How to dim a Meanwell ELN-60-48D...

[JaredWaites]

I've been reading a lot especially over at NR on the LED's. My drivers are here but I'm waiting on my LED's. I was told I'd have to make a LM317 voltage regulator and use a 12 volt wall wart...thing is, I don't know how to work with a bread board, nor do I understand circuitry.

Is there an easier way?

Actually I found it after searching (durr).

Originally posted by Stu

Get a 12VDC "wall wart" Get a large potentiometer ( variable resistor with a knob ).

It can be anywhere from 1000 Ohms to 100,000 ohms ( 1K to 100K ).

Hook the high side of the Pot ( either end ) to +12VDC.
Hook the low side of the Pot ( opposite end from above ) to 12V RTN/GND.
Also hook this line ( 12V RTN/GND ) to the Dim- line ( White on the Meanwell )

NOW take the "wiper" of the Pot ( this is the part that adjusts ) and hook it to the Dim+ line of the Meanwell ( Blue )

Remember to turn down the internal current adjust before trying it and you need to know how to measure the current through the LED string to adjust. I use a DMM in current mode & I adjust my max current to 700mA.

Then you can experiment with the Dim knob (CAREFULLY) until the max on the knob corresponds to the max current through the LED string.

The spec sheet of the Meanwell does not state the absolute maximum voltage that can be applied to the Dim+ Pin, so I would advise you to not just "turn it all the way up" with the above design as you could apply 12VDC to the Dim+ pin.

My guess is that it wont care, but I wont guarantee it.

[der_wille_zur_macht]

An LM317 strikes me as a poor choice. It has a big dropout (2.5v) so technically it might not even produce the right output voltage using a 12v input (though, most unregulated 12v supplies probably produce more than 12v so it would likely work. And, in practice, you can usually get a lower dropout if you're only pulling small currents like you would be) Also, since it's an adjustable regulator, you'll need extra components to set the voltage.

If you're going to use a voltage regulator, something low dropout and preset would be a better choice:

http://search.digikey.com/scripts/Dk...=296-8007-1-ND

Though, even that is probably overkill. I bet if you experimented, you could probably use a resistor divider to drop the voltage to a max of 10v, then a pot to adjust down from there.

Or, just buy a 10v power supply. They're rare but do exist.

Or, buy a 9v regulated supply with a voltage trimpot on it and cheat by turning it up to 10v.

A riskier way to proceed would be to just use a 12v wall wart and a pot, and never turn it ALL the way up. That said, I really doubt it would be the end of the world to actually apply 12v to that circuit, but I don't want to be the one to find out. Maybe someone else has tried it, or someone could contact meanwell and ask.

[g8gxp]

http://www.reefcentral.com/forums/sh....php?t=1662682

he used a prebuilt pot in this thread.

[der_wille_zur_macht]

That's essentially an LDO regulator with some decoupling caps and a pot set up as a voltage divider premade for you - if you don't want to deal with making your own circuit, that's a reasonable way to proceed.

[der_wille_zur_macht]

I see from your edit that Stu has verified this works just fine:

Originally Posted by der_wille_zur_macht

A riskier way to proceed would be to just use a 12v wall wart and a pot, and never turn it ALL the way up. That said, I really doubt it would be the end of the world to actually apply 12v to that circuit, but I don't want to be the one to find out. Maybe someone else has tried it, or someone could contact meanwell and ask.

[stugray]

I have not tried it. I have not experimented with the Dimmable Meanwells yet.

However If you use a 10 Potentiometer with a 2KOhm resistor on the high side THEN connect to a 12V wall wart, it should work fine.

Stu

[bstohrer]

Originally Posted by stugray

I have not tried it. I have not experimented with the Dimmable Meanwells yet.

However If you use a 10 Potentiometer with a 2KOhm resistor on the high side THEN connect to a 12V wall wart, it should work fine.

Stu

I just tried Stu's method yesterday. Used a 5K pot with a 10V wart (I actually meaured 12.1V). Worked great!

Thanks Stu!

Bob

[JaredWaites]

Originally Posted by bstohrer

I just tried Stu's method yesterday. Used a 5K pot with a 10V wart (I actually meaured 12.1V). Worked great!

Thanks Stu!

Bob

Bob,

I actually purchased 2 5k pots the other day...so that's a relief.

