DIY LED Help

[JoshuA c]

Hello,

I want to create a custom light fixture for my small, little Fluval Spec II. First, my plan for the tank is to hold zoas, mushrooms, and LPS, but I might want to try some low-maintaince SPS corals after some time so I want control over the light-intensity, with the maximum being able to maintain SPS.

 

For the brain, I want to use an Arduino, which I am quite good at using so that is not the problem. My problem is that I do not have the knowledge of high power electronics, including LED systems used in the coral hobby.

 

My plan right now is to use 3 or 4 CREE XT-E royal blue LEDs for the healthy blue light that the corals need and then 8 singly-addressable RGB LEDs for the color control (the color that we see so that the tank looks good). Do you guys think this is a good idea? Or should I use some CREE cool-white LEDs and maybe 3 RGB LEDs for color?

 

Also, what dirver(s) should I use? I'm just not very good at this stuff. I want them to be powered by a wall outlet and dimable by an Arduino (pulse-width modulation). Basically I'm asking what are some good PWM controlled dimmable-drivers that could control a few CREE LEDs?

 

Thank you for any help and suggestions.

[tanked_kiwi]

Hey mate,

I can't help on the coloured LEDs and whether or not these are the go but I have done my own light using a lumia 5.2 chip, controlled by my reefangel controller. If you're not aware, these are basically suped up arduinos so, the control will be similar.

 

Meanwell LDD drivers will be just what you're after, run off a suitably sized power supply. Have a look here http://www.ledgroupbuy.com/ldd-drivers/. These dim all the way to zero, which is nice.

 

From there its down to mounting them, wiring and all that, which sounds like you'll have no problem with. The hardest part I found is housing them nicely. How were you planning to do this?

 

The controller is usually the hard part for most, but it sounds like you've got that all under control. Will follow this, am interested to see what you end up with and how's those rgb LEDs work out.

[bob115]

I would skip the RGB LEDs and just get some single color dies and have each as its own channel to dim them up or down. Past that, as has been recommended to me, and I rather like them, try a Vero 10 5000k 90cri for your whites. If you dont want to that, definitely try to stay away from cool whites as your primary whites as the color rendering is pretty bad. I'd say try the 90cri nichia 219s if you can find them or a Cree XT-E neutral or LM2 or something along those lines.

 

Royal blues you seem to have pretty good, though another option would be say one Luxeon M, of course it depends on your drive current.

 

For other colors, I'd definitely recommend a couple hyper or true violets from ledgroupbuy. Past that You're probably going to want some sort of red, cyan, and blue. The ocean coral white at ledgroupbuy does a pretty decent job and filling this job.

 

One other thing to consider is a lime or two to adjust how bright it appears without messing with PAR levels.

 

So with that you could have blue, white, violet, ocw, and lime channels, which would leave you one more PWM pin to do whatever else with most arduinos.

 

For drivers you'll probably want the PWM enabled LDD drivers from Meanwell. Power supply is really going to depend on your LEDs. WIth how few you have you might be able to get away with a laptop charger or something similar, if not most of the LED vendors people here use sell larger powersupplies, but they'd be pretty overkill for your needs. Could look for a meanwell switching power supply in the 24v range from digikey or mouser if you can't find a suitable laptop charger.

 

I'll let Ben or Evil chime in on the exact amounts of LEDs you'd need since I'm not as familiar with that aspect.

[JoshuA c]

Hey mate,

I can't help on the coloured LEDs and whether or not these are the go but I have done my own light using a lumia 5.2 chip, controlled by my reefangel controller. If you're not aware, these are basically suped up arduinos so, the control will be similar.

 

Meanwell LDD drivers will be just what you're after, run off a suitably sized power supply. Have a look here http://www.ledgroupbuy.com/ldd-drivers/. These dim all the way to zero, which is nice.

