Hi there Johnzo,

I saw on your online store that you recently put 8.9" LED arrays up for sale. COuld you please tell me their specs please ? I need to know if they are 10mm, what mcd rating they have and if they are double layered. If they are Ill order one tonight.


Thanks
C,

why don't you just PM him if you have a question for only him?

So that anyone else who is thinking of getting this product can get the info too and doesn't have to ask him again. Free advertising anyways.

C

5mm white LED, 3.1-3.2 volts, 20mA. 6000-7000k, 16000-19000 MCD

There are 896 leds on the array, comes with power supply.

Is this bright enough to use in a semi lit room ?

How would this compare to something like this setup ...

http://www.allinbox.com/DARTG_BOX/DARTG_BOX.htm

Im just a little new to this LED thing.

Thanks for taking the time to answer my questions, $125 is alot for me and I want to make sure I get the right thing.

C

Total power used is 3.15x.02x896=56 watts. Not much. I would recommend reading up on led light panels before buying. The numbers are probably too low to use in a semi lit room. You'll probably get around 20 lumens or so on screen from this light panel. I'm assuming it's the leds with the 30 degree output angles.

That said, some people seem happy with their results using leds even with the low lumen numbers.

phutton, you are correct, these leds would be used in a light controlled enviroment.

In the near future, I will have K2 led boards that will be 100-150 watts

Hmm ok well it might be worth the wait, or I could happily put together my own K2 board if I knew what it was. Does anyone have an example of one ?

http://www.luxeonstar.com/item.php?id=1811...o=LXK2-PW14-U00

I found this on the net, would these be used in an array ?


Thanks again
C

a good, buy lengthy read... http://www.lumenlab.com/forums/index.php?showtopic=20435

many of the different LED's are discussed, testing, etc... if you're considering going with and LED light engine, this is a good topic to read... testing is still ongoing, with phutton leading the charge...

Ive read that thread, its great info.

My interest has been peeked however by these luxeon LEDs. The specs look pretty good.

Now that's what I'm talkin about!!

That would be an excellent led to use. The problem would be price. You will need enough to cover the area of your lcd. For the 10.6" that's about 60 leds. that's $300 for the leds. Another $60 for the lenses. Then throw in $40 for the DC power supply. And another $40 for the electronics, if you can build them yourself. You're looking at about $440 for the light panel. The good news is that you should get about 400 lumens on screen at rated output.

I would recommend the stars. They are simply easier to handle and provide more assurance that you will get good heat transfer to the heat sink. Therefore throw in another $60 for the star form.

I went with the cheaper ebay 1watt leds at $2.35 each in star form (about 50 lumens each). That still set me back about $270 for the whole setup. I'm hopin to get around 150 lumens on screen, which is perfectly watchable with a 72" screen. My current MH setup puts out about 100 lumens on screen.

Price is no object to me. around $500 is alright. Id rather have a good light source thats long lasting. Il either go with those K2 leds or the 10mm 150000mcd, double stacked. Its alll a matter of time, I want to get my PJ done quickly.. and I have no idea how to use these k2 LEDs. If there was a guide or something, but I know very little about wiring up LEDs.

My LCD panel is a 7.1", so it will be a little better.

How many LEDs do you think I might need ?

C

What are the dimensions. Just multiply the length by width. Whatever your area is in square inches is the approximate number of leds you will need. By the way, go to www.lumiledsfuture.com. They may have better prices. Get the stars.

Thanks for the tip.

However Im confused. Why would the stars be better than the square ones ? Ill be able to fit less LEDs on the board if I go for the stars wont I ?

Thanks
C

Actually after speaking with Luxeon they tell me that the stars are pre made circuit boards and that they will be easier to wire. However Im still a little concerned that there will be too few leds resulting in hot spotting.

Thanks
C

Whichever leds you use you will need to attach lenses to them. The lenses are almost exactly as wide as the stars. So even if you go with just the emitters the lenses will still limit you to about 1 every square inch (actually, the lenses and stars are about 0.9 inch diameter, so if you really pack em in you can squeeze a little more).

If you pack them lenses in as tight as you can into a honeycomb pattern you should have pretty uniform and complete coverage with the light panel fairly close to the lcd (let's say about 2-3 inch gap between them).

Pict of honeycomb pattern for 10" XGA LCD (8" X 6")
Click to view attachment

Hey phutton,

Which lenes did you like for the stars, I remember you reveiwed a couple of lenes. Im ready (been ready) to take the luxeon route.

By the way, I recieved the led arrays today, pretty damn bright, should make a good picture in a light controlled enviroment.

Hey guys.

I called Luxeon today and Im not sure if they gave me the right info. But they said its going to be VERY difficult to get even 50 K2s working due to the Huge amounts of voltage used and heat produced. They said for 50 LEDs the voltage would be 185V. They said a special driver would have to be made to use an array this large. Im quite confused over how to do the K2 thing, due to the complex electronics. Are these guys right ? If that much voltage and heat are indeed produced it might make the K2's a little unrealistic.

