Ensc2001 Circuits Notes

ENSC1002 Information 4 Info Session Summary Notes

4.0 Network Analysis

4.1.1 Source Transformation

* A current source is connected in parallel with a resistor Rs may be replaced by a voltage source Vs = IsRs connected in series with the resistor Rs (or vice versa)

* We can only use source transformation if the circuit has a voltage source in series with a resistor or current source in parallel with a resistor. If these conditions are not satisfied, then we must choose a different method or solve the circuit.

* Circuits made up of only independent sources and resistors that also contain inductors and capacitors are linear systems. Feature of a linear system is that if it is driven by several independent sources, then the total response to all the sources can be calculated by finding the response to each of these sources and adding them.

* An ‘off’ voltage source is a zero voltage source or short circuit, while turning off a current source makes it a zero ampere current source or open circuit

* An open circuit is a current source of zero amperes. No current through it no matter how many volts are across it. An open circuit is depicted as a broken connection between two points

4.1.3 Nodal Analysis

* The node voltage and the mesh current analysis are systematic procedures that arrive at a minimum number of simultaneous equations. These may then be solved, and calculate voltages and currents

* Nodal Analysis consists of the following steps: 1) Find all the connection points 2) Choose one of these nodes as a reference node. Choose one with the most connections or a node that appears at the bottom of the diagram 3) At the other nodes, define and label each node voltage as the voltage rise from the reference node to that node 4) For each node write KCL, but in terms of node voltages and resistor values. i =VabR = Va-VbR ; between two nodes a & b 5) Solve the simultaneous equations for the node voltages 6) Each branch voltage can then...