Simple Labs' Quick Start Kit for Arduino - Generating Sound - Buzzer + Transistor - How To?

Generating Sound - Buzzer + Transistor

Next lets see how we can generate sound using a Buzzer. The Buzzer would require more current than provided by the pins of the arduino. To provide the buzzer with more current, we shall use a transistor to trigger the buzzer. The transistor in turn will be triggered by a pin on the arduino.  If you do not know about transistors, its advisable you check it out  http://en.wikipedia.org/wiki/Transistor

Here's what our Transistor 2N2222A looks like

2N2222A

Pin Mappings for 2N2222A

E = Emitter

B = Base

C = Collector 

The Emitter of a transistor is connected to ground, the device to be triggered is connected between the Collector of the transistor and SUPPLY. The transistor can be triggered by Supplying a Trigger voltage to the Base (preferably through a resistor). Depending upon the trigger voltage, Emitter and Collector of a transistor get in contact thereby allowing current flow through the device connected.

Buzzer - The Red Wire is Positive & The Blue Wire is Negative. 

First Setup the Transistor Side like in the Image

The Blue wire going to the Collector here is the Negative of the Buzzer and the Red wire (the Positive of the Buzzer ) is connected to the '+'ve terminal of the Breadboard

Now Connect a Wire from the Other end of the Resistor to the 7th pin (digital) of the Arduino 

Here is how the Final Setup Looks Like

Try the following code where the Buzzer stays on as you keep pressing the Button in our previous program [RGB_button_ldr_buzzer.ino]

/*
  Pressing the Button changes the current active color of the RGB LED & prints the current temperature value to the Serial Monitor and Generates a Buzzer tone 
  for the duration the button is being pressed.
  The light intensity detected by the LDR determines the intensity level of the active color
 */

int intensity = 0, pin = 9;

void setup() {      
pinMode(2,INPUT);
pinMode(7,OUTPUT);
Serial.begin(9600);
}

void loop() {
  
  if(digitalRead(2)==0) // Switch being pressed
  {
    digitalWrite(7,HIGH);
    Serial.print("Temperature is : ");
    int temp = analogRead(2)/2;
    Serial.println(temp);
     if(pin<11)
        pin++;
      else
        pin=9;
     analogWrite(9,0);
     analogWrite(10,0);
     analogWrite(11,0);
  while(digitalRead(2)==0);
  delay(100);
  digitalWrite(7,LOW);
  }
  intensity = analogRead(4)/4;
  analogWrite(pin,intensity);
  Serial.print(pin);
  Serial.print("   ");
  Serial.println(intensity);
}