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...