Day 26

Day 27

Today was a short lecture on Bode plots. We had the rest of the time to work on our projects.

Above is an example of finding frequency and we see that we get a gain of a factor of 10.

After we went over bode plots, we did our first example on how to draw the plots for gain and phase angle vs angular frequency.

another example as we were still unclear on how to do them.

We had to ask for one last example since most of the class had trouble drawing the plots correctly.

Day 25

Today we went over apparent power and power factor, and did an Apparent Power and Power Factor Lab to measure a circuit's apparent power and power factor.

To the left we have the equations necessary for solving for apparent power and power factor. To the right we have an example and we find that for inductors, current lags voltage.

Above we see represent real power as P and Q represents imaginary (reactive) power in apparent power.

 Apparent Power and Power Factor Lab:

The purpose of this lab is to use apparent power and power factor to quantify the AC power delivered to a load and the power dissipated by the process of transmitting this power.

For the prelab we calculated the theoretical values of the circuit shown in blue for the 10, 47, and 100 ohms.

Our results are displayed in pink and we see that for the 10 ohm resistor and the capacitor included in the circuit we get great within uncertainty. We see that when a capacitor is placed in parallel with an inductor, the phase angle decreases dramatically.

Input wave for all three resistor values.


Output for 10 ohm resistor


Output for 47 ohm resistor


Output for 100 ohm resistor


This is the output was when a capacitor was placed in parallel with the inductor using the 100 ohm resistor.

Above are the circuits for part one and part two respectively.

Day 24

Today we reviewed Inductor and its parameters, went over average and maximum power calculation within AC circuits, and saw a demonstration to see how RMS values dictate maximum power of AC circuits.

Above is an are the equations for average power in the frequency domain. In blue we calculated how many turns it would take to make a 1H inductor.

Above we did an example of average power transfer in the frequency domain.

Next we derived max power transfer in the frequency domain.

Above we did an example on finding the thevinin equivalent impedance to find max power.

Above we have a DC source on the right and AC on the left so we see that it would take about twice the voltage of AC to produce the same brightness as DC. Due to rms currents. 

Day 21 (Day23 on notes)

Today we went over how OP Amps work in AC circuit, and did the Inverting Voltage Amplifier Lab and the Relaxation Oscillator lab to see how to see how they would work in real life.

Here we did an example of an op amp in the frequency domain.

Inverting Voltage Amplifier Lab:

The purpose of this lab is to see the amplitude gain and phase difference between the output and input signals of a inverting voltage amplifier circuit.

Our theoretical values for gain and phase shift are on the right side on the right side of the picture in the pre lab section. 
For our results shown in pink, we got a fairly close to zero percent difference for the 100 and 1000 Hz. For the 5kHZ we had a substantially higher error in gain which may be due to the op amp working outside of its frequency range.


Input wave is at 100Hz at 2V shown in orange and the output wave is in blue.

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Input wave is at 1kHz at 2V shown in orange and the output wave is in blue.


Finally, here is the input wave is at 5kHz at 2V shown in orange and the output wave is in blue.

Here is a picture of our circuit.

Op Amp Relaxation Oscillator Lab:
The purpose of this lab is to construct a relaxation oscillator, which is a type of device that will act as a switch when a certain voltage is applied to one of its terminals. This voltage is usually the voltage across a capacitor that is being charged or discharged.


Here are the predictions according to Everycircuit.


Above is what we measured with the oscilloscope with an input of 733 Hz at 2V.

There is rounding error when we measured the pots resistance with the multimeter so we were not able to get the exact value. Also we treat the op amp as ideal so that too may contribute to our fairly high error calculated above.

Day 19 (day 21 on notes)

Today I could not make it to class because I attended my friend's funeral. He was a truely kindhearted person that always saw the good in people and had such a unique way of making people smile. My prayers go out to his parents and siblings and may you rest in paradise brother. 

The program for the service

The funeral at Forrest Lawn Memorial Park

Day 20 (Day22 on notes)

Today we learned how to use phasors on the same circuit analysis techniques that we used with DC. We also did a Phasors: Passive RL Circuit Response Lab.

Above we used NODAL ANALYSIS and converted circuit components to phasors and solved for node voltages.

Here we used MESH ANALYSIS to solve for mesh currents on an ac circuit.

Phasors: Passive RL Circuit Response Lab:
the objective for this lab is to measure the gain and phase response of a passive RL circuit and compare with theoretical values. We will only be concerned with the steady-state response.

Above is our circuit layout where we will measure input and outpout voltages.

Above we have an input sin wave of 2V and 10kHz in blue and output wave in orange.

Above we have an input sin wave of 2V and 20kHz in blue and output wave in orange.

Above we have our theoretical values and our measured values. On measured data, gain is calculated by Vo/Vi and phase angle by deltaT/T*360.

Above we use SOURCE TRANSFORMATION on the left side and on the right we use THEVENIN EQUIVALENCE on the right using phasors.