kind of needs to be there to allow for Some Imperfections and Tollerances and also Mounting. If you wanted to go with an direct Metal-to-Sensor Contact Style Cooling, you will need to come up with an completely different cooling concept, which i dont really need or want to do, unless it turns out, Temperature Matters a lot for noise, then this idea is maybe worth to think about more.
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#EDIT:Grammar
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You're pretty much on top of everything, I've read your post about the Noctua fan, nice to see the results.
Lapping the cooler won't do any help because of the thermal pad, correct. I probably didn't make myself clear in my previous comment, but I meant that it would be preferable to pick a thermal pad with a better conductivity (Gelid has some fancy ones last time I looked)
I like the idea of carving fins.
Also, from what I read, a lot of the problems in image quality derive from heating, so you need to keep doing black calibration every now and then...
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You're pretty much on top of everything, I've read your post about the Noctua fan, nice to see the results.
Lapping the cooler won't do any help because of the thermal pad, correct. I probably didn't make myself clear in my previous comment, but I meant that it would be preferable to pick a thermal pad with a better conductivity (Gelid has some fancy ones last time I looked)
I like the idea of carving fins.
Also, from what I read, a lot of the problems in image quality derive from heating, so you need to keep doing black calibration every now and then...
Yes, a better Thermal pad would also be very good improovement. Need to do some Research though, cause i am not really that much into Thermal pads tbh. I know a bit about thermal paste, but no expert in that field, but Thermal pads i know very little about. Never actually bought any so far, but worked with them, if they where allready in whatever Devices. Also i dont know what is even in there right now. I expect some rather generic thermal pad with an reasonable price-Performance value, which still performs pretty good, but for sure nothing overly fancy. I am sure, there are better ones, but would have to find out about what that would be then.
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Carving finns would need to increase the Size of the Heatsink by quite a bit to even have anything to Carve into. There is room, so i think i will end up doing it. However, i will start to do an 1:1 reproduction of the Original one to get an propper comparison Value. Going Straight with a Heatsink with fins would be somewhat unfair. From the 1:1 Copper one, i will see how much room there is to extend Fins out of the Block itself.
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There are a bunch of problems with Image Quality. First of all, there is everything that isnt really Temperature, that would be Signal Processing and optimisation of Readout. Those Lines that can be very visible are mostly that i assume. Temperature wont affect those things not that mutch, if at all. They are caused by different things, and as i heard, should be improoved by an next little bit with the upcoming Firmware Update.
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Then There is Random Sensor noise. That one is actually Highly affected by Temperature.
And then there is also The Combination of the Two, when the Camera tries to remove all the Weird stuff the Sensor does for different Reasons. Main Problem Here is, that Temperature usually changes a lot, especially if the Camera is just Turned on. As i Said, quite a bit of the Cooling is Passive also, and Since the Body is a huge Billet of Aluminum, this thermal Mass first needs to get up to temperature bevore it stabilizes into an Equilibrium. From all the Testing i did, after like 1 to 1,5 Hours the Camera reaches a Very stable temperature, which only deviates by 1,5°C or less, if Room Temperature is constant. Up until a Stable State is Reached, Temperature allways Changes noticeable, even in the Short time from Doing a Black Calibration to actually starting a Recording. If you do an Black Calibration once its on a Stable Temperature, The Calibration usually doesnt run away from the actual sensor Noise that much or will even Stay where it should be. Still would propably not hurt to do a Black Calibration every now and Then when Shooting for Hours, even when warmed up.
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While now the Lines and Weird Stuff is propably mostly Software, and the Exposure/ Sensitivity and Random Noise is mostly Temperature CHANGE, there is yet an other problem, Absolute Noise Levels. When the Camera needs to adjust for More Noise or just basic different exposure for different pixels/ Rows (which gets worse the hotter the Sensor runs), it needs to bend the Values from the Sensor More, then if it had not to do that by that much. As a result of the Heavy adjustments the Camera needs to do for an Hotter image, even if it gets rid of most of the weird looking stuff, it will still mean a lower Dynamic Range as a result (At least in theory, this is kinda the Point of this whole project to find out, How much difference it really makes in the Real World, cause in Theory Colder (A very Constant "cool" Temperature, big problem with "good" cooling is, that the Camera will get very "quick" and responsive to enviromental Temperature Changes, as Heat is exchanged a lot faster, and as we learned earlier, even a few °C can Cause a big difference in Noise and Exposure, resulting in very visible Noise or other Image Artifacts. Because of this, the Huge Thermal Mass of the Chronos Camera Body is actually pretty good for Image Quality, once it is heated up = Has Reached A Stable Temp.) Overall Temperature Level should have Less Noise, and because of that also Higher Dynamic Range.
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Today i finally got around to start Milling out an Copper Heatsink, but sadly i messed up with one Measurement on the Contact pad for the Sensor when rough-Milling, and now its a full Millimeter to small, so i have to start over again another Day. Surface finish i am Getting on the Finished Surfaces themself, is so good that i would not even Bother to do any grinding or Polishing on them For now. But first i need to make one in the first place, without reading the dimensions from the wrong pad...
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I am really impressed by this project and very curious how the image noise will be affected. Great work!
