The Robot Book: Build & Control 20 Electric Gizmos, Moving Machines, and Hacked Toys (Science in Motion)

The Robot Book: Build & Control 20 Electric Gizmos, Moving Machines, and Hacked Toys (Science in Motion)

by Bobby Mercer

ISBN: 9781556524073

Publisher Chicago Review Press

Published in Children's Books/Arts & Music, Children's Books/Science, Nature & How It Works

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Sample Chapter


Getting Started

What Is a Robot?

A robot is any machine that is designed to do a task. Robots can range from robotic welders to Watson. Robotic welders and other industrial robots repeat the same task thousands of times a day, saving humans from backbreaking labor. Watson is a thinking machine created by IBM that in 2011 beat two of the greatest Jeopardy players of all time.

The word robot was first used in a play by the Czech playwright Karel Capek in 1920. He and his brother derived the word from robota, a Czech word meaning "hard work." In his play, the robots looked more like C-3PO than the robots you will be building.


Electricity can hurt you. It needs to be treated with respect. You should always get an adult's permission to take apart any electronic device. Explain to the adult what you want to do and what you need from the broken toy, cell phone, toothbrush, or other device. NEVER take apart any electronic device that has a video monitor.

When taking apart anything electronic, even if it is broken, remove the battery. If it has a cord, cut off the cord first.


Most of the bots in this book can be built using electrical tape for the wire connections. But to make robots more permanent, soldering is a must. Any good future robot builder needs to learn how to solder electrical joints.

Metals conduct electricity. Solder is a soft metal that melts easily with heat. When solder is melted between two exposed wires, it creates a permanent electrical connection. Soldering irons create the heat needed to melt the solder, but they are dangerous. You must get adult help and permission to solder.

Soldering takes practice, and you must follow safety precautions. Read and follow the directions that came with your soldering iron. Never touch the tip of a soldering iron — it will be very hot. You should solder only in a well-ventilated area, since the heat creates nasty fumes. Always solder on a surface that is not flammable. Keep paper away from the soldering iron. Many soldering iron kits come with a stand that holds the hot iron. If you are going to do many electronic projects, I highly recommend buying a soldering kit with a stand.

Another great accessory for soldering is a Third Hand to hold your piece in place. A Third Hand is available at any electronics or hobby store. This great device has at least three bendable arms and usually a magnifying glass. You can clip any piece you are working on onto the arms. This gives you two free hands — your hands — to hold the solder and the soldering gun.

Make sure you get permission from an adult before soldering. But again, almost all of the bots in this book can be built without using a soldering iron.

Where to Get Parts

This book focuses on simple robots, but you'll still need parts to make your robots get up and go. Commercial robot kits are available from LEGO, K'NEX, and other sources, but building simple bots using parts you may already have is more exciting.

Never throw out toys, computer parts, or even dead cell phones or toothbrushes without scavenging parts first. (Remember to get adult permission and help before you start taking anything apart.) Save any gears, motors, pulleys, belts, wheels, switches, lights, and battery holders. Also, keep any wire you find. Create a robot junk box for all the cool parts you scavenge.

Electronic toys that no longer work are great sources for parts. A few of the projects in this book use repurposed old toys for bots. You can also find cheap toys at thrift stores that cost less than two or three dollars each. As you take them apart, think about creative uses for their parts.

Even if your toy doesn't match the one shown in a project, you can use it to create your own robot and give it an original name like Jessica's Dazzling Dino-Bot or Max the Motor-Bot.

Parts of a Robot

Moving robots need a source of motion, and to create motion, they need a motor. The first several projects in this book — vibration bots and walking bots — are powered by simple, small motors. Electric motors are found in many common devices. Dead cell phones are a great source of very small vibration motors. Small hobby motors are found in battery-operated cars. An old computer CD drive has a motor that easily can be powered by a 9V battery. Disposable vibrating toothbrushes also have motors, and many toys have wind-up motors. Of course, you can always buy motors at electronics stores or hobby stores.

Having a motor to power your robot is essential, but you also have to get the motion to the ground to make your robot move. That means your robot will sometimes need some type of wheels or legs. Old toys are a great source for wheels, but you can also buy wheels from hobby and craft stores. Most vibration bots, or vibrots, don't even need legs, making them easy and cheap to build.

You also need wire to build a robot. Keep any wire you find in broken electronics. You can also buy a spool of wire at a hobby, electronics, or hardware store. Another good investment is a set of wire strippers. Wire strippers allow you to easily strip the protective insulation off wires you are trying to join. Wire strippers are available at electronics, hardware, and dollar stores.

Switches can help you easily control the electric circuits that power your robots. A simple switch breaks the flow of electricity and gives you more control over your device. Switches are found in many types of toys and most electronics. You can also buy switches at electrical supply stores, but it is more fun to repurpose old stuff. Plus, you can save money and help the environment by reusing objects. Of course, the easiest way to turn a toy on and off is to disconnect the battery. Many of the bots in this book can be turned off that way.

