Planning an LED lighting system build, need some advice

[george1098]

Hi all
So I've fallen in love with the idea of LED's for aquarium lighting. There are so many people on RC doing their own builds, I've decided I have to be part of it. The purpose of this post is to save me a little time.. I would like to build a small fixture for a 34 gallon cube tank with about 12 LED's (I'm thinking 2 strings of 6, 1 white, 1 blue). I'd love to sinc these with some sort of program that would allow me to dim them automatically as a sunrise and sunset effect. Just wondering if anyone could point me in the direction of some good resources to do this. I think I have a good handle on the hardware required for an LED lighting set up, but not so much on the program bit. help is appreciated!

[der_wille_zur_macht]

Can you give us an idea of your background? DIY hobby electronics experience? Programming experience? Tools you have at your disposal?

The easiest way is to just plug things into timers as you would with typical lighting fixtures. If you want gradual fading for sunrise and sunset, then you'll need something a little more complicated. The Arduino environment has become popular for this, and it's what I'm using. There are other alternatives - PICs, etc.

[george1098]

Well we can say that my DIY experience is extensive. I was in the custom aquarium building industry professionally for a number of years, and have tackled some pretty ambitious projects. I will admit however that my knowledge of electronics and wiring and such is somewhat lacking, but that's what I would like to learn in doing this project. What would be wonderful for me would be to see an actual list of the hardware required to put together an LED system controlled by an Arduino. Obviousely every set up is different, and I'm not looking to play copy cat, but some examples would be great for me. thanks for your reply.

[der_wille_zur_macht]

Ok, you need:

-An LED rig
-An Arduino

:lol:

It's almost that simple. If you want ease of use and accurate timekeeping, an RTC would be handy. Sparkfun sells a prebuilt one based on the DS1307 chip that's around $20. The Arduino itself is around $30 (also from Sparkfun, or any other vendor). Other than that, you just need a project box or enclosure, and wire to hook it all up.

Of course, you need to get a driver that's compatible with what the Arduino can produce. It has several built-in PWM pins that operate at 5v. Unfortunately none of the commonly used drivers are 100% compatible with that. The buckpuck drivers want a 5v-0v DC analog signal. You can feed them the straight PWM signal from the Arduino but it basically just imitates dimming by switching them on and off rapidly, rather than actually adjusting the output current. It still works though. Alternately you can put the PWM signal through an R-C filter to smooth it into something closer to a real analog signal. The various methods for controlling the buckpucks are pretty well described in the datasheet, so check it out if you haven't yet.

The other popular drivers are the meanwells, which want either a 0-10V analog DC signal (the D versions) or a 10V PWM signal. I've never used these but it shouldn't be a big deal to control either from an Arduino with a little circuitry in between at worst.

The other half of the effort is software, but that's the easy part (to me, at least.) There are some good examples of code out there depending on what exactly you want to accomplish.

Check out the Arduino home page if you haven't yet:

www.arduino.cc

And no worries, it's really easier to deal with than it seems at first glance. Dimming an LED driver is one of the simplest things you can do with a controller like that, so have at it. :D