CHAPTER 17 ■ DC MOTORS
Connect one end of the red jumper lead to the positive battery terminal and the other end of the red
jumper lead to the positive terminal of the motor (see Figure 17-14). If the motor isn’t labeled with positive
or negative, then select the red wire coming from the motor. If no wires are coming from the motor or neither
is red, pick either wire or terminal. If you connect the motor backwards, no big deal, it runs backwards.
Connect one end of the black jumper lead to the negative battery terminal and the other end of the
black jumper lead to the negative terminal of the motor. The motor should start spinning! If you swap the
ends of the red and black jumpers on the battery terminal, the motor spins in the reverse direction.
Primary Characteristics of DC Motors
DC motors have many significant attributes worth examining. Which characteristic matters the most to you
depends on how you are going to use the motor. Some of the more technical material may only matter to you
in more advanced stages of your hobby.
Rotational Speed Characteristic of DC Motors
A popular unit for measuring motor speed is RPM, which stands for revolutions per minute. This indicates
how many times the motor will rotate the shaft (and anything connected to it) in a minute.
For example, the second hand on an analog clock rotates around once every minute (see Figure 17-15),
for a speed of 1 RPM. If you want to get a sense for 1 RPM, just watch a clock. That’s slow!
Figure 17-14. Simple DC motor circuit built with IC hook jumper leads