Print PDF
Favorite
Email
Step 4Circuit Diagram
This project is really a very simple circuit. What we are going to be doing is running three wires from pins 9, 10 and 11. Each wire will branch to 3 220 ohm resistors, and then go on to 3 LEDs of the same color (9: Red, 10: Green, 11: Blue). These will all attach back to 1 wire that will go to ground.
Strictly speaking, each color should actually use different resistors, but the end result is in my opinion Good Enough. If you want to try and get the colors perfectly balanced, you have two options. Either correct it in the software, which is easy enough, or use different resistors for each color. In talking to Tod E. Kurt about this, his suggestion was this:
"For the color balancing you mentioned, the main thing you need to worry about is that because of the physics of LEDs, each color has a different voltage drop (Red is ~2.0V, Green is ~2.6V, Blue is ~3.3V), so really one should have different value resistors for each color. (i.e. if Red's resistor is 220 ohm, Blue's should be scaled down to about 130 ohm). I left this out of the notes because it can be confusing. You can deal with it in software by scaling the PWM values a corresponding amount. "
You may want to put together a prototype board that has only 1 LED of each color. I did this to make working with the software easier. I included a photo of the prototype board here.
Strictly speaking, each color should actually use different resistors, but the end result is in my opinion Good Enough. If you want to try and get the colors perfectly balanced, you have two options. Either correct it in the software, which is easy enough, or use different resistors for each color. In talking to Tod E. Kurt about this, his suggestion was this:
"For the color balancing you mentioned, the main thing you need to worry about is that because of the physics of LEDs, each color has a different voltage drop (Red is ~2.0V, Green is ~2.6V, Blue is ~3.3V), so really one should have different value resistors for each color. (i.e. if Red's resistor is 220 ohm, Blue's should be scaled down to about 130 ohm). I left this out of the notes because it can be confusing. You can deal with it in software by scaling the PWM values a corresponding amount. "
You may want to put together a prototype board that has only 1 LED of each color. I did this to make working with the software easier. I included a photo of the prototype board here.
| « Previous Step | Download PDFView All Steps | Next Step » |
1
comment
|
Add Comment
|
Feb 19, 2008. 7:11 PMbiojae
says:
Wow, just before I saw this step, I was thinking about using just 3 r,g&b LEDs, Cool.
Reply
 |
Add Comment
|
