Using the access hatch on the regulator enclosure, the
wires for the motor were disconnected from the power
connector and a voltmeter was hooked up in parallel with the
motor to record voltage values while testing. Rotational speeds
in rev/s were calculated from time values taken by using a
stopwatch to time 20 revolutions of the eccentric mass at lower
rotational speeds. Videos were taken of the system at higher
rotational speeds and the time taken for each revolution of the
mass was established by stepping frame-by-frame through the
video and averaging three sample revolutions. These sample
points were used to establish a voltage vs. rotational speed
trend from which the excitation frequency was calculated for
different voltage values. This can be seen in Fig. 5.