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TABLE OF CONTENTS
Section
Preface
Description
Page #
Provides credentials for the manual and the features
that the manual has to offer
Proclaims the goal and intentions of the manual and
lists general warnings you should be aware of
2
Introduction
and Warnings
Parts and Tools Individually explains and shows the workings behind
each tool and part used within the manual
Description
Provides a brief description of how all of the listed
Circuit
parts work together to accomplish the circuit’s task
Rundown
Provides a table listing part numbers and a web link
Parts List
Walkthrough/
Instructions
Glossary and
Index
Sources
4
6
14
17
for ordering and the circuit’s overall cost
Contains instructions that demonstrate how to
construct the physical circuit
18
Displays a list of defined terms used within the
manual and page numbers for each definition
28
Gives credit to all of the sources used to construct
this manual
30
1
PREFACE
Adequate research and resources have been utilized to construct this
technical manual on how to create a digital circuit. The research and resources
used come from a combination of primary and secondary resources. The
secondary research conducted for the manual was foremost geared towards the
first two main sections of the manual: the description of tools and parts and quick
circuit rundown sections. These secondary resources provided an additional pool
of information that helped to describe the functions of the parts used within the
specified circuit. In addition, these secondary resources were integral in fostering
the author’s understanding of how to correctly wire the circuit. They were also
extensively used as a guide in constructing the circuit before actually writing the
instructions. To build a stronger foundation for the writing of this manual, the
circuit was constructed a second time before the manual’s instructions were
articulated.
For the overall construction and practicality of the manual, an interview
and group usability test were performed to test, edit, and perfect the manual. To
help construct and improve this manual, an interview was conducted with a
current electrical engineer. Dr. Kam Yee, an expert in electronic hardware design,
has provided aid for the embellishment of this manual. By conducting such an
interview, substantial information has been added to this manual in order to
perpetuate your success and satisfactory. To substantiate this manual’s credibility
and practical success, a group usability test was performed in which a group of
individuals followed the manual’s instructions and created the circuit themselves.
The individuals had no working knowledge of electronics or logic design and were
successful in completing the circuit construction. To adhere to this manual’s
primary intentions, the group of individuals reframed from reading the
educational sections (the first two main sections mentioned above) of the manual
before constructing the circuit. This shows that an individual can jump directly to
the walkthrough describing how to make the circuit and still be successful in
creating it. Therefore any individual, regardless of their previous background and
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knowledge, can construct this circuit using my manual. The usability test has been
successful in showing that the manual is free from technical issues and is eminent
in user satisfactory.
This manual has been constructed with additional features to help guide
you in constructing the circuit. The manual includes a parts table that assists the
reader in locating and ordering the specific parts and tabulates the approximate
cost of the circuit. To further increase the clarity of the manual, the text has been
formatted to a size 14 font (relative to Microsoft Word’s standards) and has
enlarged images for enhanced visibility. The manual includes a large assortment
of images to guide you throughout the circuit construction process and includes a
brief glossary to quickly locate specific terms used throughout the educational
portion of the manual.
Lastly, I would like to thank Professor Kam Yee for his assiduous guidance
throughout the creation of this manual. I also owe gratitude to Jeff Clark and
Barbara Clark for their participation in the usability test and their valuable
feedback on how to embellish the manual. In addition, I would like to thank you,
the user of this manual, for utilizing this manual and getting engaged in
electronics. It is within my best wishes that you enjoy creating this circuit and gain
something meaningful out of the experience!
3
INTRODUCTION
This manual has been constructed to encompass a large range of interests.
The two primary goals of this manual are to help you construct a physical circuit
that can count the number of switches turned “on” and to give you a brief
education on how each of the circuit’s components work and how they all work in
conjunction. However, this manual has been constructed so that you can
construct the physical circuit without having to delve into its mechanics. The
manual contains three main parts. The first one is a description and explanation
of the parts and tools that will be used throughout the creation of the physical
circuit. The second main section gives a very brief run-down on how all of the
parts listed in the previous section (the first main section stated above) work in
conjunction to accomplish the circuit’s primary function. Lastly, the third main
section of this manual is the actual walkthrough on how to construct the physical
circuit.
