Canon 1100D Cold Finger Peltier Cooling - WIP

[Thalestris24]

Hi Louise,

I bought a S/H  Geoptek cool box which I've rebuilt (looked like it was thrown together)  and modded to take my 60da, haven't taken any pic's yet but it holds a steady -5 in the daytime, useful for taking darks after the event, the only draw back is that it draws 10amps so not much good for field work the manual claims 2.5 amps ?

Only got it set up for TV Powermate at the moment but looking to mod for lens attachment, will post pics if/when skys clear

Dave

Hi Dave

10A sounds a lot! For a cooler to be any use it has to have some affect on the increasing temperature of the sensor (and presumably the read electronics) during use otherwise it won't be worth the bother. I see Teleskop Express do them - not cheap! The look very bulky! I'd have thought a much smaller box would do the job. Do post about it's performance when you can.

Cheers

Louise

[Davey-T]

Wouldn't consider  paying retail for one especially as they're not assembled very well if mines anything to go buy, looks like the original design was modded by the person assembling it

Have downloaded some software to monitor sensor temp as Canon obviously didn't see the need.

Dave

[Thalestris24]

Wouldn't consider  paying retail for one especially as they're not assembled very well if mines anything to go buy, looks like the original design was modded by the person assembling it

Have downloaded some software to monitor sensor temp as Canon obviously didn't see the need.

Dave

Hi

Would that be Magic Lantern?

Louise

[Davey-T]

Hi

Would that be Magic Lantern?

Louise

No Rawdigger.

Dave

[elenhinan]

BackYardEOS show the sensor (well, sensor PCB) temperature. Also has the option to add the temperature to the filename when you capture images. It differs with about 2-3 degrees C from the temp measured with my other equipment.

Gina / Dave_D: I ordered a dehumidified element (the small round one). Has been lying on my desk for weeks now, but after I read this thread again a couple of days ago I installed it in my box. I'm waiting for a small 3V SMD linear voltage regulator to arrive by mail, so I can use the existing 5V power rail. I also have a one-wire switch that  I _could_ use to turn in on or off from the arduino, but I can't think of any reason to turn it off if it works as I hope.

Anyway, I'll post an update with some test results when I get the LDO, some inspiration and some time

[Gina]

BackYardEOS show the sensor (well, sensor PCB) temperature. Also has the option to add the temperature to the filename when you capture images. It differs with about 2-3 degrees C from the temp measured with my other equipment.

Gina / Dave_D: I ordered a dehumidified element (the small round one). Has been lying on my desk for weeks now, but after I read this thread again a couple of days ago I installed it in my box. I'm waiting for a small 3V SMD linear voltage regulator to arrive by mail, so I can use the existing 5V power rail. I also have a one-wire switch that  I _could_ use to turn in on or off from the arduino, but I can't think of any reason to turn it off if it works as I hope.

Anyway, I'll post an update with some test results when I get the LDO, some inspiration and some time

I'll be interested in how you get on with the dehumidifier element - seems a better idea than silica gel which has a limited life if any moisture gets in.  And apparently there are very few things that are truly impervious to moisture.

[Gina]

While I'm here, I've been looking at the cooling again and thinking the Peltier TEC and CPU cooler I'm planning to use on my debayered 450D, could use a smaller version of both.  Previous versions of my cooled 1100D used a 30mm square 37W TEC and a 60mm square by 50mm heatsink/fan unit but with various tests showing that very low temperatures provide negligible reduction in noise it strikes me that much less cooling is required - I got down to -14C with an ambient temperature of around 10-15C - achieving a delta T of -28C.

I now have a much smaller and lighter cooler and have ordered a smaller TEC to go with it.

Gold Tone Rectangle Clear 2 Pins CPU Cooler Cooling Fan for Computer

NEW Peltier Thermoelectric Cooler Heater Module 8.8V 29.7W PE1-07106NC-S

I have also ordered a much cheaper TEC but it's coming from China and will take weeks.  The one above, just a couple of days.  Both will work off 5v which I have available together with the usual 12v. 

DC 5V 19.4W Thermoelectric Cooler Peltier Cooler Cooling

[Dave_D]

had mine running at -5 with an ambient of 24 in my very small (slightly larger than toilet size) and stuffy 'office'. i'm just really apprehensive about continuing now as i only have the one camera and nothing to test construction ideas on... still, i'm a bit mad so what the hell

and dayum... that peltier is expensive...

