The George Washington University
School of Engineering and Applied Science
Department of Electrical and Computer Engineering
ECE 11 - LAB
Experiment # 1
Resistor color code, Solderless prototype breadboard
and PSPICE simulation
Equipment:
Name
Keithley Model 175
Digital Multimeter
(DMM)
Pair of Banana to
mini-grabber test
leads
Prototype Bread
Board
Specifications
http://www.seas.gwu.edu/~ecelabs/appnotes/PDF/equipment/k175.pdf
NONE
NONE
Table 1.1
Components:
Kit Part #
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Spice Part
Name
R
R
R
R
R
R
R
Part Description
Symbol Name
(used in schematics
throughout this lab manual)
9.1 Ω Resistor
200 Ω Resistor
3.9 KΩ Resistor
5.6 KΩ Resistor
750 KΩ Resistor
4.7 MΩ Resistor
8.2 MΩ Resistor
Table 1.2
R1
R2
R3
R4
R5
R6
R7
Objectives:
•
•
•
•
To determine the resistance values and tolerance of the given resistors by using the color
code
To measure resistance with Keithley Model 175 Digital Multimeter (DMM) and find the %
error
To use a solderless prototype bread board
To simulate dc series circuit with PSPICE
GWU SEAS ECE Department ©2010
ECE 11 – Experiment #1
Page 1 of 6
Prelab: (Submit electronically prior to lab meeting, also have a printed copy for yourself during lab)
1. Read through lab.
2. Download and Print the color code http://www.seas.gwu.edu/~ecelabs/appnotes/rcc/rcc.html
Resistance Reading Steps:
a) Find the tolerance band, which is typically gold (5%) and sometimes silver
(10%), and hold the resistor such that this band is at your right-hand side
b) Starting from the other end, identify the first band at your left-hand side, write down
the number associated with that color, for example, in the case of blue, write down
‘6’. Then identify the color band next to it, for example if the second band is red, write
down a '2' next to the ‘6’. The first two bands are called digit bands.
c) Read the third or multiplier band and write down that number of zeros, for example,
if the band is green, multiply the number indicated by the digit bands with 10^5.
The resistance of the resistor in this example, color coded by ‘blue-red-green-gold”
is 62*10^5 Ω = 6.2MΩ with a 5% tolerance.
Tolerance band
A perfect linear resistor has a constant resistance independent of current, voltage,
temperature and other factors. In reality, no resistor is perfect and even two resistors
with the same marked value may have several percent differences if measured.
Therefore, in addition to their value, resistors are marked with an indication of
inaccuracy, called tolerance, measured in percent. Most resistors have a tolerance of
5%, but if needed, resistors down to 1% are available. For example, if the nominal
value is 100 Ω and the tolerance is 5%, the measured value could be between 100*(15%) and 100*(1+5%) Ω, i.e. between 95 and 105 Ω.
Fill the following table
Resistor’s color
code
brown-blackbrown-silver
green-blue- brown
-gold
white-black-violetsilver
Nominal
Resistance (Ω
Ω)
Tolerance (%)
Possible measured
value range (Ω
Ω)
Table 1.3
3. Fill the last column of the below table about units of physical parameters
Physical
Parameters
Current (I)
Voltage (V)
Power (P)
Resistance (R)
Primary Unit
Secondary Unit
Ampere (A)
Volt (V)
Watt (W)
Ohm (Ω)
mA, µA
mV
mW
kΩ, MΩ
Table 1.4
Relationship between primary
and secondary units
1 A=
mA=
µA
1 V=
mV
1 W=
mW
1 Ω=
kΩ=
MΩ
4. Memorize the following in the event of a pre-lab quiz:
a) The resistor color code
b) The units of the above physical parameters
c) Ohm’s Law
GWU SEAS ECE Department ©2010
ECE 11 – Experiment #1
Page 2 of 6
Lab:
Part I – Resistance Measurement
a. Use the resistor color code to determine the nominal resistor value and the nominal
tolerance for the following resistors: R1 - 9.1 Ω, R2 - 200 Ω, R3 - 3.9 KΩ, R4 - 5.6 kΩ, R5
- 750 KΩ, R6 - 4.7 MΩ, R7 - 8.2 MΩ
b. Use the DMM to measure the actual value of the resistor
Measuring steps:
1. Switch on the Keithley 175 multi-meter
2. Switch measure resistance by pressing the Ohm (Ω) button
3. Enable “Auto Range” in order to get the maximum number of significant digits during
measurement
4. Hold the resistor in your left hand and connect one end of a banana-to-mini-grabber
cable to the instrument and the other end to the resistor
5. Record the resistance (value and corresponding units) from the LCD screen
c.
