AC Signals #1

The above circuit was analyzed with professor's computer.
Anticipated Vrms = 2.12 V
Actual Vrms = 1.97 V
Zcap = -717j Ohms
Vcap = ~2V
Vcap,rms = 1.6 V
t_x = 90 microseconds

Oscilloscopic Skeleton

The point of this lab was to become acquainted with oscilloscopes and how to use them for determining the frequency and amplitude (voltage) of an oscillating current.
Part 1 - Displaying and Measuring a Sinusoid
The FG was set to have f = 5kHz and peak to peak amplitude to have 5V. We measured the period with the O-scope to be 200 microseconds. The the peak to peak amplitude measurement was off by a factor of 4.: 20 V. Same with the zero to peak amplitude: 10 V.we got the Vrms to be 7.07V.

Using the DMM on the leads: VDC = 0.06 V, VAC = 4.07 V

Part 2 - Including a DC offset
The difference between the DC and the AC coupled is a change along the y axis. (voltage)
Using the DMM again: VDC = 2.5 V, VAC = 3.28 V

Part 3 - Square Wave
Again with DMM:
VDC = 2.5 V
VAC = 5.17 V

Vrms = 3.66V
Part 4- Measuring two Mystery Sources

Channel 1:
DC V= 0 V
f = 100 Hz
Pk -to- pk Amp: 0.6 V

Channel 2:
DC V=0.5 V
f = 6.25 kHz which is about 6.06 kHz (the actual frequency)
pk -to-pk Amp: 0.3 V

Thus we learned how to use oscilloscopes to learn things about alternating/time dependent currents.

Op Amp Lab

In this lab, a 741 op-amp was used to create inverting amplifier circuit under the pretense of creating a signal conditioning circuit for a sensor.

A voltage divider was devised to get a voltage of one volt for the V_IN and mimic a sensor's output.
The following data was collected on the components we used.

 Above is the layout of our circuits.

I_V1 = 8.95 mA
I_V2 = 0.95 mA
Because these aren't equal to each other, we couldn't go on to the last page of the lab because he lab was written in anticipation of each group getting a 3rd voltage source, but only 2 were available for each.

Equivalents HW using PSpice

Here's some screenshots for the evidence.

On the last one, after selecting the trace cursor to display, I used the Trace>Cursor>Peak to get teh peak wattage.

Thevenin and Norton Equivalents in PSpice

We modeled circuits in PSpice and used DC sweeps to o determine their Thevenin and Norton equivalents.

In order to do this in the first circuit, we placed a current source I2 across the terminals that we were interested in and then used a DC Sweep to change it's value from 0A to 1.0A. After running the simulation, a trace of "V(I2:-)" was added to plot the voltage across the current source I2.

 The y-intercept gave the Vth and the slope of the line gave the Rth because V=I*Rth.
Thus, the Vth = 20V and Rth = 6 Ohms.

Then we worked out the Norton equivalent. We did this by replacing the current source I2 with a Voltage source that was varied from 0 volts to 1.0V by increments of 0.1V.

Here the y-intercept gave us the I_N = 3.335 A and the slope gave G_N = 0.17 S.
In the last problem, I found the load that maximizes the power dissipation.
I put a resistor across the terminals that had values of { RL } and I set RL's value with a Global Parameter. This global parameter was swept from 100Ohms to 5kOhms with 100Ohm increments. I ran the simulation and got the following graphs. The top one was arrived at through a linear sweep, and the bottom through a octave sweep. The peaks show at 250microW with RL = 1kOhm, as expected.

Thevenin Equivalents' Equity

The purpose of this lab was to find a Thevenin equivalent of a circuit and model it to see how accurate it was.

The V_Th = 8.65V,
the R_Th = 66.0Ω,
and the I_Th = 131mA.

Here's a picture of our circuit.

Here's a the table of the components we used.

 Here's a table of the results we got from those components followed by another table of components we used.

 

However, the components in the seoncd table didn't really get the time needed to be used. We had started the lab too late and had to leave. Instead of making the whole class come back on Friday to finish the last page of the lab, Professor Mason allowed us to call it quits.

PSpice Fun

After installing PSpice, I had to run Capture Student as administrator to get the PSpice menu to show up in it.
I had to import some libraries to get the parts I need to use, and then it was simply place parts in a sensible pattern and connecting them with wire.

Below is my PSpice for working out the last problem of the 8th WebAssign assignment.