Led drivers

Led Power Supply?


*I am going mad over trying to figure out what power supply I need. I am making an arduino controlled aquarium fixture and plan on using 30x3w leds. From what I understand using resistors could cause fire and I don't want that of course. I like the look of laptop drivers like this one*http://www.gapsupply.com/LED-Power-Supply-p/12v-dc-nwp-96w.htm*but I cant figure out which one I need. I have seen all the instructables for this and everyone seems to tape 8 meanwell drivers together. I dont want a big bulky ugly mess like that just one power supply to do the job. The smaller and more compact the better. I will be running 2 rows of white on the outside and one row of red in the middle. 10x3w leds per row. each row individually dimmable via ir and tft. here is the led specs.

Whites:*http://www.ebay.com/itm/390908787444?_trksid=p2059210.m2749.l2649&ssPageName=STRK:MEBIDX:IT

Forward Voltage: 3.2-3.8V-700MA
Luminous flux: 200-230LM
Output power: 3w
Light Color:* White 6000-6500K
View angle: 120-140
LED support：Copper
Life time:50000 hours

Reds:*http://www.ebay.com/itm/31083461629...49&var=610229587957&ssPageName=STRK:MEBIDX:IT

DC Forward Voltage:2.2V~2.8V
Forward Current: 600-700mA
Output power: 3w
Light Color:* White 6000-6500K
View angle: 120-140

Any help and ideas is greatly appreciated. Thanks

Resistors selected with the correct power rating and packaged appropriatedly shouldn't be a fire hazard. If you are concerned about fire, you can mount them inside of an aluminum enclosure (assuming that you've thermally mounted the resistors to the interior surface of the enclosure, and provided sufficient surface area to keep the thermal impedance low enough so the resistors won't overheat...

Back to the power supply... have you decided on what the requirements for it are? What output voltage and current capability? How are you going to use the Arduino to dim the LEDs? Do you need a supply that accepts a dimming command, or will you pwm the power to the LEDs with a transistor?

a quick note regarding the LEDs you've mentioned... I always prefer to buy LEDs that have a published datasheet from the manufacturer. The info on that ebay page is confusing.... the red LEDs have a forward voltage of very roughly 2.5v when driven at 600mA, and produce an output power of 3 watts.... how do they get 3 watts out when there is only 1.5 watts going in? The rest of the info is similarly confusing or probably just wrong. Those look more like 1 watt LEDs with no provision for heatsinking. The quality is very suspect. I wouldn't put this much work into a project and then use parts that are likely to fail soon. Go to a reputable supplier and get LEDs from a reputable manufacuterer.

Well that's very disappointing thank you for the reply. I did purchase a meanwell dimmable driver. As for the leds I lost two bids on red and white cree xp-e and won one royal blue reel of xpe. I silverware the seller for a data sheet I should have known better. I'm always up for buying more leds for the project. The pwm I will likely have the arduino control the meanwell.

Steve K said:

Resistors selected with the correct power rating and packaged appropriatedly shouldn't be a fire hazard. If you are concerned about fire, you can mount them inside of an aluminum enclosure (assuming that you've thermally mounted the resistors to the interior surface of the enclosure, and provided sufficient surface area to keep the thermal impedance low enough so the resistors won't overheat...

Back to the power supply... have you decided on what the requirements for it are? What output voltage and current capability? How are you going to use the Arduino to dim the LEDs? Do you need a supply that accepts a dimming command, or will you pwm the power to the LEDs with a transistor?

Click to expand...

Thank you for the reply. I did buy a meanwell dimmable driver to toy with I haven't made it that far yet. But I only want use it to test with till I get everything working correctly. Then I plan on designing a pub pwm for space reasons.

a quick note regarding the LEDs you've mentioned... I always prefer to buy LEDs that have a published datasheet from the manufacturer. The info on that ebay page is confusing.... the red LEDs have a forward voltage of very roughly 2.5v when driven at 600mA, and produce an output power of 3 watts.... how do they get 3 watts out when there is only 1.5 watts going in? The rest of the info is similarly confusing or probably just wrong. Those look more like 1 watt LEDs with no provision for heatsinking. The quality is very suspect. I wouldn't put this much work into a project and then use parts that are likely to fail soon. Go to a reputable supplier and get LEDs from a reputable manufacuterer.

Click to expand...

I was bidding on three reels of cree xpe-e royal blue 660nm and white 6500k, I only won the blues. So that's why I went with these seems to be a bad move. Although I'm not really hurting much at the price. I asked the seller for a data sheet just now and he/she responded that there isn't one and to refer to YouTube to figure out how to diy leds heh. So I'm curious how you got the math for 1.5 watts? Back to the leds for my project I do not want heatsink star mounted or smd leds I want to design it so I can make them removable if you will to mess with my light spectrum at anytime. So I would have to come up with a way to clip them to a heatsink and have integrated resistors but I'm quite far from being there in this project. As for what I want just 90 watts of leds three rows colors being in the center. Each row being dimmable from Bluetooth, ir, and tft. It's all just a fun project and learning experiment for me at the moment I'm not taking it to seriously but in the end It will be for growing rare aquatic plants.

