This instructable is the written version of my "Arduino - Obstacle Avoiding Robot (with L293D)" YouTube video that I've uploaded recently. I strongly recommend you to check it out.

My YouTube Channel

Step 1: Tutorial

In this video is explained step by step.

Dual H-Bridge Motor Driver for DC or Steppers - 600mA - L293D

This is a very useful chip. It can actually control one motor independently. We will use in its entirety the chip in this tutorial. Pins on the right hand side of the chip are for controlling a one motor. Pins on the left hand side of the chip are for controlling second motor.

You can run four solenoids, two DC motors or one bi-polar or uni-polar stepper with up to 600mA per channel using the L293D.

Step 2: Hardware Required

Arduino Uno R3
Dual H-Bridge L293D Motor Driver
HC-SR04 Ultrasonic Module Distance Sensor
Bracket / Holder for HC-SR04
DC Motors and Wheels
Bovine Wheel
Plate or Chassis
Jumper or Wires
Batteries and Battery Holdes
Glue Gun or Cable Ties
Breadboard

Step 3: Create a Chassis

In this step; We are doing chassis installation.

You can use any plate for the chassis. But do not use a metal!

Let's first mount the wheels.
Then let's mount the battery holder.
Finally mount Arduino and breadbord.

Step 4: Create Power Distribution

I am using a breadboard for distribution to VCC and GND. For to be adjacent to the motor driver.

Step 5: All VCC and GND Connections

All VCC-GND connect with wires to the L293D motor drive and the batteries.

Each chip contains two full H-bridges (four half H-bridges). That means you can drive four solenoids, two DC motors bi-directionally, or one stepper motor. Just make sure they're good for under 600 mA since that's the limit of this chip.

Normally we can connect both of these to the Arduino 5V pin. We used a powerful motor, or a higher voltage motor. So we provided the motor with a separate power supply using pin 8 connected to the positive power supply and the ground of the second power supply is connected to the ground of the Arduino.