LED Array for a Pico

[1105]

I was looking on ebay and came across these. Do you think theses two would work good with one being a 10mm (white) and one being a 5mm (blue)?

 

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...=66952&tc=photo

 

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...=66948&tc=photo

 

The prices seem to be good from this seller for what you get. Let me know what you think so I can order up some LED's

[neanderthalman]

I dunno...something doesn't seem right about those white LEDs. The seller claims that the forward voltage and forward current are about 3.5V and 20mA, which is identical to the LEDs that I purchased. That means that those LEDs will use the same power as the LEDs that I used. What's troubling me is that those LEDs claim to output 80,000 mcd, whereas mine are rated for 12,000mcd. 80,000mcd seems a little huge, considering that they use the same amount of power.

 

Normally, I would recommend Besthongkong as an Ebay seller, as I have heard many great things about him. After reading those numbers, I'm not so sure he's the best to buy from anymore.

 

As far as the original question, can you use both 10mm and 5mm LEDs? Yes. It's a lot easier to mount and wire your LEDs if they're all the same size, however. There was some other ebay sellers listed earlier in this thread that sell LEDs. Try to find some LEDs from them - I can personally say that professorled's lights are good, but there are others who may be cheaper.

[mushroom head]

Any updates?

[neanderthalman]

I just removed the last screen today, so in a few days I'll take a few pics with the new light, and a few pics with the old light. The array itself is running perfectly, although I need to measure the intensity to see if it has dropped. It seems to have also solved my heat issue, so I no longer have a fan blocking my view of the tank.

 

Thanks for the continuing interest mushroomhead.

[mushroom head]

Cant wait to see your tank after u put this light and hood on! I think it will look way better than before! "Thanks for the continuing interest mushroomhead." no prob

[mushroom head]

I mean like after a few months with the hood and light on.

[Clarkie]

update please!!!!!

[neanderthalman]

alright guys, here's some updated pics. The array is running just fine, the intensity dropped a little, down to about 10,000 lux at 8", but it's still alright by me. I'll be keeping an eye on it tho, just to make sure it isn't going to die on me.

 

When I put my old hood on to take a few pictures....I wanted to cry. It really was awful, and I have no idea how I survived with that old light.

 

Here's a shot of my zoos under the LEDs

 

 

Compared with this shot, under the PCs, using same manual camera settings - slightly different angle though.

 

 

Here's a FTS, just because I can.

 

 

I was originally going to make a small stand (~1") to match the hood...but I'm starting to like the way it looks without it. I may or may not put one together.

[mushroom head]

Very nice!!!!!!!!!!!!!!!!!!!!!!!!

[Ickypimp]

Has anybody looked at cold cathode tubes for lighting ??

They seem to have a good light output fot the size of them, the invertors also generally run 2 tubes so you could runa white/blue setup,, they are very thin so an array of several pairs could be fitted(2:1 white to blue ??) they are cold... almost no heat generateI have founs a company that sells a cold cathode tube that is 7800 k and kicks out 16,000 candellas per metre squared

[neanderthalman]

16000 candela/ sq. meter sounds pretty good, but when you figure it out, it's not. I've enclosed my LEDs in a space roughly 12cm x 12cm - estimated because of the hexagonal shape. If you filled the space completely with that white cold cathode, you'd have 0.0144 sq. m - with an output of 230 candela.

 

Each of the white LEDs in my array are 10,000mcd, or 10 candela. If my array was all white LEDs, then there would be 267 LEDs each giving off 10cd. That's a total of 2670 cd, vs 230 cd from the cold cathode.

 

Also, the 230cd of light from the cold cathode would be omnidirectional, half of the light would be going up into the hood. The reflection of light back down would be poor because the cold cathode tubes filled up all of the area. I would be suprised if you managed to get 150cd after reflection. With LEDs, nearly all of the light is emitted downward...so you'd probably get at least 2000cd focused on your tank.

 

There's nothing saying that you couldn't do it. Cold cathode would probably be similar in intensity to my old PC, and who knows about fluorescence. I'd like to see someone try it out - has anyone tried cold cathode lighting over a tank/fuge?

[Perpetual98]

Damn you all. lol Now I want to order myself a bunch of LED's and get to work.

