Basic Arduino Strobe Light

This instructable will show you how to make a basic strobe light with an arduino.

You need
- 4 leds (the code can be modified for more if you want)
- an arduino (i am using the UNO r3)
- a paperclip
- a computer with the arduino ide installed
- an A/B USB cable to plug the arduino into the computer
- possibly some pliers to help bend the paperclip

(sorry for the lack of pictures)

Step 1: Assemble the Board and Leds

put a paperclip in the digital ground pin and bend it down and across  for the led leads to touch. next put the positive lead (the longer one) in pin 7 so it also touches the paperclip. Repeat for pins 9, 11, and 13.

Step 2: Install the Program

download the sketch or copy and paste it into the ide. here it is:

//leds in pins 13, 11, 9, and 7 (to make it easy to put them on i did every other pin)
//use a paperclip for ground
void setup() {
  unsigned int delayvar = 100;//You can chane this but it wont do much

  pinMode(13, OUTPUT);  //define pins as output
  pinMode(11, OUTPUT);
  pinMode(9, OUTPUT);
  pinMode(7, OUTPUT);
  digitalWrite(13, HIGH);  //blink twice
  digitalWrite(11, HIGH);
  digitalWrite(9, HIGH);
  digitalWrite(7, HIGH);
  delay(delayvar);
  digitalWrite(13, LOW);
  digitalWrite(11, LOW);
  digitalWrite(9, LOW);
  digitalWrite(7, LOW);
  delay(delayvar);
  digitalWrite(13, HIGH);
  digitalWrite(11, HIGH);
  digitalWrite(9, HIGH);
  digitalWrite(7, HIGH);
  delay(delayvar);
  digitalWrite(13, LOW);
  digitalWrite(11, LOW);
  digitalWrite(9, LOW);
  digitalWrite(7, LOW);
  delay(delayvar);


}

void loop() {
  unsigned int strobespeed = 150;  //change for a different strobe speed
  pinMode(13, OUTPUT);//defineing pins as output
  pinMode(11, OUTPUT);
  pinMode(9, OUTPUT);
  pinMode(7, OUTPUT);
  digitalWrite(7, HIGH);
  delay(strobespeed);
  digitalWrite(7, LOW);// the led on pin 7 turns off when
  digitalWrite(9, HIGH);//the led on pin 9 turns on
  delay(strobespeed);
  digitalWrite(9, LOW);// this pattern continues
  digitalWrite(11, HIGH);
  delay(strobespeed);
  digitalWrite(11, LOW);
  digitalWrite(13, HIGH);// the strobe stops
  delay(strobespeed);
  digitalWrite(13, LOW); //and starts going the other way
  digitalWrite(11, HIGH);
  delay(strobespeed);
  digitalWrite(11, LOW);
  digitalWrite(9, HIGH);
  delay(strobespeed);
  digitalWrite(9, LOW);// repeats

}

Step 3: Things to Remember

You can edit this code to fit your needs (please give me credit if you use it in another instructable, i worked hard to make it from scratch)

If you have any question feel free to comment or message me, i will get back to you as soon as i can.