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Today i finally got around to start Milling out an Copper Heatsink, but sadly i messed up with one Measurement on the Contact pad for the Sensor when rough-Milling, and now its a full Millimeter to small, so i have to start over again another Day. Surface finish i am Getting on the Finished Surfaces themself, is so good that i would not even Bother to do any grinding or Polishing on them For now. But first i need to make one in the first place, without reading the dimensions from the wrong pad...
Nice job! Keep us posted, curious for the temperature tests!
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Quick Update:
Finally got around to making another one, which is now to size for the Critical Dimensions. Kind of messed up again, the 2.0mm Drill i used to predrill the Holes broke on the Second Hole, so i had to mill it out with an Carbide endmill, and the Hole ended up about 0.4mm oversized in Diameter. But since this is just a Clearance Hole for an M3 Screw, its no problem.
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I also got myself a bunch of pretty fancy Carbide endmills and was able to improove the Surface Finish on the Contact surfaces by quite a bit. its now about as Close to an Mirror Finish as i will be able to get on my old Manual Mill.
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Here is an other Quick update, made some tiny custom Connectors for the 2mm OD Brass Tube that is planned to be used for the Watercooling Tests, to fit inside the Little Space between the Circut Boards.
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Still quite a bit of Way to go untill it is finished, Still need to mill some Channel into the Copper cooling block itself to connect it to the Tube and connect all of that Stuff together (also probably still need at least one more Of the Bigger Adapters made and find a way to attach a Temperature probe to the Incoming Cooling Water, and idealy also make some Clamp to Mount all the Stuff on the Outside of the Camera, so the tiny tubes wont break from the Weight of those big connectors and the 10mm ID Hose that will go onto it).
Initially i tried to get away with just using straight up 2mm Brass tube without any soldering, bent from a single solid piece, inside the Camera and only have some Kind of Connectors on the Outside to be absolutely save from Any potential Leaks inside the Camera. But that sadly didnt work out, even after quite a bit of trial and error. Just couldnt produce clean Bends as tight as i needed to reliably, so i chose to go with (some admittedly pretty overengineered, but i really dont want to risk any Water leaks inside there...) 90° Connectors, so i will only have to use Straight bits of tube without any bending (hopefully, or at least avoiding the Extreme Bends, if i still need to do any bending at all). Those will be Soldered when everything is ready for Assembly.
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So, i made an Small Waterblock today to fit an TO220 Size Resistor. for once as a Proof of Concept for the Final Test Cooler for the Chronos to see how well this kind of Thermal design will handle the Expected Thermal Load, and also to see how difficult it will be to drill such a small and Deep Hole. Allready very happy, i did an Testpiece bevore doing this to the Actuall cooler itself, because i broke at least 6 or Something drills trying, which all got stuck way inside the Part and are impossible to get out now. Turns out, drilling a 30mm Deep and only 2mm Diameter Hole is seriously hard to do.
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Resistor is one of those:
https://asset.conrad.com/media10/add/160267/c1/-/en/001624828DS01/datenblatt-1624828-tru-components-tcp50u-a3r90ftb-hochlast-widerstand-39-radial-bedrahtet-to-220-50-w-1-1-st.pdf (https://asset.conrad.com/media10/add/160267/c1/-/en/001624828DS01/datenblatt-1624828-tru-components-tcp50u-a3r90ftb-hochlast-widerstand-39-radial-bedrahtet-to-220-50-w-1-1-st.pdf)
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So, an 50W rated Resistor In a TO220 Package, i ordered an 3,9 Ohm one, so it will output about 36,9W of Heat when i feed it with 12V Power (Given it is rated at 1W in Free Air without any cooler attached, i guess it will dissapate up to 1W on its own Surface Area, so the Heat it pushes into the Waterblock would propably be closer to 36W), Which is close enough to the Maximum Heat output i expect from the Sensor itself and the other Big Chip that Cooling Block is also Cooling on its Backside (according to The 2.1 Datasheet, Power input is given as 40W, and considering that also includes the Fan, the display and all the Other Electronic parts inside the camera (maybe also includes some amount of power to charge the Battery when empty), 36W is really worst-Case Scenario for Sensor+The other chip, i assume it should be quite a bit less than that actually, but i dont really have any other data, so just to be sure, test it with 36W input, if that kind of whaterblock design can handle that much heat, it will be able to cool that camera).
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Will still need to wait a bunch of days for the Resistor to arrive, so i just took the next best thing i found laying around in an TO220 Case to get the size right, which happened to be some random used Voltage Regulator, will be replaced by the Resistor whenever it gets here.
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Some Flowrate Testing bevore Soldering. Current Flowrate with the Straight Tube System is 0,9L/min, which will propably go down a bit when all the 90° Bends are added into the Path of the Water cause increased Flow Resistance.
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Can get Inflow Temperature down to around 13°C, but start to get some Condensation Starting from 15° down on some Parts, so for Test use inside the Camera i will either need to stay above 15°C for the Water Input or do some Air drying or something (or get Ambient Temperature lower, which would also eliminate Risk of Condensation). Still waiting for the Resistor to arrive, to test with an known constant Heat input, but i got a good feeling about the Thermal performance overall.
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If it turns out that this will not be able to handle the 36W Heat input all that well, i can still use Multiple Water Channels inside the Cooler and Double the Flowrate (using them in parallel), which should theoretically almost double Cooling Performance. Temperature Target for this test setup would be slightly Sub-Ambient Temperatures on the Sensor itself, so i dont need to deal with Condensation / insulating the Electronics against water, which should be possible to do with this Cooler design.
