Laboratory Report

Lab #:0
Title:Current Division
Date Performed:January 1, 2006
Course: ECET 314 - 102
Instructor: R. L. Maybach
Per Cent Contribution
Lab Partner / Pre-lab / Lab Session / Report
Samuel Adams / 100 / 33 / 0
John Heineken / 0 / 33 / 20
Morten Tuborg / 0 / 33 / 80
Totals / 100 / 100 / 100

Table of Contents

Introduction

Equipment

Objectives

Pre-lab

Laboratory Results

Discussion

Lab Grading

Introduction

Equipment

Lab Station #3 plus TE model LCM-1951 Digital Multimeter (no serial number)

Objectives

This laboratory will help us understand current division, as well as understand the general nature of how to write a laboratory report (the second part of this sentence is for you – doesn’t have anything to do with the report). We will also practice our PSpice skills, as well as learn how to use the DVM in the laboratory.

Pre-lab

Using PSpice and circuit theory, determine the current in a 200  resistor, based on the circuit shown in Figure 1 below.

Figure 1. Circuit to be simulated.

The current through the 200  resistor can be calculated by first determining the input current (the current through the 1 kresistor) and then use current division to determine the final results.

To determine the input current, the two resistors can be combined, since they are in parallel. The formula used is

, where Rp is the parallel combination of the two resistors.

Based on the values shown in Figure 1, the parallel combination is 66 , and the input current would be:

The current in the 200  resistor, using the current division formula, is

To verify whether this answer is correct, the circuit in Figure 1 was simulated, and the following results were obtained when the bias Voltage display was enabled (Figure 2).

Figure 2 – Circuit from Figure 1 simulated with Bias Current display enabled

The simulation agreed with the calculations

Laboratory Results

The circuit shown in Figure 1 was wired; the power supply was set to 5 V; and the DVM was used to measure the exact output Voltage.

The output of the power supply was connected to a protoboard, having a 1 k resistor in series with the parallel combination of a 100  and a 200  resistor. The experiment also required that measurements be taken at 2 V and 10 V, and compared with calculations made during the lab. Data was initially recorded in a lab notebook, and later inputted into an Excel spreadsheet. For this laboratory, the resistors had a tolerance of 10%. The circuit was wired, and the following results were obtained:

Table 1. Results of experiment on the circuit in Figure 1.

Input Voltage / Current (200 )
2 / 0.60
5 / 1.50
10 / 3.00

These results were obtained by using the DVM to measure the current in each of the branches. Based on the tolerances of the resistors, an error analysis was done (assignment – you do the error analysis – this is where you should put that work). Based on the error analysis, the range for an acceptable current should be ----mA to ----mA.

Discussion

The measured current was within the tolerance range of the acceptable current values, based on the error analysis in the previous section. The calculations in the pre-lab and the PSpice simulation resulted in the same values. This laboratory provided a better understanding of the current division law, as well as using the bias Current disply in PSpice.

Lab Grading

Score / Wgt. / Item
Cover Page (3 per cent)
1 / Lab number and name
1 / Date performed
1 / Team members
2 / Table of Contents (2 per cent)
Introduction (5 per cent)
2 / Lab station number or list of test equipment with model and serial numbers
3 / Lab objectives
20 / Pre-lab (20 per cent) – simulations, calculations, and designs
Body (40 per cent) – separate section for each circuit
5 / Circuit title and function
20 / Measured response – including all the data required in the lab write-up
5 / Comparison of the theoretical and measured responses – either plotted on the same chart if they are curves or showing the per cent difference if they are individual points.
10 / Discussion – with answers to the questions and a credible explanation of any significant variations
General (30 per cent)
10 / Grammar, spelling, and punctuation
10 / Plot format – independent variable on the x-axis, dependent variables on the y-axis, legible data points and curves, labeled axes with units, linear or log scales as appropriate, figure numbers and captions
10 / Table format – appropriate number of significant digits, clear column headings, appropriate column widths and row heights, table numbers and captions
100 / Total

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