Figure 15 is showing the input signal only and already it can be determined that the input signal is very noisy. The waveform is showing that there is a lot of noise in the audio signal and also that the signal is not constant and smooth enough to be able to give a clear and good quality sound at the output. This is not the type of audio signal that is wanted in the preamplifier. There is random spikes that can be found in this waveform which is not good for the IC chips in the circuit and this is one of the reasons that the diodes have been added for protection from voltage spikes in the circuit.
Figure 16 is showing the output signal from the preamplifier only. Connector a second probe from the oscilloscope to the output mono jack connector in the preamplifier circuit. On the oscilloscope set the waveform to 100mv. The waveform …show more content…
The waveform also shows that the signal constant and that there is not much interference in the audio signal path. The waveform shows a signal that is wanted at the output stage o an audio preamplifier circuit. The output signal is shown as an audio signal that has enough level to be used in processing