Hello,

If you want a constant current type from meanwell, take a look at this one:
http://www.meanwelldirect.co.uk/product/LPC-20-700/LPC-20-700/default.htm

An overview of all meanwell led drivers can be found here:
http://www.meanwelldirect.co.uk/ranges/LED-Power-Supply/35/default.htm

Bertus

 

I've been reading all these posts and it seems that even though LED's require little power to run, they still require large power supplies.

 

Not really, it is the quantity of high power LEDs that require large power supplies.

 

I was wondering if this driver could be made to work I know amps are off? http://www.ebay.com/itm/150W-LED-Dr...339?pt=LH_DefaultDomain_0&hash=item5ae154db0b

 

Or what about two of these mA look to be 3000 http://www.ebay.com/itm/100W-LED-Dr...839?pt=LH_DefaultDomain_0&hash=item4cfa58d787

 

Hello,

Again the current is to high, 3.6 A (it will be needed to split evenly).

Input Voltage: 100~264VAC 50/60Hz
Efficency: >85%

Output Voltage: 36~42VDc
Output Constant Current: 3.6A

Bertus

 

Just curious, why the sudden switch to constant current LED power supplies? You aren't really going to save that much money, since they are not an exact match to what you need. The aquarium company at least had precisely what you needed, which meant you wouldn't need extra circuitry later.

Getting nervious about a large quantity of LM317's and resistors?

BTW, my personal cost (in quantity) for resistors is 2¢ each. You pay for the LEDs and shipping and I can pick some up. I have posted an offer for folks in the swap forum next to the off topic, it is not a business, but a service for members of the forums.

Shopping around I suspect you can get better prices on the LM317 than I can.

 

I started leaning more towards the constant current because I thought it was the optimum choice. I found a source for the LM317s and resistors. The cost at the web site is 10 resistors for .10 and .65 for the LM317s. I think with your diagram I have a pretty good idea on how it needs to be set up. If the none constant current would work just as well I will go that way. The problem with the reef driver was I think it was only 60w I would need 3 just to get to 180.

 

Which choice would be easier or better going with the LM317s and resitors or splitting the current?

 

Not sure. With splitting the current you have a problem dividing it in such a way that the LEDs are not at risk. It also limits your options as to how you wire it up. Think in terms of integer dividing the current, if you can't get a number you like then it is probably not a good idea.

The fixed voltage power supply is more flexible IMO. If you happened to find a constant current setup really cheap then maybe it would be a good idea, I prefer to design from the constant voltage setup.

 

Done deal then I will go with the fixed voltage supply. Now to find a fixed voltage in the 200w to 240w range. I have a link from teh source I would like to buy the LM317s from. Whcih model LM317 should I get from this list http://www.futurlec.com/cgi-bin/search/search.cgi ? Thanks again for guiding me through this proccess it is very much appreciated

 

You want a large number of resistors? We need to calculate some quantities. Figure qty 7 per chain.

 

Will the power supply dictate how many leds can be put in each chain? If not maybe 7 chains of 10 would be nice

 

This driver is for strip leds but will it work for my project http://www.ebay.com/itm/24V-10A-240...117?pt=LH_DefaultDomain_0&hash=item2a1401ce5d

 

Well the good news is my leds finally arrived on Mon. bad news the leds did not come with pcbs. Mr Marsden I think I will take your advice and build a smaller light first then go on to the large one. I would like small light to have 10 leds. I think I would go the route on none constant current on both unless with the smaller light going cc would work better. The thing I would like to know is what specs I need for drivers for the small light and the larger one. I think I understand needing to get the amp close to .75. The small lamp I think would need around 30w and the large around 240w unless I go with two smaller drivers to add up to teh 240w. I am really looking forward to building this light almost if not more than having the finished light in use. Thanks again for taking teh time to help a total noob.

 

The offer of resistors is still open, BG Micro sells a pack of 200 12Ω ¼W 5% resistors for $3, just bought a pack.

 

Mr Marsden I appreciate your offer for the resistors but I don't want to trouble you. I can pick up the resistors at the same time I buy the LM317s. The hurdle I have to get past now is the power supplies. I think I know some of the specs I need to look for but there are so many out there I am afraid I am some what lost on which one I need. I anyone can't point me to a nice source for a driver that is not CC I would appreciate that. Thanks again

 

How about the ones mentioned at the beginning of this thread, I believe I pointed it out as acceptable. Not the LED power supply, the other one.

 

This place has tons of CV power supplies at great prices.
http://www.mpja.com/

Of course now that you found out you got LED's but no star boards I wonder what you are going to do.. If you intend to make PCB's I'd start looking at LED driver chips and integrate them onto the PCB's which would eliminate the need for the LM317,etc...

 

We've been discussing LM317s all this time, partly due to their simplicity and reliability, why would you throw a new un-named and unknown current regulator at a beginner at this stage? I don't see a power supply that would meet his needs on that page either, but I would be interested in what you are thinking about.

The power supply suggested on post #7 would work, it is 24VDC with lots of current.

To the OP:

You need to reread the tutorial I referred you to. Red LEDs drop around 2.5VDC, and you can go to 21 V using LM317 current regulators. That means the maximum number of red LEDs is somewhere around 8 LEDs. 2.5VDC X 8 LEDs = 20VDC.

The dropping voltage of the LEDs vary from LED to LED, it is not as consistent as the ads would lead you to believe. This is why I was suggesting build on the small scale first (among other reasons), you can measure the real dropping voltages of the LEDs you have.

Blue LEDs drop around 3.6 V, so for a max of 21VDC you can only have around 5 LEDs, but even a minor change in dropping voltage may mean you may use 1 more or so. 3.6VDC X 5 LEDs = 18VDC