For
years, people attracted to electronics have been drawn to
radios. In olden days, radios had
big tubes and were the size of a bookcase;
today, you can create a small radio yourself by using
common electronics components.
The radio in this project involves a simple circuit,
speaker, and a coil and variable capacitor combo that you use to
tune into your favorite station. By
working on this project, you discover how to work with radio
frequency and amplification to grab
radio signals out of the air.
The Big Picture: Project Overview
After you complete this project, you’ll have
an AM radio. We know, our favorite stations are on FM, too, but
AM
(amplitude modulation)
was the first
method of modulating frequencies used in radio. Building
an AM radio is a bit easier to do,
so that’s where we start you off.
If you’re dying to discover more about
creating an FM
(frequency
modulation)
radio, check out
Basic Radio:
Understanding the Key Building Blocks,
by Joel
Hallas, published by the American Radio Relay League (www.arrl.org).
You can see the finished radio in Figure 8-1.
Here are the types of activities you’ll be
doing to create your own radio.
You will
1. Put together an electronic circuit
containing a coil and variable capacitor that you use to tune to
your favorite stations, an IC that separates the voice signal
from the radio frequency carrier and an IC that amplifies the
voice signal enough to power a speaker.
2. Install the circuit, speaker, on/off
switch, volume control, and tuner in a handy box.