DIY LED Array build

[sphil876p]

SpacedCowboy, that looks like a professional production unit you are desiging there....
I am afraid you might have to tone it down a bit, if us regular DIYers are going to be able to have a shot at copying :bigeyes:

 

[sphil876p]

LED project update:

LED project update:

Got some more work completed on my next array......
Mounted the Meanwells, and cooling fan on a acrylic framework I attached to the top of the heatsink.

Then made all of the led circuit connections. I am not going to enclose the array until I do some experimenting with optics. Going to run the array without optics first for a while, and see how the corals acclimate.
I plan to take some before and after pics of the display tank with the existing MH, then LEDs.

 

[kcress]

I finally finished the non-driver thread. Sorry it took so long. Thanks for your patience.
Check it out.

http://www.reefcentral.com/forums/showthread.php?t=1751598

 

[kcress]

Hey SpacedCowboy what are you using for schematic capture and layout?

 

[jerwin]

Hi sphil876p

I am working on a 75 gallon set up based on your set up. I have done drawn up a wiring diagram to see if I better understand what you have wired up. Can the ELN-60-48D be plugged directly into a house circuit or is there something else I am missing? I am also trying to figure out how to wire up a master Dimmer between the RB and W leds. Would apprecaite the help.

Thanks

 

[SpacedCowboy]

Hey SpacedCowboy what are you using for schematic capture and layout?

[Apologies if this is off-topic]

I use Eagle ( http://www.cadsoftusa.com/ or the parent site at http://www.cadsoft.de ). Mainly because it's cross-platform (I run it on a Mac because the Mac has a 30" monitor and 2x23" monitors arranged vertically on either side of the 30"

It's also very popular, and people like sparkfun ( http://sparkfun.com ) give away their component libraries in Eagle form. It's just been bought by Farnell, so I don't think it'll be going anywhere soon.

I also find it easy to use, and (crucially) easy to make new parts in, once you've done it a couple of times. I don't really rate the autorouter, but (coming from someone whom it has tried) optimal routing algorithms are very very hard problems.

Don't get me wrong, the autoroute is "good enough" to do most things, but it doesn't do impedance-matched tracks or bus-matched layout or anything more complex than the average point-to-point connections. You then jump in and do those yourself after the grunt-work has been taken care of. Not important in simpler circuits, but if you're trying to get some SDRAM to talk to an FPGA and an ARM CPU, impedance matching is a big deal

Eagle does handle N layers, though - I bought the 4-layer licence. The 2-layer limited-board-size version of the app is free. There's a 16-layer unlimited version above my purchase limit . It's also scriptable, and has a CAM processor for Gerber output (which is how I made it write the Gerber RS274X files my CNC machine needs as input).

Overall I'm very happy with it. It's certainly worth a download and try-out if you're looking for one of these programs. You may even be able to get by with just the freeware version - I could have done those drivers in that version...

Simon

 

[der_wille_zur_macht]

Jerwin, I would suggest NOT using parallel strings of LEDs on each driver. There are two issues with that:

1) If one LED in one string fails, the other string is going to see the entire current, which will likely cause lots more failures.

2) There's a good chance you'll have some imbalance in forward voltages from LED to LED. If you manage to randomly stack one string a bit lower than the other, they'll get unequal percentages of the drive current - which will mean one string overdriven and the other underdriven.

The ELN drivers are wired directly into your home's 120V AC outlet.

A master dimmer could be accomplished by running one 10V wall wart to dim the entire thing, with a "master" pot across it. Then, use the center terminal on the master pot as the + supply for the dimmer pot on each color. Then, you're using the master pot to control the voltage seen by the other two pots, so it will essentially set the maximum point for both.

Oh, and while it's nice to have the 1A fuses you show in the diagram, they're not totally necessary, as the ELN drivers have built in overcurrent and overvoltage protection, so they'll shut down internally if things get out of hand. Plus, in the location you have them, they'd limit the two parallel strings to 1A max, which means 500mA each string, max. You'd have to make sure the internal trimpot was set below 1A or else you'd just blow that fuse when you turned it on.

 

[kcress]

SpacedCowboy; Thanks so much for the Eagle review. I have tried it and wasn't greatly enamored with it primarily because the libraries did little for me. I also have heard mostly just negative comments about it, especially with its non-windows standard users interface.

It was nice to hear a positive review. I will give it another look.


jerwin; DWZM's comments are all good.

