True....did they give you a hard time about buying a low volume because they kind of came off to me like they only wanted to deal with companies

I found a company that stocks the 150w A and B models of the meanwell LED drivers for 83$ each and even though its not what I wanted its cheaper then 15 buckpucks and a whole lot easier then building the drivers. I had a few questions that I wanted to run by everyone.

Spec sheet-
http://www.powergatellc.com/pdfs/CLG-150.pdf

It says on page 2 that the 36v model is adjustable from 31-41 volts. If I were to power 4 rows of 10 cool whites of LEDs at 1000mA at 3.7V typical voltage it would draw 37 volts and 4A. Is this how they work? or would that be sucking too much power? Does the 36v have to be 36 or under to be safe? From what I understand I could have anywhere from 31-41v as long as I am under 4.2A, right?
Model-CLG-150-36x
Output Voltage- 36V
Amps- 4.2A
Watts- (151.2W)

The power supply will only run in constant current mode within the 27-36 volt range. If using it in constant voltage mode the voltage can be adjusted between 31 ~ 41V.

Check out note 4
http://www.meanwell.com/search/clg-150/default.htm

Crap! This project is such a pain when it comes to figuring out how to drive them. The drivers seem to be the most expensive part! Alright, so I'll either have to drop down to 9 LEDs in each row or drive them at 700mA. What do ya'll think would be better? and as for the dimming portion I just hook the proper pot between ADJ1 and 2 and I am set right? Does anyone know if these drivers can work on analog and digital or is it just one or the other? The spec sheet only says the current can be adjusted by a resistor between the two wires.

That driver does not have full external dimming control. The adjustment pot is to set the maximum current -50%/+3% of the rating. It's not used for full range dimming. Only the ELN series has full external control.

What kind of leds are you using? Whether you will be able to run 4 strings of 10 leds at 1000ma will depend on the leds vf which you won't know for sure until you get them. Look at this graph jtr1962 on candlepowerforums made of a Cree Q5 led he tested.



http://candlepowerforums.com/vb/showthread...9607&page=5

You can see that for this particular led you could run at 1000ma and the vf would only be 3.5v and you would have no problem. If the vf of the leds you recieve are higher then 3.6 V ea you could reduce the current to them and their vf would decrease. You could also run 5 parallel strings at 850ma ea as an option.

Hmmm... MCJosh, you lost me with that last post.... I understand that for LEDs you need a constant voltage, so as long as the sum of your forward voltages (vf) are between 31 and 41v we're okay (for the CLG-150-36, however we're limited to a certain current. I also get that, according to the chart, a 3.5vf LED would get 1000ma. What I don't understand is how the VF would go down when you decreased the current...

LEDs run better off a constant current source. A constant voltage source is not ideal for LEDs. LEDs have different forward voltages (the amount of voltage they drop) depending on the current flowing through them. If you wish to flow more current through a LED you will need to provide a higher voltage. The amount of current that flows through the led is dependent on the voltage that you are providing it with. Look at the graph above, you will see that at 350mA the forward voltage of the led is only 3.2 V, at 700ma the vf is 3.4 V and at 1000ma the vf is 3.5 V.

The reason you cannot reliably run LEDs with a constant voltage source is because as a LED warms up it's vf begins to drop slightly. This results in an increase in current through the led which warms it up even more and the vf of the led drops again. This results in what is called thermal run away.

I'm not sure I would trust data from anything else but the data sheets. If you test, and find your LEDs to be different from the Data sheet, thats fine. But I can't trust his numbers.

Here is a link to the CREE XR-E data sheet (or the law).

See page 4 for data on Vf at given currents.

Your LEDs vf will almost never match the data sheet....you must test to find out. Vfs vary from batch to batch and even between LEDs in the same batch. Never plan on having the LEDs you receive match the values in the datasheet exactly because their will always be variance in the values. The graph I posted above was for illustration purposes and as a loose reference only.

Agreed, which is why I use 3.7v as an approximation. Its a good average to use.

We agree. One must check ones own LEDs.

My point was that one should not design their setup based on someone elses numbers (like the table that was posted). IOW, posting it may be dangerous to the naive.

The graph was just to illustrate to Ajmckay that an led will drop a different amount of voltage at different currents. You don't like the graph, ok its gone. I don't want it distracting from the main point of this thread which is the meanwell power supplies.

Isit? I was told by the sale executive that the mod was done by Taiwan before shipped out !

