Facebook
Google
GitHub
LinkedinAC Electric Circuits
Design Project: Audio Tone Control
4 questions By Tony R. Kuphaldt
-
Question 4 of 4
Note: when testing the frequency response of the tone control circuit, you may need to replace the transformer/speaker assembly with a non-inductive resistor of equivalent impedance, and measure Vout across it.
Reveal answerUse circuit simulation software to verify your predicted and measured parameter values.
Notes:A good source of audio signal is the headphone output jack of almost any radio, media player, or other portable audio device. Students like being able to do a lab exercise that directly relates to technology they’re already familiar with.
I have experienced good success with the following component values:
- C1 = 0.1 μF
- L1 = 200 mH (actually two 100 mH inductors in series)
- R1 = R2 = 1 kΩ
- T1 = 1000:8 ohm audio output transformer
- Rpot = Rpot2 = 10 kΩ
- Speaker = small 8 Ω unit (salvaged from an old clock radio or other inexpensive audio device)
An extension of this exercise is to incorporate troubleshooting questions. Whether using this exercise as a performance assessment or simply as a concept-building lab, you might want to follow up your students’ results by asking them to predict the consequences of certain circuit faults.
