Hacking Electronics illustrated Diy Guide For Makers & Hobbyists - PDF DOWNLOAD

Page 122

HowTo-Color (8) / Hacking Electronics / Simon Monk / 236-3 / Chapter 5

CHAPTER 5:  Batteries and Power

95

Controlling the Voltage from a Battery The thing with batteries is that even though they may say 1.5V, 3.7V, or 9V on the package, their voltage will drop as they discharge—often by quite a high percentage. For example, a 1.5V alkaline AA battery when brand new will be about 1.5V and will quickly fall to about 1.3V under load but still deliver useful amounts of power down to about 1V. This means that in a pack of four AA batteries, the voltage could be anything between 6V and 4V. Most types of battery, whether single-use or rechargeable, exhibit a similar voltage drop. This may not matter much; it just depends on what the battery is powering. If it is powering a motor or an LED, then the motor will just go a bit more slowly, or the LED will be a little dimmer as the battery discharges. However, some ICs have a very narrow voltage tolerance. There are ICs designed to work at 3.3V that specify a maximum working voltage of 3.6V. Similarly, if the voltage drops too low, the device will also stop working. In fact, many digital chips such as microcontrollers are designed to work at a standard voltage of 3.3V or 5V. To ensure a steady voltage, we need to use something called a voltage regulator. Fortunately for us, voltage regulators come as convenient three-pin, low-cost chips that are very easy to use. In fact, the packages just look like transistors, and the bigger the package, the more current they can control. Figure 5-6 shows how you would use the most common of voltage regulators, called the 7805. Using just a voltage regulator IC and two capacitors, any input voltage between 7V and 25V can be regulated to a constant 5V. The capacitors provide little reservoirs of charge that keep the regulator IC operating in a stable manner. Figure 5-6  A voltage regulator schematic

05-ch05.indd 95

1/15/13 11:34 AM


Turn static files into dynamic content formats.

Create a flipbook

Articles inside

Index

15min
pages 290-305

Hardware and Miscellaneous

0
page 287

EAGLE PCB

0
pages 281-282

Introducing: The Oscilloscope

0
page 279

AC Voltage

1min
page 275

Resistance

1min
page 273

How to Use a Lab Power Supply

0
page 278

Summary

1min
page 271

How to Reuse a Cell Phone Power Adapter

1min
page 270

Desoldering

0
page 268

How to Check a Fuse

2min
pages 264-265

How to Test a Battery

0
page 266

Summary

1min
page 261

How to Make a Software VU Meter

0
page 259

You Will Need

1min
page 252

How to Make a 1-Watt Audio Amplifier

1min
page 251

How to Take Something Apart AND Put It Back Together Again

0
page 263

How to Make an FM Bug

1min
page 247

How to Use a Microphone Module

3min
pages 245-246

How to Sense Magnetic Fields

1min
page 237

Converting a Stereo Signal to Mono

1min
page 244

Software

1min
pages 235-236

How to Use an Accelerometer

1min
page 233

Soldering Audio Connectors

2min
pages 242-243

How to Measure Temperature

0
page 231

Software

1min
page 230

You Will Need

1min
page 225

Using a Gas Sensor with an Arduino

0
page 223

8 Hacking with Sensors

1min
pages 220-221

Summary

1min
pages 174-175

Breadboard

1min
page 222

How to Charlieplex LEDs

1min
page 169

How to Type Passwords Automatically

1min
page 172

How to Drive a Servo Motor with an Arduino

1min
page 166

You Will Need

0
page 156

How to Use a Alphanumeric LCD Shield with Arduino

0
page 163

How to Control a Relay from a Web Page

1min
page 155

Software

4min
pages 159-162

Construction

0
page 157

Software (Brightness

2min
page 151

How to Use Arduino Shields

1min
page 154

Software (Flashing

1min
page 150

How to Measure Voltage with an Arduino

1min
page 146

Trickle Charging with a Solar Panel

1min
page 130

6 Hacking Arduino

1min
page 132

Modifying the Blink Sketch

4min
pages 136-138

Testing a Solar Panel

1min
page 129

How to Use Solar Cells

2min
page 128

Trickle Charging

1min
page 127

Calculating How Long a Battery Will Last

1min
page 125

Controlling the Voltage from a Battery

1min
page 122

Simple Charging

2min
page 117

Hacking a Cell Phone Battery

2min
pages 120-121

How to Charge a LiPo Battery

1min
page 119

Charging Batteries (in General C ................................................. 88

1min
page 115

Summary

0
page 109

Design

0
page 107

Storing Charge in a Capacitor

1min
page 106

Troubleshooting

0
page 104

You Will Need

0
page 94

Construction

4min
pages 101-103

How to Power Large Numbers of LEDs

0
page 95

How to Measure the Forward Voltage of an LED

0
page 93

Construction

1min
page 92

Breadboard

1min
page 91

Design

1min
page 90

Common Transistors

1min
page 74

LEDs for Illumination

0
page 88

Trying It Out

0
page 85

Summary

0
pages 80-81

Construction

4min
pages 68-71

Breadboard

1min
page 67

What Is Power?

1min
page 55

Ohm’s Law

1min
page 54

You Will Need

1min
page 36

Where to Buy Things to Hack

2min
page 29

Soldering

1min
page 37

A Basic Toolkit

2min
pages 30-31

Capacitors

1min
page 49

Summary

0
page 45

Joining Wires

1min
page 38
Issuu converts static files into: digital portfolios, online yearbooks, online catalogs, digital photo albums and more. Sign up and create your flipbook.