I got a normal switching power supply from them while negotiating for the ELN.
There is a label on the power supply that have the brand,model number,
,input and output voltage and current and at the bottom right hand corner it say
MADE IN CHINA.

But who cares today what product is not MADE IN CHINA?

ya..you're right..who care where it come from as long It's cheap and reliable .

btw, is your transaction with them in USD or SGD as I was told to pay USD when PS stock in .

All my transaction is SGD.
USD very troublesome.
You so lucky get the ELN so cheap.I still negotiating

Any updates?

I'm very interested.

Also, would it be possible to dial down the current to 700ma to run the royal blues?

Not yet.

If you want to run the LEDs at 700mA, just run two strings in parallel. You won't be able to dial down the max current that low.

I have not posted in a while, work has kept me busy. I have had two of them running for a couple of weeks, and they are working great. I look forward to your review of how we can make these dim.

Hey Evil, any updates? I am thinking of ordering a couple more that are dimmable, unless you can crack the code. I am starting the next wave of this DIY project, and that is the Arduino, I have mine and I am working on getting several bits of code working. Did you get the PWM dimmable one, or the PWM dimmable one?

I have looked at it, but haven't played with it yet. Most of the parts seem pretty straight forward. There are two transistors that I need to figure out what they are yet.

Bump. Updates?

Nope

Well I am slightly confused now, I just read this whole thread from start to finish. Last week I knew nothing about electrical circuits. I learned that wiring leds in series adds voltage to the line, while wiring in parallel adds current to the line. We therefore use constant current, variable voltage drivers. As long as you stay under the max voltage, the current remains constant. If you use a 1A buckpuck capable of firing 6 3.7v leds, wiring them in two strings of 3 would yield 22.2V and 500mA to each LED. So my questionable area and my limited understanding is..

with these new drivers, say you used the 48V 1.3A version... You could run 13 LEDs off of the voltage, but the onboard potentiometer only dials down the current to a little less then 1A. So we would not be able to adjust color temp because all the leds would run at 1000mA. We could only adjust the number of leds of each color, which is not good because we still need a certain number for coverage. So we wish to buy the controllable drivers and then wire in a homemade pot so that we will be able to dial down the current farther, just like on a buckpuck. But we can't buy the controllable ones because they don't manufacture them large-scale.

I'm wanting to light my ten gallon. Could I not buy two of these with the +3/-25% pots:

Run 10 or so cree Q5 whites on one driver at 1A.
Run 13 cree royal blues on another driver wired in two strings in parallel adjusted between 700mA and 500mA? I could also run some uv leds on this circuit..

In my situation.. would this be effective? this could give me an adjustable color between 10K and 14K?
This would cost me $60 for the drivers as opposed to $80 for buckpucks.

Almost. You tripped up on the parallel strings. Two strings of three LEDs would only net 10.2v (3 LEDs in series) at 500mA per string (1000mA total).




The onboard pot is only designed to limit the maximum current limit. It really isn't useful for full dimming control. The dimmable version that we can get can only be dimmed by a pwm signal. You can use the circuit I posted earlier to accomplish that. The dimmable version isn't very practical when you are only buying one or two. If we can get a bunch ordered, the price is a lot more attractive. I have been contemplating offering these on my next group buy (soon!).




Well, you could use them, but with running strings in parallel, there is a lot more to go wrong and harder to diagnose if you don't know what you are looking for. You also need to have equal strings when running in parallel (can't run 13 LEDs total).

If you can wait, I'm sure we can get a bunch of people that want to buy these and organize a group buy for them so you can get the adjustable version.

I can definitely wait. I'll be looking out for a group buy. Should I have around $50 saved up if I want to buy 2?

$65-$70. After 5 units, the drivers were about $32 each and you will need to cover shipping.

I have been running the non-dimming versions with out issue for a couple months, so I was working with the Arduino and decided to order two dimming versions. They arrived today, and I was hooking it up to the Arduino using the PWM function, I know it only drives at 5 volts, but just to play with dimming. It worked to 50% dimming (100% duty at 5v.) I was measuring the current, and the lights would fire up at .25 amps (.125 amps per string) and ramp up to .66 amps. Evil do you have a circuit on allowing the Arduino to drive to 10v still using PWM from the Arduino, or any other thoughts on getting this to work fully? Thanks.

I'm not evil, but you probably need to use a fast NPN transistor to switch a 10v source using the outputs on the Arduino. Should be cheap, about $1-2 for a few transistors at radioshack You need to provide a 10v source if the meanwell supply doesn't do it.

