# Difference between revisions of "Traffic Light"

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

## 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

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