 

From there its down to mounting them, wiring and all that, which sounds like you'll have no problem with. The hardest part I found is housing them nicely. How were you planning to do this?

 

The controller is usually the hard part for most, but it sounds like you've got that all under control. Will follow this, am interested to see what you end up with and how's those rgb LEDs work out.

I like the Lumia chip, but I think it costs a bit too much for me. Also, I want the driver to be powered from a wall outlet as opposed to a battery or something. Could I possibly use a computer charger to power these like bob115 suggests?

 

I also looked at your build really quickly. How did you power you LEDs?

 

As for the mounting, I haven't gotten that far yet. I'm trying to get everything planned, first. And yeah, I've been programming for awhile now, so I can do that part. Its the electrics I have a problem with. I'm in college, but as a Bio/Chem major. I only tinker with electronics as a hobby in my spare time.

 

Bob115, would I need separate drivers for each color LED? I don't want to do that to keep costs down and reduce the space this takes up. That's what's nice about the singly-addressable LEDs, they only take one pin on the arduino and are powered by the 5V+. That, with the pin for the blues, would mean I would have plenty of pins for everything else. (Also, I will probably control these with a ATtiny85 slave anyways.)

 

Thanks for the help so far guys. I want to keep it simple but still give me the control over the intensity of each color. Keep the help comming!

[tanked_kiwi]

I like the Lumia chip, but I think it costs a bit too much for me. Also, I want the driver to be powered from a wall outlet as opposed to a battery or something. Could I possibly use a computer charger to power these like bob115 suggests?

 

The Lumia chip is nice, but it would be completely overkill on your tank. As it is I'm only running it at 50-60% on my tank. It is expensive and I'll likely use individual LEDs next time. it does make for a nice compact light without any disco effect. You definitely don't want to power this off a battery. I'll go over what bob's suggesting below.

 

I also looked at your build really quickly. How did you power you LEDs?

 

I used 1 LDD per channel, all powered from a 180w Ledgroupbuy power supply. Basically, you need a seperate LDD for each colour/colours you want to control. You run the leds within each channel in series and then run channels/LDDs in parallel. Each LDD takes a PWM signal for control. The Lumia chip is effectively just 25 LEDs on 1 chip, running exactly like this, 5 channels of 5 LEDs each.

 

 

As for the mounting, I haven't gotten that far yet. I'm trying to get everything planned, first. And yeah, I've been programming for awhile now, so I can do that part. Its the electrics I have a problem with. I'm in college, but as a Bio/Chem major. I only tinker with electronics as a hobby in my spare time.

 

Yea makes sense. I'm no expert either, but hopefully this will help some. No doubt some of the more experienced will be along to help with other options and led colours.

 

Bob115, would I need separate drivers for each color LED? I don't want to do that to keep costs down and reduce the space this takes up. That's what's nice about the singly-addressable LEDs, they only take one pin on the arduino and are powered by the 5V+. That, with the pin for the blues, would mean I would have plenty of pins for everything else. (Also, I will probably control these with a ATtiny85 slave anyways.)

 

Thanks for the help so far guys. I want to keep it simple but still give me the control over the intensity of each color. Keep the help comming!

 

You will need 1 LDD per colour/channel if you go this way. If you had say 3 channels of 3 LEDs each, you would need 3 LDDs and should easily be able to power this with a laptop charger.

[bob115]

You would need separate drivers for every individually addressable channel you wanted. Also, any LED thats running straight off of an arduino isn't going to be anywhere near bright enough to be worth anything. Look at your XT-Es for instance, they go up to 5W per LED, arduinos have I think a 40mA current limit so that puts them at 200mW max output. Unless you were talking about 5v pass through, in which case I'd really not recommend just putting the LEDs straight off the power supply because as LEDs get hotter (and damn do they get hot) their resistance goes down which in turn makes them draw more power and get even hotter, and I'm sure you can see where this is going. Pretty quick they can kill themselves with thermal run away.