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Resistor arrived, and cooler seems to hadle the Heat pretty well. Have no propper Setup for a Temp Readout on this cooler Block, but it feels somewhat still cold to the Touch, even after like 30Min running, i would assume Block Temp at around 25°C (at 13,4°C Water Temp), so successfull Test. Means This should easily be able to handle the Heat output from the Sensor even with only a Single Brass inlet.
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Watching the video on YouTube, I realized that on the radiator that cools the camera sensor, it is flat without ribs that would help the sensor to cool more intensively. Now in the 3D program I tried to develop external cooling for the camera with a more powerful cooler (4000 rpm 60 * 60 * 15mm) with the installation of a dust filter and cooler protection. But the question arose of how you can add fins to this radiator or how you can replace it with the same size but with fins
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Watching the video on YouTube, I realized that on the radiator that cools the camera sensor, it is flat without ribs that would help the sensor to cool more intensively. Now in the 3D program I tried to develop external cooling for the camera with a more powerful cooler (4000 rpm 60 * 60 * 15mm) with the installation of a dust filter and cooler protection. But the question arose of how you can add fins to this radiator or how you can replace it with the same size but with fins
https://vk.cc/bX9SD0 (https://vk.cc/bX9SD0)
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I am also still trying to figure out how to actually make this a practical cooling solution for daily use. My current best bet would be 3mm Heatpipes, a somewhat modified Cooler Block ( a bit "fatter" cooler block with thinner Thermal pads, maybe also larger in size with fins. And yes, fins will fit. Not with the Same Size block tho, needs to be larger, but there is quite some Empty space for that between the Circut boards, needs to be an Flat cooler) with two 3mm Heatpipes ( The ones i got are rated for 18W Heat load at 70°C) which will connect to some kind of External Contact surface which i want to mount on the Bottom Of the Camera like a camera cage. Doesnt need to be huge, can have a rater Small footprint while still allowing access to the Battery if needed. To this Outside Copper Surface i will be able to mount Air coolers or Waterblocks, even Peltier modules would then be possible, because outside the Camera i will have plenty of space, but will still be able to get the external more beefy cooling solution off quickly if i need a smaller Camera to move very Quickly when shooting (without first needing to open the Camera and Replacing the Cooling block on location). .
This is so far the most promising idea, because it still is a "hybrid" approach to cooling, meaning i can go full Watercooled or add any very beefy external cooler of any kind very easily, but the Camera will still work as-is as a Standalone Unit if needed (as the block itself still does the same work as bevore and the Heatpipes wont obstruct the usual cooling in any way, if any they improove heat transfer across the Block and add surface Aera), also its a drop-in replacement which doesnt need extensive permanent modification of the Camera itself and can be easily reverted to standard configuration.
Its also is a very capeable cooling solution at the Same time, it should be able to get the sensor quite a bit down in temperature if not even pretty close to Room Temp (if the Heatpipes still can transfer enough power at those Temps and you add an Waterblock or Peltier Module).
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Now for your idea, i also allready tried this ( if i understand correctly you are trying to make a shroud for the front air intake holes to push More air in with an powerfull fan), force feeding the Camera with more air, and it does improove Cooling, yes, but not by all that much. You can only get so much air inside, and at a certain point, the Internal Fan will even start to limit the amout of air you can Push through. so if you can Manage to get some Serious increase over the Current amount of Airflow (like order of magnitude kind of increase, which would most likely need the internal fan to be removed and also some way of preventing the air from exiting through the Bottom intake holes, by either a second intake Shroud or closing it), it might be worth a try and can actually improove Sensor Temperatures by quite a bit, but with only a single fan i assume it would propably be hardly noticeable. For reference, i used an 14krpm 40x40x30 Server fan, which pushes some Serious air and also has plenty of Air pressure, not sure which exact fan you are planing on using, but even with that one i could only get like 2 to 4°C improovement (didnt make a fancy shroud, to be fair, had a way more sketchy setup), and i am not sure if that would be worth it for me, camera sounding like an actuall Jet Engine (this small server fan is really loud, against this one, even the Stock Chronos fan seems very reasonable and quiet. https://forum.krontech.ca/index.php?topic=521.msg3922#msg3922 ). Now 2 to 4 °C is still something, but if i would do something like this i would maybe go with an even More Powerfull Fan to make the Effort at least worth it, like some of the bigger server Fans, which can push quite some air, those could get the Camera down quite a bit in temps.