I will say that you can run strings in parallel but you will need to add fuse protection to each string. This way when one string opens the other that will now have 2X current running thru it will also promptly open. You would want to size your fuses carefully.

Also the Vf of the various LEDs could cause one string to be bright and the other not so bright. So as you build keep in mind you might need to re arrange the LEDs to get better balance. This is probably a fairly low eventuality but you should keep it in mind. Like gluing down LEDs could be a real problem if this needs to be done.

One way to avoid that is to actually measure the Vf of all the LEDs before assembling them. You run exactly the current you will be running them at thru them, one at a time. You measure the voltage across the LED while this current flows. Then you write the voltage on each one.

Ultimately you want the two stings you run in parallel to have stacked up voltages that are identical. Or you can wing it and hope for the best...

 

[der_wille_zur_macht]

Well, I wouldn't say an exhaustive search of the options was performed [grin] - there may well be a better one available, but ...

• According to the datasheet it supports up to 40V input with 0.5v overhead, and 1.5A max output. That's a comfortable headroom over what I'll actually want it to do.
• It supports PWM dimming
• It's cheap at $3.19 each or $2.80 for 10 and very few additional components required
• The circuit is basically lifted directly from the datasheet and replicated so it has a better-than-average chance of working
• The device runs cool, from all accounts. Despite that, I poured a lot of copper to try and help things along.
• It's small & surface-mount so I can fit several on a board, but it's easy surface-mount. I have an SMT oven, but you could trivially solder this thing by hand if you used conductive thermal adhesive for the center pad.

I thought of bumping the voltage up and getting more LEDs per driver, but it's just not worth it in terms of the cost of the PSUs. The 24v ones are cheap (24V @ 8.3A for $20) whereas the 36v ones are far more expensive (36v @ 8.5A for $97); both of these from mpja.com. The drivers are so cheap, it's not worth it.

Simon

Thanks for the info. I ruled it out early in my project because the ground pad under the chip scared me away (sadly I'm not lucky enough to own a reflow oven.) I ended up with the NCP3066 from OnSemi, which has similar features (current set by external resistor, PWM dimmable) but requires a more complicated design with more external components. Looking back at your chip now, it's pretty attractive from a simplicity standpoint. I'll be looking forward to hearing how it works.

 

[der_wille_zur_macht]

SpacedCowboy; Thanks so much for the Eagle review. I have tried it and wasn't greatly enamored with it primarily because the libraries did little for me. I also have heard mostly just negative comments about it, especially with its non-windows standard users interface.

It was nice to hear a positive review. I will give it another look.

Eagle is all I've ever used (on Windows and a Mac) though only on a minimal hobbyist level. The UI is a little cumbersome and has a rather proprietary feel to it, but it's pretty customizable as far as hotkeys, etc. I'll second the suggestion about SparkFun's libraries, too.

 

[jerwin]

Thanks guys for the comments.

I read on one of the post you could do that. I was trying to save on buying 2 more of the ELN-60-48D. So I guess I dont totally follow you when you are talking about wiring up the master Dimmer. I will have to say from when I started reading about LED hoods this really is far fewer parts then the earlier ones. So from what I read this is the far safer way to configure the lights to last.

Thanks again

 

[der_wille_zur_macht]

You CAN run parallel strings, if you fuse them individually (each string) and are prepared for differences in voltage drop across the LEDs to screw with intensity, and are OK with a max current that's half of what the drivers are rated for.

Is there any particular reason why you want a master dimming control? The concept sounds interesting but having a separate pot on each driver can accomplish the same thing. I can't read what's in the little white boxes above each driver pair so I'm struggling to understand what you're trying to show there.

 

[james3370]

You CAN run parallel strings, if you fuse them individually (each string) and are prepared for differences in voltage drop across the LEDs to screw with intensity, and are OK with a max current that's half of what the drivers are rated for.

Is there any particular reason why you want a master dimming control? The concept sounds interesting but having a separate pot on each driver can accomplish the same thing. I can't read what's in the little white boxes above each driver pair so I'm struggling to understand what you're trying to show there.

my personal reasoning for a master dimmer is this.....set "master dimmer" to wide open & then -

* 1 dimmer for all the whites
* 1 dimmer for all the blues
* adjust the white & blue dimmers to get the color bablance you want
* adjust the "master dimmer" to control the overall lighting brigtness (to simulate a cloudy day or to acclimated corals, etc)

 

[jerwin]

James has the reason what I want. To be able to set the individual blue and whites to be the max look that I want. then to be able to adjust the master for the type of day I want it to be. Bright, Cloudy. I would like to do this with out having to add another power source.

