breadboard shield costs about $15, and often requires
soldering connector pins in order to electrically attach it to
the Arduino. However, there’s no rule that you must use a
separate mini breadboard. If you prefer the breadboard
shield, by all means use one. In a future installment, I’ll
show the ArdBot II with a unique third-party miniature
Arduino board that is designed for easy connection to servo
motors and common sensors, bypassing the need for a
separate breadboarding area.
Power for the ArdBot II comes from a pair of battery
packs. A set of four AA batteries provides operating juice
FIGURE 4. Cutting and drilling template for the servo mounts.
for the motors, while a separate nine volt cell gives power
to the Arduino. Why two sets of batteries? While other
power arrangements are certainly possible, this one ends
up being among the least expensive and easiest to
implement. The Arduino’s built-in five volt regulator requires
about 1.5 volts of overhead. That means the (nominal) six
volts from four AA batteries may not provide enough
voltage to adequately operate the Arduino.
I say “may not” because the output of the four-cell
pack is not a predictable six volts. As the batteries wear
down, the voltage drops — possibly to a level below the
You can also use the two-pack battery
feature to power just the Arduino without
the motors. This is handy, for example, when
you’re experimenting with a new sensor and
you want to keep the ArdBot II tethered to
for the top and
bottom decks for
the ArdBot II.
42 SERVO 08.2013