CIRCUITS by Ulaby & MaharbizAll rights reserved. Do not reproduce or distribute.

© 2013 National Technology and Science Press

REVIEW OF LECTURES 01-04REVIEW OF LECTURES 01 04

06/27/2013 ECE225 CIRCUIT ANALYSIS

Summary of Chapter 1y p

All rights reserved. Do not reproduce or distribute. © 2013 National Technology and Science Press

Units, Multiples, NotationAll rights reserved. Do not reproduce or distribute. © 2013 National Technology and Science Press

, p ,

Charge & CurrentAll rights reserved. Do not reproduce or distribute. © 2013 National Technology and Science Press

g

Unit of charge = coulombg

Voltage & PowerAll rights reserved. Do not reproduce or distribute. © 2013 National Technology and Science Press

g

PowerAll rights reserved. Do not reproduce or distribute. © 2013 National Technology and Science Press

Rate of expending or absorbing energyp g g gy

ddd vidtdq

dqdw

dtdwP

Energy conservation

0P

Units: wattsUnits: wattsOne watt = power rate of one joule of work per second. 1 W = 1 A x 1 V

Passive Sign Conventiong

All rights reserved. Do not reproduce or distribute. © 2013 National Technology and Science Press

Summary of Chapter 2All rights reserved. Do not reproduce or distribute. © 2013 National Technology and Science Press

y p

Ohm’s Law

Voltage across resistor is proportional to currentVoltage across resistor is proportional to current

iR

iR

Resistance: ability to resist flow of electric current

resistivity

All rights reserved. Do not reproduce or distribute. © 2013 National Technology and Science Press

Kirchhoff’s Current Law (KCL)( )

Sum of currents entering a node is zeroSum of currents entering a node is zeroAlso holds for closed boundary

All rights reserved. Do not reproduce or distribute. © 2013 National Technology and Science Press

Kirchhoff’s Voltage Law (KVL)All rights reserved. Do not reproduce or distribute. © 2013 National Technology and Science Press

g ( )

Sum of voltages around a closed path is zeroSum of voltages around a closed path is zeroSum of voltage drops = sum of voltage rises

Resistors in SeriesAll rights reserved. Do not reproduce or distribute. © 2013 National Technology and Science Press

Equivalent resistance (series) is sum of resistances

Voltage divided over resistors (voltage divider)

Resistors in ParallelAll rights reserved. Do not reproduce or distribute. © 2013 National Technology and Science Press

Source TransformationAll rights reserved. Do not reproduce or distribute. © 2013 National Technology and Science Press

Hence,

For the two circuits to be equivalent :

R1,R2,R3=Delta

R3,R4,R5=Delta

R1,R3,R4=Y

R2,R3,R5=Y

Circuit with no two resistors sharing the same current or same voltage

All rights reserved. Do not reproduce or distribute. © 2013 National Technology and Science Press

All rights reserved. Do not reproduce or distribute. © 2013 National Technology and Science Press

Hence,

( Assuming no connection at node 3)

Simultaneous solution leads to:

All rights reserved. Do not reproduce or distribute. © 2013 National Technology and Science Press

All rights reserved. Do not reproduce or distribute. © 2013 National Technology and Science Press

Summary of Chapter 3 (Parts 1 & 2)y p ( )

All rights reserved. Do not reproduce or distribute. © 2013 National Technology and Science Press

Node-Voltage Methodg

Node 1

Node 2Node 3

Node 2

Node 3

All rights reserved. Do not reproduce or distribute. © 2013 National Technology and Science Press

Node-Voltage Methodg

Three equations in 3 unknowns:Solve using Cramer’s rule, matrixinversion or MATLABinversion, or MATLAB

All rights reserved. Do not reproduce or distribute. © 2013 National Technology and Science Press

Mesh-Current MethodAll rights reserved. Do not reproduce or distribute. © 2013 National Technology and Science Press

Two equations in 2 unknowns:Solve using Cramer’s rule, matrixinversion, or MATLAB

All rights reserved. Do not reproduce or distribute. © 2013 National Technology and Science Press

Mesh-Current Method

Mesh 1But

Mesh 2Hence

Mesh 3

Nodal Analysis by Inspectiony y p

Requirement: All sources are independent current sources Requirement: All sources are independent current sources

All rights reserved. Do not reproduce or distribute. © 2013 National Technology and Science Press

Mesh by InspectionAll rights reserved. Do not reproduce or distribute. © 2013 National Technology and Science Press

y pRequirement: All sources are independent voltage sources