Product specifications

Instrumentation Laboratory Exercise 39
4.5 Test procedure
Ensure that the sensor is placed beneath a hole in the motor's disk.
Measure the voltage when the CdS cell is fully illuminated. This is the
static light value. Now rotate the motor so the light is blocked.
Remeasure the dark static value of the voltage. Now spin the motor
up by applying 5 V to it. Notice what happens with the amplitude of
the signal. As the speed of the signal increases, the sensitivity of the
sensor is reduced, decreasing the peak- to- peak amplitude.
You can vary the speed of the motor by rubbing it with a piece of
paper. At several speeds stop the program and estimate the
peak- to- peak amplitude of the signal as well as the speed of the
signal (in Hz). You should get data like the following (at low and high
speeds):