CHAPTER 25 ■ LAUNCHING THE LINE-FOLLOWER
The other two jumper leads should be hooked to TP1 and TP2, respectively. If you didn’t specifically
make a loop of wire for each test point (see Figure 25-6), simply connect the hooks to the first and third leads
of trimpot R2.
Figure 25-6. A multimeter test lead IC hook firmly grasps a loop of wire for a sensor test point
Figure 25-5. Hole in the side of the robot’s body with IC hook jumper leads inserted for measuring the voltages
on the board during operation
With the robot powered up but with the line-following switch in the center position (motors off ),
manually place the robot over various points in the course. With a multimeter, measure the voltage at the
test points to determine how easy it would be for the comparator chip to compare them.
To measure the voltage of the test points, the black test lead of the multimeter must be connected to the
IC hook jumper lead of the robot’s negative power bus. The red test lead of the multimeter can be hooked up
to the IC hook jumper lead for either TP1 or TP2, but not both at the same time.
Adjust the brightness-balancing trimpot (R2) and the headlight-brightness trimpot (R10) and observe
the effect on the measured voltage of each sensor test point. With an external light, such as a flashlight, light
up the floor and cast shadows under the sensors to determine if the ambient contamination significantly
affects the outcome.