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In terms of external cooling solutions involving air, i guess easiest and most effective one would be to just get yourself one of those Moveable air-conditioner Units and making some kind of "Blimp" for the Chronos, but not for Noise like in the old days, but as an Air Shroud, in which you would feed the Air-Conditioner Air, going at full blast, putting out 15°C or Colder air. (for Reference: https://search.yahoo.com/yhs/search?p=arri%2Bblimp ). I think this would be way more effective than your idea, considering cooling solutions which wouldnt need to fumble with the cameras internals. Because a thing i also didnt understand at first, the Copper Cooler experiment helped me a lot to understand it better, is how the current Thermal design actually works. This Small Cooler Block made from Aluminum attached to the sensor isnt really meant to dissapate all that much heat directly into the Air, but rather to transfer it into the Metal Case/ Body of the Camera, and the Fan itself seemingly doesnt mainly cool the Sensor itself. The Fan (as far as i understand it and how it actually seems to work in the end, not absolutely sure about the intentions when designing the Thermal solution for this Camera) seems to mainly directly cool all the other internal Components which are not connected to the Case by contact pads or heatsinks, and at the same time provides some base forced Airflow through the Case, which in turn happens to Cool the Case down a bit. So actually this is more of a passive Cooling solution (talking about the Cooling for the Sensor itself) than an Active one, because it seems that for extended runtime of the Camera (everything longer than 30 or 60 Minutes), when the Thermal Mass of the camera reached thermal Equilibrium, the Camera outer Surface seems to do quite some of the Cooling, if not the mayor part of it. The Fan sure helps to cool the Metal of the Camera Case down a bit, because any kind of Airflow will massively improove cooling in such a situation, but considering all of the above said things about the current thermal design of the Camera, i propably wouldnt go and try to just push more air through the airpath inside. The current airflow with the Stock fan is somewhat at a sweetspot, where it still does help quite a bit with cooling, but doesnt need utter overkill Fans and Shrouds, from this point on, you will allways need to up your Airflow Way more to still see little improovements in cooling for the Internal Airflow. As you allready said, when pushing those amounts of air, as would be needed to considerably lower Sensor Temps from just that, dust buildup would propably become an actuall problem. Because the Small Sensor Cooler block itself doesnt really do all that much in terms of Air Cooling surface, might as well cool the outside of the Case better with additional fans or bolt some heatsinks onto the outside. Pushing more air through the Camera will keep the Sensor Cooler for the first 5 Minutes of use, but for longer runtimes above 40 Min, cooling the outside better will propably outperform internal Airflow with way less effort. Now Considering that the Outside Surface is doing a lot of the Cooling, blowing really cold air from an Air Conditioner Unit at it would not only increase temperature difference between outer Surface and Air, thus increasing Dissapation, but also would add considerable outside airflow. An AC Unit is Still Pretty Bulky tho, not the kind of thing you want to have to bring to any shooting location, except for Studio work, where the camera will be setup all the Time and doesnt need to move all that much.
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Still kind of a difficult topic, because no matter the amount of Airflow you will be able to generate, as of now the Cooling solution still has the problem that the thermal resistance between the Sensor and the Case is still pretty high, meaning even if you could Force the outside Of the Case to 22°C Room Temperature with massive Fans or something, Sensor would propably still sit at something like 30 to 35°C (or even worse possibly). So sure, this will work for the Average user propably, but the thing is, that this sensor just has way more potential Image Quality available, which needs a better cooling solution somehow. Now if you can even get it to 35°C on the Long runtimes, thats allready a huge win, but everything below that will almost sure need Internal Modification or use of an AC Unit or something like that.
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so, this Cooling Project has been quite an Rollercoaster of Emotions so far. Two Weeks ago i finally finished The Cooler, prepared Brass tubes of Correct Lenght and soldered them All up. Put the Camera back together to test Waterflow, when i did that, the Water Hose popped right off (had put it on without hose-Clamp cause i didnt really expect any serious Pressure Buildup), and ended up completely Showering the Camera (with luckily no battery inside).
That scared me good for a Moment.
Ok, tried that later again with hose Clamp on, nothing happened, besides me Shorting out something inside because the Still rather Flexible Blank Brass tubes touching something on the RAM or whoever knowes where on the PCB. Camera survived fine however, just Instantly shut down when it was Shorted out, and turned on just normaly after that.
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After Taking it apart to investigate what was going on, i realized, i must have pluged the Path for the Water When soldering one of the Two Connections of the Cooler-Block itself. All of the Connections where drilled to a very Tight fit, and would hold reasonable Water pressure even without even soldering them. The hole on the Block itself however ended up beeing slightly oversize, because of the Depth i had to drill there. So, because of this, and because of the time i needed to solder all that up (tried to solder it all up in one go, to avoid needing to heat all that mass up again, and instead do it all while still hot), some Solder propably was able to flow inside there and Plug it up completely. I had not tested with air bevore, so i only figured that out once i tried with water.
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As i figured, there would be no clean Way to save this cooler after that, i had to start over completely once again.
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Now, i also didnt want to risk drilling a even smaller hole that deep into the Cooler (drilling a 2mm Hole of that depth was allready more than Hard enough), but needed to predrill it, and then carefully drill it to size, to achive a tight fit on there to avoid risking the Same mistake again. I thought about that for quite a while and figured, it would be easiest to just modify the Cooler Shape, so i had way less material to drill through. As the Sides of that 4mm Thick Flat on the "Back" of the Cooler besides the Sensor Cooling pad dont really do anything (apart from adding Surface area and mass, which is well justified in normal use, but doesnt change anything for a test like this), i just removed them, and was now left with only 12,5mm to drill through instead of the 28mm on the Original version. This allowed me to predrill and then carefully Drill both ends to size, just like i did on the 90° Connectors. This worked out very well and i ended up with a nice tight fit on the Holes on the Cooler this time. The Additional Space from removing the material there also allowed me to do some rather Large Radius bends, to minimize the amount of connections and Amount of soldering i had to do on there, to further minimize the risk of any mistakes happening like bevore. just for good measure i also put some beefy Heat-Shrink on there to help overall rigidity and also prevent from bare metal touching anything on the PCB´s, with the hope that it will also help a bit with avoiding condensation inside the Camera.