Depending on your level of interest and pre-existing knowledge, you may
skip directly to the construction of the circuit or you may wish to obtain a quick
understanding of how the circuit works before you construct it. Either way, it is
the intention of this manual to allow its user, regardless of their existing
knowledge of electronics and logic, to be able to jump directly to making the
circuit. The first two main sections are optional and are for individuals who have
limited knowledge with electronics. Expect to take several hours to construct this
circuit. Also, it is very likely for you to misplace a wire in the circuit due to the
complexity of the wiring. It is a good idea to frequently check your port
connections after every step. Troubleshooting techniques are not covered in this
manual so pay close attention to your connections. Please take heed of the
warnings listed on the next page as well. I hope that you, as the reader/user of
this manual, thoroughly enjoy constructing this basic logical circuit.
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!!!WARNINGS!!!
1. Please keep the circuit parts out of the reach of children. These parts are
extremely small and pose a significant choking hazard to young children.
Supervision by an individual over the age of 18 is strongly advised for
individuals younger than 10 years of age working on this circuit.
2. Make sure to always use a resistor when needed (this limits the circuit’s
current). Do not hook the electronic components directly to the nine volt
battery. The unrestrained current can damage the parts used (this
happened to the seven segment display during the construction of this
manual).
3. Do not connect any of the electronic components directly to the nine volt
battery even with a resistor in place. This may damage the chips and seven
segment display used. The voltage must be dropped down to five volts for
this circuit.
4. Keep track of your circuit parts and wire segments and make sure to clean
your work area when you are done working on the circuit. The many pin
connections and wire segments used can easily penetrate a foot.
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DISCRITPTION OF PARTS AND TOOLS
Breadboard:
A breadboard is a circuit board that has pre-wired contacts hidden beneath
its surface. The purpose of a breadboard is to allow its user to create prototype
electrical circuits before implementing a permanent circuit. The advantage of
using a breadboard is that it is easy to manipulate and install electrical
components without the need of soldering utensils that result in permanent
connections. The breadboard displayed in figure A is a typical breadboard as seen
in many electronics stores. As seen in figure A, a breadboard consists of a port
grid that contains columns (A-J on two sides of the breadboard shown) and rows
(1-63 on the breadboard shown). In the center are two additional columns, one
marked with a red strip and the other marked with a blue strip. These provide
leads for power (the red strip) and ground (the blue strip) connections. For the
two middle rows, power is distributed through the entire column. This means that
any wire connected into one of these ports will be directly hooked up to either
power or ground. Unlike the center columns, the outer port grids to the left and
right of the middle columns distribute connections along each horizontal row. In
other words, if components on the breadboard have a lead that lies on the same
row, any power distributed to this row is shared by all of the components. To
illustrate the general idea behind a breadboard, figure B shows how power is
distributed to some LEDs (light emitting diodes) in order to light them up. Notice
that all three LEDs are lit up because their leads are connected to the same
horizontal row (they all receive power).
LED leads
are in the
same row!
(Figure B)
(Figure A)
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Four Bit Adder:
The four bit adder chip in essence takes four bits (or digits) from two binary
numbers and adds them together (see figure C). The four bit adder chip takes in
nine different inputs and produces five distinct outputs. Of
the nine different inputs, four are from the first number to be
added, four are from the second number to be added, and
(Figure C)
one is from an initial carry that ripples through the adder.
With regards to the outputs, four are sum bits and one is an output carry. In this
case, the four sum bits together represent, in total, the resulting binary number
after adding the two initial numbers together. The end carry/output carry
represents the most significant bit of the resultant output number.
The four bit adder chip diagram shown in figure D contains 16 different
pins. The pins labeled A1, A2, A3, and A4 are pins reserved for the incoming bits
of the first binary number where A4 is the most significant bit and A1 is the least
significant bit of the represented binary number. In a similar fashion, B1, B2, B3,
and B4 are pins reserved for the corresponding bits of the second number to be
added. C0 and C4 represent the input carry and output carry respectively. The
pins labeled with a ∑ symbol represent the output sum bits. Again, ∑4 represents
the most significant bit and ∑1 represents the least significant bit of the output
number. Lastly two pins remain, those labeled Vcc and GND. For these two pins,
the pin labeled Vcc is reserved for a connection to a power source (usually the
positive end of a battery) and the pin labeled GND is reserved for a connection to
ground (usually the negative end of a battery).
