# Difference between revisions of "Traffic Light"

We are converting a regular traffic light to a linux-peace-love?? traffic light.

## Materials

• 3 * 3W RGB LEDs.
• Controller => Arduino pro mini
• Power Supply 230Vac to 5Vdc
• Transistors =>
• Resistors
• How do we gonna make the images?

Maybe it would be a good thing to make a system to mount it, so it will no longer need to lay stand on the ground.

## How it works

LED properties:

• Uledr = 2.0->2.5V
• Uledg = 3.2->3.6V
• Uledb = 3.2->3.8V
• I = 350mA

resistor calculation:

• URr = VCC - UT1 - UT2 - Uled = 5V - 0.3V - 0.3V - 2.0->2.5V = 2.4->1.9V
• URg = VCC - UT1 - UT2 - Uled = 5V - 0.3V - 0.3V - 3.2->3.6V = 1.2->0.8V
• URb = VCC - UT1 - UT2 - Uled = 5V - 0.3V - 0.3V - 3.2->3.8V = 1.2->0.6V
• Rr = 2.4V / 0.3A = 8R
• Rg = 1.2V / 0.3A = 4R
• Rb = 1.2V / 0.3A = 4R

note: we use the highest voltage and a slightly lower current as safety.

Because we use multiplexing...

• Rr = 8R / 3 = 2R666
• Rg = 4R / 3 = 1R333
• Rb = 4R / 3 = 1R333