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Chapter 13

Chapter 13: Sensitive Sam Walks the Line...................................................................

In This Chapter

Getting the overview of all Sam can do

Looking over the very cool (and somewhat complex!) schematic

Arming yourself to deal with building issues

Getting your shopping list in order

Walking through the steps to make the circuit and assemble the cart

Trying out Sam and taking things further

O

kay, we have to admit this right upfront: This project is Earl’s absolute

favorite in this whole book. Sensitive Sam is a motorized cart. You stick

black electrical tape on the floor to create a little path or track for Sam, and

Sam uses his sensors to follow the tape around corners and in interesting

loops you devise for hours of fun. He also has a little horn you can blow (to

warn the cat that he’s coming). What’s not to love?

In this chapter, you discover how to give Sam the “eyes” he needs to sense

where he’s going and also how to build a radio remote control device to tell

him what you want him to do. Although you’ll find lots of little components

and connections going on here, don’t be intimidated; after you get going, we

think you’ll find it’s a pretty fun project. (Earl did!)

The Big Picture: Project Overview.............................................................

You’re probably wondering what this Sam guy looks like and what he’s capa-

ble of. Glad you asked. Here’s the low down on Sam, who

Has three wheels:This design makes the cart stable. If you use four

wheels, you need to include a suspension mechanism to ensure that

all wheels stay in contact with the floor at all times. We use one unpow-

ered wheel in front and two independently powered wheels in back. This

way, if the motor for one of the wheels in back is shut off, the cart turns

in the direction of the motor that was shut off (left or right).