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I noticed that the Thermal Pad on the Sensor itself also wasnt making all too great contact with the Cooler block. Dont know why that is, could be me having taking it apart way too often by now, didnt really pay all that much attention to it when i first opened it. However, the Thermal Pad on the Sensor is also a bit small for my taste, it doesnt really cover as much surface Area as it could, i will replace mine with new ones soon hopefully. However, because of that i raised the Height of the Contact surface on the Copper Block by 0,15mm to increase Contact pressure, and ensure it would at least have good contact on the Surface covered by the original pad. On the Other Cooler i used Some Layer of thermal Paste to ensure good contact, which isnt ideal, but still performed well enough.
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If anyone is interrested, The Cooling pad on the Sensor and on the Other Chip behind it on the Same Cooler are 1mm Thick, as is the one on the Backside of the Display to cool an Chip there. The other Pad to cool the PCB behind the Sensor is 2mm Thick.
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Put everything together, and this time it went Smoothly. Also tested it with Air first this time, airflow was there, and it seemed not to leak.
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First Quick test is looking good, Water this time also does what it is supposed to do, go through the Camera, but not Spread inside it.
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Lowered Room Temperature to 21°C, and got down to a sustained Sensor Temperature of 24,5°C (Left it running for about an Hour, went up to 26°C sometimes, but remained fairly stable) with an Water-Temperature of 10,7°C. At this Temperature, Condensation started on parts of the Water hose used, so to avoid it completely, room Temperature would need to be lowered even more.
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So far havent Done any Image-Quality testing with it yet, just did 4 Black Calibrations along the Cooldown of the Camera, and it seems that Light Sensitivity increases when cooling down, and The Static Vertical Line Patterns get a lot less visible, and the Sensor has a way more orgainc (moving) "grain" like Noise, which i like a lot. This wasnt a real test however, but about the Result i assumed this whole experiment would lead to. But a lot more Testing has to be done here. Will also test very high temperatures to confirm this observation, but need to rig this up quite a bit better and set up some propper lights and stuff, so far i am very happy this finaly works as well as it does, and hasnt killed the cam with water.
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I just made a new Thread for the Test Results, as i want to keep this Thread to the Hardware Aspects and Cooler-Designs itself, and the New one should be more about how it influences the Image Quality to keep them both on topic and a bit more organized:
https://forum.krontech.ca/index.php?topic=635.0
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Now after the first tests, I really think its worth designing a more refined version of this cooler to make it possible to use in the Real world and not only in an experimental Setup. .
So lets have a few theoretical thoughts about the whole situation and define how an Ideal Cooler would look like, bevore trying to build one.
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From what we know so far, A stable Temperature is still by far more important than the absolute Temperatue on the Sensor for Image Quality, as even a few degree Drift up or down completely messes up the Image (see test Results in the Other Thread/ Second Test i did/ Shot without Black-Calibration after Temperature Change, If you havent allready noticed yourself while using it), so The Cooler needs to be able to maintain the Sensor Temperature at the Lowest Possible Temperature as Steadily as Possible.
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Also, with the Stock Cooler-Block Design there is still way too high thermal Resistance beteween the Cooler itself (which i got close to 10°C at some points while testing), and the Sensor Substrate. Right now Temperature Difference between the Cooler and Substrate is still way over 12°C. This means, an Ideal Cooler would also reduce the Thermal Resistance from the Sensor Package Surface to the Cooler itself as far as somehow possible.
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Furthermore there should be some consideration about Condensation and different Environments, the Cam maybe will end up in. Mainly Room /outside Temperature and Humidity of the Air which can Cause Condensation inside the Camera, given the Cooler is cold enough compared to the Air Temperature. So now an ideal Cooler would Keep the Sensor just as cold to avoid Condensation, but as close to room Temperature as possible, or even Below that. But as Environment Temperatures Can Change in a very wide range, Cooler Block temperature would also need to be adjustable in case of using a Powered Chiller or similar.
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Next, it should be Independently Controlled. Air Temperature can have very rapid changes for different Reasons, or even Drift around because of Lights in a Small Room, or Air outside heating up during the Day and cooling in the Night. So ideally the Cooler would remain the Same Temperature all along, and would be decoupled from the Air Temperature around it.
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Ideally it would also be Failsave/ Hybrid Cooling. Meaning, that even if whatever cooling solution Used, it will still work when it fails/ Wouldnt need to be Powered if not wanted for some Reason. Now, as the Stock ("passive") Cooling Solution works "Well enough" for general use, and still produces good Footage for the Most part, this would be good enough cooling as As kind of a Backup for a sub-Ambient Sensor Cooling solution.
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It should also be small footprint and not add a ton of Size or weight to the Camera itself ("car Radiator" Ect.). Would also need no/ only very little Permanent Modification on the Stock Camera and Easily removeable if needed.
