Page 149 - Making things move_ DIY mechanisms for inventors, hobbyists, and artists

Chapter 6 Options for Creating and Controlling Motion 129

FIGURE 6-5 DC motor family, clockwise from top left: DC
motor, DC gearhead, hobby servo, and stepper motor (images
used with permission from SparkFun Electronics and
ServoCity)

Standard DC Motors
The most basic motor you’ll use is the standard DC motor, also called a DC toy motor.
You’ll find these in everything from toy cars to electric screwdrivers. The insides look
like our DIY motor wrapped in a motor housing that resembles a can. Coils of wire are
secured to the central shaft, and magnets are attached to the inside of the motor
housing. There are also slightly more sophisticated versions of the DIY motor’s scraped
ends (a commutator) and paperclips (brushes) that enable the field to flip back and
forth, as opposed to turning on and off. This makes even small motors more powerful
than the DIY version in Project 6-1.
The motor has only two electrical connections, so all you need to do to make a 9V DC
motor turn is hook it up to a 9V battery. To reverse the direction, reverse the connections
to the battery. If you lower the voltage, it will still work over a certain range, but spin
slower. If you raise the voltage, it will spin faster. 2

DC toy motors usually need between 1.5V and 12V. They spin at speeds anywhere
from 1,000 to 20,000 rpm or more. A good example is SparkFun’s ROB-09608.