Taqpol's DIY LED prototype build, detailed pictures

[Taqpol]

In May I am going to be moving to North Carolina and upgrading my tank at the same time. As of now the current plan is to have a 180 gallon tank lit with four blocks of 24 3w Cree XR-E's (spotlighting two major islands) and another one or two strips of 24 LEDs for coverage in the middle of the tank. On top of all of that I am contemplating building my own Arduino controller and using 8 channels of PWM to simulate sunrise and sunset over the reef. Before I got too deep into all of this I wanted to build my own test fixture so I could actually hold it in my hands to see what was what.

I ordered a 24 LED (12 cool white, 12 royal blue) kit from www.rapidled.com and an 8.4"x10" aluminum heatsink from www.heatsinkusa.com on Monday night and both packages arrived here today! The LEDs will be driven by two Meanwell ELN-60-48P drivers.







I already have a question about dimming though. Can dimmable Meanwell drivers be ran (in a constant current mode) if I don't have anything attached to the DIM + and - leads? I want to be able to dim this puppy in the future, but right now i just want to get it set up and running.

[Taqpol]

Also, when building dimming circuits I have heard that you have to go inside the meanwell and adjust an internal pot that controls the maximum current. I think that pot is this one next to where the LED and dimming cables exit the fixture:



Can someone confirm that for me?


Lastly, this is my multimeter and while I am somewhat electronics illiterate I'm pretty sure it only goes up to 200 mA max:


Since I will want my max amperage to be at least 700 mA do I need to find a new multimeter? Can someone suggest a good yet cheap one I might be able to pick up at a local store?

[lighthouze08]

where are you moving to in NC?

[Taqpol]

I'm also going to post this here just so I don't forget what page of the massive DIY LED thread its on. A very good description of how to solder LEDs on stars by RC member kcress:

Soldering... It's a bit of an art form. It you're an expert you could probably solder the stars with anything but a torch. But if you aren't accomplished a 'just right' soldering iron is required. Something around 25 to 40watts. The biggest problem would be one too small as then you damage what you are soldering by sitting there with the heat on, waiting, and waiting for the solder temperature to be reached. Meanwhile the device is being roasted.

You need "rosin core solder." Make absolutely sure it's not 'ACID' core solder. Acid core is solder for soldering radiators and copper pipe. The acid remains and will dissolve your electronics in short order. No-core or plain solder is also very bad as there is no cleaning action which is vital to an acceptable solder joint.

You want lead solder too - NOT "lead free".

Let your iron heat up fully. Then wet it with your rosin core solder until it's blobbed up in a wad. This lets the rosin act on the tip to clean it. Wipe this blob off on a moist sponge,(not a sopping wet, just barely damp). If you have no sponge use a damp folded up paper towel.

Wipe with a very fast twirling dragging motion as you are trying to clear all the solder off the tip before you cool the tip to the point that the solder freezes again.

Apply a weee bit of solder to the tip and then immediately apply the tip to the star's pad. As soon as you apply the tip to the pad take your solder and touch it to the exact point where the tip meets the pad. You are trying to maximize heat transfer from the tip to the pad. You do this by filling all the voids with a molten metal thermal bridge. Pause for, perhaps, one or two seconds move the solder to a distant place on the pad and hold it there. When the pad heats up enough to melt the solder feed the solder in at a good clip until the pad has a large mound of solder on it.

Do the same thing to your wire if it is un-tinned. (actually do this before you do the pad!) Better(superior) would be to use only pre-tinned wire in the first place.

Now once you have your mound of solder on the star pad bring over your wire hold it on the Star's pad. Place the tip on top of the wire. You want to reheat the pad thru the wire. When the wire sinks into the blob hold the position and watch the blob. You want the entire blob to melt again. The instant the blob has remelted remove the tip while holding the wire EXACTLY where it is. No wiggling allowed! Coffee shakes need not apply..


There! One down a bazillion more to go. LOL

Aaaaaand I have yet another question. I have 20g wire laying around that seems perfect, but should I use stranded or solid wire for wiring between the LED stars?

[Taqpol]

Originally Posted by lighthouze08

where are you moving to in NC?

Going to grad school in Durham!

[widmer]

Looks like you're off to a great start. As far as I know, your multimeter is just fine. Simply turn the dial to the "10A" option which is in its own little red-lined section. Then physically unplug your red lead and plug it into that corresponding socket. All you have to do is wire up your LEDs and break the connection, connecting in the multimeter in series as if it were just another LED.