How about these as a substitue. 825,000 mcd and 55 degree angle!

http://www.besthongkong.com/product_info.p...products_id=492

Well the LCD Im using is 7". It measures 3.5x5.5. Thats 20 square inches. Id be using the stars, so thats about 20 Star LEDs. No problem for cost, but two concerns. First, would this be enough light ? Would this be brighter than the projector listed here...

http://www.allinbox.com/DARTG_BOX/DARTG_BOX.htm

or would 20 K2's be brighter than these ?

http://www.besthongkong.com/product_info.p...products_id=492

My other concern is how the heck these things are supposed to be wired up. How you translate them into a plug you put in the wall.

Sorry for asking so much, but Im not the best electrician.

Thanks
C.

Hi guys,

just one more thing to check out.

That PJ from all in box, does seem to work with ambient light

http://forum.allinbox.com/aspectgeek/Proje...ujet_8236_4.htm

take a look at the bottom of the page.

C.

I decided to go with the OP-005 lens. It gives the brightest and smoothest spot. It also is only 75 cents apiece. I opted not to go with the lens holder. I plan to just glue it to the led. You can get these at www.futurecb.com. I think do a search on Dialight OP-005 and it should come right up.

Welll, I would be apt to say this guy doesn't know what he's talkin about. Or at least he's too simplistic to take seriousely for a DIY project. Leds are basically current controlled devices. As long as you can ensure the same current through each led you should get uniform light output. The problem is that the leds are all slightly different, so if you simply connect them up to the same voltage supply in parallel they will then let through slightly different currents based on slightly varying voltage-current characteristics. That is why the Luxeon guy envisioned all 50 leds in a series string. That would garuntee that all of the leds got the same current, regardless of what their individual voltage-current characteristics were.

I have a 24 volts supply. I'm connecting 10 strings of 6 leds onto the voltage bar. If I didn't have some type of current controlling circuit on each string they would all have slightly different currents going through them and may not give uniform output. I'm building a circuit to ensure that the current through each string in 0.5 amps. That's all you gotta do.

Do a google on "Dan Instructables led" and read his DIY led projects to get a better feel for how to build circuits for leds.

By the way, it would be fairly easy to get 180 volts. Simply connect your typical 120volt AC supply to a half bridge rectifier with a capacitor. You will then have a voltage near that high. If you send the AC through a small step up tenrsformer, first you can design the voltage you want. Then you can put the whole thing in one series string to ensure the same current through each led.

Let's say you can squeeze about 25 leds in there. Then you'll get about 25x130 lumens = 3,250 lumens from the light panel. Only about 5% of this will be transmitted onto the screen. That's about 162 lumens on screen. Not bad numbers. That's basically what I'm hopin for.

As far as the circuit, all I can say is read, read, read. There is no way top short cut it unless you want to pay someone to build you one. Your gonna have to figure it out and build it. There is a led current controlled ciruit on ebay that you can buy, but you'll need several for 25 leds.

your also gonna have to attach them to a heat sink and fan.

Hmm this seems a bit complex for me... Also the heat involved is a bit high for me.

I think Ill just go with the 825,000 mcd 10mm LEDs, or just order a pre-made 8.9" from Johnzo. My health is somewhat poor, and it stresses me out all this electrical stuff. I don't mind to learn a bit, but this seems a little out of my league.

Thanks for all your help
C.

that's fine. But keep in mind the heat output will be basically the same regardless of which type of leds you use. The heat is simply based on the power input. If you put the same power in the 10mm leds then they will put out about the same amount of heat. The 10mm leds also have the same issues with current control.

But if you are more comfortable with them I say go for it. the best part about DIY is doing it your way. One good thing about those 10mm is that they have been done before, so there is some comfort to treading on slightly proven ground.

One final thing, if you look at the screenies from the allinthebox double layer pj you will notice that single color images are blotchy. That's because there is no real current control in his light panel. Some of the leds have a little more current flowing through them than others. So the light output is not completely uniform among his 896 leds. This is one of the worries I have for mine. However, I expect it to be easier to control the current in my 70 leds.

phutton brings up the fact that some of the areas of solid colors are blotchy.

Could the plastic defuser from a florescent fixture be used to spread out the hot spots? Or would the defuser adversely effect the light output to much?

I have new led arrays for the 10.6, I will post picture later.

5mm LED's w/ 6500K, and there is 1700 of them.

Johnzo,

How much?

$155 + ship.

I just bought from johnzo this LED panel. As soon as I receive it I will post pics

Great cant wait to see some pictures!

yeah me too...after seeing the pics at the trading post, I'm very exited!!

I hope this unit delivers because if it does, then you can make a really small pj. You lose a fresnel and with it you lose its focal length distance that would make a larger box. Its just led board, panel, fresnel, triplet, and a fan of course.

So I have high hopes....they are 6500k, the image should not look too blueish and I think that it can be fixed by calibrating the unit.