The next step is to add a bit more functionality with a new type of chip, an H-bridge. An H-bridge is a fairly simple device. It basically consists of a set of switches and adds the additional functionality of allowing the direction of the current to be reversed so that the motor can either be run in the forward or the reverse direction.

Let's start this example by building the H-bridge circuit and controlling just one motor. To do this, you'll need an H-bridge. One of the most common is the L293 dual H-bridge chip. This chip will allow you to control the direction of the DC motors. These are available at most electronics stores or online. You'll also need a capacitor; you can use the 1 microfarad capacitor from the previous example, if you'd like. The capacitor limits the fast changes in the signals that are sent to the motor. Once you have your H-bridge, build the following circuit with Arduino and a breadboard:

The following table shows...