LAB 1: Pulse Width Modulator
NAME OF GROUP MEMBERS &
1. CHAN WEI NICK
2. SARAVANAN A/L SUKUMARAN
NAME OF INSTRUCTOR
MOHD ERDI BIN AYOB
To implement the pulse width modulator by using µ741.
To measure and analyse the pulse width modulation circuit.
Input and Output Signal Waveform
Table 1: The input and output signal waveform of sinusoidal, square and triangle wave.
1. What are the functions of VR1?
VR1 is a variable resistor used to adjust the input terminal Vin(+) operation voltage. When we adjust VR1, then the Vin(+) input terminal operation voltage will change, which means the reference voltage comparator will change, thus the output signal of pulse width will also change too. If the VR1 is fixed, it means that the operation voltage of Vin(+) input terminal is fixed.
In this experiment, three different waveforms, the sinusoidal, square, and triangular waveforms are used as an input signal to investigate the properties of pulse width modulation (PWM).
With that said, it is found that the output of the PWM signal is always at a peak of positive 5 volts and negative 5 volts. This is most probably due to the design of the PWM trainer itself, where the output signal is filtered at VR1 so that the output is always constant at 5 volts and negative 5 volts. This assumption is verified by the function of VR1, whereby adjusting the variable resistor VR1 will change the reference voltage of...