5.5 Transistor Lab Experiments

5.1 (a) Build the following circuit which uses a low-side transistor switch to turn one of your car motors on and off depending on the value of a control voltage. (You will need to use the TIP120 power transistor for this circuit rather than the TIP31C shown.) (b) Next, replace the control voltage with a GPIO output pin on your Arduino Uno and cause the motor to turn on and off under program control. (You’ll need to hold the car in the air while doing this unless you manage to attach the Arduino Uno to the car chassis.) Try bypassing the transistor entirely by connecting the Arduino Uno GPIO output pin directly to the car motor. Can you operate the motor this way? Why or why not?

5.2 Build the following emitter-follower circuit that controls the speed of your one of your car motors based on the light intensity shining on the CDS cell.  Your car should spin on the ground at a speed that depends on the light shining on the CDS cell.