10W/20W High Power White LED

[DanPBP]

Hello Guys,

Has anyone tried those 10W or 20W high power white LEDs?

Long time ago I tried a 5W luxeon star LED but I'm looking for something brighter to light up a small table (3x6 feet).

Thanks!

Daniel.

[Ioannis]

I don't know what are "those" LEDs you my mean, but what I have tested so far in the range of 80 Watts is disappointing in the sense of efficiency.

I think you have to look for the ratio lumen/watt and this should be as high as possible. A number of 65-70 is good enough.

The two module I tested, consumed at 31,8Volts about 4,8A and this gives the equivalent light of a halogen about the same power (150Watts) and with the necessity to use about 1 sq. meter heatsink.

So I do not think this is easy to use. When the efficiency rise at higher level sure LED will be widely used everywhere.

Recent announcements from Cree and Lumileds show that the 100 lumen/watt is near or done (http://www.philipslumileds.com/produ...on-rebel-white).

Ioannis

[sayzer]

I had one for testing.

15V, 2100mA, 140°, 2400Lumen.

US$80.

-------------------

[Melanie]

You can buy 4W (& 7W) Cool White or Warm White single power LED's in an industry standard MR16 (or GU10) Base with integral heatsink. They come in beam-widths of 16 or 32 degrees and can run from 12v DC or AC. They are plug-in replacements for halogen modules. I have them for lighting in the hallways in my home. I recall they cost me around $30 each a couple of years back. Despite the manufacturers hype, I'm only getting about 5,000 hours out of them - which, considering the purchase price is dissappointing.

What is much, much better, are the MR16 Tri-Colour LED Modules (1W or 2W again they run from your standard 12vAC Halogen Lighting circuit) with an integral IR Receiver (about $50 which includes the IR remote a couple of years back, but about half that price now). I have those in the Bathrooms right above the water jets and glass panels in the shower... so if you feel like showering in Green, or Blue or Pink water, just set the mood... those would be just PERFECT for a glass table. The Remote also has flicker, fade, auto-selection and all kinds of other modes that would turn your Glass Table into your very own Disco Lighting Hub... Attached is something similar with a ready to screw-in ES base...

[DanPBP]

Hello Guys,

Thank you very much for your answers! I forgot to mention which LEDs I'm talking about. These are the ones:

http://cgi.ebay.com/1-PC-10W-WATT-ST...item27ada81b9d

http://cgi.ebay.com/20W-White-Led-10...item27ad5b8aec

I'm only going to use them for about 3 hours a week, so I don't need something expensive.

Thanks!

Daniel.

[DanPBP]

Hey Guys and Melanie,

Today, I got the 10W white LEDs I was talking about...



These things are too bright!!! And, also, too hot!!! The diameter is 22.5mm and they are huge!!!

I'll put some pictures soon, when I have the circuit for them (3S LiPo + heatsink + cooler) up and running...

Thanks!

Daniel.

[rsocor01]

These things are too bright!!! And, also, too hot!!!

Yes, they are bright. I bought a few 1.5W white power LEDs a few months ago for one of my projects and I was really surprised to see how bright they are.

They are also hot. You need to design your PCB board with some means to disipate the heat (heat sinks).

Robert

[DanPBP]

Hey Guys,

Which transistor or mosfet can I use to control (on/off/pwm) these LEDs?

They need 12v and 1A, if possible, I don't want to add a heatsink to the transistor.

Thanks!

Daniel.

[Byte_Butcher]

Hmmm... welll.... There's probably about a million devices that MIGHT be suitable.
What package styles are you willing to consider will narrow it somewhat. What's readily available to you might narrow it a lot more.

Look for an N-channel MOSFET that has a good low RDS(on) that's specified at a LOW gate voltage. (Vgs)
A PIC running on 5 volts may not put out much more than 4 volts on it's I/O pin, so it's important that you can turn the MOSFET on good and hard with a Vgs less than 4 volts.
It doesn't do any good to have a small RDS(on) if it takes 8 volts of gate drive to get it....

I use a lot of these but they are in an SOT223 package. They will handle over an amp easily if they are on a circuit board that has adequate pad area under the FET's
http://www.fairchildsemi.com/ds/FD/FDT439N.pdf

But you probably don't want SMD?
A TO-220 or similar package would easily dissipate enough heat for what you want without further heatsinking.


steve

[Ioannis]

Look for the BUK9575 from NXP. Logic driven MosFET.

http://www.nxp.com/documents/data_sh..._9675-100A.pdf

Ioannis

[alicesmile]

arrel produced the 1st version of the PID code to drive just one channel. I then compiled and ran it to see how it performed. Over the course of several evenings I managed to get the values tweaked enough to maintain a stable temperature that would drift no more than 0.5 a degree in the course of the evening.

Armed with the feedback, DT then went on to work on multiple channel PID loops, and after a few weeks of frantic PM's between him and Henrik came back with some further code for me to test and try. The result was that after some further tweaking at my end, we managed to have 4 independent channels all running at the same time and in the test rig, maintaining a constant temperature.