(Figure D)
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Resistor:
Resistors are used within circuits to limit the amount of current that flows
through a circuit (see figure E). Current can be easily thought of as
the rate at with electrons (or charge) flows through a circuit. The
(Figure E)
higher the current, the more electrons (and thus charge), that
passes by a given spot in a circuit. For many electronic components, resistors
must be used to prevent damage to the parts. If too large a current flows through
a given circuit component, the component may be destroyed or malfunction and
produce incorrect results. The Ohm is the general unit used to measure
resistance. For our general purpose, we will be using 750 Ohm resistors to reduce
the amount of current flowing into our chips and seven segment display unit.
On the surface of any resistor are four bands of color. Table 1 shows the
corresponding numbers that each color on the resistor stands for. The first two
bands on the resistor are the first two corresponding digits of the resistor’s
resistance. The third band on the resistor acts as a multiplier that multiplies the
first two digits of the resistance by a specified power of ten. The fourth band
represents the tolerance of the resistor in terms of percent and specifies by how
much the resistance of the resistor may deviate from its stated value. As an
example and using table 1 to reference colors, a resistor having a color display of
yellow, blue, brown, and sliver respectively has a total resistance of 460 Ohms
and a tolerance of ten percent. The first two colors yellow and blue represent the
number 46, while the third color (brown) multiplies the first two numbers by ten
(see table 1).
Table 1:
The column labeled number represents the
corresponding number for each type of color for the
first two bands found on a resistor. The column
labeled multiplier represents the specific power of
ten that the first two digits are to be multiplied by
and is for the third band on a resistor. The column
labeled tolerance gives the specific percentage of
deviance that the resistor may vary by in terms of
resistance. This is the fourth band on a resistor.
(Table 1)
8
Seven Segment Display Unit:
A seven segment display uses seven separately lit segments to represent a
number, letter, or symbol. A seven segment display unit diagram is
shown in figure F. Each segment is designated to a letter
representation. Various segments of the display are lit individually
to produce a desired pattern of light. For example, if we wanted
(Figure F)
the seven segment display to represent the number 3, we would
want the segments labeled a, b, c, d, and g to be lit while the other
segments remain blank. The seven segment display also includes an
optional eighth segment that acts as a decimal representation. Logic
circuits can be used in conjunction with seven segment displays (as
in our case creating this circuit). This can allow a seven segment
display unit to change its representation with regards to the power
(Figure G)
being supplied to the different segments it contains.
As shown in figure G, the actual seven segment display has ten pin
connections. Seven of the leads (pin connections) are for the seven segments, one
lead is for the decimal segment, one lead is to be hooked up to ground (the
negative end of the battery) and one lead is another optional ground connection.
Figure G shows what each lead affects (notice that they are not so neatly in
order). In this diagram, dot stands for the decimal point connection and com
stands for the grounding connection.
8-Position DIP Switch:
An 8-position dip switch (see figure H) is nothing more than an array of
eight separate switches aligned together. The unit contains
eight separate toggle switches labeled 1-8 on the surface of
the unit. In total, the switching unit contains 16 pin
connections, two for each switch. The overall unit can be
thought of as eight switches running in parallel together with
(Figure H)
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each individual switch’s set of two leads paralleling the others. The switching unit
contains two rows of pins overall. Each row contains one pin connection for each
of the eight switches. To hook up just one individual switch, one would simply
hook up the corresponding pin connections from both rows to the proper switch.
In figure H, the second row of pins is hidden from view but is located on the
opposite side of the switch. If you do not need to use all of the switches, the other
pins simply receive no wiring connection.
BCD to Seven Segment Converter Chip
A BCD to Seven Segment Converter Chip (see figure I) takes any number
coded in BCD and produces outputs that can readily be
hooked up to a seven segment display unit (see the
description on a seven segment display unit listed in this
(Figure I)
section). BCD stands for binary coded decimal and is an
intermediate means by which both humans and computers can interpret a
represented number easily. Computers use a binary system to perform functions
(one that just uses the numbers 0 and 1 only) while humans use the decimal
system (a system that is based on powers of 10) to perform and interpret
arithmetic. BCD is essentially a coding system that is represented in binary but at
the same time breaks a large binary number into smaller segments in which a
human can better understand. The code contains four binary digits (the digits can
only be a 0 or 1 as stated earlier) that can represent a number from zero to nine.
Instead of viewing a very long binary number and having to translate the large
number back into a decimal number, in BCD, one only needs to analyze each
individual strand of four digits to decipher a number contained between zero and
nine. The BCD to seven segment converter chip takes such a
represented number and distributes a current to specific
segments of a seven segment display in order to produce a
physical number displayed in decimal (our nature
(Figure J)
10
representation of numbers).
