My 1100D modding thread *IR Cut mod finished* ETA CARINAE images Stock VS Modded

[wasyoungonce (Brendan)]

Problem would be power dropped over potentiometer. I draw Peltier ~ 2.5amp I (nominal), your lower Peltier voltage from 12V to lets say to 5V. of course you lower Peltier voltage it's I draw will change as well.

Thus that this stage we have 7V dropped across pot. Power across pot P = EI, P = 7 x 2.5 = 17.5 watts energy dissipated thru pot...a lot.

This is why proportional voltage control is difficult.....if you used a transistor to lower the voltage you would have similar power drop across it.

This is probably why devices control is done with PWM...changing mark space ratio, driving a FET and Peltier.

[rcheshire (Rowland)]

It's not such an easy thing to do. Maybe for a dew heater drawing a few watts. Tellurex say they have developed a linear style using MOSFETS with reduced efficiency. No details that I can find.

[2stroke (Jay)]

So the work goes on with little time i have lol, i striped some un-needed parts of the top section to make it fit inside the enclouser and also free it of non needed fuctions to save weight and hopefully EMF. I still need the top section as it has the dam switch and also mode dial bah. Heres a few pic's hopefully next post i can start the dam coldfinger itself lol.

[rcheshire (Rowland)]

You're braver than I Jay. I've been playing around with a 5mm Neoprene jacket on my dslr. Cooling is to the plate on the bottom of the chassis - removed the plastic cover to get to it. Best reduction measured at the bottom plate is 20 below ambient, but I dont think this is conducted to the sensor. Have a recirc fan blowing air within the camera body flowing over silica gel. Dark noise improvement is markedly better. If I insulate the cold finger at the bottom plate, I get another 5C below. I've toyed with the idea of using reflective foil under the neoprene. Sealing around the lens seems OK and so far no condensation, even at -5C, with a dewpoint of +5C. Except for one or two controls the Neoprene is flexible enough to push buttons without cutting holes. For the other controls and screen I've cut flaps that fold back in place. See how it goes...

[2stroke (Jay)]

Thats a whole new approach you have gone with there, that's really thinking outside the box haha. Good to hear you getting great temps with it, the only problem would be getting the temp down to start with which could be solved in a fridge

Sort of going right out with this mod, have a whole spare camera in parts so i can afford to experiment a bit. Will do a full pc run with the final strip down, no back lcd or buttons / plastic so only the top is left.

[rcheshire (Rowland)]

Yeah. It's takes about 10 minutes to get down to max diff, but I think a while longer to chill the chassis and anything connected. The internal recirc fan should even out the air temp inside the camera, I hope. Keep up the good work.

[2stroke (Jay)]

Quick shots of the 1100D stripped down with no back or front working in BYEOS. The flash has also being stripped out along with some of the functions on the top, this is also the final product in terms of strip down as there inst much else to take off it lol. Starting the coldfinger after this post XD

[2stroke (Jay)]

Well its on with the cold finger, i have just mod the cmos housing so no cutting is required for the studs, also i will use longer screws to replace toughs that hold the cmos in place. Now why longer screws you ask? because they will also force the cold finger down firmly against the cmos back maximizing transfere of cooling and also hold the cmos. No more cold finger sliding all over the place either and also no need to worry about contact with the pcb and those prom pins sticking down w00t. Now for anyone else out there these nubs are only used to guide the cmos bracket to the housing and can be removed with a twist action with a pair of pointy nose pliers Kitty not recommend in work space