Circuits

HW2 – Due: Tuesday January 20th
in the class
Q1: Let’s assume that you want to buy an amplifier for your MP3 player. You can find a low
cost amplifier at RadioShack (http://www.radioshack.com/product/index.jsp?
productId=2062620#tabsetBasic). To find if the amplifier is suitable for your system you need to
look at the amplifier spec. You can find the user’s guide at: HERE
Find the answers of the following questions using the information in the document and your
circuit knowledge:
1. How much is the maximum output power?
2. What is the power supply voltage?
3. What is the frequency range?
4. How much is the input impedance, Rin?
5. If your MP3 player has the output impedance of 15 kΩ, find the voltage at the input of
the amplifier, Vi, when the no-load voltage at MP3 player, Vs, is 20 mV.

15 kΩ kΩRin

+-

Rin
+Vi-

Vs

RadioShack
Amplifier
MP3 Player

6. How much is the sensitivity? (the minimum voltage required at the input of the amplifier)
7. Considering the circuit in section 5, is the amplifier input larger than the sensitivity of the
amplifier?