You Have a Message! Make an LED Flash
IN CHAPTER 4, YOU EXAMINED SOME of the features of a mobile phone and learned how to make an LED illuminate just like the charge indicator on a phone. Another useful phone feature is an LED indicator that flashes when you receive a text message or a phone call. The experiment in this chapter shows you one method of making an LED flash on and off using an inexpensive integrated circuit that requires only four other components.
How to Make an LED Flash
To make an LED flash on and off, you need to build ...