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After some More Research on the Sensor itself and the Other Chip:
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https://www.ti.com/lit/ug/sprugz8g/sprugz8g.pdf?ts=1612518695233&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTMS320DM8148 (https://www.ti.com/lit/ug/sprugz8g/sprugz8g.pdf?ts=1612518695233&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTMS320DM8148)
https://www.luxima.com/product_briefs/LUX2100.html (https://www.luxima.com/product_briefs/LUX2100.html)
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It seems like the Sensor Itself has a TDP of 3,9W and the other Chip also Cooled by the same block is referenced with 2W if i Recall correctly ( this is a almost 4000 pages Long thing, and they dont even Bother giving any Thermal Specificaion in there, they only reference a example Power draw in a Footnote somewhere, but i cant be bothered right now to work myself through there again to find it. Mad Respect to anyone at Krontech Programing these and integrating them btw., I consider myself as someone who has quite a bit of a understanding of how Electronics and Computer work, but this datasheet looks extremely intimidating to me, never seen anything like this.).
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Now this seems a lot more Manageable than the 40W Heat ouput i assumed bevore. Based on the Fact, that they dont even bother giving much information on the Thermals of the Other Chip, and the Observation, that they seem to work just fine no matter what, as long as they dont overheat, i wouldnt worry too much about cooling it better, and now only the Sensor with its 3,9W Needs To be cooled better.
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Peltier module coupled to the heat sink 8) ?
I had to think about this a lot recently.
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When i actually looked into Peltier Modules, i found this thing here:
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https://www.conrad.de/de/p/quickcool-qc-32-0-6-1-5as-peltier-element-3-6-v-1-8-a-3-91-w-lxbxh-10-x-8-x-2-5-2237012.html
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Which happens to be a 3,91W Peltier Module which is 10x8mm In Size and 2.5mm Thick, meaning, it could realistically be made to fit inside the 12,5x9x3mm Space behind the Sensor, with a Modified Cooler Block. Should be able to handle the Heat Output from the Sensor very well, and the Additional Heat on the Block from the Peltier shouldnt be a huge problem Really, as the Other stuff doesnt care as much about Temps.
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So far i assumed that Peltiers where way to big to realistically be an Option here, but this one Changed my mind, and i really am Considering using one right now.
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But there is still like at least 4 Different Ways a Peltier Module Could be used to improove Cooling:
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1. Like described above, Modify the Cooler to Make Space behind the Sensor and fit an extremely small Peltier Module In there, Cold Side Contacting the Sensor as directly as Possible, hot side with a Silicon Heat Pad between touching the Slightly Modified Cooler Block to achive Correct Mounting Pressure.
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2. Somehow Cool the Entire Cooler Block With an Peltier, very similar to what i did with the Watercooling just now.
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3. Another Attempt would be to Cool the Whole Camera Body itself from the Outside with Peltiers and Some Kind of Heatsinks on them, maybe something like CPU-Coolers on the Hot side, Cold Side Touching the Camera Body.
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4. Would be somewhat more elaborate. Making an Intermediate Cooling block which is Very Closely Connected to the Sensor Package Surface; something like Thermal Paste, contacting it directly; which is cooled by a big Peltier Module somewhere, Hot side of the Peltier would interface with Heatpipes connected to some External Cooler, and the Small Intermediate (actively Cooled) Sensor Cooling block would then Be connected with thermal pads to a Cooler Block similar to the Original one, which would still cool the Other Chip on the Back, and would provide Backup cooling in case the Peltier isnt active for whatever Reason.
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Those also come with a Lot of Problems to Solve.
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2. is Problematic, because it doesnt really improove the problem of the Still Rather High Thermal Resistance between the Cooler Block and Sensor Package, meaning this Peltier would need to cool the Block down to way below Ambient Temps to even get remotely close to ambient Temps on the Sensor Substrate. From the Earlier Tests with the Waterblock, this kind of attempt also means that the entire Camera body will have a very close Temperature Relation to the Cooler Block, meaning it will also be cooled down to the Cooler Block Temperature eventually, and at well below Ambient Temps, this means it acts Like a Reverse Heatsink, pulling heat from The Room, or the Room starting to heat up the Camera, however you want to put it. This Results in the Need of a Very beefy Peltier Module, which usually is really big and very hard to fit anywhere inside there, needs tons of Power, and also needs a Huge Heatsink to cool the Hot side.
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3. Would be about the Same thing like 2., but resulting in slightly worse Sensor Temps with the Benefit of way easier Mounting and Cooling of the Module.
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4. Is propably the Most propper Way to do this, but is quite elaborate. Because there are now two independent cooler Blocks, the Sensor can be cooled with an way smaller Thermal Resistance, and the Resulting Temperature of the Camera body is way more loosely Coupled to the "cold" Part of this Cooling System, meaning the Camera Body doesnt pull as Much heat from the Room, and the Peltier could be way smaller. More direct access to the Sensor like this also means that there no longer is a need to "overcool" the Block as much as bevore to achive reasonable low sensor Temps, meaning also less heat input from the Surroundings because lower Temperature difference to begin with. However, still pretty tricky to fit in there i assume, because it still would propably need a decently sized Peltier Module.
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1. Is Great, because it is the only one of the bunch wich doesnt need any additional External Coolers of any kind (But is also the Only one that wont Work in case the Peltier isnt running), but has some of its own problems. First off, i assume it wouldnt do all that great when for some Reason the Peltier isnt working. Possible Reasons include a lack of Power, because whatever you used to run it is out of power; and the Controller / Peltier itself just simply dying. Also fitting a temperature Probe in there for some kind of Control-Circut could be challenging, because of the Very Limited Space. All the Other ones will still do fine without the Peltier, as they are simply a slightly Modified Stock Cooler with boosted performance by an Peltier Module. This one is different, it relies completely on The Peltier for the Cooling.