[Dave_D]

Gina / Dave_D: I ordered a dehumidified element (the small round one). Has been lying on my desk for weeks now, but after I read this thread again a couple of days ago I installed it in my box. I'm waiting for a small 3V SMD linear voltage regulator to arrive by mail, so I can use the existing 5V power rail. I also have a one-wire switch that  I _could_ use to turn in on or off from the arduino, but I can't think of any reason to turn it off if it works as I hope.

fingers crossed it was a good find

[Dave_D]

I now have a much smaller and lighter cooler and have ordered a smaller TEC to go with it.

Gold Tone Rectangle Clear 2 Pins CPU Cooler Cooling Fan for Computer

just tried with a similar cooler off an old nvidia 8400 and couldnt get below 9 degrees for some reason...

[Gina]

just tried with a similar cooler off an old nvidia 8400 and couldnt get below 9 degrees for some reason...

How much cooling power are you using? 

[Dave_D]

was running full power to bring the temp down to the setpoint but it just wouldn't go below 9 degrees. just put the original cooler and fan back on and the temp is sat happily at -1

thats with a 30w peltier... now at -7

[Gina]

Ah yes, I see.  Could be that the cooler just isn't quite good enough with a 30W TEC.  I'll be experimenting when I get the lower power TEC.

[Gina]

I've got the Peltier TEC now and I'll be testing once I've found some bits I need to do it.  Like a couple of DS13B20 digital thermometers to check the temperatures.  Though I could get a reasonable idea without.  If ice forms on the copper strip I can assume it's below zero C   I can tell roughly how how the cooler is by feeling it.  I shall need to find my thermal grease though.

[elenhinan]

I got the voltage regulator some days ago, and installed it yesterday. I've let the system run for ~2 hours now, with no camera inside and the lens-opening taped shut (I hope) with some kapton tape.

Pics of PD3 installation and voltage reg, with two 1uF capacitors between Vin, GND, and Vout:

The results are a bit lackluster. It's quite humid here right now (raining), so when I close the enclosure it starts at about 50%. After two hours it's down to 42%-ish. Plot included below:

As can be seen, the real drop in humidity is in the range 6-7% over two hours. So changing a filter/whatever and the dehumidifier would not cope with the insurge of new, humid air.

I guess a better solution would be to microwave some desecant-bags, and put them in. Then use the PD3 to keep the humidity under control. This could be done by adding a battery-holder for a 3.6V battery (e.g 18650 rechargable lithium battery). These are the same size as an AA battery, and you can get these cheap on the internet with charger. With a capacity of between 2000-3000mAh available, with a power consumption (according to rosahl) of 0.02W one battery should (in theory) last about 1 month.

If this works, there would be no need to open the camera before each use and "recharge" the desecant, and the desecant would work as a buffer when changing lens/filter whatever. Either way, I'm not taking the pd3 out, since it would leave a hole, and even if the effect is low, it's there

I'll run the PD3 for some hours more, and see if I can do a logarithmic/exponential curve-fit.

[Dave_D]

that's a bit disappointing  was hoping these dehumidifiers could really have been a benefit 

[Gina]

Yes indeed!

[elenhinan]

Combined with silica gel I don't think it's completely useless, as it can help if there's a tiny leak. Also, using a separate battery it can hopefully keep it dry on the shelf for a month at a time. That said, given the price and work it's probably not worth it, as changing the silica bag really isn't that hard.

The larger models would probably fare better, the MDL3 can remove ~50x more water per unit time than the PD3. If they could get the rel. humidity down 10% in ~3 minutes that would be very good. Then again, they're quite large (96x63 mm^2) and expensive (£84). Not really worth the hassle IMHO

[elenhinan]

BTW. I let it stay powered on all night, after putting a silica-gel bag straight from the oven into the box. The rel. humidity is stable at 6%, so at 25C ambient the dewpoint is -15C.

[Matdark]

Hi there, sorry to "hijack" this thread but I'm desperately looking for help :/ I also know that that this post is a bit old, but I'll try anyway ...  I have followed all the steps of this tutorial to the letter http://astrophoto-chris.blogspot.fr/p/hypermod-toute-les-infos.html (except  insulation around the cold finger for now and I  have two power supplies, one for the camera and another one for the regulator/ fans / peltier) but big problem: everything works until the I power cooling: LOTS of lines / interference in live view, and of course on pictures. Completely unusable. I tried everything, changed the cables, connections, and by process of elimination, identified the culprit: it is the peltier module. When I unsolder its wires, the problem disappears. I don't get it, I've been looking all around the internet and couldn't find a similar case. I have spent dozens of hours on it, it drives me crazy ... Please help !!!!

[Gina]

Interference from the PWM Peltier current control is my suggestion.  I have an LC filter feeding the Peltier TEC.