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peltier/TEC

chipdouglas

chipdouglas

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I have been reading some on wiki but the info isn't really sinking in. Are Peltier's and TEC's the same thing? :undecided:
 





chipdouglas

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thanks elektro. after reading today on wiki about TEC's and what types of objects use them, i realized I had one laying around in my old mini car fridge. so i ran out to the shop and took it apart. PRESTO!!!! TEC. it gets icy after about a minute, and that is with out a fan. now i need to get the parts to make a labby. here is a pic. Oh and it is 12vdc rated.
 

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Jaseth

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Pretty neat piece of TEC heatsink, but don't you think it might be a bit overkill for a poor little labby if it gets icy after 1 minute? You want to keep your lasers warm and prevent them from becoming hot, you don't want a cool/frozen laser.
 
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ElektroFreak

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^A TECs temperature depends on the current flowing through it, so it is variable. He'll be able to set the temp. to whatever works best. This is called temperature tuning.
 
Jaseth

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Oh ok I thought TECs were pretuned from the factory to always cool within a certain temperature range, such as many freezers' -18°C to -6°C range.
How do you know what current to provide for the temperature you want to maintain? Trial and error using a thermometer?
 
chipdouglas

chipdouglas

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So elektro freak.... I used an un regulated power source, is that the reason for the ice? And would a ddl circuit work or do tec's need whole amps?

@jaseth..... It might be overkill if it was a tec for a fridge. But I am also saving up for 20k galvos....
 
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ElektroFreak

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chipdouglas said:
So elektro freak.... I used an un regulated power source, is that the reason for the ice? And would a ddl circuit work or do tec's need whole amps?

@jaseth..... It might be overkill if it was a tec for a fridge. But I am also saving up for 20k galvos....
Click to expand...

A DDL driver is perfect. They have been fairly commonly used with TECs for a long time. If you're building a DPSS laser using that TEC, then temperature tuning is a must. It really can be just as simple as powering up the laser and adjusting the TEC as it warms up until you get to a maximum sustained power. You'll be able to tell if you've gone too high or too low enough because the power will drop.

A more complex (and also much better) DPSS arrangement includes up to three TECs. One cooling the diode, one cooling the vanadate or YAG, and one reversed so that it heats the KTP. Of course, this can only be done with discrete (separate) crystals.

TEC cooling visible diode lasers is good for the diode, but diodes don't require the kind of temperature tuning that DPSS systems do. Basically, any temperature close to 25C is ideal for diodes.
 
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chipdouglas

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@elektro and jayrob..... You guys always give solid and understandable advice/help. I will do the ddl route then and just play with settings till I hit the sweet spot.

@elektro and jaseth.... I'm gonna lurk the forums for used galvos first but will probably buy a new set up I found for 425usd.
And the module I will use first is actually the one elktrofreak recently did a review on...the o-like green one.
 
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ElektroFreak

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^I just noticed that you asked if TECs need whole amps. They are usually rated in whole amps, but for the kind of cooling required for a small DPSS laser (no freezing temperatures or anything like that) a few hundred mA would work.
 
MarioMaster

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Also, for more accurate regulation a small controller with a thermistor could be used. Temperature stability is more important for DPSS lasers though, diodes don't really care if there's a 5 degree temp swing.
 
chipdouglas

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@elektro....again.... So a ddl would work. Would I wire everything like this.... All positives (LD pos- tec pos- pwr sup pos, to ld neg, tec neg- pwr neg) or do I need two drivers? One for LD and one for TEC?
 
MarioMaster

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chipdouglas said:
@elektro....again.... So a ddl would work. Would I wire everything like this.... All positives (LD pos- tec pos- pwr sup pos, to ld neg, tec neg- pwr neg) or do I need two drivers? One for LD and one for TEC?
Click to expand...

You need one for the TEC and one for the diode. The TEC will need a few hundred mA to keep the laser cool.
 
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