# Circuit Analysis of Linear Network and One Nonlinear Element

Topics: Ohm's law, Resistor, Light-emitting diode Pages: 13 (2406 words) Published: November 8, 2005
Circuit Analysis of Linear Network and one Nonlinear Element

ETEE3153

Experiment #4

Submitted: September 5, 2005

By, David Scott

Lab partner: Blake Griffin

Prof. Jack Carter

Submitted: 10/27/2005

Microsoft Word

OrCAD Pspice student version 9.1

Main Body
The purpose of this laboratory experiment is to learn simple techniques for analyzing a circuit with a nonlinear element. It gives details as to what methods to uses when using nonlinear elements. This experiment will give us a way to get the characteristics of the circuit through simulation and actual lab measurements.

The lab begins with describing that most our time in network analysis deal with linear circuit. In order to analyze the circuit, we have to know the characteristic of the nonlinear element and the characteristic of the circuit at the points where nonlinear elements are connected. The characteristics of a device are described as voltage vs. current. The devise must be experimentally determined by either the manufacturer or determined experimentally by a user. The characteristic of a resistor is a straight line, because voltage and current are proportional, through Ohms Law (V=IR or R=V/I). This equation shows that the slope is the value of the resistance which intercept at zero (line that passes through the origin). This information, along with a visual representation of it, is shown in the lab book with the visual representation shown in Graph 1 (Ambrose 4-1):
The DC characteristic of a network at two terminals is a DC load line which is a straight line in linear networks. The equation for the DC load line can be determined from two experimentally or calculated points. The two points are the open circuit voltage point (0, Voc) and the shout circuit current (Isc, 0) point. This information, along with a visual representation of it, is shown in the lab book with the visual representation shown in Graph 2 (Ambrose 4-2):

Once the two characteristics are know then the two curves provide the operating point (voltage and current). I. PSPICE Results
PSPICE analysis was preformed before class to get an understanding of what was to be done in the lab. Figure 1 will be used throughout this laboratory experiment to show what happens when different loads are applied to a circuit with linear elements.

The equipment that was used in this part of the lab, are as follows as described in the lab book (Ambrose 4-2):
Power Supply: Variable voltage, variable current
Ammeter: 0-10 milliampere range
Volt Meter: 0-2.5 volt range
Resistors: 10, 50, 100, 500, 1000 ohm
Diode: 1N4148 PSPICE and 1N914 in lab
LED:Red LED in lab
Before class a PSPICE simulation was preformed on Figure 1. Below in the PSPICE program from the first simulations with 0ohms as the load (represented by 2Pica ohms): R1 1 2 150
R2 2 0 300
R3 2 3 300
RL 3 0 2pohms
V1 1 0 DC 3.0V
.op
.DC V1 3 3 3
.print DC I(R1) I(R2) V(RL) V(V1) V(R2)
.probe
.end
PSPICE for 0Ohms
The next PSPICE program uses a 1000 ohm resistor as the load. This program can be seen below: R1 1 2 150
R2 2 0 300
R3 2 3 300
RL 3 0 1000ohms
V1 1 0 DC 3.0V
.op
.DC V1 3 3 3
.print DC I(R1) I(R2) V(RL) V(V1) V(R2)
.probe
.end
PSPICE for 1000ohms
Next, the circuit load was replaced with a Diode (1N4148) instead. This is seen in the PSPICE program below: R1 1 2 150
R2 2 0 300
R3 2 3 300
D1 3 0 D1N914
V1 1 0 DC 3.0V
.op
.DC V1 3 3 3
.print DC I(R1) I(R2) V(D1) V(V1) V(R2) I(D1)
.probe
.model D1N914 D(Is=168.1E-21 N=1 Rs=.1 Ikf=0 Xti=3 Eg=1.11 Cjo=4p M=.333 + Vj=.75 Fc=.5 Isr=100p Nr=2 Bv=100 Ibv=100u Tt=11.54n) .end
PSPICE for a Diode
Finally, for the last part of the PSPICE, an infinity (500Giga-ohms) resistance load across the A and B terminals. The program for this is below: R1 1 2 150
R2 2 0 300
R3 2 3 300
RL 3 0 500gohms
V1 1 0 DC 3.0V
.op
.DC V1 3 3 3...

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