Need DIY reading lamp ideas, Cree XPG on a Meanwell ELN60-48D

[redfishsc]

I am a reef keeper (some of you reefers on here may recognize me), but because of time and money constraints, I'm taking down my tanks (grad school mess).


I have an LED array (8 Cree XRE in royal blue) that I think I'm going to change over to an all-white (XPG).

The Meanwell should be able to easily drive 13 XPG at 1300mA.

I do have a 10K pot as a dimmer.


Anyhow, I would like to convert this into one monster reading light. Any given semester I typically read 1500 to 4000 pages in grad school and would like something I can dim.


I'm a carpenter/cabinet maker so I can build pretty much any enclosure I want.

BUT I NEED SOME IDEAS!


The heatsinks I have are from heatsinkusa.com and are 24" long, 2" wide. I have two of them and can cut them any way I want, I'll probably make a 8X12 array.

Thanks!!!

Matt

 

[purduephotog]

Actually, I'd be interested in your royal blue setup- got a photo? I'd use it to grow plants...

I have built a setup using the meanwell- I really like it (obviously you have too). Are you certain you want the xp-g? You can put 3x bridgelux units on there and power them at only slightly over spec with that power supply.

As for dimming- I suppose you've already got the controller with the integrated dimmer in it. I know there are two types of meanwells, and there was some earlier confusing talk about an add on circuit for dimming. Never saw what happened with that and the reefs.

 

[purduephotog]

http://www.newark.com/bridgelux/bxra-w1202-00000/high-brightness-led-arrays/dp/60R6548

• High Brightness LED Arrays
• Luminous Flux:1320lm
• LED Color:Warm White
• CCT:3000K
• Color Rendering Index:82
• Viewing Angle:120°
• Forward Voltage:15.1V
• Forward Current:1.2A
• Mounting Type:SMD
• Opto Case Style:SMD

 

[redfishsc]

I like the Bridgelux in the pics, but they are 3000K. I hate 3000K lol, I much prefer 6500K.

I have 13 XPG on order. It's way overkill, but I do have a dimmer.


The Meanwell ELN 60-48D (note the D on the end) is very, very, very easy to dim.

You need:

1 9 volt REGULATED or SWITCHING power supply, $10 shipped. Anything that is not specifically a regualted or switching power supply will throw more than 9v and can ruin the Meanwell dimmer. It should only be given 10.5v max. 9v will work just fine, you just have to crank up the internal SRV2 screw inside to get it to give max current output.

1 10K potentiometer, $2-3.

Digital multimeter.



Wire up the 9v power adapter with the 10K pot.

Open the Meanwell and locate SRV2 screw (current output).


Hook up digital multimeter inline with the LED's.


With LED array on, and 10K pot on minimum setting, slowly turn up the 10K pot to maximum setting (don't overdrive your LED's).

Fiddle with the 10K pot and the SRV2 screw so that your 10K pot is giving you whatever max current you want when wide open.

Put cover back on Meanwell and done .

 

[redfishsc]

Actually, I'd be interested in your royal blue setup- got a photo? I'd use it to grow plants...

I have built a setup using the meanwell- I really like it (obviously you have too). Are you certain you want the xp-g? You can put 3x bridgelux units on there and power them at only slightly over spec with that power supply.

As for dimming- I suppose you've already got the controller with the integrated dimmer in it. I know there are two types of meanwells, and there was some earlier confusing talk about an add on circuit for dimming. Never saw what happened with that and the reefs.

At the moment I'm not going to get rid of the blues. I have an extra heatsink to attach the XPG's to. I have 13 whites on the way.

I'm going to try to make a pedestal base lamp (at some point in time lol) out of wood and have the controller and all inside the body of the lamp.

Not sure how I'll do this yet but I have some ideas.

 

[blasterman]

Actually, I'd be interested in your royal blue setup- got a photo? I'd use it to grow plants...

FYI....the 3-watt blue LEDs sold at Satistronics are identical in color to RB Crees, and a lot cheaper. Maybe 1/4-1/3 less bright.

I like the Bridgelux in the pics, but they are 3000K. I hate 3000K lol, I much prefer 6500K.

Bridgelux makes cool-white, and they are much more efficient.

However, I'd still use 3watt emitters if they are going to be used as direct lithing. The reason being is that a dozen smaller LEDs provides a more diffuse light source than a fewer brighter ones. Not sure about you, but a 2000lumen point light source is like trying to read under an arc lamp with every molecule and object casting a harsh shadow.

This is why I prefer to spread LEDs out in long rails.

Also why I'm working on better means of diffusing LEDs.

 

[redfishsc]

I'm thinking of spreading the lights out over a 4X12" heatsink. 12 or 13 of the XPG's.




What do you think? Is that enough dispersion?

I won't be using optics.


I've also thought about using some of that textured acrylic sheeting for a diffuser, the stuff that's often used on flourescent light fixtures. I could make it removable.

 

[deadrx7conv]

Heat sink depends on how hard you drive the XPGs.
At 1w, your 1 LED per 1x4 of aluminum should be plenty. But, if you start pushing the LED's to 2,3,4,5w...., you'll have to watch the temps and add more surface area or fan cooling.

You might want to look at optics. I find the XPGs blinding to look at even if you just glance at them. But, if they are ceiling mounted high enough, and you don't stare at 'em, maybe the optics aren't needed. But, I'd consider some type of optic or maybe even frosted to tame the LED output.

 

[redfishsc]

Yeah I think I will need some sort of frosted cover.


I do plan on putting a 12v computer fan on it for cooling. The enclosure will be wood so I really don't want any heat buildup in it.

 

[blasterman]

I've also thought about using some of that textured acrylic sheeting for a diffuser,

Acrylic sheets typically used for fluorescent ceiling lights has limited success with LEDs. It's better than nothing, but the facets in the panel tend to act like tiny lenses. You have to test it first and make sure the distance is right.

Frosted glass works fantastic for diffusing LEDs, but it's tough to find and can be hard to work with. Frosted acrylic is better yet (not the same thing as milk plexi), but is even tougher to find, or, you have to buy a big sheet of it like Acrylite. I've got so frustrated with this issues I'm resorting to simply bouncing the LEDs off a white surface or panel.

 

[redfishsc]

Do you think I could take some glass or plexi, both of which I have LOTS of, and just run a random orbit palm sander over with something like 220 or 320 grit? That should put a nice hazy pattern on it.

Or maybe lightly sand blast it with a light duty gun and some fine grit glass beads.....?

 

[purduephotog]

Do you think I could take some glass or plexi, both of which I have LOTS of, and just run a random orbit palm sander over with something like 220 or 320 grit? That should put a nice hazy pattern on it.

Or maybe lightly sand blast it with a light duty gun and some fine grit glass beads.....?

I looked at using chemical etchants. That was expensive.

I made some using sandblaster. That took forever.

Apparently there is a film you can apply to the outside of the glass (away from the source) that does quite well. I didn't know about this option until later...

 

[blasterman]

Sandblasting is your only practical option to etching your own glass or plexi. Chemical etching is not a practical option.

I forgot about transparent Window film. I've tried it and it does work better than fluorescent diffusers but not quite as well as frosted glass. This would be my suggestion because it will work on both glass or plexi. It's also not hard to find.

You want to double up on frosted window film when diffusing LEDs.

 

[Dave_H]

Sandblasting is your only practical option to etching your own glass or plexi. Chemical etching is not a practical option.

Anybody tried just sanding plexi with 400-grit waterproof sandpaper?
It should not be too big a chore for small pieces/low volume. It
worked for me on a small lantern clear diffuser dome.

Dave