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FrozenGate by Avery

Cheap tecs?

Hey, sorry to go off topic a little, but I was wondering something.

whenever you run a diode with too many mA, it causes the life to decrease partly because of the heat generated?

so if you use a good heatsink and one of these thermoelectric coolers, can you safely run a 20x diode at more powerful outputs (such as 250 mW or above) and not worry about destroying the diode quickly?
 





I don't know how long my open can diode will last...but it is putting out a little in excess of 300mw's.. ;D

With no TEC, it heats up quickly, and the power output drops quickly too.
 
I see.
Is that with or without a heatsink?

and, if it runs more efficiantly with the cooling devices, that probably won't HURT the diode, so why not use them, right?
 
Following is a picture of mine...ignore the big heatsink. I have my TEC mounted to it with double sided sticky tape as well as the PC board.
 

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Sorry for the crappy quality of the pic:
 

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both of those tec's seem to be about the same size. looks like gazoo's is about 30mm x 30 mm and the other one is 40mmx 40mm
 
Hm this is not good, i only have one lm317 that i need to drive the diode, can i just use a resistor in series with the battery to power the tec, would i be able to get to the range i want, cool but not freezing and making ice,  Any rough suggestions on the value, id be using a 7.2v ni-cd battery pack.

I also have a variable resistor, the kind that take about 20 turns to go from lowest to highest resistance, one is 5k one is 5meg would one of those work, there big so they might be okay connected straight to the battery.


....lazer.... ;D ;D ;D
 
I, personally - and others may disagree with this, but... would not bother to run a regulator on the TEC circuit IF: 1. I was running from batteries that were less than 90% of the Vmax of the device and 2. I was planning to run the device at currents at 50% or less of the Imax of the device.

So from my perspective, the answer is that yes, a resistor should be fine if you're operating from 7.2 volts on a device made to run up to 15vdc. These things don't care if the voltage or current is STABLE, only that it doesn't exceed the device's maximums. And as I think you noted earlier - you don't want this thing to cool enough to cause frost or even condensation, so you're not going to be operating anywhere near your maximums.

As for suggesting a value - you're probably going to want to start by pumping about 1/4 it's max I into it. You'll want a pot that can take an amp or two at your voltage to avoid burning the pot. Just say no to burning pot... ;) I'd just manually tweak the pot until I got the cooling response that was sufficient for the diode's operational characteristics, ie., make it so the diode feels slightly cooler than room temp when running at a higher-than-normal duty cycle.

Sound good?

These devices are fun to play with - they respond immediately and are very easy to just try things out on to get them set up. It'll probably take you less time to work your resistor values in than it did to read this post!

One last note - if you're operating your diode and TEC from the same batteries, it should work out well in that if your TEC battery is going dead, and you're losing cooling ability - your diode should be ready to go to sleep as well! :) If, however, you're running separate batteries for LD & TEC, you may want to be sure the TEC battery never dies before the LD battery does...

D
 
Okay thanks, i have an idea ill just use 2 of the tecs and put the pot on one of them ;D That link gazoo gave is a good place, i thought they were alot smaller until i saw gazoos pick, and i get 5 of them, 1 for laser, 4 for making a mini freezer or something ;D

I think i will run them on the same battery a 2000mah 7.2 one since that should last a while, that would be bad if the tec lost its cooling and the diode was still running at 400ma, bet that would get hot.

...lazer... ;D ;D ;D
 
At the very most you might need to run it at 5 volts which will be about a half an amp. So your pot would need to be capable of handling a minimum of 2.5 watts. The 3 watt 25 ohm rheostat RS has might be ideal as long as you don't run it higher than 5 volts. Still, running it with a regulator would be better. You could always get a 5 volt regulator and the rheostat at RS.
 
Well good thing is i found where the other lm317 was that came out of some charger ;D, Good thing because the trimpot i have is only 1watt.. Not very good unless its on a tec itself, Im gona make a super cooler with one of these, im gona hook it to a computer pwer supply and put it on a bigger heatsink with a fan, that should get nice and cold, are the ones you linked sealed where water wont get inside of them and mess em up?

...lazer... ;D ;D ;D
 
The ones I linked to are not sealed. If you want to play and get it freezing cold, then it would be better to get sealed ones. If you are looking for something to cool your diode down with, then the ones I linked to are good. But you can always seal them with silicon. Next time I order a peltier I am going to get a sealed one to play with and mount it to that big heatsink in the picture above. It is a Thermaltake CPU heatsink with a fan already mounted to it. I need to redo my labby and mount it all in a nice enclosure. I plan on eventually making it portable. :)
 
Well now i only have 1 diode left :'( I was reflecting the other one off a mirror onto something when it reflected back into the aixis chamber and it broke it :'( now its a .05mw laser no point in that, I have no clue why it did that i was so mad, when i saw it go to the dull glow i was like nooo... it cant be broken.. well lasted a week.., I might try harvesting one from a 20x since now i dont want to push the last one i have, for know i might try to find a good deal on a sealed peltier to run it max power and make a good soda cooler or something, i found a 15v 600ma transformer wich should run it at like max power with a fan to the heatsink to make it coldor, If i cant find a good one i might get the ones you showed me, i mean 10 dollors for 5 with heatsinks i dont think i can find ones without heatsinks that cheap.. to seal it could you just like put the entire thing in like a thin ziplock, (not the freezer ones that have thicker plastic) and i could melt the edges of it and make a plastic seal all around it, as long as i dont get air in it i think it might work good?

....lazer.... ;D ;D ;D
 
your best bet for sealing it would just be to grab a tube of silicone sealant - usually labeled for things like bathroom use
 
Hm i think I might have some, i think its the kind that goes in the caulk guns, would that kind work, its clear?

....lazer....
 
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