Ideas for exposed LDs?

[Gazoo]

Hey falchionsmight,
Look at the bright side (no pun intended). If you kill your diode, you will be in lots of good company ;D Many of us have killed more than a few.

Using a liquid cooled system is a good idea, and I had thought of it. However condensation might still be a problem around the heat sink area and inside of the diode. Finding ways to totally prevent it can be done as TEC's are used to cool CPU's. I thought about using a sealed module but there would still be air inside of it. I don't have an answer, but Daedal and Pseudo are or will be experimenting with peltier cooling so hopefully we will get an answer. As Daedal said, controlling the temperature would be a huge plus.

 

[Daedal]

Well... falchionsmight, I'm sorry I missed your post at the end... I truly NEED helping hands around here... both mine and my GF's are not enough... I sometimes end up needing more than 4 hands! lol ;D

As about the TEC cooling... Let's see... Liquid cooling on a TEC's hot side to keep the cool side cold enough to cool the LD. Let my start off my hoping you don't expect this thing to be portable at this point...

Also... If I do finally get away from all the nice mess I have myself in right now, I will definitely get a nice circuit up that will switch the TEC on and off periodically so a point where the temperature is good enough to where the condensation wouldn't be an issue. If it's not an issue in FL, trust me it probably isn't anywhere else. ;D

Also, thinking about it logically... I was messing with a tiny TEC that I have (prolly as small as the one that's used in the D4Thing so very tiny) and that thing was freezing water and not needing that much heat dissipation. Also, condensation was not that much of an issue even when I wasn't running it on switched mode. All I did was control the Voltage/Current at around 4V .5A and this thing was very cool to the touch but not cold enough to create condensation on a glass plate or any of the optics I tried to cool on it. The hot side was good enough and content just being hooked up to an aluminum block (not even plastered or glued, just put on there... and the block was a bit rough, so I know heat dissipation wasn't optimal. The thing was cold, but not FREEZING... water wouldn't freeze up until I let the power loose until about 6V/1A. Although it is cool to boil ice on something this tiny!! Especially when IT made the ice! ;D ;D

So... I'll keep you all updated as things happen, but I'm sure getting a peltier to cool a LD is not gonna be that difficult, but it will either drain your batteries KILLER FAST or it will need its own power source/batteries. That is unless you want the batteries to drain in a few hours...

--DDL

 

[Daedal]

I believe I omitted this part in my last post... cooling an LD will probably be (at least how I'm designing it so far) a bench-top or labby-style laser kind of thing. I can't think of a logical flashlight that is not custom made that would be able to house all the electronics, batteries, provide enough heat dissipation, and still be portable... except for something like a laptop-sized thing.. ;D

--DDL

 

[falchionsmight]

I have no intention of making this thing a portable pen laser ;D I'd like to, but it looks like to keep this little monster happy, I'll have to pamper it, and give it lots of juice, and lots of air conditioning...(sorry for the metaphors ). Just as an update I've been playing with it at 330 mA, I think it's still at the same 4.4 volts, and with a lens out of the DVD optics (it might be from a CD player, I forget which one comes from where, I've got quite the collection now), and this thing will make a floppy smoke instantly, I can melt it fast enough I could etch words into the plastic. It also pops balloons (sharpied) and will make sharpied caps pop.

As for the TECs where is the best place to get them from? I'd love to see a very small TEC like you mention in your reply Daedal, that sounds like too much fun... I hope it doesn't cost too much. I'm pretty close to broke right now, Just bought a brand new computer (well, I'm happily living off my parents for room and board, and food, so I get to save up my cash and get awesome toys like lasers... and a MacBook Pro... but when you "NEED" stuff for school it's all justified... right? ;D). Thanks for all the help, and I'll be sure to keep updates about my diode's adventure posted.

 

[Gazoo]

How about this peltier. It is very small, runs on low voltage and current, and would be easy to use in a larger flashlight.

http://cgi.ebay.com/Peltier-Junctio...48249769QQihZ005QQcategoryZ4661QQcmdZViewItem

 

[Daedal]

I'm with you in the same boat there falchionsmight, broke that is... :-[ Jobs seem to be scarce right now and I'm not a very happy camper right now...

The peltier I have I had gotten from a local shop. It was about $7 I think, but it's very much worth it. They had about 10 or so of them... I might just go grab a few more for later experiments if I have enough money...

Gazoo, that's a pretty cool setup for a peltier. I like it. You wanna try it out and tell us what you find?