I'm not sure if you are questioning, but I'm guessing that no active cooling will be necessary considering the heat sinking that's going on

[Taqpol]

Originally Posted by widmer

Looks like you're off to a great start. As far as I know, your multimeter is just fine. Simply turn the dial to the "10A" option which is in its own little red-lined section. Then physically unplug your red lead and plug it into that corresponding socket. All you have to do is wire up your LEDs and break the connection, connecting in the multimeter in series as if it were just another LED.

I'm not sure if you are questioning, but I'm guessing that no active cooling will be necessary considering the heat sinking that's going on

Thanks for help with the multimeter! It makes sense now, but those things scare me....

I will definitely be actively cooling with some kind of computer fan hooked to a wall wart, but for right now I am more concerned about figuring out the wiring of the meanwell.

[ReefEnabler]

If in doubt about the 200ma max thing, there is another, probably more accurate way to measure current with that multimeter, but you will need a resistor. A 1% tolerance 0.1ohm resistor is best, but you can also use a 1ohm or 1/2 ohm since 0.1 ohm is likely not at Radio Shack.

Hook the resistor up in series with your LEDs. Connect your multimeter probes to both ends of the resistor, and read the voltage in mv.

Current = Voltage / Resistance
I = V / R

So if you have a 1ohm resistor (what I used), then the reading (in mV) will actually be the direct reading of mA (current). If you used a 0.1 ohm resistor, you multiply the value by 10 first... just plug your mV reading and resistor ohms into that equation.

Also note that a 1% tolerance resistor need not be used. Regardless, you should set the multimeter to the ohms setting and measure the ohms of your resistor first, which should take the guesswork out of it, especially if you had to settle for a 10% resistor which is more common.

Wish I could help with the question about running the PWM meanwells without a dimming signal but I haven't messed with em yet, just the buckpucks.

I'd recommend stranded wire between LEDs, it puts less stress on the solder joints and IMO is just easier to work with. I did use solid wire on the first and last connection of each of my LED strings since that's what my quick disconnects needed, and it does seem to work just fine. 20g sounds fine; I used it in between my stars. Kcress will tell you to go higher gauge like 22-24, but stugray, myself and others have used thicker wire like 18g and it works just fine, but Kcress probably does have a point about thicker wires putting unnecessary stress on the stars/solder joints. Thicker wire is only really beneficial if we are talking about long wire runs, so I wouldn't go with beefy wire between the LEDs.

good luck!

[sammy113]

I'm pretty sure you won't get accurate results by testing the meanwell without being hooked to the whole rig. It will auto adjust. It is recommended to turn down the SRV2 pot to the lowest (~700ma) then adjust and measure while having all the LEDs connected (make sure you don't break it though. It only turns around 270 degrees side to side. I though it was like a screw and turned like 200 times lol) You can get constant current from it by just pluging the DIM -, + wires to a 10V max power supply. I'm currently using 9V wall wart while I get something to Dim with. You could even use a 9V battery.

[ReefEnabler]

ooo I like the 9v battery idea

[sammy113]

yeah works very good. I had a 72 LED lamp On for more than an hour with one of those
Also have toyed with AA's to get "dimmed" effects.
Also a poor man's dimmer could be a multi-voltage power supply. Ranges from 2.4V to 12V. Just need to make sure you don't crank it up to 12V

[kcress]

The MW needs to be hooked up and running the LEDs before you bother trying to "dial it in". Do however turn it DOWN before powering up your string with it the first time.

Widmer has the meter setup explained well. Follow that.

A warning. Remember not to power the MW and then close the circuit on your string. It will FLASH ONCE and that will be the end of it. This can easily happen when you are measuring the current by breaking the string and inserting a meter. Then you get the bright idea to remove the meter (string now open) then you re-hook the wires to get the string back on without actually turning off the power first... FLASH!

I doubt you'll need any fan on that sink at all if air can flow easily across it.