Higher-end robots also contain sensors to help them "think." You can build robots that sense light and dark, and robots that sense obstacles and turn. Eventually, all robotic engineers turn to computer programs to guide their robots. I will leave that for you to investigate independently after you've completed the beginner projects from this book.


Vibration Bots

This chapter focuses oh creating bots powered by vibrating motors. Everything from cell phone vibrators to dead toothbrushes to hobby motors will be used to power these easy-to-build devices.


This simple bot uses a toothbrush head and a vibrator from a dead cell phone or pager.

The idea for this easy-to-make vibration bot was first published by Evil Mad Scientist ( From that beginning, Brush Bots (or Bristle Bots) have become a robotic sensation, with many people creating their own variations.

Robot Gear

Cell phone or pager vibrator motor
Needle-nose pliers or wire cutters
Double-sided tape (or tiny rolls of clear tape)
Button battery

Step 1: Remove the miniature vibration motor from a dead cell phone or pager. This motor is what causes a cell phone or pager to vibrate when put in silent mode. It is a very tiny electric motor with a weight on the end, outside the motor case. The weight is off center, so when the motor runs it vibrates. As you remove it, keep as much wire intact as possible. (You can also buy these motors at electronics or hobby stores if you don't have a dead phone or pager at hand.)

Some cell phones have a round vibration motor that looks like a small battery. This type of motor will also work, but you will usually have to solder wires to it first because it has very short lead wires. Here is a picture of the round pancake-style vibrator motor.

Step 2: Using needle-nose pliers or wire cutters, cut the head off a toothbrush. If the toothbrush has been used, make sure you wash it thoroughly first.

Step 3: Push the bristles of the toothbrush in one direction several times. This will slightly bend the bristles in one direction, which will help your Brush Bot vibrate in one direction instead of skittering in multiple directions.

Step 4: Put a small piece of double-sided tape on the back of the toothbrush head. (You could also use a tiny roll of regular tape with the sticky side out.) Place one of the exposed wires from the motor onto the tape and press it down.

Step 5: Place a button battery on top of the wire and press it into the tape. The wire already stuck to the tape needs to be sandwiched between the motor and the tape. It does not matter which way the battery faces because the motor can spin in either direction.

Step 6: Place the motor on top of the double-sided tape. You want the weight to slightly hang over the end of the toothbrush head. One exposed wire should be stuck to the sticky part of the tape. The other wire should be up in the air and free.

Step 7: Bend the free wire so it makes contact with the top side of the battery. Your Brush Bot should start vibrating. If not, check the wire connections. Put the vibrating robot on a smooth surface and watch it go. You can gently prod it with your fingertips to move in one direction. You may also want to use a small piece of tape to hold the top wire in place if it comes loose. But if your wire is bent down, it will probably stay on without tape. To turn off your Brush Bot, simply pick it up and disconnect the top battery wire. This will break the electric circuit.

Step 8: You can add decorations to your bot if desired. Googly eyes, pipe cleaners, and strips of confetti are all good choices to give your Brush Bot its own personality.

Robot Science

The weight at the end of the motor is off center. This is called an eccentric weight. The eccentric weight causes the motor to vibrate as it spins. Normally, you don't want motors to vibrate because that wastes energy, but this vibration is useful to allow pagers and cell phones to work in silent mode. The vibration will cause your Brush Bot to vibrate and move around a tabletop.


Create a very fast brush bot from an old toy car.

Robot Gear

Pull-back toy car
Screwdriver (optional)
Needle-nose pliers
Double-sided tape (or tiny rolls of clear tape)

Step 1: Find a friction-powered pull-back toy car. This is the type of toy car that you pull backward and then let go to make it race ahead. The better the car works, the better your Wind-Up Brush Bot will be.

Step 2: Remove the top of the car. For a cheap plastic car like the one shown, the top just pops off. A tab is located in the front or underneath the car; press the tab in and the top comes off easily. For a higher quality pull-back car, you might need a screwdriver to remove the top.

Step 3: Remove the friction-powered motor and the rear wheels from the car's frame. You will probably need to bend back a plastic tab with a screwdriver. Take care in removing this motor and you might be able to rebuild the toy car when you are done.

Step 4: Using needle-nose pliers or wire cutters, cut the head off a toothbrush. If the toothbrush has been used, make sure you wash it thoroughly first. Tape the motor to the top of the toothbrush head. Double-sided tape or a roll of clear tape will work.

Step 5: Wind up the wheels to store energy in the friction motor. You most likely will have to do this by hand — the tape will not be strong enough to allow you to pull back the car part on the ground like when it was in original car form. Once wound, place the bot on a table or other smooth surface and let it go.

