Exercise EE1-03.R2

Prof. Dr. Thorsten Jungmann (last updated 2025-12-07)

Relates to EE1-03 Sources

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Task

An audio amplifier delivers a maximum output power of $P_{\mathrm{out}}=100\mathrm{W}$ to a loudspeaker. The amplifier has an efficiency of $\eta =70\%$.

a) What electrical input power $P_{\mathrm{in}}$ must be supplied to the amplifier?

b) What power loss $P_{\mathrm{loss}}$ occurs in the amplifier?

c) The amplifier is supplied internally from a power supply with a direct voltage of $U=36\mathrm{V}$. What current $I$ must the power supply deliver when the amplifier delivers its maximum output power?

d) What is the maximum permissible internal resistance $R_i$ of the power supply if the supply voltage is not to drop by more than $5\%$ at full load?

Solution

a) $P_{\mathrm{in}}\approx 143\mathrm{W}$
b) $P_{\mathrm{loss}}\approx 43\mathrm{W}$
c) $I\approx 3.97\mathrm{A}$
d) $R_i\le 0.45\Omega$

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