[Padrino]

Originally Posted by Taqpol

I'm also going to post this here just so I don't forget what page of the massive DIY LED thread its on. A very good description of how to solder LEDs on stars by RC member kcress:




Aaaaaand I have yet another question. I have 20g wire laying around that seems perfect, but should I use stranded or solid wire for wiring between the LED stars?

yOU SHOULD USE STRANDED WIRE, THE PURPOSE FOR THIS IS ITS FLEXIBLE AND WILL NOT GET DAMAGED OR CRACK WHILE YOU ARE WORKING WITH IT
sorry about the caps. This looks great Alex. I think i may have to try this as well.

[Taqpol]

Ok guys, thank you so much for your help!

I have an adustable wall wart that is 3v - 6v - 9v - 12v so I guess I could just use that on the 9V setting plugged into my DIM wires for the time being. I would like to set up a more permanent dimmer with controls, however. After doing some google searching (It will be nice when RC gets their search function upgraded) I found this RC thread that talks about dimming a Meanwell ELN-60-48-D. In it (page 1) stugray and evilc66 get in a discussion about making a controller to reduce a 12V wall warts voltage to exactly 10V and then adjust it using a pot:

http://www.reefcentral.com/forums/sh....php?t=1793374

Stugray advises using a master pot to lower the voltage down to 10V and then using a second pot to achieve dimming:

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 suggests using an LM317 and a simple circuit to adjust voltage:

Not to bad when you paint by numbers. All of these parts can be bought at Radioshack. This will accept 12-32v and still work perfectly.

Can someone tell me which of these seems to be the easiest/safest method? I've built circuits before, but never on just perfboard. I would also like to be able to power my 12V dc computer fan off of the wall wart, if I used the same wall wart for the dimming circuit and the fan (I'm sure it has enough amperage for both) then would I just run the fan "parallel" to the dimming circuit and branh off before I hit the first pot?

In the same thread they also mention that the D and P Meanwells are almost identical and at least for testing purposes you can use a 0-10V signal produced by one of the above circuits on the PWM Meanwell like it was a D Meanwell. I would like to do that now just to see what the dimming effects look like before I try and build a microprocessor.

Does all of this sound good?

[Taqpol]

I got a lot done today, but like all of these projects I did think i would get even farther.

Marked out the LED placement, I used roughly 1.75" between LEDs and 2" between rows:


Blue LEDs in place for a sense of scale:


I then drilled 1/8" holes through the heatsink on either side of where an LED will end up. This will allow me to pass wires through the heat sink and hide everything in the fins:


I also ground down some perpendicular channels so I can pass wires between the fins without going up and over:


Turtle Wax Polishing Compound was used to buff out any scratches and give a better surface for heat transfer. Right before I mounted the LEDs I also wiped down the surface with isopropanol and a lint free cloth:


RapidLed's kit came with Arctic Alumina Thermal compound so I used it. Like all two part epoxies you mix it in a 1:1 ratio on some kind of plastic sheet (I wax paper):


I then used the provided spatula to apply some mixed compound to the underside of the LED star, after I wiped it down with isopropanol and a lint free cloth:


Press it into place on the heatsink. A slight twisting motion as you apply pressure really makes sure the thermal compound fills up all the imperfections:


I think I used a bit too much. One things for sure, these puppies are not coming off anytime soon:


Finished fixture:

[Taqpol]

Also, following kcress's instructions (which I quoted on this page), soldering the XR-E cool whites which did not come pre-soldered was easy. I did these before I mounted them to the heat sink because I heard that the heat sink made it harder for the solder pads to heat up.

Touch the pre tinned soldering iron to the solder on one side of the pad:


Move the solder away and feed it in at a good clip until you get a nice mound:


I used a 30 watt soldering iron for everything I did today.

I decided to use stugray's dimming circuit method as it did seem easier to me. Here was my proof of concept involving two 5Kohm pots and gator clips.

While testing voltage across my second pot, I use the first pot to adust my maximum voltage. This is being fed by a 12v wall wart that was producing 12.1v on its own:


Then I wired it up so the multimeter would see what the meanwells dimming circuit sees. The wiring goes like this:

Wall wart positive -> 1st pot high side
1st pot wiper -> 2nd pot high side
1st pot low side -> unconnected

2nd pot wiper -> Meanwell DIM+ (multimeter positive)
2nd pot low side -> wall wart negative

Meanwell DIM- (multimeter negative) -> wall wart negative

Note that the 2nd pots low side and the DIM- both connect to wall wart negative.

