Download presentation

Presentation is loading. Please wait.

1
LectR1EEE 2021 Exam #1 Review Dr. Holbert February 18, 2008

2
LectR1EEE 2022 Basic Circuit Analysis Methods While Obeying Passive Sign Convention Ohm’s Law; KCL; KVL Voltage and Current Division Series/Parallel Resistance combinations

3
LectR1EEE 2023 Default Sign Convention Passive sign convention : current should enter the positive voltage terminal Consequence for P = I V –Positive (+) Power: element absorbs power –Negative (-) Power: element supplies power Circuit Element + – I

4
LectR1EEE 2024 Ohm’s Law V = I R The Rest of the Circuit V I + – R

5
LectR1EEE 2025 KCL (Kirchhoff’s Current Law) The sum of currents entering the node is zero: Analogy: mass flow at pipe junction i1(t)i1(t) i2(t)i2(t)i4(t)i4(t) i5(t)i5(t) i3(t)i3(t)

6
LectR1EEE 2026 KVL (Kirchhoff’s Voltage Law) The sum of voltages around a loop is zero: Analogy: pressure drop through pipe loop v1(t)v1(t) + + – – v2(t)v2(t) v3(t)v3(t) +–+–

7
LectR1EEE 2027 KVL Polarity A loop is any closed path through a circuit in which no node is encountered more than once Voltage Polarity Convention –A voltage encountered + to – is positive –A voltage encountered – to + is negative

8
LectR1EEE 2028 In General: Voltage Division Consider N resistors in series: Source voltage(s) are divided between the resistors in direct proportion to their resistances

9
LectR1EEE 2029 In General: Current Division Consider N resistors in parallel: Special Case (2 resistors in parallel)

10
LectR1EEE 20210 Equivalent Impedance If we wish to replace two parallel resistances with a single resistor whose voltage-current relationship is the same, the equivalent resistance has a value of: Parallel elements share the same two (distinct) end nodes

11
LectR1EEE 20211 Steps of Nodal Analysis 1.Choose a reference (ground) node, V=0. 2.Assign node voltages to the other nodes. 3.Apply KCL to each node but the reference node; express currents in terms of node voltages. 4.Solve the resulting system of linear equations for the nodal voltages. V1V1 V2V2 R

12
LectR1EEE 20212 Steps of Mesh/Loop Analysis 1.Identify mesh (loops). 2.Assign a current to each mesh. 3.Apply KVL around each loop to get an equation in terms of the loop currents. 4.Solve the resulting system of linear equations for the mesh/loop currents. I1I1 +– VRVR I2I2 V R = (I 1 – I 2 ) R R

13
LectR1EEE 20213 Nodal and Loop Analyses Nodal Analysis Recipe 1&2) Identify and label N nodal voltages plus the ground node (V=0) 3) Apply KCL at N nodes (supernode makes constraint eq.) 4) Solve for the nodal voltages Loop Analysis Recipe 1&2) Identify and label M mesh currents 3) Apply KVL at the M meshes (a current source makes a constraint equation) 4) Solve for the mesh currents

14
LectR1EEE 20214 Superposition Procedure 1.For each independent voltage and current source (repeat the following): a)Replace the other independent voltage sources with a short circuit (i.e., V = 0). b)Replace the other independent current sources with an open circuit (i.e., I = 0). Note: Dependent sources are not changed! c)Calculate the contribution of this particular voltage or current source to the desired output parameter. 2.Algebraically sum the individual contributions (current and/or voltage) from each independent source.

15
LectR1EEE 20215 Source Transformation A voltage source in series with a resistor is transformed into a current source in parallel with that resistor; and vice versa. VsVs RsRs IsIs RsRs +–+–

16
LectR1EEE 20216 Basic Approach to Finding the Thevenin/Norton Equivalent Circuits with independent sources: –Find V oc and/or I sc –Compute R Th (= V oc / I sc ) Circuits without independent sources: –Apply a test voltage (current) source –Find resulting current (voltage) –Compute R Th (= V test / I test )

17
LectR1EEE 20217 Thevenin/Norton Equivalent R Th V oc Thevenin equivalent circuit +–+– R Th Norton equivalent circuit I sc

18
LectR1EEE 20218 Op Amps Generally apply KCL or nodal analysis Ideal Op-Amp Relations i – = 0 = i + v – = v + + –

Similar presentations

© 2021 SlidePlayer.com Inc.

All rights reserved.

To make this website work, we log user data and share it with processors. To use this website, you must agree to our Privacy Policy, including cookie policy.

Ads by Google