Electronics for Kids: Play with Simple Circuits and Experiment with Electricity

Electronics for Kids: Play with Simple Circuits and Experiment with Electricity — page 9
7 Controlling Things with Electricity 131 Meet the Transistor 132 Why Use a Transistor 133 How the Transistor Works 134 Controlling an LED with a Transistor 135 Project 14 Build a Circuit that Senses Touch 136 Shopping List 138 Tools 139 Step 1 Place Components on the Prototyping Board 140 Step 2 Check Your Component Placement 140 Step 3 Solder the Components and Trim Excess Legs 140 Step 4 Solder the Touch Pad 141 Step 5 Power It Up 142 Step 6 Test the Sensor 142 Step 7 What If the Touch Sensor Doesn’t Work 142 Try It Out Can the Touch Sensor Detect Different Touches 144 Resistors That Can Change Value 144 Meet the Potentiometer 145 Meet the Photoresistor 146 Dividing a Voltage with Resistors 146 What Does a Voltage Divider Look Like 147 Calculating the Voltage from a Voltage Divider 147 How a Voltage Divider Can Help Measure Light 148 Project 15 Build a Sunrise Wake-Up Alarm 148 Shopping List 150 Tools 151 Step 1 Place Components on the Prototyping Board 152 Step 2 Solder the Components and Trim the Legs 152 Step 3 Add the Buzzer to the Board 153 Step 4 Make the Remaining Connections with Wires 154 Step 5 Add the Battery Clip to the Board 155 Step 6 Set a Wake-Up Call 156 Step 7 What If There’s No Sound 156 Try It Out Temperature-Controlled Fan 157 What’s Next 159 8 Building a Musical Instrument 161 Meet the Integrated Circuit 162 ICs and Datasheets 162 How to Make Sound with Electricity 163 xiv CONTENTS IN DETAIL