Reference no: EM132435284 , Length: 10 pages
Assignment - Laboratory Work Report
Assignment Brief - Clear statement of the work that students are expected to undertake: An individual, word processed laboratory report based on the experiments performed with the audio amplifier needs to be submitted.
Further Information - Learning Outcomes assessed in this assessment:
1. Describe and illustrate the understanding of science and engineering principles using a range of verbal, written and graphical techniques when researching and analysing real world problems. (UK-Spec, 3rd Ed. SM1m, EA1m)
2. Demonstrate engineering laboratory skills with an overview awareness of Health and Safety issues. (UK-Spec, 3rd Ed. EP6m)
3. Analyse, interpret and present experimental data obtained from instrumentation with knowledge of the characteristics of the particular equipment (UK-Spec, 3rd Ed. EA1m, EA4m, EA3m, D2m)
4. Demonstrate knowledge and understanding of engineering principles and methodology through engagement with experimental work and by using them to analyse engineering processes. (UK-Spec, 3rd Ed. EP3m)
Laboratory - Audio Amplifier
Objective: The objectives of this laboratory are (i) to measure the maximum amplification of an audio amplifier; (ii) to measure the frequency response of the amplifier.
Procedures -
1. Connect the stereo coupler and extension cable to the input of the audio amplifier.
2. Connect the signal generator to the black and red connector on the jack extension cable.
3. Connect the oscilloscope to the signal generator (Channel 1) and to one of the speakers (Channel 2).
4. Record a diagram of the experimental setup in your lab book.
A - Maximum Amplification
5. Imagine that your audio amplifier has a gain of 20 dB. Explain what this means.
6. Set the volume of the speaker to maximum by adjusting the potentiometer.
7. Set the input signal to a sine wave of amplitude 50 mV (approximately, you may need a lot less or more depending on your amplifier) peak to peak and 17 kHz frequency and observe both signals on the oscilloscope (input and output at the speaker).
8. Now increase the amplitude of the input signal until you see distortion (this is called saturation or clipping) of the output signal. Set the amplitude just below the saturation point.
9. Measure the amplitude of the output signal and calculate the maximum voltage gain of the amplifier using equation (1).
B - Frequency Response and Bandwidth
10. Set the input amplitude (still a sine wave) to around 100 mV Vpp. You will probably want to reduce the volume of the amplifier by at least half. Note that you need to select an amplitude that will not saturate as you change the input frequency. Before recording your data, do change the frequency over a large range to make sure you do not saturate the signal.
11. Record the output amplitude as you change the frequency from 20 Hz to 500 kHz (20Hz-50-80-100-200-800Hz-1kHz-2-4-6-8-10-12-14-18-20-50-100-200-500kHz).
12. Plot a graph of output voltage gain as a function of the input frequency using the semi-log graph paper provided.
13. Comment on the graph plotted. Calculate the bandwidth of the audio amplifier tested.
14. Demonstrate how -3 dB corresponds to a voltage reduction of √(1/2). Carry out a similar demonstration for the power gain knowing that:
Power Gain (dB) = 10log(Pout/Pin)
C - Signal to Noise Ratio
15. Set the volume level to about half way (loud enough but not too much). Without connecting the input, measure the noise level.
16. Now inject an input (sine wave) of 100 mV Vpp amplitude and measure the output signal. Calculate the SNR in dB.
17. Now reduce the volume to something just audible and repeat the procedure. Compare the two SNR values.
D - Limits of Circuit Design
18. Start with a square wave of amplitude 100 mV (Vpp) and 150 Hz. Record the input and output waveforms in your lab book.
19. Record the output waveforms as you increase the frequency to 1500 Hz, 6 kHz, 12 kHz, 40 kHz and 120 kHz.
20. Comment on what you observe (think about the charge or discharge of a capacitor within the amplifier circuit).
Need Maximum 10 pages, excluding cover page and table of contents and using an appropriate style (Harvard or APA or British standards).
Attachment:- Laboratory Work Report Assignment File.rar