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.