Canon 1100D Cold Finger Peltier Cooling - WIP

[Dave_D]

Hmmm... about £17 for the RD4 which is 30 x 24 x 5.5mm. Sounds like a plan.

[Dave_D]

HAHA I've been looking at that exact same encoder  

One thing i'm curious about... are you using a parallel LED display?

[russellhq]

HAHA I've been looking at that exact same encoder

One thing i'm curious about... are you using a parallel LED display?

I've no idea I'm using the same one you have in your picture if that helps.

[Dave_D]

this is the back of my LCD (not LED lol)... only 4 wires.

dunno if you're interested, but here's part of my sketch that defines a snazzy little degree symbol

// degrees character

byte degree[8] = {8,20,8,0,0,0,0,0};  <-this bit

void setup()

{

  lcd.begin(16,2);

  lcd.backlight();

  lcd.createChar(0, degree);  <-this bit

}

// do the shizzle

void loop()

{

  int ReadDHT = DHT11.read(DHT11PIN);

  lcd.setCursor(0, 0);

  lcd.print("Temp=");

  lcd.print((float)DHT11.temperature, 0);

  lcd.write(byte(0));   <-and this bit

[russellhq]

That looks like it has an extra part! What does that do?

I saw elenhinan had created a nice looking °C character:

// custom chars for lcd

byte celsiusChar[8] = {

0b11000,

0b11000,

0b00000,

0b00111,

0b00100,

0b00100,

0b00111,

0b00000

};

[Dave_D]

The extra bit is a serial to parallel converter. very handy for saving on I/O ports.

And elenhinem has a better symbol so i'm going to steal it as i coded for C and F, just don't use F at the moment

[Dave_D]

Just got a reply from Rosahl and the RD3 and RD4 can operate down to -20 C within spec.

What are your thoughts about a good hermetic seal of the cold chamber? is it a realistic proposition as you've dabbled with the physical mechanics of the cold chamber.

[Gina]

I like the look of the Rosahl device - continual dehumidifying   Just in case you can't get a perfectly sealed dry chamber.  Apparently water molecules can slowly permeate through most plastics which was one reason I started a build using a soldered up copper dry chamber attached to an aluminium plate.  But actually sealing this turned out to be a real headache, so I'm now working in printed plastic in the hope that I can get this airtight

[Dave_D]

Just ordered a dht22, encoder and peltier.

I'll cobble together a bit of code for scrolling through menu/display options when it arrives.

Just been reading an interesting page about beer brewing with an arduino controlled peltier using setpoint cooling. might see if i can get the sketch to save a bit of time

[Gina]

Feel free to use my sketch if you like and if you can't find it in my various threads I'll dig it out and post it again.  All my sketches and designs that I post on here are for general public consumption.  ie. placed into the Public Domain for anyone to use in any way they like.

[Dave_D]

Which thread is it in? You make so many

[Gina]

I dunno, I make so many

[Dave_D]

I dunno, I make so many

hah found it

salvaged this from an old shuttle computer. copper block is 45 x 60mm and should easily dissipate 60+ watts. will probably trim the larger block down a bit to save some weight. will have to wait for my peltier to arrive to make certain though

[Gina]

Just got a reply from Rosahl and the RD3 and RD4 can operate down to -20 C within spec.

Can you actually buy these and how much do they cost?  I've tried Googling and although Rosahl show PayPal and cards on their web site they have no prices or any info on buying them.

[Dave_D]

Can you actually buy these and how much do they cost?  I've tried Googling and although Rosahl show PayPal and cards on their web site they have no prices or any info on buying them.

You can only get them from Westside International. go to the faq page on rosahl.co.uk and there's links for price and how to buy.

[Dave_D]

Been fiddling around with encoders and whatnot... going to have to dig out a couple of 0.01uf caps for debouncing as it's nowhere near good enough in it's standard form. definitely one of those times when i wished i hadn't thrown out 1000's of components years ago when i got bored with amateur radio...

