DIY LEDs - The write-up

[skippyreef]

Also the UV are 5W with Vf of 4.2 max drive 0.7amps. Would I run this in a string of 12 or could I go 13. What would you do?

 

[widmer]

Mine [meanwells] get HOT. Don't know if that's normal, but that's my experience.

This reminds me, I have been meaning to ask one of our gurus what they think about the buck pucks getting really hot. I was wondering if it would be good to attach them to the aluminum heat sinks with some thermal epoxy...

 

[kcress]

The drivers certainly have heat to reject so you don't want to physically stack them. Notice that they are around 85% efficient? That means 15% of whatever power you are driving thru your LED chains shows up directly as heat coming off of the driver.

 

[kcress]

wid; Probably better would just be forced air across them.

 

[slevesque]

Thanks Bill, in line with the other suggestion.

For a 30 Breeder (36"18"x12") I guess 24 would be sufficient.

 

[skippyreef]

Here is the first 36 inch section (have to wait for epoxy to set prior to wiring) I just finished.

 

[Reef_Matrix29]

This reminds me, I have been meaning to ask one of our gurus what they think about the buck pucks getting really hot. I was wondering if it would be good to attach them to the aluminum heat sinks with some thermal epoxy...

This topic keeps coming up and I'm wondering if it is certain kinds of meanwells or just the dimmable ones, because my meanwells (non-dimmable ELN''s) are maybe room temp or a tad above that while running 10 hour cycles each day. I experienced no dramatic difference when I was running them at 700, 500 or 350mA current and I'm 6 different drivers with no discernible difference. Can anyone comment as to their drivers running hot if they are dimmable as well?

 

[der_wille_zur_macht]

It all really boils down to efficiency. As kcress mentioned above, you can pretty much calculate the amount of heat the driver has to dissipate if you know the power it's operating at and it's efficiency. Efficiency of these drivers can vary considerably depending on operating conditions - for instance, if a driver is rated up to 24v of output, and you're only running three LEDs on it, it might be more or less efficient (probably way less) than if you were running 23.9v of LEDs on it.

With respect to dimming, it depends on how the dimming is implemented. If the output is simply switched (i.e. in response to a PWM signal) then the driver is only actually on X% of the time, so it won't be producing heat 100-X% of the time.

Since the commercial drivers are all essentially black boxes with respect to the above two factors, it's hard to predict results other than anecdotal evidence from other users. Meanwhile, in the various DIY drivers I've built, I can tell you EXACTLY under what conditions they'll run hotter or cooler.

Also, of course, ambient conditions. Throwing a 1" square buckpuck in a 2" square project box, vs. having it out in the open in somewhat drafty conditions, will definitely make a difference in the perceived heat.

 

[skippyreef]

IN this pic you can see the single UV bulb. Not super bright but hoping it will help with coloration.

 

[der_wille_zur_macht]

Not super bright

By definition, UV is beyond the range of what we see as light, so it shouldn't appear bright at all. Any light you CAN see from it is off-spectrum radiation, not the intended UV radiation.

On that same note, it can also be very damaging to eyes and skin, so I would be super-extra careful to not run it unprotected (like you are in that photo.)

 

[skippyreef]

Think an elliptical lense would be helpful in terms of protection?

 

[der_wille_zur_macht]

It would probably depend on the specific wavelength and intensity of UV and the material the optic was made from.

I should note that I'm not an expert on this subject; just know enough to be very careful.

 

[skippyreef]

This is a 400nm wavelength. I did not want to go any lower than that.

 

[skippyreef]

This wil have an acrylic splash guard too.

 

[Jay1982]

I'm using the 20mm star board for my XPGs. I'm currently waiting for the order to arrive from cutter but in the meantime I want to get all my supplies, I plan on drilling the heatsinks and screwing the leds on. How big should the holes be for the screws? Also, are nylon screws the way to go? Or would metal screws with nylon washers be better?

 

[adova]

Unless you are just in love with the idea of screws (and the work of screwing them on and drilling), I would recommend using some thermal tape. I am using BondPly 100 .5 mil.

When I tried the screwing method, I found that the #6 screws and washers go in the way of the optics. I am sure there was a way to get them to work better, but this tape is just too easy in comparison. Strong enough to hold the lamps, but easy enough to remove i the case of replacement...

 

[Jay1982]

Well, I ordered 1 Arctic Alumina Adhesive 5g tube. Should that be enough for 72 LEDs?

 

[adova]

I have never used adhesive, but I am a bit confused - you are going to use adhesive and screw them down? I may be wrong, but I would not think you would need both. If you are going to screw them down, just use a thermal transfer paste (as apposed to adhesive)...

 

[Jay1982]

I bought the adhesive incase I wasn't going to screw them down.

If anyone thinks I'll need more, please let me know and I'll order some more before my LEDs get here

 

[The Grim Reefer]

I got the pre cut tape that Nanocustoms is selling. Works great so far, knocks on wood.

I would contact the manufacturer to make sure the lens will filter UV. I am not sure if all acrylic does and you want to be careful about that. Even at 400nm the LED can be dangerous to your eyes. Your eye doesn't react to blue light very well so it doesn't close up to prevent too much light from entering. You should not look directly at even the blue LED's for very long, or any other high output source of blue light.