So you are pushing 12.1 volts to the dim+ wires on the Meanwell with no adverse effects?

[bstohrer]

Originally Posted by JaredWaites

Bob,

I actually purchased 2 5k pots the other day...so that's a relief.

So you are pushing 12.1 volts to the dim+ wires on the Meanwell with no adverse effects?

Jared,

I only ran my 12 LED "test rig" for about 10 minutes with the wall wart because I was afraid to fry the Meanwell. I used a bench power supply (at 10V) to do longer runs for my temperature measurements. I also tested a few other wall warts and they all run 2 volts higher than spec???? Maybe my new VOM is out of calibration? I'll check it in a few minnutes and post back.

Bob

[bstohrer]

Originally Posted by JaredWaites

Bob,

I actually purchased 2 5k pots the other day...so that's a relief.

So you are pushing 12.1 volts to the dim+ wires on the Meanwell with no adverse effects?

Actually, the 10V wall wart is giving me 11.4 volts when wired up. When I set the bench supply at 10V, my VOM reads - 10.12 so wart must be a little high.

My gut feeling is that 1.4V over on a control circuit will not do any damage due to low current.

I still will wire in a master pot to drop the voltage to 10V. It will then feed the 8 seperate pots that I will use to control each Meanwell individually. 5K Pots are cheap, only $1.50 at Amazon.

Bob

[olliefb]

i bought a 10v, 2amp adaptor from ebay and its coming from hongkong. I will measure the voltage when it arrives but wondering if 2 amp is too much? I will hook up 3 meanwells(parallel) on a single pot and was wondering what might be the value(ohms) of the pot. Thanks..

[der_wille_zur_macht]

The current rating on the power supply is a MAX rating. It will only supply what the circuit asks for, which in this case will be a few mA. A supply with a 2A rating will have no problem supplying that load.

[JaredWaites]

Ok so it should be fine to run a standard 12 volt wart on the meanwell... I plan to confirm this by emailing Meanwell.

[bstohrer]

Originally Posted by JaredWaites

Ok so it should be fine to run a standard 12 volt wart on the meanwell... I plan to confirm this by emailing Meanwell.

Right now I'm leaning towards supplying the 0-10 volts with the Reef Keeper Light and the ALC module. I'm hoping to run 4 Meanwells off each channel. does anyone know if that is doable?

My backup plan will be to use the wall wart and a few timers to phase the lights on and off one or two at a time.

Bob

[olliefb]

im planning to dim my meanwell with a 10v pot but couldnt find a 3 gang linear pot. I found a 3 gang audio taper pot but read somewhere in the big thread that a linear pot is what you should use. 3 gang pot because i'm controlling 3 meanwells for each blues and white dimming ckt. Any body know what value of pot should use or can the audio taper pot be used instead? Thanks.

Thanks der wille for the quick reply on my previous question...

[der_wille_zur_macht]

You don't need gang pots - you can supply the "same" signal to multiple meanwells by just wiring them all the the same pot.

[JaredWaites]

der_willie,

I was told by evil on Nano-Reef that running the 12 volt to the dimming wires will fry the circuit...but it doesn't seem that way with 11.4 going to the wires anyway with a 10v wart.

To be on the safe side I've contacted Meanwell...plus I think it can be done safely anyway just want to further make myself feel good beforehand :P

[stugray]

As I mentioned above:

If you are using more than 12 Volts and you are worried about the dim pins,

Put a 2kOhm resistor in series with the 10k Pot.

If the 2K is hooked right to the 12 Volts and then the 10k is below that, you will drop 2 volts across the 2k.
That leaves 10 volts to drop across the 10k Pot.

Attach wiper pin of the 10k Pot to the meanwell Dim+ pin and you cannot apply more than 10 volts.

If you want to use a 5k pot, use a 1K resistor at the top and it will work the same.

Stu

[Skeptic_07]

I think this is a 10v wall wart.. its $15 but hey, it'll work, if its actually 10v. My only concern is that the 10V in the title is a model # of some sort.

http://www.amazon.com/Live-Wire-Solu.../dp/B001OSY5RG

edit: searching around some more i came up with this one. Is OOS but i think it would be useful for people using these drivers.

http://www.fantasyworldhobbies.com/c...oducts_id=6076

[evilc66]

My concern with running a 12v supply with just resistors (2K drop resistor and a 10K pot) is that not all 12v wall warts have the same output. Some of the really cheap ones can output voltages as high as 16v with little to no load. Stating that a resistor and a pot can work for any situation is a risky one. Anyone that has worked with electronics long enough will know that those power supplies are all over the place.

