ThermoElectric Coolers (TECs)

Daedal,

Your welcome and if I see them listed again I will post. I know others want them.

Yeah, for the size they impress the heck out of me.. ;D It is my first peltier, but I couldn't believe how cold it got when pushed to the max.

i was impreesed as hell with the first TEC that i got, but then i used thermal tape to tape it to a heatsink, and now it has chips all over it and i can't move it :-/ i'm going to order a couple more tonight though, they are very fun to experiment with!

Gazoo said:

I saw that peltier too and I don't think there is a huge difference. But if you can wait a few days, there is a good chance he will relist the ones we bought.

I am almost certain you will need a bigger heat sink. As soon as I receive the second peltier I ordered, I can try it with that type of heat sink. I have some I plan to pull off of an old motherboard.

I did use Daedal's circuit to power the TEC and have had excellent results. It only draws 200ma's at most to keep the diode cool, so I know the heat sink I am currently using is an overkill. But it makes for a nice stable platform for mounting everything onto it.

Click to expand...

I have the heatsinks but the peltior is in transit. I have no LD yet either. All of the parts are converging on me...and SenKat.

They are tiny heatsinks but these are slightly larger than most vid chip heatsinks I have seen. If I don't drive the peltior hard they may work. The trick here is to figure out how much heat actually needs to be pulled off and work up a combination of passive and active heatsinks.

A better design would be to machine a bit of copper to add a bit of mass, frame the peltior, encircle the module and accept a video card heatsink.

I'm building something much the same. I will use a 317 circuit for the LD and the same circuit for the TEC. I don't need over 500 mA for the TEC so why not ?? All will be powered through a 7805 (boosted a bit) for voltage regulation.

Mike

I am familiar with the boosting trick for the 7805. It is a trick I learned year ago, but it works very well. The 317 running the peltier does get a bit on the hot side. I put those little clip on heat sinks just to play it safe.

why not use a temperature feedback circuit? it would be easier i think?

JES,
I fully agree. There are always better ways to design things and I am going to take my time with the next peltier I receive.

I have an open can diode mounted in a Meredith module. Meredith sells a small cooling block that attaches to the module. Link follows:

http://www.mi-lasers.com/cgi-bin/shopper.cgi?search=action&keywords=diode_optics

I am planning on ordering the block and possibly another module. This time I want to try the one with the acrylic lens. Anyway, that cooling block will make it much easier to design something that is more professional looking.. ;D But unfortunately they are much more expensive than the Aixiz modules. On the other hand the thing I like about the small Axiz module is that it can be mounted in almost anything.

i was just playing with an old pelt a minute ago, it can't freeze water anymore, but it gets damn hot when you switch polarity. i'm ordering some new ones tonigh and they should be here tommorow or friday

things said:

why not use a temperature feedback circuit? it would be easier i think?

Click to expand...

Very good idea. Manufacturers recommend against the on off approach. This would be the easiest.

A PWM circuit is recommend that provides precise current flow to he peltier at all times to maintain temperature. I would not mind finding an easy circuit of this type to build.

i've heard somewhere that petiers don't like to be PWMed below 2khz as it puts too much stress on them. if we could find a temperature controlled circuit that slowly limited the power according to the temperature, all our troubles with controlling them accurately would be gone!

or was it above 2khz????i forget now, but i'll check up on it later?

Eventually, I hope to use a thermister or PTC to comtrol the current to the TEC. It will need to be fast acting or the hysterisis will be wild.

Mike

JES said:

[quote author=Gazoo link=1187495006/60#70 date=1188347023]

I have the heatsinks but the peltior is in transit. I have no LD yet either. All of the parts are converging on me...and SenKat.

They are tiny heatsinks but these are slightly larger than most vid chip heatsinks I have seen. If I don't drive the peltior hard they may work. The trick here is to figure out how much heat actually needs to be pulled off and work up a combination of passive and active heatsinks.

