D8 - Thevenin

We started the day talking about how stressful Thevenin job was and so he created a useful technique to make is life easier. The Thevenin's Theorem. We honored him by doing an example in class.

White board work of Thevenin. First step is to short voltages and open currents. Second step is to remove the resistor that takes up the a,b nodes. Third find the Rth. We found to be 4 ohms.

White board of the Thevenin circuit symbol version.

We then tried a much harder problem.

White board work of the second Thevenin example.

Another picture with the right side of the work shown.

We then move onto the lab of the day.
Thevenin's Theorem:

Left side of the white board work. Rth is 7.4k Ohms

Right side work of the White board, Va = 2.5V and Vb = 2.96, Vth = 0.46V.

Picture of circuit used on a breadboard.

Voltage measured is 0.437V, Theo was 0.46V percent error of: 5%.

Picture when load was connected to circuit, note that the voltage is half of last time which makes sense sense V is divided by two equal resistance of 7.4k ohms.

White board work, Theo is 0.23V Real is 0.21V, percent error: 8%.

The power vs load plot is missing(?Maybe Edgar has it?) not sure how to represent. Peak would be 7.4K ohms and to the left and right should be lower power. Pload = Vab^2/RL

In summary:
We learned the origins of Thevenin's Theorem and why and how useful it is in modern circuit analysis. Did a couple of examples in class. The steps required for finding Rth is to short voltages and open current sources. The steps required for finding Vth is to remove the a,b resistor if there is one and find Vth. Lastly we did a lab where we matched up Theo to Real measured values of Vab and RL compared, our percent error were low as 1% and 8%. Highest power was when Rth = RL.

D7 - Superposition and Source Transformation

We started the day with a lab so motivate people to arrive on time.
Time-varying Signals:
Prelab pictures.

Picture of the wave forms for lab. This one is of the triangle wave. Sine and square wave picture was lost.

Picture of the circuit used, r1 and r2 both 1k ohms.

Picture of waveforms together, notice the edge left on each square, feeding circuit.

White board work of equation used to derive numbers.

White board representation of the wave used to put into circuit.

The value gotten from the waveform program. This one is from the sine wave.

The value gotten from the waveform program. This one is from the triangle wave.

The value gotten from the waveform program. This one is from the square wave.

We then talked about linearity property. And then to super position. We then tried out some examples.

White board work linearity property.

Another picture showing our answer of -1.8V

We then did a superposition example.

White board work. Do one loop and then the other, and add them for the element in question.

We then worked on the second lab of the day.
Superposition 2:

Picture of the circuit used for superposition.

White page work for finding equivalent resistance by source transformations.

White page work of finding equivalent resistance for the other "side" by use of source transformations.

White board values of V expected versus measured. Percent error.

White board work with numbers of real versus measured.

Another picture with percent error.

Another picture with percent error for resistors.

Lastly we did a source transformation example in class. White board work below.

White board work of source transformation.

In summary:
We started the lab with a lab using diligent wave form. Used one waveform to feed sine, triangle and square waves and recorded their useful values such as amplitude, frequency, and period. We talked about linearity properties, superposition and source transformation and using all three can help diagnosed circuits. We did our second lab of the day with the superposition, which we took out one side of power did work, and then did the other and summed the values to get the end result. Our percent error was l% and lower for the voltages recorded.

D6 - MESH ANALYSIS and Transistors

We started the day with a quiz that required the usage of mesh. We broke apart the circuit into 3 loops and use math matrix to solve. We then talked about which tools are useful for circuit analysis and the white board.

Why choose Node: When Voltage source is easy, and is in parallel. When current source is easy, and is in series.

We then moved onto a circuit example in class. White board work shown later. We then moved onto the lab.
Nodal Analysis Multiple Source 2:
Prelab: White board work, with predictions.

White board work of schematic and prediction values.

Picture of the circuit on breadboard.

White board with real resistors values and prediction of current. Our percent error was little over 10% since we used a 22k ohm resister instead of a 20k resistor, and over all each resistor was a few ohms below rated.

We then talked about diodes and how they are a PN junction and have polarity. They have a drop of 0.7V to bypass the "gap". We then talked about a transistor. They are two types PNP and NPN. Each having a CBE, NPN are activated with postive voltage on B. PNP are activated with a negative voltage on B. Each flow must be greater than 0.6V to run a transistor. We then talked about BJT.
Ic = alpha*Ie, Ic = beta*Ib; alpha = 0.98 to 0.9999 beta = 50 to 10000
Ie = (1+beta)Ib and beta = alpha/(1-alpha)
We then worked out an example.

We transformed the transistor into equivalent circuit.

We then moved onto the last of the day.
A BJT Curve Tracer:
We followed the instruction of the lab. Pictures are not available currently.

Values calculated for the circuit.

BJT graphs, note the gummel to the left.

Matlab work needed.

Wave forms being feed from diligent.

White board work we did earlier.

White board work done earlier in class.

In summary:
We started the day with a quiz, learn what technique to use when, series use mesh, parallel use node. We then tried out our circuit analysis on a lab to see if we got the same numbers, which we did. We the talked a good amount on diodes and transistors and BJT. They all involve doping, and a minimum of 0.6V is needed to by pass that. Two types of transistors NPN and PNP, NPN is preferred. Lastly we move onto BJT gummel plot lab. Which we did and agreed with data sheet.

D5 - Nodal and Mesh Analysis

We started the class with the idea of a super node. A super node is voltage source between two nodes. Super nodes require the usage of KCL and KVL to be useful.

White board work of the first example of a super node problem.

We then moved on to the first lab of the day.
Nodal Analysis.
The prelab required the schematic drawn out with resistors values and use node analysis on it.

Could not find the white board example, here it is on the lab paper.

Here is white board work on what the voltage on Va should be, -0.0718V

Picture of our setup testing the voltage, and current of our circuit.

Data for the Nodal analysis lab, we recorded the actual resistors and ideal and then compared the currents and found our voltage percent error to be 10%.

Another picture but with all of work shown on the white board.

We then moved on to talk about mesh analysis. Mesh is a loop of current going clockwise. We apply KCL and KVL to each mesh loop. We then tried examples in class.

White board work of the mesh example. Every circuit username: Climactacus Pass: E442016

We then moved onto talking about Cramer's rule. And then closed out the day with color coding examples of resistors.

White board work of the color coding exampels of resistors. First two bands mean a number while the third means the power of it in term of tens.

More color coding examples.

More color coding examples.

Prof. Mason color coding translation of colors and names. The colors of the left were the examples done on the white board.

In summary:
We started the class with introduction of super nodes and how they become to be. A super node is a voltage source between two nodes, it can be come useful when KCL and KVL is applied to it. We spent most of the class time working on examples with node analysis, both on white boards and in lab. The lab was to show us how effective nodal analysis is when diagnosed or designing a circuit in the real world. We ended the class with into on mesh analysis and why clockwise is chosen for loops. Color coding of resistors is better than numbers because its cheaper and easier to see.