RGBike POV - Open project

Step 2 Working principle

So... You may ask. How do I plan to control the 48 LEDs? The 16 red, 16 green and 16 blue, with only a LED driver IC with 16 outputs?
Well... I'm going to light one colour at a time.

Imagine one line of the image in the wheel. This line is composed by red, green and blue points. These points will light up, in the same instant, one colour at a time. This alternation between the three colours is so fast, that you seem to see only one line.

If you alternate between all these colours, you won't see three lines of different colours, you'll see white.

To control the width of this line in the wheel, we only need to control how many times this line is repeated.

Since the driver IC sinks the LEDs, this method requires common cathod RGB LEDs.
I used cheap 'Piranha'/'Superflux' RGB LEDs from China.

Comments

[karnold70]

As strange as it may sound, I agree with both of you. I'm looking forward to using SMT parts, but I'm not quite there yet. I invested in a very nice station, complete with vaccum pump 'desolder' pencil and Hot Air Pencil. But getting the hang of uing the parts... just a bit daunting. Through Hole are definatly simpler and more forgiving.

[wa7jos]

Don't be afraid of SMT components. Once you get used to them, they're easier than through hole. For a project like this, it could significantly reduce the size of the PCB, and the mass of the assembly. It would probably handle the stresses better too. All of the components you need are available in SMT versions. I would avoid the QFN package on the TLC5940 (they are difficult to hand solder), but the SSOP package is a breeze. You will need a good controlled temperature soldering iron with a small tip. I have a Metcal, but others work well too. You need some very fine "angel hair" solder. Depending on your eyesight, some magnification is nice. I have access to a stereo microscope, but a $3 head visor works well too. Use a flux pen to pre-flux the pads (a few at a time). Use tweezers to place the components on the pads. The flux is sticky enough to help hold the components. Solder one pad at a time. Go easy on the solder. Clean up any bridges with solder wick. Try it, you'll like it.

[Hazard]

Everything you've said, I've done it. I'm not afraid of SMT parts... But the point of this project is for other people to make it. This is one of the features I decided, that it would be easier for a begginer to hand solder. What good is an instructable if no one can follow it? Still, I think this is an difficult project as it is, for those that are 'beginners'. It requires you, at least, to have some experience in PCB building, electronics, programming and soldering. With SMT parts I would scare most of the people away.