Perform the following tests:
close the switch
and while looking at the oscilloscope waveform across the incandescent lamp
change the potentiometer setting from minimum to maximum resistance
Answer the following questions
1. What is the minimum and maximum conduction angle ?
2. What is the minimum and maximum phase retard angle ?
3. Describe how the potentiometer is able to control the phase retard angle of this circuit
4. Describe why the potentiometer is unable to retard the phase beyond the maximum angle
Modify your SCR circuit as shown in this diagram
Perform the following tests:
close the switch
and while looking at the oscilloscope waveform across the incandescent lamp
change the potentiometer setting from minimum to maximum resistance
Answer the following questions
1. What is the minimum and maximum conduction angle now ?
2. What is the minimum and maximum phase retard angle now ?
3. Explain how this circuit is able to give a greater range of phase control than the first circuit
4. Determine the true power delivered to a load in a half-wave phase control circuit for the two values
of ZERO and NINETY degrees of phase retard (by replacing the incandescent lamp with a 100-ohm resistor and making appropriate
measurements and calculations)
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