Calculate Percentage Error
For a given resistor, we can measure the percentage difference between its nominal (or
expected) resistance and measured resistance, which is called percentage error, using
the following formula:
PE =
| NV − MV |
* 100%
NV
PE stands for percentage error, NV for nominal value and MV for measured value.
d. Complete Table below using steps described above.
Resistor
Reference
Designator
R1
Color Code
Nominal
Resistance
(Ω)
Tolerance
( %)
Measured
Resistance
(Ω)
Percent
Error
(%)
R2
R3
R4
R5
R6
R7
e. Do all the resistors fill within the tolerance indicated by the color code?
GWU SEAS ECE Department ©2010
ECE 11 – Experiment #1
Page 3 of 6
Part II – Solerless prototype breadboard
Fig 2.1 – Physical top view of breadboard
Fig 2.2 – How the holes are interconnected in the breadboard internally
We use solderless breadboards (Fig 2.1) to connect components and build circuits in ECE 11. In
a circuit, the legs of components are placed in the holes (the sockets). The holes are made so
that they will hold the component in place. Each hole is connected to one of the metal strips,
depicted in yellow (Fig 2.2), running beneath the board.
There are 4 rows or strips connecting the holes on the top of the board and several columns in
the middle. Each row and column forms a node. A node is a point in a circuit where two or more
components are connected. On the breadboard, a node is the row or the column of holes that are
connected by the strip of metal underneath.
The long top and bottom row of holes are usually used for power supply connections. The rest of
the circuit is built by placing components on the breadboard and connecting them together with
jumper wires. When a path is formed by wires and components from the positive supply node to
the negative supply node, we can turn on the power and current flows through the path and the
circuit comes alive.
Chips with many legs (ICs) are placed in the middle of the board so their legs are on different
nodes.
a. Use the Ohm function of the Keithley Model 175 to verify the connection of the
breadboard. [Hint] If the resistance between two nodes in the board is 0 Ω, that means
that two nodes are connected. If the resistance is too high (OverLimit), two nodes are not
connected. Call the GTA over to show how you verified the breadboard’s
connections.
GWU SEAS ECE Department ©2010
ECE 11 – Experiment #1
Page 4 of 6
Part III - Cadence PSPICE simulations
Circuit 4-1a
Circuit 4-1b
Circuit 4-2
Your GTA will give a short demonstration on how to use Cadence PSPICE. Once this is
complete, perform the following steps:
a. Through simulation, find the current through each resistor of Circuit 4-1a. Calculate the
voltage drops using ohm’s law as well as node voltage difference. Form a table to show
the results.
b. Through simulation, find the current through each resistor of Circuit 4-1b. Calculate the
voltage drops using ohm’s law as well as node voltage difference. Form a table to show
the results. How does the position of the GND node affect your simulation result? How
does the location of ground affect the currents, node voltages or voltage drops?
c.
Through simulation, find the current through each resistor of Circuit 4-2. Calculate the
voltage drops using ohm’s law as well as node voltage difference. Form a table to show
the results.
GWU SEAS ECE Department ©2010
ECE 11 – Experiment #1
Page 5 of 6
Part IV - Lab Writeup:
In your report you are expected to give solutions to the exercises in all 3 parts of the lab. Follow
the lab report format posted on the ECE11 class website. Include your simulations as well as all
your hand calculations for each circuit in your report.
GWU SEAS ECE Department ©2010
ECE 11 – Experiment #1
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