Lab 03: Audio Amplifier

In this lab, I created sound using a speaker, an amplifier circuit, and a function generator. To begin, I soldered wires to the leads of an 8 Ohm speaker and connected the function generator directly to it. The function generator was producing a 1kHz sine wave of amplitude 50 mV. At this frequency and amplitude, the sound produced by the speaker was very weak, I almost didnt hear it producing any sound. Increasing the amplitude of the generator increased the volume, but it was still a weak showing.

To improve the volume of sound produced by the speaker, I placed a common emitter amplifier between the function generator and the speaker. Using the CE amplifier produced immediate results, with a much louder and clearer sound. For comparison, I ran this test again, but with the CC amplifier instead of the CE amplifier. In this configuration, the sound produced was noticeably weaker than that of the CE amplified speaker.

Finally, I combined both the CE and CC amplifier in series between the generator and the speaker. This combination is referred to as a two stage amplifier, and is commonly used for audio amplification. In this configuration, the sound produced was clear and loud. Out of curiosity, I experimented with increasing the input amplitude for this amplifier and obvserved the resulting output voltage at the speaker. Increasing the amplitude increased the volume at a uniform rate, up until a certain point, at which the output waveform distorts and the sound produced becomes fuzzy and unpleasant. I reason that this was the input voltage overpowering the amplifiers beyond their limit and therefore clipping the input signal.