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Right now, i like 4. best, because it should give the best Performance, is failsave and could still be made with very little modifications to the Original cam, while beeing easily and Quickly removable if needed (Fixed Peltier Inside, removable external Cooler, resulting in a camera with some kind of Thermal Interface Surface on the Bottom, which is just slightly bigger than Stock), but Fitting the Peltier of the Power needed for this design inside can Proove to be tricky. Big Advantage of this design is also, additional Heating of the Sensor could also be impemented rather easily if ever needed, if i somehow find a way to make that work.
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I maybe actually end up using 1. at least for Testing, because its just so much easier to build. Maybe i like it when i use it, and keep it that way, we will see.
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However, i now actually think Peltier Modules are the way to go, because they allow for an Adjustabe Stable Temperature on the Sensor below any other Temperature possible with other Small and Portable Cooling solutions. I did actually also think about Connecting the Cold side of Peltiers with the Sensor via Heatpipes, but heard, Heatpipes perform pretty bad for really low Temperatures, so i dropped that Idea. Would open up quite a few additional Options, so if anyone knows more about Heatpipes at low Temperatures, let me Know. Any other Ideas or Information is also very Welcome, thanks.
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Something that might be worth considering is to just use all the components of the camera and put them into a new, much larger, custom case. If your use case is in-studio, perhaps having something large like the size of a cinema camera would be OK. That might also open up the possibility of using high end air cooling with a second battery or power supply if needed.
You might want to make a custom case for your water cooling ideas as well just to give yourself more room to work.
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Something that might be worth considering is to just use all the components of the camera and put them into a new, much larger, custom case. If your use case is in-studio, perhaps having something large like the size of a cinema camera would be OK. That might also open up the possibility of using high end air cooling with a second battery or power supply if needed.
You might want to make a custom case for your water cooling ideas as well just to give yourself more room to work.
Thanks for the Idea, havent really thought about that yet.
But not really the direction i want to go with this.
Really like the Form Factor of the Chronos as is, and even the Current Size is allready somewhat on the Large side for what i am used to (when ready for use). While i sometimes have the Luxery of Studio-Type work, the majority of filmmaking i am involved in needs to move way Quicker, like on location shooting with very limited time available. So i want the Camera to be as Small and Modular as possible, and it does a well enough job at that as it is. So speaking about current overall Design of the Camera, it would work really well in my usecase.
In my opinion, the Grip can use some Work, upgrade the internal Display to a High-Resolution display that can be Flipped and maybe a Cage, and it would be close to Perfect.
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While that Rehousing would indeed make things a lot simpler in terms of Cooling design, this would also mean starting another way bigger Project along with it, Basically designing (and Fabricating) an Entirely new Camerabody. And making that As Functional and Polished as the Current Chronos Package is, isnt really worth it for me.
. Also to clarify, main Problem isnt really the Lack of total Free Space inside the Camera itself, i was able to fit plenty of Brass Pipes and stuff in there Without too much Problems with still half the Insides Empty, Problem is that the Two PCBs are so close together (and there is also Chips to be cooled on two sides of the Space where the Sensor Cooler will have to be. Genius design if you want to save yourself the Work of cooling them Seperately somehow and Saving space, not so great if you Try to fit some wicked Custom Cooling solution in there and dont care too much about the other Stuff around it). So just designing a new Enclosure wouldnt quite be the end of the Story (even if it would still make things a bit easier), as that would remain unchanged. To make more space, where its actually needed for easy sensor cooling would mean to also Redesign and Rewire the Connections to the Sensor Board, to allow for different Spacing/ Alignment of the Boards. Now even i dont want to mess with that stuff. Way too much opportunities to Produce Way more Problems than there allready are. We are still talking about reasonable High Frequency Data Bus Stuff, pretty Delicate Tec, wont touch that. As they Say, never touch a running System. Did things like that and worse with some Older and Never Nikon Cameras i got for cheap allready partialy broken, but for sure wont do that with an fully functional Camera that is as Expensive unless i actually have to. (See https://forum.krontech.ca/index.php?topic=464.msg2499#msg2499 (https://forum.krontech.ca/index.php?topic=464.msg2499#msg2499) )
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So in my opinion, if i where to do anything like this, go all the Way and also modify the Electronics (Prepare for a lot of Troubleshooting most likely), and make a completely custom Camera at that point, or just find a Way to make a Drop-In Replacement work, as i am Currently trying to do.
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Thing is, i am sure i could if i tried hard enough, but i really dont want to. People, including myself Capture amazing Footage even with the Stock Cooling on theirs, and rather than spending Way too much time building an all Custom Camera, i still want to be left with some time actually using it and Having Fun with it. So i am trying to find a Cooling solution that is as Easy and Low-Effort as possible, with best results, so People could copy it; or If its practical enough and easy to implement, maybe even used by Krontech as a Reference Design for Future Versions / Revisions of current Cameras. At the Very least it should contribute to the further Developement in terms Of Image Quality of the Krontech Cameras, if nothing else.