[vangvace]

Do you happen to know what the PAR is on your array?

 

What about the color temp./spectrum of the leds you used?

[neanderthalman]

Not a damn clue. That kind of information just isn't available for LEDs yet, and I don't have the equipment to measure it myself. What I do know, is that the LEDs are supposed to be 6500K, but appear to have a color closer to 10,000K. The blue LEDs are 460 nm, one of the two actinic wavelengths.

 

I really would like to know just how much of the light is PAR, but I honestly can't tell you. What kind of setup would one need to measure PAR? I just might be able to swing something this fall at school. I do a lot of labs with optics, and I'll bet that one of the mystery machines in the lab rooms might do it. If taking the measurement is pretty quick and easy, then they might let me measure it. I figure I'd need to basically graph the spectral output...but I don't know anything about how to find the PAR from that. Anyone know where to go from here?

[Blind Tree Frog]

LED's don't have reflectors, why would they have a PAR?

 

EDIT:

Misread his question, he asked for the PAR of the array, not the individual LED's.

 

Still, I'm not sure I see the point of the question. PAR numbers are just the diameter of the lens as far as I know, but I don't get why'd you be asking the size of the array.

[Styxnpicks]

Originally posted by Blind Tree Frog

LED's don't have reflectors, why would they have a PAR?

 

EDIT:

Misread his question, he asked for the PAR of the array, not the individual LED's.  

 

Still, I'm not sure I see the point of the question.  PAR numbers are just the diameter of the lens as far as I know, but I don't get why'd you be asking the size of the array.

 

PAR = photosynthetic active radiation

[Blind Tree Frog]

That PAR, gotcha.

[vangvace]

I think a PAR meter is around $300 new. It would be a better comparison of the PCs to the new LED array. A guy in my local club bought one with the submersible attachment. It's neat beause it gives you a better idea of how much light is actually going where. It's also neat because he has used it on a bunch of different lighting setups.

 

A spectral graph would be pretty cool to see how the leds compare to bulbs.

[neanderthalman]

hmm....not worth $300 to me. Knowing the PAR would help determine just how much better the LEDs are to the PC. Even if the LEDs don't emit as much PAR as the PC, they might still be better. Say the PCs were 50% PAR, that means that 200 of the 400 lux would be PAR. In order to have 200 lux of PAR from the LED, then only 2% of the light would have be PAR. Suffice it to say, I'm not too worried about having less PAR than the PCs, since the intensity of the LEDs is so much higher.

 

I'll do a search and see what I can find as far as PAR ratings of other light sources.

[neanderthalman]

I just did some reading on the subject, and I beleive that the PAR has a tendency to go up as the color temperature goes down. This makes sense to me, as I read somewhere once that corals grow better under warmer lights, but so does nuisance algae. Algae doesn't grow very well with 6500K or higher lights, but the corals do fine.

 

Since the LEDs are spec'd as 6500K, I'll bet that they've got a pretty good PAR rating.

[EPICTANKHERE]

YGPM

[bravocms]

Hello,

 

I was wondering what kind of power supply you are using? Computer supply or what? Thanks, bravo

[neanderthalman]

My first array used a cell phone charger, but it can't provide enough current for the big array that I built. I used an old computer power supply (pre-ATX maybe). The trick was to find an old computer power supply that still had a power switch, not a power button.

 

Back in the Win9x days, after shutting down windows, the computer would display a black and orange screen telling you to turn off the power. Sometime during the reign of Win98, power supplies changed. The motherboard could now signal the power supply to shut off, and the power switch was replaced by a power button.

 

You COULD use a newer power supply, if you knew how to convince the power supply to turn on. With the older power supplies, all you have to do is bypass the power switch.

 

HTH

[kinktao]

It's easy to convince a new power supply to turn on.

There is a single green wire on all power supplies, as long as you ground that to another black wire it will turn on.

 

Try taking a paper clip, and connecting it to the green pin, and then connecting the other end to the black pin. Hit the switch, and bam it's on. Do a yahoo search if you need a diagram. Tons of them.

[bravocms]

K Great! Thanks for the help. I will try a little internet searching and I actually have access to some really old power supplies from a friend of mine that owns a computer shop. He has got some antique stuff!! Thanks again, CMS