Datasheet

Chapter 6 • Light-Sensitive Navigation with Phototransistors
210 • Robotics with the BOE Shield-Bot
• How to use the Arduino’s constrain function to set upper and lower limits for a
variable value
Robotics Skills
• Using a pair of phototransistors for autonomous sensor navigation in response to
light level
Engineering Skills
• Subsystem testing of circuits and code routines
• The concept of resolution, in the context of the Arduino reporting a 10-bit value
from an analog input
• Using an equation to get a zero-justified normalized differential measurement
Chapter 6 Challenges
Questions
1. What does a transistor regulate?
2. Which phototransistor terminals have leads?
3. How can you use the flat spot on the phototransistor’s plastic case to identify its
terminals?
4. Which color would the phototransistor be more sensitive to: red or green?
5. How does V
A3
in the circuit above respond if the light gets brighter?
6. What does the phototransistor in the circuit above do that causes V
A3
to increase
or decrease?
7. How can the circuit above be modified to make it more sensitive to light?