This Instructable will explain how to create a proximity sensor/alarm using an ultrasonic emitter/receiver and LEDs.

Step 1: Connect Ultrasonic Emitter/Receiver

1. Select the Ultrasonic Emitter/Receiver and connect it to the breadboard.

2. Connect a Jumper Wire to the GND pin on the Ultrasonic sensor and to the grounded rail (-) on the breadboard.

3. Connect a Jumper Wire to the VCC pin on the Ultrasonic sensor and to the positive rail (+) on the breadboard.

4. Connect a Jumper Wire from the grounded rail to the GND (ground) Pin on the Arduino.

5. Connect a Jumper Wire from the positive rail to the 5v Pin on the Arduino.

6. Connect a Jumper Wire to the Trig pin on the Ultrasonic sensor and to pin 12 on the Arduino

7. Connect a Jumper Wire to the Echo pin on the Ultrasonic sensor and to pin 11 on the Arduino

Step 2: Add an LED

1. Place an LED (any color) into the breadboard

2. Connect one end of 220 Ω (ohm) resistor to the top lead (+), should be the longer lead, and the other end into Pin 3 on your Arduino Board.

3. Connect a Jumper Wire to the bottom lead (-) and to the grounded rail on the breadboard.

4. Connect a Jumper Wire from the grounded rail to the GND (ground) Pin on the Arduino.

The green LED has the same setup as our green LED.

1. Connect the led to the breadboard.

2. Connect a 220Ω resistor to the positive(+) lead of the LED and to a Pin 5 on the Arduino.

3. Connect the negative lead to the ground rail.

The red LED has the same setup as our yellow and green LEDs.

1. Connect the led to the breadboard.

2. Connect a 220Ω resistor to the positive(+) lead of the LED and to Pin 6 on the Arduino.

3. Connect the negative lead to the ground rail.

Attached is SonarAlarm.ino which contains all of the code for running the Sonar Proximity Alarm project on an Arduino Uno.