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Lecture 3 : Resistive Circuits & Nodal Analysis Nilsson 3.3, 3.4, 3.7, 4.1-4.4. ENG17 (Sec. 1): Circuits I Summer 1 2014. June 25, 2014. Overview. Voltage Divider Current Divider Voltage / Current Division Δ-to-Y Equivalent Circuits Node Voltage Method NVM w/Dependent Sources
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Lecture 3:Resistive Circuits & Nodal AnalysisNilsson 3.3, 3.4, 3.7, 4.1-4.4 ENG17 (Sec. 1): Circuits I Summer 1 2014 June 25, 2014
Overview • Voltage Divider • Current Divider • Voltage / Current Division • Δ-to-Y Equivalent Circuits • Node Voltage Method • NVM w/Dependent Sources • NVM Special Cases
Voltage Divider • One voltage supply, multiple voltage levels
Load • RL = load = 1+ circuit elements that draw power from circuit • May alter voltage across parallel element • But not if RL >> R2
Example • Wheatstone Bridge • 2 voltage dividers in parallel
Overview • Voltage Divider • Current Divider • Voltage / Current Division • Δ-to-Y Equivalent Circuits • Node Voltage Method • NVM w/Dependent Sources • NVM Special Cases
Current Divider • One current supply, multiple current levels
Example • Similar analysis
Overview • Voltage Divider • Current Divider • Voltage / Current Division • Δ-to-Y Equivalent Circuits • Node Voltage Method • NVM w/Dependent Sources • NVM Special Cases
Voltage Division • Generalization of voltage divider circuit
Current Division • Generalization of current divider circuit
Overview • Voltage Divider • Current Divider • Voltage / Current Division • Δ-to-Y Equivalent Circuits • Node Voltage Method • NVM w/Dependent Sources • NVM Special Cases
Unable to get Req • For example, Wheatstone bridge circuit (below) cannot be simplified with standard parallel/series rules • Must use circuit transformation
Defining Delta/Pi and Y/T π Δ T Y
Delta-to-Wye Circuit Transformation • Equivalent resistance between nodes • Note: resistor values are NOT THE SAME
Recap • Voltage Divider • Current Divider • Voltage / Current Division • Δ-to-Y Equivalent Circuits • Node Voltage Method • NVM w/Dependent Sources • NVM Special Cases
Planar Circuit Not Planar Planar Nodal good for either Mesh good for planar
Identify • Node • Essential Node • Path • Branch • Essential Branch • Loop • Mesh
Simultaneous Equations • How many unknown currents? • How many equations needed?
Node Voltage Method – Setting Up • Identify essential nodes • Define reference node • Apply KCL to each non-reference node, express current in terms of node voltages • Solve simultaneous equations
Overview • Voltage Divider • Current Divider • Voltage / Current Division • Δ-to-Y Equivalent Circuits • Node Voltage Method • NVM w/Dependent Sources • NVM Special Cases
Dependent Sources • Only need to add equation to describe relationship of the dependent source
Overview • Voltage Divider • Current Divider • Voltage / Current Division • Δ-to-Y Equivalent Circuits • Node Voltage Method • NVM w/Dependent Sources • NVM Special Cases
Recap • Voltage Divider • Current Divider • Voltage / Current Division • Δ-to-Y Equivalent Circuits • Node Voltage Method • NVM w/Dependent Sources • NVM Special Cases