IN THIS CHAPTER

Trying your hand at ready-made project kits and other hobbyists’ circuit designs

Arming yourself with testing and simulation tools

Discovering the fundamentals of computer architecture

Delving into programmable microcontrollers and single-board computers

Ready to build on your newfound knowledge of electronics? Want to expand your horizons and create programmable electronics projects? This chapter provides you with a list of ideas for enhancing your electronics experience.

Surfing for Circuits

Thousands of project ideas are available on the Internet. Use your favorite search engine to find projects in topics or specific parts that interest you. For instance, search for simple audio circuits or 555 timer circuits to get loads of ideas — some with complete explanations, schematics, and photographs of a breadboarded circuit. Or choose an idea for a circuit and see if one is out there already. A search for door alarm circuit, for example, turns up many simple circuit ideas and even YouTube videos.

Getting a Jumpstart with Hobby Kits

If you want to make some cool things happen but don’t want to start from scratch, you can purchase one or more electronics hobby kits. These kits include everything you need to build a functional circuit: all the electronic components, wire, circuit board, and detailed instructions for putting the circuit together. Some even include an explanation of how the circuit works.

You’ll find kits for light-sensitive alarms, simulated traffic signals, electronic combination locks, adjustable timers, decorative light displays, and much more. Many of the parts sources mentioned in Chapter 19 provide ready-made kits at reasonable prices. You can practice your circuit-building and analysis skills using these kits, and then move on to designing, building, and testing your own circuits from scratch.

Simulating Circuit Operation

If you have a complicated circuit design or just want to understand more about how a particular circuit will behave when powered up, you can use a circuit simulator. This software program uses computer-based models of circuit components to predict the behavior of real circuits. You tell it what components and power supplies you’re using and how they should be wired, and the software tells you whatever you want to know about the operation of the circuit: the current through any component, voltage drops across components, circuit response across various frequencies, and so forth.

Many circuit simulators are based on an industry-standard algorithm called SPICE (Simulation Program with Integrated Circuit Emphasis); you can use them to simulate and analyze various circuits — analog, digital, and mixed signal (that is, incorporating both analog and digital). You can download a free evaluation copy of one such simulator, Multisym, and try it out yourself by visiting www.ni.com/multisim/try/.

Scoping Out Signals

An oscilloscope is a piece of test equipment that displays how a voltage varies with time as a trace across a cathode-ray tube (CRT) or other display that contains a calibrated grid. You use a scope to visualize what is happening to rapidly varying voltages in your circuits. If you’re interested in building audio amplifiers and other circuits that have time-varying signals, such as sound, an oscilloscope can come in handy and help you understand circuit operation and pinpoint errors. A good scope costs a few hundred dollars but you may be able to find some great deals on eBay or Craigslist.

Counting Up Those Megahertz

You can use a frequency counter (or frequency meter) to help you determine whether your AC circuit is operating properly. By touching the leads of this test device to a signal point in a circuit, you can measure the frequency of that signal. For example, suppose you create an infrared transmitter and the light from that transmitter is supposed to pulse at 40,000 cycles per second (also known as 40 kHz). If you connect a frequency counter to the output of the circuit, you can verify that the circuit is indeed producing pulses at 40 kHz — not 32 kHz, 110 kHz, or some other Hz.

Generating a Variety of Signals

To test a circuit’s operation, it often helps to apply a known signal input to the circuit, and observe how the circuit behaves. You can use a function generator to create repeating-signal AC waveforms in a variety of shapes and sizes — and apply the generated waveform to the input of the circuit you’re testing. Most function generators develop three kinds of waveforms: sine, triangle, and square. You can adjust the frequency of the waveforms from a low of between 0.2 Hz and 1 Hz to a high of between 2 MHz and 20 MHz. Some function generators come with a built-in frequency counter so you can accurately time the waveforms you generate. You can also use a stand-alone frequency counter to fine-tune the output of your function generator.

Exploring Basic Computer Architectures

In Chapter 11, you find out how logic gates (AND, OR, NAND, and so on) process bits (1s and 0s) of data and that you can purchase specialized integrated circuits (ICs) that contain logic gates. Chapter 11 also shows you a basic circuit diagram of a half-adder circuit that uses just two logic gates. Circuits such as the half-adder form the foundation of computer architectures. By connecting multiple logic gates in just the right way, you can create circuits that compute, store, and control information (series of 1s and 0s organized into groups of 8 called bytes). Start your journey into the fascinating field of computer architecture by building digital logic circuits that use LEDs as output indicators. (Check out www.doctronics.co.uk/4008.htm for a detailed description of how to build a 4-bit binary full adder.)

Microcontrolling Your Environment

In Chapter 11, you get a peek at a microcontroller, which is a tiny computer on a chip. You create a program on your computer, and download the program onto the chip. Then when you power up the chip, it follows the instructions in your program. The BASIC Stamp and PICAXE microcontrollers are inexpensive alternatives that use the easy-to-learn BASIC programming language. However, the beginner-friendly Arduino microcontroller system, which uses a C-like programming language, has exploded in popularity in recent years due to its simplified integrated development environment (IDE), versatility, affordability, and enormous online user community.

You can purchase a complete Arduino Starter Kit — including a microcontroller, IDE, project book, breadboard, cables, servomotor, photoresistor, tilt sensor, temperature sensor, and other discrete components — for less than $85 on https://store.arduino.cc. (And eBay lists some knock-off Arduino kits with gobs of cool extras for around $50.) These comprehensive microcontroller kits enable you to program circuits to interact with your environment, take readings from sensors, make decisions based on those readings, and execute actions based on those decisions. Arduino can provide you with an entrée into the field of robotics. Check out Arduino For Dummies by John Nussey (Wiley Publishing, Inc.), and keep an eye on the growing field of user-friendly microcontrollers, because new features (such as integrated Wi-Fi) and competitive products are appearing on the market.

Getting a Taste of Raspberry Pi

The Raspberry Pi is a series of single-board computers that you connect to your TV or monitor and a standard keyboard. The original Pi runs the Linux operating system, but the second generation Pi runs both Linux and a version of Windows 10. You program the Pi using Python or any one of a number of IDEs. Although it’s not as beginner-friendly as Arduino, the Raspberry Pi is as inexpensive (roughly $35) and has a large online user community. Intended as an educational tool for teaching kids programming skills, the Raspberry Pi is enjoying tremendous popularity and finding itself at the heart of many computer-embedded hobby projects, such as an Internet radio and an infrared bird box. You’ll learn more about programming rather than down-and-dirty electronics with the Raspberry Pi, but you certainly can come up with ideas that integrate the two skill sets. Check out Raspberry Pi For Dummies, 2nd Edition by Sean McManus (Wiley Publishing, Inc.), or visit www.raspberrypi.org.

Try, Fry, and Try Again

Perhaps the best way to expand your knowledge of electronics is to develop your own ideas, design some circuits, build and test them, and then go back and tweak your design. Sometimes the only way to find out what the limitations of various parts or designs are is to fry a few LEDs, toast a couple of ICs, or stay up all night probing the depths of a nonworking circuit until you figure out what’s wrong with it. To quote a popular science teacher, Valerie Frizzle, “Take chances, make mistakes, get messy!” (But, please, take safety precautions no matter what else you do!)