Hey there everyone!
So I recently ordered some RGB LED strips from e-Bay (sorry the link is for e-Bay UK, I’m a UK guy so!) and I’m planning on turning these into a lighting system for my bedroom at home. In this post I’m going to take you through how far I’ve got so far and I’ll probably finish it in the next post.
So I ordered the LED strips first (the LED strips are 5050 SMD RGB LED’s and I got the 60LED/m type. I had to make sure they were common anode. This is very important), planning to test them with some N-Channel MOSFET’s I had hanging around and just a simple 12V DC adapter to power them. And control it from my arduino due. So once I first got them I hooked them up with the 12V power supply going into the power and the FET’s sinking the line from each colour.
I really should have checked the power output of the DC adapter because the 0.3A it could provide got used up quickly! It screamed at me and, as Dave Jones from the EEVBlog would say, released the ‘magic smoke’. Not a good start. After this I checked the consumption rate of the LED’s and was surprised to say the least that these things gobble up a huge 6A! So I needed an alternative really.
My next build thought took me to an ATX computer power supply, so I went down to my local computer store and tried to see if they had any old ones in the back (this is one of the best tips I can give you!! Ask for the old stuff, and you get it cheap!) unfortunately they didn’t. So I went to my friend and asked if he knew anyone who had one, well, turns out he had one. It’s an old Dell N220P-00 220W power supply. I had a little bit of trouble getting it to run as outlined in the previous blog post, but eventually I got it running. After a small hiccup with mains voltage from a capacitor!
So now I could test the strips fully, I started by simply hard wiring the red, the green, and the blue individually, then did white to see how it looked. I was really impressed, these things are BRIGHT for £15 (Around $23).
So now I hooked them up to a micro-controller, I took the 5V line, the 12V line and the Gnd out of the power supply and hooked it up with the 5V line going to the micro-controller, the ground line connecting to both the micro’s ground and the ground after the mosfets (see schematic for mosfets) and the 12V line going into the RGB strip common anode.
For the micro-controller I used a Sparkfun Arduino Pro Mini, I really like this chip because it is small, inexpensive, and easy to embed in projects! The only disadvantage is that you have to also buy an FTDI adapter for it, but this is just a tradeoff for it’s size!
I programmed the chip (code available on GitHub) with the test code I wrote, this code simply changes through the spectrum of colours slowly!
I then cut the strip in two (there are special sections along it where you can cut it) and rejoined it with wire so it would run as two parallel tracks, and used phone cable to extend the wire at the end. I used phone cable because it is 4 wire inside, perfect for RGB strips, and it can easily be attached with clips to walls. It is also white which means it doesn’t stand out too much. I finally mounted the two strips in my room where I wanted them and turned them on.
The results so far are brilliant! I really like them!
In part 2 I will build the controller for them, so they do more than just fade! (Hopefully I can get them reacting to the music from my speaker system)
Tom Cousins