Some tips on thermoelectric cooling: 1) Make sure you purchase sealed thermoelectric modules(the elements are sealed completely typically using silicone). If the units are not sealed condensation will form on the thermoelectric elements and they will literally fail within an hour or two. 2) Pressed fin type heatsinks work well in removing the heat. Blow the fan inward against the fins, do not blow laterally across the fins. Your best heat removal comes with turbulent air flow, not laminar air flow(which is why blowing inward, perpendicular to the fins is best). 3) Any ripple on your DC current will add unnecessary heat to the assembly(ie: heat that works against your cooling capability). Setups like you see for cooling microprocessors are a good analog and you should set up something like that to cool your modules. 4) As the temperature diffence between the cold and hot side of the thermoelectric increases the cooling capability goes down. Hence the better your heat removal capability(heatsink/fan) the better off you are. 5) When you assemble the thermoelectrics, sandwiching them between the heatsink and the cold plate make sure you use a torque driver to get the same torque across each screw. Use something like a bellville washer on each screw to equalize the pressure: http://www.rctek.com/fixings/bellville_washers.html If you have uneven pressure across each of the screws you could end up damaging the thermoelectric modules as they are fairly fragile. Also use an insulating washer on the screw on the cold plate side to isolate heat transfer along the screw from the heatsink to the cold plate. Good luck with your project.
Date: Tue, 24 Jun 2008 13:50:31 -0400From: [EMAIL PROTECTED]: [EMAIL PROTECTED]: [EMAIL PROTECTED]: Re: gEDA-user: Using SMT Thanks everyone. The Project: I'm a quadriplegic and during the summer I have difficulty regulating my temperature and am usually restricted to indoors and air condition when the outdoor temperature exceeds 80 degrees. I've been working on a design to mount a thermoelectric cold plate in the backrest of my wheelchair. This cold plate will have the capability of cooling or heating via a PWM controlling an h-bridge. I'm using a microchip dsPIC DSC to monitor thermocouples in the backrest, interface to the user and control the power to the cold-plate. I'm about 80% done with the code and trying to get my spare chair prototyped while the summer is still here (central Massachusetts). On Tue, Jun 24, 2008 at 1:29 PM, John Luciani <[EMAIL PROTECTED]> wrote: On Tue, Jun 24, 2008 at 1:12 PM, Robert Butts <[EMAIL PROTECTED]> wrote: I'm about to start bread boarding a desin. I have a few surface mount chips that I got SMT-to-DIP adapters for. I also purchased SMT paste. I have never worked with surface mount devices. How do you paste the chip to its footprint? How do you get the excess, if any, paste out? I have a feeling it's got something to do with heating it. Thanks, Rob I use wire solder, water soluble flux and a fine tip soldering iron. A list of the toolsand supplies I use are at http://tinyurl.com/6b2vy9(* jcl *)-- http://www.luciani.org _______________________________________________geda-user mailing [EMAIL PROTECTED]://www.seul.org/cgi-bin/mailman/listinfo/geda-user _________________________________________________________________ Introducing Live Search cashback . It's search that pays you back! http://search.live.com/cashback/?&pkw=form=MIJAAF/publ=HMTGL/crea=introsrchcashback
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