Traffic Light

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Revision as of 21:24, 3 December 2013 by Robinjanssens (Talk | contribs)

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We are converting a regular traffic light to a Peace-Love-Linux traffic light.

PEACE - LOVE - LINUX

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

Schematic

LED properties:

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

resistor calculation:

  • UR = VCC - UT1 - UT4 - Uled
  • URr = 5V - 0.3V - 0.3V - 2.0->2.5V = 2.4->1.9V
  • URg = 5V - 0.3V - 0.3V - 3.2->3.6V = 1.2->0.8V
  • URb = 5V - 0.3V - 0.3V - 3.2->3.8V = 1.2->0.6V


  • R = UR / I
  • 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.


The power consumption of the resistors need to be calculated

  • PR = UR * I
  • PRr = 2.4V * 0.35A = 0.84W
  • PRg&b = 1.2V * 0.35A = 0.42W

Conclusion: We will need resistors which be able to consume 2W for red and 1W for green and blue. (according to the safety standard of 25% spare)

Because we use multiplexing...

  • Rr = 8R / 3 = 2R666 (We used 2R5 which as 2 resistors of 5R 1W in parallel)
  • Rg = 4R / 3 = 1R333 (We used 1R5 which as 2 resistors of 3R 1W in parallel)
  • Rb = 4R / 3 = 1R333 (We used 1R5 which as 2 resistors of 3R 1W in parallel)