Trip 2. DC Circuit Analysis
The second trip introduces the fundamentals of DC analysis. Principle of superposition, Thevenin and Norton equivalent voltage and resistance are presented. Power transfer design issues are being addressed. Nodal voltage analysis and loop current analysis are presented in theory and experiment. Finally, the behaviour of inductors and capacitors at DC is introduced. More refined functions of the Topnotch Meter are explored. Please click to preview the experiments in this Trip: 1, 2, 3, 4, 5, 6.
![1](javascript:ReplaceContentInContainer('content-exp',' <h3>Experiment 1. Extracting the DC Average</h3>
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<img src="./images/exp1MeasuringResistor.jpg" width=" 333 " align=" right" style=" float:right; padding-right:10px; padding-bottom:5px;">
<p> The goal of this experiment is to show how the DC average is being extracted from a wave in two ways: a) using solely a measurement instrument and b) using a measurement instrument and a capacitor.
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<p> <b>The Topnotch Meter</b> is set to generate a square wave. In the first part of the experiment the square wave is connected to a 10K resistor. The DC average level is measured with the Mini-Scope. Taking into account the resistor divider the value corresponds to the <b>Topnotch Meter</b> Generator settings. In the second part the square wave is connected to a 470uF capacitor. The DC level on the capacitor corresponds to Generator DC offset voltage.
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![2](javascript:ReplaceContentInContainer('content-exp',' <h3>Experiment 2. Principle of Superposition</h3>
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<img src="./images/exp2PSuperScope.JPG" width=" 333 " align=" right" style=" float:right; padding-right:10px; padding-bottom:5px;">
<p> The objective of this experiment is to illustrate the principle of superposition. A simple circuit is constructed where two sources are superposed: a 9V battery and the <b>Topnotch Meter</b> Generator. A test voltage is measured and proven to be a linear combination of the two sources. A theoretical calculation is performed as well. The theoretical and experimental values of the test voltage are compared. The Generator value is swept over a range of values meant to prove the superposition concept.
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<p> The principle of superposition has far reaching consequences. This experiment demonstrates a simple practical application of this principle.
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![3](javascript:ReplaceContentInContainer('content-exp',' <h3>Experiment 3. Thevenin Equivalent - Power Transfer</h3>
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<p> The goal of this experiment is to demonstrate the role of the Thevenin equivalent circuit as well as the power transfer theorem. A simple circuit with 5 resistors is powered from a 9V battery. The first goal is to find the Thevenin equivalent voltage and the Thevenin equivalent resistance using both theory and measurement. After this step is completed the resistance for optimum power transfer is demonstrated to be the Thevenin equivalent resistance. The power transferred is measured for several resistors and the maximum value is obtained for the Thevenin resistance. Details such as the real, measured value of the battery are taken into consideration.
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![4](javascript:ReplaceContentInContainer('content-exp',' <h3>Experiment 4. Nodal Analysis</h3>
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<p> The goal of this experiment is to introduce Thevenin equivalent computed using Nodal Analysis. This time a slightly more complex circuit formed with 7 resistors has to be analyzed. The Thevenin equivalent resistance and the Thevenin equivalent voltage are computed using theoretical nodal analysis, LTSpice and Matlab. Agreement must be obtained between the Thevenin equivalent voltages and resistances measured, computed using hand analysis, computed using Matlab and simulated using LTSpice.
The student is introduced to the free simulator LTSpice which is used during the entire adventure. The mathematical software Matlab is not free but it is available for evaluation purposes.
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![5](javascript:ReplaceContentInContainer('content-exp',' <h3>Experiment 5. Loop Analysis</h3>
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<img src="./images/exp5VTH.jpg" width=" 333 " align=" right" style=" float:right; padding-right:10px; padding-bottom:5px;">
<p> The goal of this experiment is to introduce Thevenin equivalent computed using Loop Analysis. A circuit formed with 7 resistors has to be analyzed. The Thevenin equivalent resistance and the Thevenin equivalent voltage are being computed using theoretical loop analysis, LTSpice and Matlab. Agreement must be found between the Thevenin equivalent voltages and resistances measured, computed using hand analysis, computed using Matlab and simulated using LTSpice.</p>
<p> This experiment complements Trip 2 Experiment 4. The nodal analysis is based on KCL and the loop analysis is based on KVL. The two analysis methods are fundamental.
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![6](javascript:ReplaceContentInContainer('content-exp',' <h3>Experiment 6. L and C at DC</h3>
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<img src="./images/exp6LandCatDC.JPG" width=" 333 " align=" right" style=" float:right; padding-right:10px; padding-bottom:5px;">
<p> Although this trip is named DC analysis it ends by introducing frequency dependent devices namely inductors and capacitors. The goal of this experiment is to present the behaviour of inductors, whose symbol is L, and the behaviour of the capacitors, whose symbol is C, at DC. While an electronics engineer should know that at DC an inductor is a short circuit and a capacitor is an open circuit, this experiment presents a circuit where these two fundamental facts can be tested.
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<p> The early introduction of frequency dependent devices serves also as a bridge for the following trip which studies Ls and Cs in more detail and in the context of signal transforms.
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Experiment 1. Extracting the DC Average
The goal of this experiment is to show how the DC average is being extracted from a wave in two ways: a) using solely a measurement instrument and b) using a measurement instrument and a capacitor.
The Topnotch Meter is set to generate a square wave. In the first part of the experiment the square wave is connected to a 10K resistor. The DC average level is measured with the Mini-Scope. Taking into account the resistor divider the value corresponds to the Topnotch Meter Generator settings. In the second part the square wave is connected to a 470uF capacitor. The DC level on the capacitor corresponds to Generator DC offset voltage.