Q1: A sound system is designed to give 25watts into an 8ohm speaker. The amplifi
ID: 2082063 • Letter: Q
Question
Q1: A sound system is designed to give 25watts into an 8ohm speaker. The amplifier and speaker diagram as shown in fig.1
Draw the equivalent maximum power transfer circuit of fig.1, and Analysis the circuit by,
(a) What would be voltage provided by this amplifier to the speaker?
(b) What power will be delivered to the load
(i) If the load is a short circuit
(ii) If the load is an open circuit
(c)If the different speakers of load resistance 2ohm, 4ohm,6ohm,8ohm,16ohm, 32ohm and infinite ohms are used in the system, calculate the power delivered to the speaker in each case, and draw a curve showing the variations of the output power Po with load (speaker) resistance RL.
(d)Plot a graph of power transferred to the speaker as a function of the load resistance RL from 2ohm, 4ohm,6ohm,8ohm,16ohm, 32ohm and infinite ohms. Calculate the maximum value of RL from the graph. Use MATLAB software.
(e)Write a MATLAB code to find maximum value of RL.
(f)Compare and comment the results (d)&(e).
Explanation / Answer
(a) Given Pout = 25W and RL=8 ohm
Therefore Pout=Vout2 /RL =25
We get Vout = 14.142V
(b) (i) Let P1 be the power delivered when load is short circuit ( RL=0)
P1 = Vout2 /RL = infinity
(ii) Let P2 be the power delivered when load is open circuit (RL=infinity)
P2= Vout2 /RL = 0
(c) Power delivered when RL=2 ohm
PO1=14.1422 / 2 = 100W
Power delivered when RL=4 ohm
PO2=14.1422 / 4 = 50W
Power delivered when RL=6 ohm
PO3=14.1422 / 6 = 33.33W
Power delivered when RL=8 ohm
PO4=14.1422 / 8 = 25W
Power delivered when RL=16 ohm
PO5=14.1422 / 16 = 12.5W
Power delivered when RL=32 ohm
PO6=14.1422 / 32 = 6.25W
Power delivered when RL=infinity
PO7=14.1422 / infinity = 0W
By plotting the values of Power in y-axis and Resistance on x-axis we get the graph.
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