One thing i'm wondering... i'm nowhere near ready for making cold fingers and totally hacking the camera up, so what i was wondering is, how effective, for a temporary solution, is cooling the entire camera enclosure? but keeping it above dewpoint. got most of the equipment, just waiting for my peltier to arrive, but soon as it does, can cobble together a sketch to cool to a degree or so above dewpoint.

imaging session on wednesday showed an exif of over 30 degrees so i want to knock this down substantially

[russellhq]

You could take a look here at what Gary Honis has achieved with an enclosed camera:

http://dslrmodifications.com/rebelmod450d16c.html

He reported a drop of 23C, which I reckon would be worth your while to give it a shot.

[Gina]

I did some experiments of this too a couple of years ago - there's a thread about it here somewhere.  You certainly can make a difference but you need to cool the enclosure below freezing to get the sensor temperature down anywhere near zero C.  The trouble is the thermal resistance between the sensor and other heat emitting parts in the camera to the outside.

What I did find, is that cooling the metal frame via the tripod bush was quite effective.  The frame goes right inside the camera and near the image sensor.  It is electrically connected to the shield over the imaging processor board too though how good the thermal conductivity will be I'm not sure.

I used a cast aluminium box to contain the camera with the latter fastened to the box with the tripod bush.  The Peltier TEC was placed on the outside of the ali box with thermal paste between it and the box.  A large CPU cooler took away the heat produced by the hot side (thermal paste essential here too).  You'll need thermal insulation around the box or you'll be using all your cooling to produce ice on the outside of the box.

If you can manage to seal the box to keep damp out then several bags of silica gel will keep the camera dry and stop condensation.  This sealing is easier said than done I have to admit. 

It's worth replacing the camera battery with an external power connection.  You can get a battery eliminator if you don't want to open up the camera.  The memory card isn't necessary as you can disable saving to card from the Menu and only use the USB connection.  This way, if you set the mode to "M" and power to "ON", access to the camera isn't necessary.  It can be switched on/off by switching the external power.

[Dave_D]

Hmmm... seems like a lot of effort for a temporary solution. May as well just wait then and do the job properly.

[Dave_D]

Hardware debounce almost working. Still getting the odd bounce. Would upping the capacitors from 0.02uF be any better?

[Dave_D]

*note to self.

when testing shiny new peltier that dropped through the letter box by connecting it to 12v worth of D-cell batteries, make sure you aren't holding it in your hand at the time....

today, i shall award myself 10 'stupid points' 

[libraryman]

I did some experiments of this too a couple of years ago - there's a thread about it here somewhere.  You certainly can make a difference but you need to cool the enclosure below freezing to get the sensor temperature down anywhere near zero C.  The trouble is the thermal resistance between the sensor and other heat emitting parts in the camera to the outside.

What I did find, is that cooling the metal frame via the tripod bush was quite effective.  The frame goes right inside the camera and near the image sensor.  It is electrically connected to the shield over the imaging processor board too though how good the thermal conductivity will be I'm not sure.

I used a cast aluminium box to contain the camera with the latter fastened to the box with the tripod bush.  The Peltier TEC was placed on the outside of the ali box with thermal paste between it and the box.  A large CPU cooler took away the heat produced by the hot side (thermal paste essential here too).  You'll need thermal insulation around the box or you'll be using all your cooling to produce ice on the outside of the box.

If you can manage to seal the box to keep damp out then several bags of silica gel will keep the camera dry and stop condensation.  This sealing is easier said than done I have to admit. 

It's worth replacing the camera battery with an external power connection.  You can get a battery eliminator if you don't want to open up the camera.  The memory card isn't necessary as you can disable saving to card from the Menu and only use the USB connection.  This way, if you set the mode to "M" and power to "ON", access to the camera isn't necessary.  It can be switched on/off by switching the external power.

I made and still use Gary's mk 3 designed cooler box..sealing can be a small issue and it can be rarther large.. Other than this, it works well achieving about 12 /14 degs C drop.

I used expanded foam for insulation but i believe there is thinner sheet available that insulates just as well ....for pipe work etc?

Ray

[Dave_D]

first pre, pre, pre, pre alpha code is running, rough, but it works 

not put in setpoint or any bells and whistles, but it only took 30 minutes to get a working prototype so that's good enough for now.

http://smg.photobucket.com/user/vanityassassin/media/VID_20140628_184651_zpsw0ra5q5q.mp4

[russellhq]

Can't get link to work.

[Dave_D]

Grrrr i'll sort it soon as i finish cooking