Experiment: Audio Signal Level Adjustment with Voltage Divider

Objective

To learn how a voltage divider can be used to adjust the level of an audio signal, bringing it within the input range of audio-processing equipment or an ADC.

Materials

• Audio signal source (e.g., audio player or signal generator)
• 2 x Resistors (e.g., 10kΩ and 5kΩ for the voltage divider)
• Microcontroller with ADC capability (optional)
• Amplifier or audio processing module (optional)
• Breadboard
• Jumper wires
• Oscilloscope or multimeter

Circuit Diagram

Connect the circuit as shown in the diagram below. The voltage divider scales down the audio signal to make it compatible with the input range of an ADC or amplifier.

Theory

Audio signals can vary widely in amplitude and may exceed the input range of an ADC or amplifier. A voltage divider reduces the signal amplitude proportionally, preventing distortion or clipping. The output voltage from the divider is given by:

V_out = V_in * (R2 / (R1 + R2))

By choosing appropriate resistor values, we can ensure that the audio signal falls within the safe input range.

Procedure

1. Connect the positive terminal of your audio signal source to one end of resistor R1.
2. Connect the junction between R1 and R2 to the ADC or amplifier input.
3. Connect the other end of R2 to ground.
4. Power on the circuit and play an audio signal through the source.
5. Observe the output using an oscilloscope or measure it with a multimeter, comparing the input and output levels.

Observations

Record the amplitude of the original audio signal and the reduced signal at the output of the voltage divider. Note how the voltage divider attenuates the signal to a manageable level without distorting its waveform.

Conclusion

This experiment shows that a voltage divider can effectively reduce an audio signal's amplitude to prevent distortion or clipping in audio processing circuits. This approach is valuable for safely interfacing with ADCs or amplifiers that have a limited input range.