Robot Science

Friction motors work by storing energy. As you pull the car back on the floor, you store energy in a coiled strip of metal. When you put it down, the coiled metal unwinds and causes the car's wheels to spin. How far a Wind-Up Brush Bot moves is a function of how strong the friction motor is. Most will last only a few seconds. But they are still fun to make and don't require batteries.


Brush bots sometimes tip over. The Brush Bot Extreme has a simple modification, outriggers, to keep itself upright and pointed in the right direction.

Adult supervision required

Robot Gear

Paper clip
Needle-nose pliers
Basic Brush Bot (see page 6)
Double-sided tape
Super glue (optional)
Cell phone or pager vibrator motor
AA or AAA battery
Clear tape

Step 1: Unfold a paper clip until it forms a skinny S shape, as shown.

Step 2: The paper clip might break in the middle as you unfold it, but that is OK — you want two pieces anyway. Bend it back and forth to break it in half, or use needle-nose pliers to cut it. (Needle-nose pliers have a built-in wire cutter, at the rear of the opening.) You should have two strips of steel, and one will be slightly longer than the other.

Step 3: Straighten each strip of steel with needle-nose pliers.

Step 4: Bend both ends of each metal strip to the height of the toothbrush head of your Brush Bot or even a tiny bit shorter than the height of the toothbrush. These metal strips are going to become outriggers to help keep your Brush Bot from tipping over.

Step 5: Cut off a toothbrush head with the needle-nose pliers like you did for the original Brush Bot. (Or, you can reuse the original Brush Bot after you pull off its motor.) Place the outriggers across the top of the toothbrush head. Pull off the paper from the bottom of a piece of double-sided tape and put it over the top of the toothbrush head. For a permanent Brush Bot Extreme, add a few drops of super glue under the tape. Be sure to get adult help and permission if you plan to use super glue.

Step 6: Pull the top backing paper off of the double-sided tape. Place the motor on the front of your Brush Bot Extreme. Bend one wire back and push it into the top of the double-sided tape.

Step 7: Place the battery on top of the wire and press it down into the double-sided tape.

Step 8: Take a small piece of clear tape and press the other wire into the tape. Leave the tape dangling in the air.

Step 9: Pick up the Brush Bot Extreme. Press the tape and wire onto the top of the battery. Put the bot down and let it take off. You can stop it by picking it up and pulling off the top tape.

Robot Science

Brush bots can be very top-heavy depending on the size of the motors and the batteries. They can tip easily because a heavy top raises their center of gravity (COG). The COG is a point in the middle of an object where all of its mass is located. Any time the COG gets close to the edge of an object, like when the bot is shaking back and forth, the object might tip over.

Here is a quick way to demonstrate this: set a toy car on the table on its wheels. Push the top of the car sideways. It is very stable because the COG is far away from the edge of the car. Now stand the car up on the side. If you push the car it will fall over easily. The COG (inside the middle of the car) is in the same spot in both cases. But in the second case, the COG is closer to the edge of the car, so it tips easily.

By adding outriggers, you move the edge of the car away from the COG. The Brush Bot Extreme won't tip as easily because of the wide base. Cranes, bucket trucks, and many large construction vehicles use outriggers for this same reason. You can modify and add outriggers to any of your vibrots.


A larger vibration bot can be made from an old vibrating toothbrush and a fingernail brush.

Robot Gear

Needle-nose pliers or wire cutters
Disposable, battery-operated vibrating toothbrush
Fingernail brush (Note: Dollar stores are a great place to buy a cheap toothbrush or
fingernail brush)
Decorating materials (pipe cleaners, wires, markers, stickers, and googly eyes)

Step 1: Use wire cutters or pliers to cut off the toothbrush's head. You will use the remaining part of the toothbrush (its handle) as the motor.

Step 2: Use a piece of tape to secure the brush motor to a fingernail brush, as shown.

Step 3: Your Nail Bot is ready to go, but add some decorations first. For example, you can use a piece of colored wire or a pipe cleaner to create eyes (or antennae). Wrap the piece of wire several times around the tapered end of the brush. Push up the wire between the nail brush and the toothbrush to hold it in place. Leave an equal amount on each end.

Step 4: Using needle-nose pliers, pinch the end of the wire and start rolling it up. Roll the wire around the end of the pliers until you get the desired length.

Step 5: It might be easier to slide the wire off and do the other eye. Make the eyes equal in length.

Step 6: Slide the eyes back on and push them down until they are held in place between the two brush bodies.

Step 7: Your finished Nail Bot is ready to go.

Step 8: Pick it up and turn it on using the switch on the brush handle. Put it down on a smooth surface and watch it go.

Step 9: Use your imagination to devise a different decoration style. Your Nail Bot should reflect your originality and creative flair.

Excerpted from "The Robot Book: Build & Control 20 Electric Gizmos, Moving Machines, and Hacked Toys (Science in Motion)" by Bobby Mercer. Copyright © 2013 by Bobby Mercer. Excerpted by permission. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher. Excerpts are provided solely for the personal use of visitors to this web site.
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