Traffic Light

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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 DC 5V 50W
  • Transistors
  • Resistors
    • 12 * 10K
    • 6 * 5R
    • 12 * 3R
  • 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.

Electronics

Schematic

LED properties:

  • UledR = 2.0->2.5V
  • UledG = 3.2->3.6V
  • UledB = 3.2->3.8V
  • I = 350mA

resistor calculation:

  • UR = VCC - UT1,2,3 - 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 / 0.35A = 6.857R
  • RG = 1.2V / 0.35A = 3.429R
  • RB = 1.2V / 0.35A = 3.429R

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 1W for red and 0.5W for green and blue, or 2W and 1W if you use the safety standard of 25% spare

Because we use multiplexing...

  • RR = 6.857R / 9 = 0R762 (We used 0R8 implemented as 2 resistors of 1R6 1W in parallel)
  • RG = 3.429R / 9 = 0R381 (We used 0R4 implemented as 2 resistors of 0R8 1W in parallel)
  • RB = 3.429R / 9 = 0R381 (We used 0R4 implemented as 2 resistors of 0R8 1W in parallel)


The base resistors of the transistors we took some basic 10K resistors.


The power of the power supply

LED max current 350mA => 9 LEDs is 3.15A.

P = U * I = 5V * 3.15A = 15.75W (a 25W supply should be enough)

if we calculate the power we give the leds it wil be maximum about 3.3V(average max LED forward voltage) * 350mA = 1.155W => 9 times = 10.395W without other parts of the circuit.

Lenses and Images

I was thinking of making a mold out of wood using the CNC and use resin & hardener to make the lenses