Exactly.

Any progress on a mod to make the non-dims into dims?

Haven't had a chance. Been focusing on my new tank. As soon as that is up and running (today), I will have more time to look at it.

Cool.
Any shots of the new tank?

I have shots in my tank thread. Check sig.

Just receive my ELN-60-24P today.
Connect up 2 strings of 6 LEDs per string in parallel.
The LED never light up.
Try to adjust the voltage and current port on line.
But still cannot light up?
Is it I need to connect up at least 4 parallel strings then can work?
Or I need to add a resistor per string if less than 4 strings?
Please advise

These power supplies don't have an inverse input curve, meaning, you have to supply voltage to the dimming control to get any light out of it. Other drivers will go to 100% output with zero input.

You can either get a 10v DC power supply and wire a pot inline, or use the pwm circuit I posted earlier in this thread.

Thank Evilc66. So the Dim + and - need to be connected before it can work.
My is a PWM model(end with P) so I need a PWM to work right?
Or I still can connect a 10 vdc with pot across the Dim + and -

Cheers

This was something I never got a real clarification on, even though I asked the question. If you have access to a 10v power source, try it. Use something like a 10K pot. If it doesn't work, the pwm will.

Thank evilc66.
I will try out and see which one work.

Cheers

Hi Sherman,

What's the outcome? 10V workable? or still need PWM circuit?

Busy at work.No time till weekend.

Is this the Australia supplier that was mentioned? I was debating ordering but it seems they take my credit card info down before giving a shipping quote and I was a bit skeptical?

http://www.computronics.com.au/meanwell/eln-60p/


Australia currency is 45 converted to USD is about $32 + whatever shipping costs.

6-12 week lead time from them, plus shipping time. Wait a few weeks for my group buy and you can get them at a good price.

excellent! i cant wait for the group buy!


My question is that if i use the eln-60 at full power running 4 strings of 5 leds (10 whites and 10 royal blues), how would that work out? Unless i missed something, the 4 strings would be running at each just under 700mah? Would this work out? I plan on waiting on the dimmable ps group buy, but was just wondering how this would work out on a non dimmable, not fiddling with an external pot. thanks evil for all the help btw, very much appreciated!

Depends on which version you buy. The ELN-60-24 will be your best bet to do this. The 2.5A current will be divided by each string of LEDs. With 4 strings, you are looking at 625mA at the LED.

Honestly, I wouldn't recommend running LEDs in parallel unless you know exactly what you are doing. Ideally, you should be running current mirrors (3 total) to make sure the circuit is safe if there is an LED failure. If you run unprotected parallel strings, a single LED failure can destroy your entire array. Series strings are much safer in that regard. The ELN-60-48 will support 13 LEDs in series at 1A.

Unless I can find a simple, cheap way to implement current mirrors, I will probably be only ordering the ELN-60-48 in the group buy just to make sure that everyone has the most success and reliability.

Evil, I respectfully disagree on this point. If iMaGin3 decided to run 4 parallel strings at 625mA ea I think this would be a safe setup without current mirrors. Lets say a led did happen to fail on one string. Then the current would be divided between 3 strings instead of 4 and each string would be receiving 823 mA. This is still very safe. In the unlikely event that another string failed, then the current would be divided by 2 strings which would result in 1.25 Amps per string. While this is not good long term, it still does not spell disaster in the short term with good heat sinking, and he will have plenty of time to notice the burnt out strings and fix them before any possible damage could occur.

I agree that it may be a problem in setups which are already pushed to the max to begin with but in cases like the one above I believe there is no problem running series-parallel circuits of LEDs.

The problem doesn't lie strictly with current though. The change in forward voltage will affect all LEDs in that string potentially causing damage as the driver attemps to keep the voltage high enough for the other strings. It is widely accepted in the high power LED world that series strings are desireable, and parallel is not.

Okay, Ill probably just run the ELN-60-48 with a string of 13 in series. Ideally, I would like enough lighting over a 12" cube and I think 13 will be enough running 7 royals and 6 whites. Keeping softies and LPS, perhaps a clam too (temporary of course! ) So the current for the string would be running at 1.3A at max ( I know too high)? With the dimmable PS, can I turn the string down to about 800mah or so? Would I have any trouble with the colors (hopefully about 14k or a bit "bluer" ) running them all on the same string at the same current? Thanks!

Current Mirrors? Is that you are talking about (red arrow).


Source: Meanwell Powersupply Tech note.