 

The LDD drivers aren't all that expensive to begin with, so I'd just bite the bullet and do it right instead of potentially frying a $20 string of LEDs.

[JoshuA c]

So I could go with one of these for the blues and another for the whites? How do I figure out how to power them?

[bob115]

Just hook up your powersupply. These turn your constant voltage supply into a constant current supply. So instead of varying the current with the load it will instead vary the voltage with the load while the current remains constant.

[JoshuA c]

How do I find the right power supply for multiple drivers?

[bob115]

The voltage of your supply should be at least 1-2 volts higher than the highest voltage string. The current needs to be greater than the combined current of all strings.

[Horerczy]

Depends on the type of driver used where the current is concerned.

 

If using LDD drivers you just need to factor total wattage and match the voltage properly. LDD drivers will covert excess voltage to current and request less current. There's some effciency drop in this but it's nothing major unless you're supplying a driver with 52VDC and it's only discharging ~5VDC.

[JoshuA c]

Okay thanks guys!

I'll look into it and try to get a plan together and come back and ask you guys if I've done it properly. I won't be able to do it for a couple of days, so don't think I've just vanished. Give me about a week and I'll be back.

[bob115]

Depends on the type of driver used where the current is concerned.

 

If using LDD drivers you just need to factor total wattage and match the voltage properly. LDD drivers will covert excess voltage to current and request less current. There's some effciency drop in this but it's nothing major unless you're supplying a driver with 52VDC and it's only discharging ~5VDC.

 

Ah yeah forgot about that aspect. But yeah whole thing isn't too too difficult.

[JoshuA c]

Could I use a buckpuck instead of a driver? If I want to go with 3 whites and 3 blues on separate lines could I use buckpucks instead? It seems like they are used more frequently for powering fewer LEDs than meanwell drivers. I'm not entirely sure what buckpucks are, so I may be way off base here.

[JoshuA c]

Okay. I've done a bit of looking around, and I found the Mean Well LDD-700HW dimmable driver. Could I use one each of these to power the blues and whites? For the blues, I think I will use the CREE XT-E Royal Blue LEDs, and for white, Neutral White CREE XP-G2 LEDs. Do you guys think that these are good choices in terms of good for the corals, and in terms of visually nice for humans?

 

Also, how do I figure out what power source I would need to power both of these? If I'm right, I could power both drivers from the same source, depending on the source, of course. But what numbers need to match? It would have to take 120V from the outlet and output what voltage for the drivers? Do the drivers automatically output the correct voltage from the LEDs?

[JoshuA c]

Here is my math in trying to figure out the power supply requirements:

 

So with all three blue LEDs, the voltage range is 8.55-10.5V. For the white LEDs is it 8.4-9.3V.

 

Their current range is from 350-1500mA.

 

The Mean Well LDD-700HW drivers each output at most 3 volts less than their input. Therefore, for the blue LED driver, it would need at least 13.5V. The white LED driver would need at least 12.3V.

 

In total, that is 25.8V. Therefore, should I be looking for a power supply that changes 110V AC into about 30V DC at 2000mA? Would that power both of my drivers? Thanks in advance.

[bobcorr]

Since you will be powering the LDD drivers in parallel, you will only need a power supply that provides the highest needed voltage, i.e 12.5V + the 3V LDD overhead. A 24V switching power supply that supplies about 40 - 50 watts will give you plenty of overhead. There are many of these available on ebay, amazon and from led suppliers like steve's leds, rapidled and many others.

 

Bob

[JoshuA c]

Since you will be powering the LDD drivers in parallel, you will only need a power supply that provides the highest needed voltage, i.e 12.5V + the 3V LDD overhead. A 24V switching power supply that supplies about 40 - 50 watts will give you plenty of overhead. There are many of these available on ebay, amazon and from led suppliers like steve's leds, rapidled and many others.

 

Bob

Awesome! Thank you!