Circuit Theory

This course follows on from the Circuits and Systems course offered to the first year Engineering students at ADFA. In this course the Kirchoff's current and voltage laws will be revisited and may be we will put extra emphasis on dependent current and voltage sources. Following from there we will look at RL and RC circuits and understand what do the terms natural and free response mean. Having understood what we mean by a solution we will go to the problem of the RLC circuits and analyse the circuits both for steady-state and transient analysis.

The formal course description and other supporting material will be made available from time to time.

Assignments

• Assignment 1 --- due Thur 2 April 1998.
  A partial solution as PSpice scripts is available for downloading.
A complete solution will be handed out in the Lecture or can be picked up from my office.
• Assignment 2 --- due Thur 4 June 1998.

Tutorial Documents

Please have a look at some of the Tutorial documents I have prepared to assist students in understanding some concepts and using some standard software packages.

Downloads

• MicroSim DesignLab Evaluation - Version 8.0 (16471 kb) can be downloaded from our ftp area.
  
• MicroSim DesignLab Evaluation - Version 7.1 (13624 kb) can be downloaded from our ftp area.
  

When you analyse an electrical circuit you cannot find current and voltage in only one element of the circuit without finding currents and voltages in all parts of the circuit. So before you begin to analyse any circuit you should ask yourself which all voltages or currents I need to know to know every other voltage and current. An easy answer is that you either need to know all the node voltages or loop currents to fully analyse a circuit. Having decided whether you want to go for node voltages (KCL) or loop currents (KVL) please keep the following two golden rules in mind.

1. KVL equations should have ONLY loop currents as the unknown variables.
2. KCL equations should have ONLY node voltages as the unknown variables.

In other words KCL is used to find node voltages and KVL is used to find loop currents. The most common reason for getting incorrect answers is because students declare many more unknown variables than the problem needs. For example most of the students use element currents to first write the KCL or the node equations and then they write these element currents in terms of node voltages. A sound principle in analysing circuits is to first make sure that you have as many equations as are the unknown variables. If you use more variables than are needed then you can never be sure of this since you have many redundant equations. With a little bit of practice you can write KCL directly in terms of node voltages.

Last modified: Tue Apr 14 15:46:17 1998