Single White LED

[Ken Coker]

Dear All.

 

Does anyone have a source for single white LEDs ? The idea is that the LED should work as a point source for children to do shadow work with on a "miniature" theatre. Ideally it should be battery powered; experiments so far suggest that it needs to be brighter than a 3W source - it needs to work in ambient classroom light.

 

Many thanks

 

KC

[Brian]

Anything at that sort of power level is going to need a heatsink. 3W leds get quite hot but are you sure you need 3W? Wouldn't a 1W with decent optics do the trick? Something like a Luxeon Star/O with 10 degree optics?

[Jonny DMX]

Hi Ken,

 

Try looking at the Osram LINEARlight Optics and the LINEARlight Flex. It comes in a number of flavours including sideways firing and cool and warm white. The LEDs are surface mounted onto a small PCB on the LINEARlight Optics and onto a very thin flexible PCB on the LINEARlight Flex. You can cut the PCBs every 56mm on which you will have 4 LEDs, I would imagine that a little bit of careful screwdriver work could reduce that to a single LED. It might be worth noting that there are also ultra bright versions of the "light" but these do get hot to touch and will need to be built into something. There are other LEDs like the K2s and Golden Dragon? which will be brighter but they will also be more expensive and require a heat sync of some type. If you're down in London we have all the samples of the Osram product here if you want to have a look. It might be worth talking to Ceri at AC about the Osram product and say you spoke to me about it, he should know the product well.

 

The only other thing I can think of is a single LED torch of some type? (mag light?) sometimes thay can be surprisingly bright. Hope that helps,

 

Jonny

[niclights]

I was also going to suggest a torch but so tricky to combat ambient light! I have one with a 5W luxeon source that runs off 2xCR123 batteries. At full power it will give 100 lumen which will combat daylight but will get very (very!) hot used like that and last around 1 hour. So it is possible but something makes me think LED might not be the best route here.

[Ken Coker]

Dear All

 

Thanks for all the suggestions. I'm not sure LED is the answer either, but for a variety of reasons the client really wants it. (I'm kind of tidying this job up for someone rather than starting from scratch.)

 

The torch option is indeed favorite, and I have the larger LED Maglite source...which sometime last month everyone thought was ideal....

 

Nic: I'd be very interested in the 5W source. Can you send me some details?

 

Thanks

 

Ken

[gyro_gearloose]

How about a Lamina 8.6W led? 250 Lumens!! Datasheet at Farnell here

 

I've got one of them and it is quite bright. Heres a pic of the complete assembly, consisting of LED PCB, heat sink, optics, and 1A constant current driver. The extra wires coming off the PCB are because Lamina also make an RGB LED assembly which uses the same PCB.

 

http://i157.photobucket.com/albums/t41/gyro_gearloose/LaminaLED.jpg

 

The whole lot cost me about £45. The heat sink is needed as the LED gets quite hot, and the hotter it gets, the dimmer it gets so good heat sinking is essential.

[Meduza]

The LED Maglite is quite weak due to that it has very poor heatsinking and thermally limits itself to about 1W power after at minute or so.

 

There is much better options out there, like these:

http://elektrolumens.com/Lucidus-XR3/Lucidus-XR3.html

http://elektrolumens.com/DeCree/DeCree.html

http://elektrolumens.com/QuadStar-Phazer/Q...tar-Phazer.html

 

Of course there are lots of other manfacturers that also

produces such flashlights, but Elektrolumens is one of my

absolute favorites!

[niclights]

I deliberately didn't give details of the 5W torch because it is stupidly expensive! Here's link to all models where you can check lumens v. cost/battery life. The money means you can drive a tank over them but maybe that's excessive for the classroom? (or perhaps still not durable enough.... :) )

 

The battery side of things is the real problem. Note that you can get rechargeables but these are much more expensive and difficult to get in UK. More importantly, rechargeable versions of the standard batteries do not fit in the barrel (even if you remove label).

 

I like Gyro's solution best. Tidy that up in a some conveniently sized metal cylinder and you've got a good, cheap, chunky and durable unit. But no batteries!

[Ken Coker]

Thanks All

 

As ever, the client, having had months to solve this, wants it done by Monday...equally as ever, it must cost nothing, not have to plug into anything and take up no space in the van.

 

Many of the, very good, replies above I have incorporated into an email to the client. My suspicion is we'll end up either with a 1W solution with added optics or a carefully shielded birdie and reflector.

 

I'll let you know how it goes.

 

Thanks again

 

KC