Hardware Hacking Projects for Geeks

248

Part II: Advanced Hacks, Tools, and Techniques

Project Overview

The first steps of this hack will be to build and attach an IR transmitter to

the front of the vehicle, and then attach an IR receiver to the top. Next, you

will build a small microcontroller board with a radio receiver and attach

it to the IR transmitter and receiver. Finally, you will attach a radio trans-

mitter to the remote controller. After hacking the hardware, you will load

software onto the microprocessor.

Hardware Assembly Instructions

This project is suitable for toy-quality, battery-powered cars as well as gas

and battery professional-level vehicles. The circuit board you’ll build will

borrow power from the vehicle, but can also be powered from its own bat-

teries.

To complete this hack you will first disassemble two battery-powered

radio-controlled cars. One you’ve completed that step, you will add a laser

cannon, a hit sensor, and a control circuit board, and finally, you’ll modify

the remote control.

1. Disassemble the radio-controlled cars

Buy two remote-controlled cars from your local toy store or grab one from

your kid’s room. I built my car using a Nikko Humvee 1/14th scale 49 MHz

model #140001BC.

Be sure to buy one 49 MHz car and one 27 MHz car; if you get both cars at the

same frequency, each controller will control both of them.

Take off the top cover of the car chassis. You’ll need access to the main

circuit board. Next, remove all the screws that are holding the main circuit

board in place and carefully pull it away from the body. Do not cut any

wires.

2. Locate power on main circuit board

Search the main board to see where the battery wires connect. Determine

polarity using a multi-meter. Solder a 5- to 6-inch length of wire pair to

these points and add a small connector of your choice. You will use these

wires to power the circuit.

Radio-Controlled

Vehicle Power Systems

Most RC vehicles you’ll find in toy

stores are battery-powered. Some

higher-end (“hobbyist”) vehicles

use a chemically powered engine

(typically a combination of methanol,

nitro methane, and oil). These more

powerful engines move the car very

fast—over 20 miles per hour in some

cases. Electric power is also popular

for higher-end as well as lower-end

cars. Electric-powered vehicles are

cleaner to operate (no messy liquid

fuel) and can be operated indoors.

This hack can be made to work with

either kind of car, but in the instruc-

tions I’ll assume you’re hacking bat-

tery-operated vehicles.

Connectors

For projects in which I need small

connectors, I use simple 0.100-inch-

spaced “break-away” strip connec-

tors. These small sockets can be eas-

ily made into either male or female

connectors. I usually mount the

connector on a circuit board with the

female end facing out. I then solder

wires into the female end of another

connector, leaving the male end

untouched, to make a compact and

quick connector. You can get these

connectors from DigiKey.

Project Overview

ch13_rc.indd 248

1/22/2002 4:44:22 PM