Thanx;
DDL

 

[Gazoo]

I believe I omitted this part in my last post... cooling an LD will probably be (at least how I'm designing it so far) a bench-top or labby-style laser kind of thing. I can't think of a logical flashlight that is not custom made that would be able to house all the electronics, batteries, provide enough heat dissipation, and still be portable... except for something like a laptop-sized thing.. ;D

--DDL

No doubt it would take a hefty flashlight to be able to fit everything into it. I have one of those 10,000,000 candle power flashlights I purchased at Sam's club. It is powered by two 6 volt 6 amp gel cells hooked in series. It also has LED lighting and a 12 volt cigarette lighter output. I would not want to hack this particular flashlight. But it has enough room in the head to house a TEC. I know it would not be as efficient as using switching supply, but it would be portable.

I do have a couple of questions. What would be the most efficient way to drop the voltage from 12 volts to around 3 volts for the peltier I provided in the link? I suppose everything could be stripped out of a flashlight like the one I have and rewired to use two D batteries, and then use a boost circuit for the laser diode. Or maybe better yet use one of the 6 volt batteries. I am just brain storming and trying to figure out the cheapest way of making this portable....if possible.

And more importantly, is it going to be easy and cheap to design a temp. controlled TEC?. Can you post a schematic of the circuit you have in mind to do this if you have gotten that far? Thanks.

 

[Hemlock_Mike]

Now I had to order one of those stacked coolers. I might need one.
The most efficient way to lower 12 to 3 volts is with a switching supply, otherwise you get a lot of waste heat.

Mike

 

[Gazoo]

I decided to order one too. It is very small but should provide ample cooling for a diode. I only wish I knew how to control the temp. And I would think it would draw much less current at 3 volts than at 5 volts, and would still provide adequate cooling. I found a switching power supply that plugs into a cigarette lighter and has various voltages. It provides 2.75 amps max at 3 volts output and is reasonably priced. Well anyway, I guess I will have to wait until the peltier gets here and then decide how to use it..lol.

 

[Gazoo]

Now I had to order one of those stacked coolers. I might need one.
The most efficient way to lower 12 to 3 volts is with a switching supply, otherwise you get a lot of waste heat.

Mike

Hey Mike,
I received my cooler today and man it is just as small as they described it. If you figure how it is supposed to be hooked up, would you please let me know? Thanks

 

[Hemlock_Mike]

Gazoo --

I got mine today too. Nice piece of stuff !!! If you hook them backwards, the cold side gets hot -- they work both ways. I have no idea how much V/I to feed it but it will be mounted to a heatsink first.
I plan to machine a flat area on an Axixs module to match the cold side and put the hot to a big heatsink. That's all I know so far.

Mike

 

[Gazoo]

Mike I couldn't wait so I hooked mine up before you posted and I have tested it out. It does not draw anywhere near 4 amps. At 3 volts it only draws about 500ma. At 6 volts it is drawing a little over an amp. For my testing I wired it up so the bigger flat side is the hot side. Then I applied a little arctic silver compound to the hot side and pressed it on a heat sink. There is nothing holding it on other then the arctic silver. The smaller square gets really cold. I am sure if I was using arctic silver adhesive and had it clamped down tight it would get even colder. But what surprises me the most is the small amount of current it draws. Lovely for making a portable device... ;D I don't have anything to measure the temp of it...darn..

 

[Gazoo]

WoW!!! This is amazing. I put some small droplets of water on it and they froze within seconds. Then I laid an Aixiz module on it and it got freezing cold within a minute....with only 3 volts at 500ma. I know I am excited as this is the first time I have ever played with a peltier. I plan on flattening the front part of the module just a little bit, and using thermal adhesive to glue it on to the peltier. This way it will still be easy to unscrew the back side in case the diode goes poof. I might put some arctic silver on the threads of the module to help the cold conduct. Anyway for my next experiment I plan to lay the module on the peltier as I did before, and apply power to the laser. I really need to get some arctic silver adhesive...lol.

 

[Hemlock_Mike]

Gazoo --
That is what I was hoping to hear. Thanks for the preliminary specs.
That's a good start.

Mike

 

[Gazoo]

I have a very crude setup...lol. Well, I don't know if it is just me and I have some more experimenting to do. But I did cool down the module, and then ran 220ma through it. I know I can go higher but I wanted to see what the effect would be. Well it seems as though it is putting out much more mw's when cooled. I don't have a meter yet so when you get set up Mike, perhaps you can confirm this. One thing for sure, once you are ready to fire up that peltier you are going to love it

 

[Gazoo]

By the way I do not recommend running anything more than 5 volts into the peltier. The only reason I ran 6 volts was because I wanted to see if the current it was using would be considerably more. It wasn't. From the limited experimenting I have been able to do, it doesn't seem to condensate at 3 volts. At 4.5 volts, it does but it still isn't bad.