Come in and join me....

[Zombo]

Cree Q5's on a star! You have to click on the "Buy 3+ and Save ($5.91 ~ $6.11)" tab and follow the instructions.

[coolwaters]

Cree Q5's on a star! You have to click on the "Buy 3+ and Save ($5.91 ~ $6.11)" tab and follow the instructions.

 

 

you said you got 13 for $63...

 

anyways my 30w LED doesnt seem very bright but thats because it has 5 blues. which is 10 times dimmer then the whites. wished i had a PAR meter...

 

WC is better since its a higher kelvin rating

http://www.dealextreme.com/details.dx/sku.11023

 

WG is more of a 6k look while WC is 7k ish.

http://img170.imageshack.us/my.php?image=c...mpcwfulloe4.jpg

[coolwaters]

Evil do you think a lot more people would be able to do this with ease if those LEDs came in AC powered? well there is but its hard to get them...SSC has AC LEDs but i think they only come in white...

 

if you can find some that are blue and white let me know =)

[iglowce]

was the LED fixture DIY?

[evilc66]

Mine? Very.

 

Coolwaters, the only LED that I have seen that is natively AC is the SSC Acriche LED, and the output was pretty low (and I think warm white too ). I think a lot of people would be more nervous about wiring up components in an AC circuit becasue of the potential shock hazard. At least low voltage DC won't kill you.

[coolwaters]

i got shocked at 110v its not too bad. just make sure you get some rubber gloves one =p

 

dont think there was a case of someone dying from AC shock. theres tasers that are a million volts AC.

 

anyways i thought it would be simpler and also it saves a bit of money cuz it doesnt need a PSU or a regulator.

 

the efficiency was too bad. 80lm/w.

[evilc66]

It's very easy to die from AC shock, providing the current path crosses your heart. It's not the voltage that will kill you, it's the current. The big issue with AC is that combining the frequency and the current causes your muscles to contract, preventing you from letting go. The longer you are on there, the more it's cooking you. Anything over 30mA can cause respiratory failure, and over 100mA can lead to cardiac failure. I'd rather not deal with it if I can get away with it.

[coolwaters]

well said evil.

[evilc66]

For some reason, AC scares the hell out of me. I have no trouble working with DC circuits passing 600A+, which could kill me far quicker if I'm not paying attention (I work as an electrical engineer in heavy truck). As a general rule, I would say that AC is more dangerous to the average DIYer than DC. With the low currents we are dealing with, the worst you will get from a DC short is a burn.

[richfiles]

The source voltage is the last thing to deal with. You have to do a little adding to get this one straight. First figure out how many LEDs you want to put in series (I'm doing 2). So for me, I have 2 LEDs @ 3.4V each. The voltage regulator needs 3V to operate properly, so add that in too. You will want to minimize the reserve voltage so the regulator doesn't have to work as hard. So we have 3.4+3.4+3=9.8V. While you could go out and find a 10V power supply, a 12V one is more common. Anything higher than that for two LEDs will just be wasted in heat, and will shorten the life of the regulator.

 

I build a product that used to use 10 volt regulators (7810). Would put out up to 1 amp. Those got discontinued as far as I know, and now we are stuck with 9 volt regulators (7809), which is not enough for your application. There is a solution though.

 

Use a 7805 (5 volt) and a 7905 (negative 5 volt) and a power transformer with a center tap secondary winding. Use a bridge rectifier to make a DC voltage from the transformer, and make the ground your center tap connection. The 2 regulators will each regulate 5 volts above or below your ground. Don't use ground for your LED current regulators though. Use the -5 volts as your ground (or negative connection), and +5 volts as your positive connection, and you'll have a 10 volt power supply. You can add some capacitors in parallel across the + and - and across the center tap and unregulated + and - from the bridge rectifier to provide DC smoothing (your light might flicker, or your current regulator may fail to work with an unfiltered DC).

