Lab Day 21

Inverting Voltage Amplifier Lab

In this lab assignment, we concerned with the steady-state response of electrical circuits to sinusoidal inputs. The input and output signals both have the same frequency, but the two signals can have different amplitudes and phase angles. We then measured the gain and phase responses of an inverting voltage amplifier circuit and compare these measurements with expectations bases on analysis. 

This is the pre-lab with the picture of the circuit. On the top right corner, we calculated the cutoff frequency of the circuit, the amplitude gain, and phase difference.

Picture of the 100Hz.

Picture of the 1KHz.

Picture of the 5KHz.

The chart of the bottom half shows the measurements to calculate the amplitude gain, phase difference, and it is compared with the results from the pre-lab with the %error.

OP Amp Relaxation Oscillator Lab

A "relaxation oscillator" is constructed by using some type of device that will act as a switch when a certain voltage is applied to one of its terminals. The "switching voltage" is usually the voltage across a capacitor that is being charged or discharged accordingly. 

We determined the value of R using the formula for the period T.

This is the picture of the circuit.

This is a picture showing the voltages for the OP Amp relaxation oscillator.

Lab Day 20

Phasors: Passive RL Circuit Response Lab

In this lab assignment, we measured the gain and phase responses of a passive RL circuit and compared these measurements with expectations based on analysis.

This is the pre-lab, where we showed that the amplitude gain and phase difference between the input voltage and input current are shown. Also the cutoff frequency for the circuit. 

This is a picture of our circuit.

We used the function generator to apply a sinusoidal input at Vin. The oscilloscope displayed both Vin and Vl.

We calculated the measured gains and phase differences between Iin and Vin for the three frequencies.

With the measurements we used to estimate the gain and phase difference between Vin and Iin and the gain and phase difference between Vl and Iin.

These results were compared with the value from the pre-lab, We do not have the ability to directly measure a time-varying current, so we used Iin=(Vin-Vl) / R

Lab Day 19

Impedance Lab

The purpose of this lab was to measured the impedance of three separate circuits and compare it with our calculated values. 

The output current from the 47 Ohm resistor and output voltage 100 Ohm resistor was measured.

This picture is showing the output at 10KHz.

The output current from the 47 Ohm resistor and output voltage from the microH was measured. 

This picture is showing the output at 10KHz.

 The output current from the 47 Ohm resistor and output voltage from the 0.1 microF was measured.

This picture is showing the output at 10KHz.

Here are the results from the three circuits, including their voltage and current measurements.

Conclusion: Today we went over impedance and admittance, and how to solve for them within circuits involving resistors, inductors, and capacitors.

Lab Day 18

Today we went over the components of a sinusoidal graph, learned that phasors are complex numbers that represent the amplitude and phase of sinusoidal graphs, and how to use phasors to determine sum of the magnitudes and angles. There was no lab during this day. (Function generator shown in class)

Lab Day 17

RLC Circuit Response Lab

In this lab, we emphasized modeling and testing of a second order circuit containing two resistors, a capacitor, and an inductor. The step response of the given circuit was analyzed and tested. The measured response of the circuit was compared with expectation values based on the damping ratio and natural frequency of the circuit.

This is the output of our circuit.

Pre-Lab

 We know the damping ratio by using  α = 1/2RC ω=1/(LC)^1/2  we can then calculate the damping ratio = α/ω.

In Lab

Since the capacitor and inductor in parallel, the damping ratio can be calculate by knowing the X% differently subtracting the voltage changing ratio of times the n is equal to -0.118 which is off a little.

Conclusion: Through this lab we can see how a huge discrepancy between theoretical and experimental values. This shows that what happens on paper doesn't always translate into real world phenomenons.