# Traffic Light Circuit with 12 Leds and 4 Dopler Motion Detection Units.

Hello everyone, well my current project requires me to create a circuit with 12 Total LEDs (4 red, 4 green and 4 yellow).

The whole idea is to simulate a 4-way traffic light stop basically, 2 sides opposed to each other.

In the image i have attached to the post i have used 220ohms resistors.

What the final result that I am trying to achieve is to have left side Red LEDs light up, with right side green LEDs on, etc.

My questions are this:

1. will the Arduino be able to power 2 LEDs from a single Pin like in my simulation with 220omhs on each LED?
2. will there be enough power for the 4 Motion Detection Units Plus the LEDs, or should I power the unis from another source, etc?

1. Yes. The red LEDs will have the lowest forward voltage of all the colours, probably 1.8V. The 220R resistor will drop the remaining 5.0-1.8=3.2V. So the current through it will be 3.2/220=14.5mA. The Arduino pin will need to source twice that, so 29mA. The absolute max current for an Uno/Mega pin is 40mA, but you should keep below 25~30mA for long life, so 29mA is just about OK.

2. No idea as you have given no details about the motion detectors or how you are powering the whole circuit.

PaulRB:
2. No idea as you have given no details about the motion detectors or how you are powering the whole circuit.

The 4 Motion Detection units i am using are MDU1100T_Tuneable .

For power, up until now, i was thinking of just using the Arduino.

Acidust:
The 4 Motion Detection units i am using are MDU1100T_Tuneable .

Have you found any example circuits or code for these being used with Arduino?

Acidust:
For power, up until now, i was thinking of just using the Arduino.

Arduino does not have any power. You need to power it.

PaulRB:
Have you found any example circuits or code for these being used with Arduino?

Arduino does not have any power. You need to power it.

There is no example done with this and an Arduino that I can find.

Those were given to me to use with the Arduino for this project.

Connecting the IF to one of the analog inputs provides data back according to the mass and the distance of the object used.

Power wise i was going to use a USB cable from a laptop while i give the presentation. Sorry for some reason i thought that was kind of the standard.

Ok, thanks. There are several ways to power an Arduino, other than usb.

The data sheet says the sensors can use up to 60mA each, so 240mA. The LEDs could be 4 (or 8?) on at once (UK traffic lights have a different sequence to US, red and amber on at same time), so that's 4x30=120mA or 8x30=240mA. Total 360mA (US) or 480mA (UK), plus 50mA for the Arduino itself, so 410mA or 530mA. Limit for usb is 500mA.

However, 40mA is typical for the sensors, 60mA is the maximum. The amber and green LEDs may use a little less current than the red, because of their higher forward voltage. And the Arduino may be more like 30~40mA. So I suspect you won't go over 500mA, but it could be close.