 

The link below actually shows an adjustable version of this power supply. It uses the LM317 and LM337 and some extra resistors to make it adjustable. You an skip the resistors and use the 7805 and 7905 if you want a fixed 10 volts (non adjustable). I don't know if there is any difference in efficiency between the two setups. By tuning the voltage as close to teh required voltage as you can, you minimize the power wasted by your current limiting device (regulator, resistor, etc). You will waste some power in the form of heat with this power supply too. if you can find a transformer that is rated to + / - 12 volts (24 total), you will be wasting less power than the + / - 15 volts (30 volts total) that the website I linked calls out for.

 

I'm sure there's a more efficient way to do this, but for cost effectiveness, this isn't a bad start. Make sure any 120v AC is enclosed. If you are concerned about it, get a plastic enclosure put the power supply in and run the + and - regulated wires out of the box to the LED setup at the aquarium.

 

One more thing... since this will be used near water, it is 100% necessary to add a fuse. you can but panel mount fuse holders for cheap, and can mount right on your box. put 1 fuse holder in series between your on/off switch and the plug. if a short happens, then the fuse will blow out for protection. Never trust a circuit without protection.

 

 

http://www.aaroncake.net/circuits/supply3.asp

 

Hope this is useful!

[evilc66]

I definitely appreciate the info. When building the regulators like I did, finding an adjustable power supply like that can be advantageous. Most anyone building LED arrays will use commercial buck regulators that can tollerate the higher than required input voltage. Plus, DC switching power supplies are so damn cheap nowadays. The major limitation for what you posted in this application is the current output. 1A will be capable of running one string of LEDs, but no more.

[evilc66]

Looks like after a little discussion on another thread that had me get my new PAR meter out, it looks like some of my test data is a little off. I'm still getting about the same number on my LEDs, but it looks like some of the MH testing I did is now incorrect. Don't know if I'm going to make the effort or not to retest. Oh well.

 

What is going to be interesting is the new LED setup that I'm going to build for my new 40B project. Got the LEDs on the way already, and a new driver design that should be pretty cool.

[sjmusic2]

I just found this thread (and coolwaters) - thank you all for the great info.

 

I am currently designing a circuit to handle 18 x Seoul P7 white (Vf 3.6, 2.8A) and 8-10 x K2 royal blue (Vf 3.85, 1A) (for my 48" tank) which has developed a life of it's own already. I started off with a 555/ mosfet current regulated circuit which I was told would work, but not too efficiently. So I am now working on using MCU's (PIC12HV615 or similar), a pot for dimming, current feedback control and will incorporate temperature sensing IC's in a feedback loop to prevent thermal overload. The efficiencies should be very good and the cost not too high. I have a cctv psu (12-13.5v, 20A) to drive it.

 

Now here's the problem, and you know there always is one, my electronics knowledge is not up to scratch for this so I have a friend of a friend who is an Electrical Engineer who should be able to advise me on the schematic and the coding.

 

If any of you guys are interested, I will post the details once I have them.

 

If you have any thoughts or comments, feel free to post.

[coolwaters]

lol when i google "nano reef DIY LED" this thread pops up LOL.

 

why are u using Luxeon K2 royal blue? the Crees are so much better. like 2 times better.

and cheaper at Dealextreme.

 

_____

 

sjmusic2 welcome to Nano reef.

 

it would be great if u can post a parts list on a regulator =p that can drive P7s and lots of 700mA LEDs.

[evilc66]

Definitely post the schematics of what you are working on when you are done. That would be cool to see.

 

One word of advice though, you are going to need a lot more blues to get a good color temp running 18 P7's. I would suggest not going to DealExtreme for the Cree blues, as they are only XR-C series LEDs. If you want XR-E royal blues (which will be far better than the K2's, unless they are the TFFC versions tht are hard to find right now), you have to go to ETG. They have the best prices in the US (which is expensive by Chinese standards), stock royal blues all the time, and will sell in small quantities.