Using this setup I was able to get any voltage from 10v to 0.0v:




Of course I wasn't content to leave it simple. I proceeded to make a circuit that would take my 12V wall wart and power a computer fan as well as the master pot and two 0-10v pots in parallel to control both of my Meanwells:




This board, along with my meanwells, will be mounted in a radio shack project box with the adjustable pots sticking through the case for use as an "external ballast".


I do want to make sure of one thing before I continue, so someone with meanwell experience please let me know. In the thread I linked above they say the P and D meanwells are very similar and that you can dim a PWM meanwell with a 0-10V source just like what I have made. Is this true? I plan on using some kind of arduino based true PWM signal in the future but this seems much simpler for testing.

If this will not work is there any way I can convert my 0-10V signal into a PWM signal?

[nowlan]

I have used 2x ELN60-P.

Originally hooked up to a 9v battery.
These last about a week before the voltage starts to sag.

I do NOT recommend driving the P models with less than 9v.
Take the effort to make the pwm circuit floating around.

I did notice that my lights were dimmer after 1-2 weeks on battery, and recording less than 5v from my battery.
So it does work, but never designed for it.

I ended up buying a non dimming ELN60 model instead.

You can also achieve 10v by using 3 diodes in series.
3x 0.6-0.7 = ~2v.
You can easily get 10v from a 12v plug pack.

To calibrate current, SVR2 is on the far right of the board.
You can dial it down if your using XPE for Royal Blues.
XPG can take full grunt otherwise.
I suggest turning it off whilst adjusting.

Final warning, if you look at datasheet, the output voltage is between 24-48v.
You want to hook up enough leds in series, to take the min 24v.
Otherwise risk magic smoke.
I used a lab power supply to test my wiring, and put meanwells on last.

---
You also want to do something about the rough edges on the Fins.
The sharp edges can possibly cut the wire insulation over time.
Need grommets ? Debur holes too.

I would suggest going under the heatsink like everyone else does.
I have drilled a hole through my heatsink, to tie a hoop.
This takes strain off the wires. Meanwells live on a shelf.

Also, good idea to run an earth to the heatsink itself.
You dont want to get shocked if anything ever comes loose.

--
Dont want to sound critical, just sharing my experience.

[kentrob11]

Lookin good...

[noahm]

Thanks for posting. I can't get enough of these LED threads. I am still a couple years out on a major move and tank upgrade, so after that, and after you guys work out all the kinks , I can start my own LED build.

Looking good

[Taqpol]

This is coming along really fast! I forgot how much I enjoy soldering and electricity stuff.

ALL of the blue LEDs wired in series!


Wiring hidden in the fins:


With all that done and my voltage regulator working, its time to wire up some drivers!

Standard AC power chord, soldered and heat shrink'ed with a lighter:




Hooked everything up with aligator clips. With no LEDs the driver was producing almost exactly 48V!

[Taqpol]

As suggested I hooked my multimeter up in series with the LEDs after turning the SVR2 pot down all the way (counter-clockwise). It turns out my multimeter does work just fine after I switched the positive chord to the 10A socket.



Lights! with my dimming circuit on full blast (10V) and the SVR2 pot all the way down the rig only drew 0.15A yet I was still seeing spots.


Adjusted the SVR2 pot until my amp meter read 0.7A, this level is almost blinding without optics!


The lowest I can go with my dimming circuit pot is 0.09A, it will shut off after this.


60 degree optics, fully dimmed.


60 degree optics, full power.


The ceiling above me. I am really impressed by the spread of 60 degree optics.



So my question now is why is 700mA the max, I thought these LEDs were rated all the way up to 1A. I don't think I would (or need) to go that high, but if I'm looking for a little more PAR down the road would it hurt to go up to maybe 800-850 mA saying that I have enough cooling?

[Padrino]

Alex,
Thats awesome. Could you list out all the products and where to get them for people that might want to follow in your footsteps.

Any chance you could test the PAR at different distances under water. I am looking to upgrade and i may want to give LEDs a chance.

Do you ever need to replace the bulbs?

[Eel-byte]

I was suprised how quickly things move when you get going. Nice job. Next one I do, I'll conceal the wires.

[Anthonius]

wow great job... almost looks ready to hang on the tank... i cant wait to see... i just ordered my leds and a heat sink... next payday hopefully i can buy my drivers... im really excited. looks good tho.

[crvz]

great project. any plans with the finished product? Or is it really just a test rig?