Easy one first: 1.5W input power comes from the input current times the input voltage: 600 mA * 2.5V = 1500 mW = 1.5W. Of course, that's only an approximation, and will vary based on the LEDs, temperature, drive current, etc.

Running at 1.5W, the LED will need some heatsinking. Running at 3W, you will need better than casual heatsinking. This is much easier to do if they are soldered down, which is why getting them on stars is so popular. Soldering them, while doable as a DIY project, isn't trivial. The stars can be attached to the heatsink with two screws each, making replacement a snap, er, well, a screw...

Now the bad news. You cannot run a string of reds and one or more strings of whites on the same driver. The reds will need around 25V, the whites around 35V. But that's not the real problem. You could solve that with resistors. The real problem is you want to be able to control them independently. That right there means you need multiple drivers, or a multi-channel driver.

How about a DMX controller? They are made just for this sort of application, and can handle anywhere from 3 to 24 or more independent strings. And I imagine you could find someone who's already written a DMX interface for Aurduino.

You'd need to select resistors for each string to run them all on the same supply voltage, but that's not a problem. By the way, I hope whoever told you that resistors were a fire hazard isn't reading this, because I'm going to call him/her an idiot. Properly selected and installed, resistors pose absolutely no fire hazard. And doing it properly may not be obvious to the untrained, but it's not so hard you can't learn it in a few posts on this forum. The Meanwell supply might be more efficient, but it would be less reliable than a well-chosen resistor, if only because of its complexity.

Or if you're really into DIY, all you really need to run a string of LEDs is a power supply, a resistor, a transistor, and the Arduino. Oh, and some way to connect them. And guess where you can get some help selecting those components?

numberonekiwi said:

as I cant post attachments yet so cant post a circuit for it yet.

Click to expand...

You have the same rights to post images as every other member even in your first post - Norm


Posting photos

1.5 watts = 600mA x 2.5v

The mere fact that the seller defines the output as 3 watts is a big red flag. Nobody measures LED output in watts.

If you have 90 watts of power going into LEDs in a reasonable sized package, you have to heatsink the LEDs.
You can bolt an LED star to the heatsink, such as this...

I like how my phone autocorrects it's quite entertaining. The seller will not give me the specs so I will spend 14 dollars to humiliate them for fun it makes me happy inside. Numberonekiwi hijacking isn't very nice. DIWdiver the stars take up a lot of space are unnecessary and tacky looking so that's is why I do not want to use them. I appreciate the math explanation. I haven't heard of a dmx driver I will look into it thank you.

I bought the driver because it had three outputs maybe I got lucky on my shopping spree. The Rapid LED DDC-01 PWM Daylight Controller is a lighting controller for the MeanWell ELN-60-48P driver. There are two modes of operation, the first is manual mode and the second is one of three
daylight programs. Manual mode enables the user to manually set the output intensity for 3 individual output channels. Daylight programs have a fixed sunrise, day length, and sunset. Maximum intensity
can be changed manually in daylight program mode for all channels simultaneously only.

What driver did you buy? The ELN-60-48P has only one output. You'd need more than one of those drivers to take advantage of the multiple-output controller.

I only got the rapidled ddc-01 pwm controller to play with for now. Thank you guys for the information to help me understand that wattage I ended up getting a refund. I'm not to nice to people who rip people off. Then again it was my fault for not knowing. Today I recieved my tft screen, Bluetooth board, and rtc board so now I get to play with that for a bit till I find a decent deal on quality leds. I won't be using those red ones or the 6500k other than to prototype with. I'm thinking about just ordering cree xp-e reds and 6500k to match my royal blues I have coming.

I got my reel of cree xp-e royal blues in the mail today. And holy Crap can you see the difference from the red leds I have. I can't even look at it it's so bright. They are tiny I don't even know what to do with them. Smd isn't part of my design as I want them interchangeable so I don't know what to do with them. Plus they are so small I can't even work with it.

super tiny.

Maybe I'm missing something, but if you don't want to do stars, and you don't want to do SMD, what exactly was your plan for using these SMD components?

I want the buttons so I have the ability to take them off the pcb whenever and swap them out. But I just figured that out with the cree's

I still don't get how you are going to attach the LED's to the heat sink if you don't want to reflow them to stars first?

Here's an extremely over complicated way. Where the heatsink actually goes through the pcb. Or I could just get the stars and stop over thinking.

Pcb is black heatsink is striped

You don't need to mount LED stars on a PCB. Attach the stars to the heatsink. Just run wires to the LEDs. If you'd like, you can tack the wires down to the heatsink with an adhesive, such as RTV.

How would you attach the pins to the PCB?

Diver I would use female pin connectors soldered to the pcb. Steve the whole reason behind this overtly complicated led project is to make it look clean. I do not want wires all over the place. No offense to anyone But every diy led light I've seen looks sloppy, poorly made and hand crafted.