 

We have been running a 50/50 or slightly heavy on the blue mix with the Q5's and the blues on DealExtreme, and that seems to get a good 14K color temp. You will have to run on the heavy side to offset the high output of the P7.

 

Might I also suggest looking at the Cree MC-E instead of the P7. Same dies, but each die can be run independantly of each other. Benefit of this is that you can run the 4 dies in series with a single driver @1A instead of the P7 @ 2.8A.

 

PS, did you come over from RC based on that post I made?

[sjmusic2]

Hi Coolwaters,

 

I researched the blue LED's a while back and to be honest I don't remember why I picked the K2 over the Cree's !!

 

I have the basic design of the circuit done, but I'm awaiting guidance on specific component values etc. Once I have this I'll be happy to post everything I have for you. I am considering using a 14 or 20-pin HV PIC instead of the 8 pin to allow for more I/O if required.

 

A good read is... http://www.microchip.com/stellent/groups/d...oc/en027001.pdf

 

Microchip also have excellent datasheets that provide example circuits and sample code eg. :

 

http://www.eetasia.com/ARTICLES/2007AUG/PD...OURCES=DOWNLOAD

 

http://ww1.microchip.com/downloads/en/AppNotes/01138A.pdf

 

Enjoy !!

[sjmusic2]

Hi Evilc66,

 

Thanks for the info...I'll probably need to play around with the ratio of white to blue, but I am including separate dimmers for each color, so I can hopefully change the color mix a little - although I don't want to have to run the P7's way down to achieve a 10-14k color !

 

>PS, did you come over from RC based on that post I made?

Actually, just from a google search...most places I had researched were using resistor-based current limiters or simple 555 pwm circuits. I was looking for a very efficient circuit as I will have high power output and 10-12hr/day usage. My biggest problem is I can easily follow a schematic, but I'm a novice at MCU circuit design - hence the need for 'professional' help

[coolwaters]

Evilc66 wats a good place to get Blue LEDs? or even the MC-E?

[evilc66]

Coolwaters, ETG that I posted a link to is the cheapest place in the US, but they are still double what DX and KD want. But, they are a Cree authorized distributor (along with Arrow Electronics), and will have stock of all the new stuff, and better bins. You just pay for it.

 

sjmusic2, are you using an mcu to drive a buck/boost circuit, or are you just trying to chop the output via pwm?

 

While I'm all for DIY, maybe you should look at the Luxdrive Buckpucks. Small, cheap and have an external input for a +5v pwm input for dimming control. They will take up to 32v and can drive up to 9 LEDs (at a max Vf of 4.1v). They have different versions that can drive at 350mA, 700mA, and 1A. Granted, not enough to drive a P7, but will drive 2 MC-E's.

[coolwaters]

u have to contact ETG by email if u want to buy something?

[evilc66]

No there is a phone number.

 

310.202.6400

[sjmusic2]

evilc66,

 

Basing the design on the schematic in app. B of AN1138 (linked above), ie. buck circuit with current feedback loop (minus the ICSP etc.). The LED temp sensores are daisy-chained tmp05s into the mcu and the dimmer (pot) will go into an ADC pin on the mcu. This circuit should be very efficient and also dimmable without shifting color spectrum.

 

Too late for the buckpucks as I already have the P7's !

[evilc66]

I see. Looks like you know what you are doing.

 

Do me a favor, when you get your details all straight, start your own thread so it's easier for everyone to track the progress of your project. Don't want all your good work lost in 20 pages of a project that isn't yours.

[sjmusic2]

>Looks like you know what you are doing.

 

Looks can be deceiving but I'm learning lots along the way !!

 

I'll be happy to start a new thread with the details - didn't mean to hijack this one.

[evilc66]

No trouble. Just didn't want to see all your hard work buried in this thread.

 

I have been tempted to start playing around with the arduino based controllers. Seems easy to set up.