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As Far as studio Use goes, i assume even the Watercooler i documented above would be a very solid Solution for Some Usecase like this. If you dont move your Camera a lot, this should work fine For you. Maybe put a bit more effort into The Tubing, use some Propper Fittings and Replace coolant with Alcohol, run it outside and Cool it with an Peltier there in some kind of external Box (as Some People do with their PC Cooling, can provide examples if needed), make everything look Neat and build it into a Closed Loop, and you are good to go. I however dont really like the idea of Fluids inside there, and am actually too lazy to Build this into a finished System, as it still will end up taking up a lot of External Space and will be pretty much a permanent Fixture on the Camera (Which will also need power, so add some huge Battery also). If i only did studio Work, i would maybe just use the Cooler i last build and be happy with it, but this is sadly not the case, quite the Opposite actually.
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Thanks for your Input Anyways!
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Peltier module coupled to the heat sink 8) ?
@CS223 and @ anyone who has experience with Peltier Modules (i have none so far), do you have any reccomendations on a temperature-Control-Circut or finished Board/ Unit for Low-Power Peltier Modules? Ideally small size ofc, and if possible some kind of external Display/ Break-Out Potentiometer for Setting The Temperature on the Go.
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Peltier modules are voltage specific from what I recall and need to have decent regulation. So in that regard I would use a PWM circuit, or try anyway, in order to control the cooling level of the module. At least on an experimental basis. On a design basis, I would use a thermostat with feedback similar to how a heated crystal oscillator works so as to keep the imager temperature consistent regardless of the environment. You would want something along the lines of a PID controller as opposed to a slam-bang thermostat. Another option might be a heat pipe on the imager with a Peltier module on the other end if module space is an issue.
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Another option might be a heat pipe on the imager with a Peltier module on the other end if module space is an issue.
Was thinking about this also, but since thermal Load Ratings of The heatpipes i looked at, are allways given at 70°C, i figured, they are propably not all that Efficient at really low Temps. Bought some and Tested on some ICE Cubes, they do get cold very fast on the other end, when you manage to get decent contact to the Ice, but no real Experience with Low Temp Heatpipe-Stuff, and also couldnt really find any Info anywhere about that...
If you think it will work well, i am down to Try it maybe.
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Peltier modules are voltage specific from what I recall and need to have decent regulation. So in that regard I would use a PWM circuit, or try anyway, in order to control the cooling level of the module. At least on an experimental basis. On a design basis, I would use a thermostat with feedback similar to how a heated crystal oscillator works so as to keep the imager temperature consistent regardless of the environment. You would want something along the lines of a PID controller as opposed to a slam-bang thermostat.
Thanks for the Infos on the Regulator, and yes, they are Voltage Specific, the one i linked above wants 3,6V and 1.4A to run on full power. Looked a bit into it, and Driving Peltiers seems like a whole rabbithole on its own. However found some old Thread on another Forum about PWM Driving Peltiers, seems to be a bad idea to drive them with PWM, seems to want a Linear Regulated Driver.
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https://www.mikrocontroller.net/topic/313553
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[Its in German and about Astro Stuff]
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I really dont want to build anything which ends up in Programming something, and every else available to Purchase as a ready-to-use-Unit seems to either come in a Huge Form Factor, is very unprecise or surpremely expensive (while those expensive nice ones then lack on-the-Fly adjustment options, and seem to allways need to be connected to a PC to change anything, which also sucks for this Project).
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https://www.meerstetter.ch/products/tec-controllers
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I am kind of surprised, that there arent any Controllers for Low power which are easy to use and not huge, but will do some More Research on this and see if i can figure out Some Simple Solution. Otherwise i might end up building some Really basic Linear Driver with some OP-AMPs and a FET or Transistor and a bunch of Potentiometers to be able to adjust everything.
I assume they should be at least be driven Current Limited or something to not kill them instantly. Guess the "or try anyway" attempt would be worth a Try and just Use some cheap available Thermostat Unit. Not too sure how well it would end up working, because for the #1. Design i wrote about above, there isnt all that much Thermal Mass involved on the Cold side, so it could be end up beeing way to slow, and causing a lot of Temperature Changes all the Time. Pretty sure, it would work fine with most other designs, where there is a Cooler Block of certain Mass involved, this could end up beeing very precise and reliable if tuned in a bit.
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Currently thinking about revisiting this with new Cooling Hardware and Firmware to finally figure this out.
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Ok, Epic Fail.
The 2.1 finally running with a Peltier on the Sensor and a Air-Cooler mounted to it, to cool the whole thing.
However, the added Thermal Load from the Peltier is actually that high, that the Largest Air-Cooler i could Physically fit inside there is not Able to dissipate all that Heat, even with Forced Ventilation from a High Static Pressure Server Fan directly to the Cooler.
Put a lot of work into this, hoping to get it working without using Heatpipes, but seems i have to come up with an even more Powerful Thermal Solution to finally get to effectively cool the Sensor.
This just is not working and just produces much more heat overall, causing the Temperatures to run away.
Stopped Testing when it was raising over 79°C, as i finally got an Answer from Krontech saying, that 80°C is the Max. Operating Temperature of the Sensor and Processor. When reached, it will Force the internal Fan to 100% Power for 10 Seconds, and if 80°C is held for 10 Seconds it will Shut itself off for safety.
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Hoping to post Updates on this soon, but this whole Experimental Cooling Concept now needs a Major Rework to have realistic Chances to actually work after these First Test Results.