A better design would be to machine a bit of copper to add a bit of mass, frame the peltior, encircle the module and accept a video card heatsink.

Click to expand...

Hello Jes,
I received my other peltier today and I did not forget you.. The results are very promising.

The heat sink I pulled off the motherboard is just a little over a half inch square. The ones posted in the auction are just a bit bigger I think, but also have a much better design

I ran the peltier for 5 minutes at 200ma's and the heat sink did get a little warm, but the cool side did stay nice and cool. The temperature in my home is 80 degrees F. and the humidity is 60%.

The pic follows and I apologize for the crappy quality. Note: I did have the heat sink turned over with the peltier facing down when I did the test, although it would not have mattered because the heat sink behaved.. ;D

Gazoo said:

Hello Jes,
I received my other peltier today and I did not forget you.. The results are very promising.

The heat sink I pulled off the motherboard is just a little over a half inch square. The ones posted in the auction are just a bit bigger I think, but also have a much better design

I ran the peltier for 5 minutes at 200ma's and the heat sink did get a little warm, but the cool side did stay nice and cool. The temperature in my home is 80 degrees F. and the humidity is 60%.

The pic follows and I apologize for the crappy quality. Note: I did have the heat sink turned over with the peltier facing down when I did the test, although it would not have mattered because the heat sink behaved.. ;D

Click to expand...

That is excellent news. I may try mounting one of these on the peltior and another passive on the other side of a module. I wonder how much cooling the peltior needs to do to keep a LD happy when it is being pushed. Mike has posted that on his test there isn't any benefit to going beyond 400ma on the GB LDs. I wonder how close to that we can go without getting into condensation issues on the peltior. What is the upper-range temperature on these GB LDs?

Another thing I noticed about the heatsinks; the fins were slightly bent together. I thought 'oh that will be easy to fix' but then thought that perhaps I should try pulling them apart and having the base curve more snuggly against an aixiz module.

Are you planning on sealing your peltior? I wish I could do some machining. I just do not have the equipment and it isnt in the budget right now either.

I got goggles today from WickedLasers. They were in China a week ago. They were at JFK yesterday. They made it from JFK to my house in a day. A nice guy from the Post Office drove up and had me sign for them. We live in interesting times.

Thanks Gazoo!

Here is a long story short..I do not recommend pushing these diode that hard. I saw Mike's post and I think he was pushing his open can diode, but he will need to confirm this. I did it for only a second and it did not last very long after. If you want the diode to last awhile, do not exceed 250ma's and run very short duty cycles..maybe 10 seconds.

Please refer to the sticky I posted in this section for the dew point calculator. This will tell you how cold you can have your module without worrying about condensation. The rule of thumb is to have it just a little bit cooler than the ambient temperature. Condensation will kill these diodes...I learned the hard way.. :'( So how much current does it take? Well in my home with the temperature at 80, and the humidity at 60%, 200ma's is more than enough There is absolutely no need to seal the peltier.

I am really not quite sure what you mean by the fins being bent with the ones you received. It almost sounds like you were planning to mount the module in between the fins or something like that?

Enjoy the goggles. I love mine..

Gazoo said:

I am really not quite sure what you mean by the fins being bent with the ones you received. It almost sounds like you were planning to mount the module in between the fins or something like that?

Click to expand...

No. I was thinking of a passive heatsink that I may mount on the opposite side of the aixiz module from the peltier heatsink. The base of the heatsink was thin enough to allow a very slight bend to occur to one of them during shipping since the guy sent it in an envelope and it probably sat under a box during its journey. The fins were no longer vertical, they were slightly pressed inward. I was thinking that if they could do that, perhaps with a torch and some slow pressure, they could be coaxed into a form that would allow the base of the heatsink to hug the aixiz module.

I would mount the peltier in a straight one in the conventional manner.

It was perfectly clear in my mind but mud in print. Funny how that happens sometimes.