Precut and predrilled
BeginnerBot base and
control panel, with all
Three-cell battery holder,
hookup wire, double-pole,
toggle switches (example:
Tamiya motors, wheels:
Marlin P. Jones
FIGURE 11. This shows where to mount the switches, battery
holder, and other parts on the BeginnerBot control panel.
(Some of these are surplus
sellers, so stock may come
FIGURE 12. Build
four standoffs (they
act as feet) using
screws, nuts, and
acorn (cap) nuts.
Attach to the control panel as shown.
to assemble the machine screw and two nuts to make the
skid. Likewise, refer to Figure 11 for how to mount the
switches, corner standoffs, and cable clamp on the control
panel. Figure 12 shows the construction of the corner
standoffs, which serve as “feet” for the control panel. The
switches attach to the control panel using their own
threaded nuts. Use one or two 1” squares of Velcro® to
secure the battery holder to the underside of the panel.
FIGURE 13. This shows how motor reversing is accomplished
using a double-pole, double-throw switch.
Don’t use longer screws, because they’ll stick out too much
and could drag against the floor. When using a skid, the
motors are on the “top” of the base; remember, however,
that the BeginnerBot is invertible — meaning it can be
operated motor-side up or down. In future installments, I’ll
show a variation of the robot where the motors face down.
Figure 10 shows a side view of the base, indicating how
50 SERVO 08.2011
Wiring the Motors and
Phase 1 demonstrates the control of a robot using
switch control. A set of two double-pole, double-throw
(DPDT) switches operate the motors, and show how
differential steering works. You can practice using the
switches to see how different positions affect the motion
of your robot.
For a full appreciation of how to control the
BeginnerBot, choose miniature DPDT toggle switches that
have a center-off position, as well as momentary “on”
action. In electronics catalogs and online shopping carts,
you’ll often see these listed as: (on)-off-(on) or (mom)-off-
(mom) where the (on) or (mom) in parenthesis means
that the switch is spring-loaded. Releasing the toggle
returns the switch to its off position.
Each switch controls one motor. In the center-off
position, the motor is unpowered, so it doesn’t move. The
motor turns in one direction when the switch is pushed
toward either on position. With the switch pushed toward the
other position, the motor turns in the opposite direction.
Figure 13 shows the concept of how a DPDT switch is
wired in order to reverse the direction of a motor. Note that
in one position of the switch, current from the battery flows
through the motor one way; when the switch is in the other
position, current from the battery flows through the motor in