Power an LED using VIN port

Projects General Guidance
1

Hi,
I found a broken Christmas light set and thought i could use the blink function of the arduino.

its made of two LEDs,connected to another two and so on about 75 bulbs.

i was wondering if i can power it using the vin port.and use the following code.

void setup() 
{
  pinMode(13, OUTPUT);
}

void loop() 
{
  digitalWrite(13, LOW);  
  delay(100);             
  digitalWrite(13, HIGH);
  delay(100);  

}

supplied volatage 6V

thank you.

please tell me if you can do anything cool than blinking or a cool pattern thanks

2

Each LED needs between 2V and 3.5 depending on the colour.
Exactly how have you wired them?
If they are in seriese Vin has not enough voltage.
If they are in parallel then you also need a resistor on each LED and a transistor as the Arduino pin can not provide enough current.

For effects you need an addressable LED strip.

3

thank you for the reply, this one has a common ground wire and a positive wire.
Leds Re connected between these two wires keeping a 2cm gap.

so the negative sides of all LEDs are connected to ground and the positive sides of all LEDs are connected to the positive line.

what should i do next.

also i noticed if i connect to vin and gnd directly without cooonecting to any digitals pins its morre brighter

4

You should buy or make a constant current supply to drive it with.
Never connect them direct to an Arduino pin as you will exceed the maximum current for a pin which is less than 40mA

5

how can i make a constant power supply,

could you guide me to get a correct mosfet

6

how can i make a constant power supply,

I said a constant current power supply.

[Constant current supply for LEDs](http://www.lmgtfy.com/?q=Constant current supply for LEDs)

But first you need to know what current it needs to put out, have you measured it?