So here is another question. Back to running 2 sets of 13 on one 60-48D. So I could put in a 1 amp fuse to protect each strip of 13 LEDs. Could I also put in a device to help balance out the current on each leg also? I am thinking out about those other people besides my self that want to do this. By taking off those 2 60-48D. That is cutting about $80 off the total build of the project. Was trying to simplify it down to just the basic parts you need and give the over all wiring diagram here for any one to use.

2nd question. From what I read on here. Is there a problem if I deicide to run only 12 leds in series instead of 13?

I really appreciate every ones input. I am just about to start to order the stuff I need and just working out the last kinks in the wiring from all the post I have read on here.

Thanks
J

 

[der_wille_zur_macht]

IMHO you're better off with 12 LEDs than 13. 13 is pushing the envelope for those drivers, 12 is pretty much the norm. I guess I didn't catch earlier that you were talking about 13. At any rate, if I remember correctly, the bottom end for output on those is pretty low (a few volts) so you can run fewer if you want.

And you are correct about the fuse - you'd want one fuse in series with each of the two parallel strands (think of it as if it was another LED in each strand.) I don't know of any way to balance, though I'm sure you could come up with something. In the end, if you do what kcress suggested (sample each LED you'll be using, and "bin" them yourself based on precise voltage measurements to get the strands as close as possible) it shouldn't be a real big issue.

For the master pot, wire each drivers' pot as you normally would, but instead of connecting one side to the + from the power supply, connect it to the middle of the "master" pot and then connect one end of the master to the power supply. Hope that makes some kind of sense.

 

[tahiriqbal]

James has the reason what I want. To be able to set the individual blue and whites to be the max look that I want. then to be able to adjust the master for the type of day I want it to be. Bright, Cloudy. I would like to do this with out having to add another power source.

So here is another question. Back to running 2 sets of 13 on one 60-48D. So I could put in a 1 amp fuse to protect each strip of 13 LEDs. Could I also put in a device to help balance out the current on each leg also? I am thinking out about those other people besides my self that want to do this. By taking off those 2 60-48D. That is cutting about $80 off the total build of the project. Was trying to simplify it down to just the basic parts you need and give the over all wiring diagram here for any one to use.

2nd question. From what I read on here. Is there a problem if I deicide to run only 12 leds in series instead of 13?

I really appreciate every ones input. I am just about to start to order the stuff I need and just working out the last kinks in the wiring from all the post I have read on here.

Thanks
J

You need to look at Meanwell ELN-60-48D's datasheet as they are actually rated up to 52 Volt. If you could take the driver out of the housing you will see a screw, this could be adjusted from 1.2Amp to just under 990mA or near enough. Running your LEDs in parallel is not advisable unless you take extra care and go with current mirror path. Once again you need to bear in mind what kcress have said about each LED performance, batches, BINs, brands etc , which could easily upset the current flow and may not be suitable for parallel setting.

I think four strings of six LEDs may work in parallel providing LEDs are from same batch and all other necessary precautions have been considered.

 

[sphil876p]

Let there be Light

Let there be Light

:dance: Got the array wired and mounted...

10 royal blue and 4 white in one string set to 500ma, and 14 white on one string at 350ma set with Pots...
I am not running optics to begin with to combat intensity issues I experienced with my first array...
I have set the max level possible for the pots to run the strings at 950ma.

 

[jerwin]

Morning everyone

Well I think I am just going to go with 4 sets of 12 leds. and 4 moonlight leds.

I have modified the wiring diagram again to see if I have the master dimmer set up right. To me this does not look right but maybe guys that with more eletrical back ground can say so. To me wiring like this does not seem to get me what I would want. I would want to find tune the lights with the single dimmer to set the max they could be. then use the master dimmer to dim the whole light set up from min to the max of the single dimmer lights. So I am using the single dimmer to get the lights where I like them. and master to control the whole light set up.

I really do appreciate the help. I do see a lot of these projects going on but rarely see the wiring diagram.

Thanks
J

 

[der_wille_zur_macht]

Jerwin, it's hard to interpret the different colors on your diagram, and whether the intersections are connections or not. Can you redraw it using standard symbols perhaps?

 

[SpacedCowboy]

Just as a data-point for anyone ordering from DealExtreme, I ordered my LEDs on 21st November, and they arrived today. I didn't go for the express-delivery option, so it took ~3 weeks for me to get them.

Given the price difference ($4.36/led), I think that's worth it