CHAPTER 17 ■ DC MOTORS
Simple DC Motor Circuit
DC brush motors are very easy to experiment with. You only need a motor, battery, and red and black
alligator or IC hook jumper leads. No resistors or other components are necessary.
Selecting a Motor for the Simple DC Motor Circuit
The motor must have only two wires or connector terminals. If the motor has more, it’s probably not a
permanent-magnet DC brush motor and therefore isn’t appropriate for this experiment. You don’t want a
brushless, stepper, or servo motor, usually indicated by attached electronics or more than two wires.
Small, two-wire DC brush motors are all basically the same (see Figure 17-11). Some motors have long
wire leads but other motors only have metal connectors. Some have gears or pulleys attached to their shafts,
while others have plain shafts. Despite these cosmetic differences, they’re all fine for this experiment.
It’s easy to identify a DC brush motor if the selected motor is labeled something like “DC Motor,”
“DC 3V,” or “DC 12V.” You’re unlikely to find a label that indicates the motor is a definitely a “brush” or
“permanent-magnet” motor, because that’s usually assumed unless the motor is marked otherwise.
However, a motor marked “brushless,” “servo,” or “stepper” is definitely not correct for this experiment.
Obviously it’s reassuring to have a copy of the datasheet for the motor just to be sure, but it isn’t necessary.
You can purchase ordinary DC motors for around $1. Table 17-1 lists a couple of sources for assorted
grab bags. You can purchase individual DC motors from almost any electronic store or catalog company. You
can also salvage motors out of toys.
Figure 17-11. Various DC brush motors
Table 17-1. Suppliers of DC Motor Assortments
Supplier Part Number Price Quantity
Electronic Goldmine GP21 $2.49 3 assorted
Jameco 18294 $7.95 5 assorted