Book Image

Arduino Development Cookbook

By : Cornel M Amariei
Book Image

Arduino Development Cookbook

By: Cornel M Amariei

Overview of this book

Table of Contents (16 chapters)
Arduino Development Cookbook
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Transistor driver


Each Arduino digital pin can output a limited amount of current, an absolute maximum of 40 mA. This is enough to power an LED, a small buzzer speaker, or maybe a small vibrating motor. However, we need more current for our applications most of the time.

Using a transistor driver, we can easily power up more demanding loads. Here, we will quickly explore how to build a general transistor driver.

Getting ready

Following are the ingredients for this recipe:

  • An Arduino board connected to a computer via USB

  • A resistor between 220 and 4,700 ohm

  • A standard NPN transistor (BC547, 2N3904, N2222A, TIP120)

  • A standard diode (1N4148, 1N4001, 1N4007)

How to do it…

Follow these steps to connect an external load to the Arduino using an NPN transistor:

  1. Connect one of the terminals of the load to 5V or VIN. If we are using a load that requires a voltage higher than 5 V or higher current than the Arduino 5V can provide (around 500 mA), we can use the VIN pin and connect an external power supply or...