Mech E Lab Report

Abstract:

The objective of this lab was to characterize the performance of an amplifier using an oscilloscope and to find the gain of an op-amp. Oscilloscope is widely used in the field of mechanical engineering to display the time dependence of voltage signal coming out the sensors. The sensors are used for detecting changes in temperature, pH, vibrations and strains. Since the sensors have very low output voltage which needs to be amplified using an amplifier so that they can be detected by the oscilloscope. Oscilloscope converts the analog signals to digital signal by sampling the data at a fixed rate of time. The lab was structured into three parts, in the first part, measurements were taken of the electrical signals using a digital oscilloscope while toggling the AC and DC coupling mode to analyze the effects. As seen in Figure 3, AC coupling removes the DC offset component of a voltage signal which is supplied by the function generator to the oscilloscope. In the second part, the DC response and the frequency response of an op-amp was observed and its operational range was determined. The amplifier had an amplification factor of 1.225 and a gain of 1.762 decibels. The operational range of the amplifier was the linear region of the plot in figure 4 and was found to be from -4 to 6 volts, the operational range of frequency was found to be 0-10 kHz. The resonance frequency was found to be 60 kHz but around the saturation point distortion and clipping was observed. In the last part of the lab the Nyquist criterion was verified, according to which the sampling frequency needs to be two times greater than the maximum frequency in order to avoid aliasing. For a sample frequency of 1000Hz, aliasing was observed for frequencies just above 500Hz as per the Nyquist criterion.