While an LM317 isn't the best choice, it's a readily available one for anyone that walks down to the local Radioshack. With a 12v power supply (that usually outputs higher than that anyway), getting 1.25v to 10v output is no problem. Even if you use a regulated 12v supply, with the 2.5v drop off, you can still adjust the driver up to the desired current with SVR2 with the lower 9.5v input. It's still safer than running up to 12v.

I have talked with Meanwell tech reps on this issue and they cannot and will not warranty damages to the driver from input voltages higher than about 10.5v. Because this isn't an inverted input driver like the Buckpucks, if you kill the dimming circuit, you have a useless driver. Spend the extra few dollars to regulate the voltage.

[JaredWaites]

Originally Posted by evilc66

My concern with running a 12v supply with just resistors (2K drop resistor and a 10K pot) is that not all 12v wall warts have the same output. Some of the really cheap ones can output voltages as high as 16v with little to no load. Stating that a resistor and a pot can work for any situation is a risky one. Anyone that has worked with electronics long enough will know that those power supplies are all over the place.

While an LM317 isn't the best choice, it's a readily available one for anyone that walks down to the local Radioshack. With a 12v power supply (that usually outputs higher than that anyway), getting 1.25v to 10v output is no problem. Even if you use a regulated 12v supply, with the 2.5v drop off, you can still adjust the driver up to the desired current with SVR2 with the lower 9.5v input. It's still safer than running up to 12v.

I have talked with Meanwell tech reps on this issue and they cannot and will not warranty damages to the driver from input voltages higher than about 10.5v. Because this isn't an inverted input driver like the Buckpucks, if you kill the dimming circuit, you have a useless driver. Spend the extra few dollars to regulate the voltage.

So as long as you know what your wall wart is putting out then you can pair a resistor to make sure suited for that voltage...correct?

[evilc66]

That's possible, but the output voltage can change with heat too. It would probably be good to err on the side of caution and drop a little more voltage. A voltage regulator takes away all of these concerns and issues though. It's not like they cost all that much. This way it's the same circuit with the same part values for every power supply instead of trying to figure out custom values for every power supply.

[stugray]

evilc66,

"While an LM317 isn't the best choice, it's a readily available one for anyone that walks down to the local Radioshack."

Agreed, and I have a LED light running on my QT with two CREE XR-E using just a LM317 as a driver.

However - you need to install at least two Caps and a variable resistor in the circuit.
This is a little beyond most DIYers ability to solder discrete parts together without a PWB. ( although DWZM could easily do a VERY nice LM317 driver PCB for us ).

Anyway, if the variability of wall warts bothers you, lets say:

Get TWO 5k Pots.
Hook high side of POT 1 to Wallwart ( unknown voltage < 24V )
Hook Wiper of POT 1 to High side of POT 2 ( insulate low side of Pot 1 )

Hook Low side of POT 2 to wall wart ground

Turn on wall wart & measure voltage across POT 2
Adjust POT 1 until max Voltage across POT 2 = 10.0 VDC

Hook wiper of POT 2 to Meanwell Dim+
Hook wall wart Ground(RTN) to Dim-

NOW you can get 0-10V by adjusting POT 2 regardless of voltage of wall wart. ( DO NOT adjust POT 1 ever again )

Sorry if that sounds complicated but it's not.

Stu

[evilc66]

Honestly, I think it's more complicated than a simple LM317 regulator circuit, but lets just agree to disagree here.

I do think that anyone who is building a DIY LED array has the capability to assemble a simple circuit. It's not like we are asking them to build an Atmel controller from scratch. It's a few simple discrete components soldered to a perforated breadboard. If you can solder to the pots, you can solder this up.

[stugray]

Ok,

"but lets just agree to disagree here."

But 2 POTs vs:

2 Caps
1 POT
1 LM317
1 Perfboard
1 Heatsink for LM317 if supply voltage is much above 10V

Thats two components versus six.


BUT agreed - if you can grasp the variable resistor network concept, then the LM317 is not much more difficult & more reliable in the end.

Stu