As seen in figure J, the converter chip has 16 pins in total. However, we will
be particularly interested in only 13 of these pins. Again, from figure J, we see
that on the left side of the chip there are four pins labeled A, B, C, and D. These
letters represent the pins that contain the inputs to the chip for the incoming BCD
number representation. The order of the bits is D, C, B, and A with D being the
most significant digit of the number and A being the least significant digit of the
incoming BCD number. The pin labeled GND represents ground and will be
connected to the negative terminal of the battery. We will disregard the other
pins on this side of the chip for our project. On the right side of the chip are pins
labeled a, b, c, d, e, f, and g. These pins are the outputs of the chip that are to be
connected to the seven segment display. Each letter of a particular pin coming
from the output of the converter is to be connected to that same letter
representation on the seven segment display chip. For example, the output pin
labeled a on the BCD converter is to be hooked up to the pin labeled a on the
seven segment display unit. The remaining pin labeled Vcc simply tells us to hook
that particular pin to our power source (the positive end of our battery).
9 Volt Battery
A nine volt battery will be used in this project to provide our circuit with
power (see figure K). A battery provides a particular
circuit with a voltage or potential difference. This
voltage (or potential difference) can be viewed as the
pressure that forces electrical charge to flow through the
(Figure K)
circuit. Electrons (what electrical flow consists of)
conventionally travel from a source of high potential energy to a source of lower
potential energy. A battery provides this difference in potential energy for us.
With one terminal of a battery having a higher amount of potential energy than
the other terminal, electrons readily flow from the high potential energy terminal
on the battery to the lower potential energy terminal. The normal electrical
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convention today has the positive side of the battery represent the terminal with
high potential energy and the negative side of the battery represent the terminal
with the lower potential energy. Thus, we conventionally say that current flows
from the positive end of a battery to the negative end of a battery in a given
circuit. Viewing the positive side of a battery as the starting point in an electron’s
journey to the battery’s negative end, the positive side of a battery is referred to
as power. If within this manual you are instructed to connect a wire to power, this
means to hook the wire up to a path that leads to the positive terminal of the
battery. If you are instructed to connect a wire to ground, this means to connect a
wire to a path that leads to the negative terminal of the battery. In many
electronic components, for example, a pin connected to power is where current
(electron flow) enters the component and a pin connected to ground is where
current leaves the component.
5 Volt Regulator
The five volt regulator (see figure L) takes a higher voltage from a given
battery and steps it down to a voltage of five volts. For this
project, it will take the nine volts coming from our battery and
produce an output of five volts (see the section labeled battery
(Figure L)
to get a better understanding of a battery and voltage). This
step-down in voltage is imperative because it will be protecting our chips (the full
adder and BCD to seven segment converter) from damage due to an excessive
voltage. This also, in turn, will reduce the circuit’s current (electron flow) as well.
The voltage regulator has three simple pins. With the black square on the
regulator (the actual chip) facing the viewer as in figure L, the pin on the left side
of the regulator is to be connected to power (the positive end of the battery). The
pin in the middle is to be connected to ground (the negative end of the battery)
and the pin to the very right is to be connected to a source that is to receive the
new lower voltage. In summary, the larger voltage enters the regulator through
the pin farthest to the left and leaves the pin farthest to the right as a lower
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voltage. This new lowered source of voltage will be the voltage distributed
throughout our circuit.
9 Volt Battery Clip
The nine volt battery clip (shown in figure M) is used as a means to produce
lead connections that can fit into ports on a breadboard
(see the section of a breadboard for more detail on
breadboards). The black connector end of the battery clip
snaps onto the two terminals of a nine volt battery and has a
(Figure M)
red and black wire protruding outwards from the clip. The
red wire represents power (the positive end of the battery) and the black wire
represents ground (the negative end of the battery). The ends of the black and
red wires can be striped of insulation and inserted into a breadboard’s ports.
Wire Striper
Figure O displays a wire striper that can be used for this project. The wire
striper is used to take the insulation off the ends of a particular wire. The wire
striper that we will be using for this project will be one that can stripe 22 gauge
wire (the size wire that we will be using). The wire striper shown in figure O is one
that can be ordered from Jameco Electronics (see the parts list section of this
manual to see how to order one). To use this particular pair of stripers, simply
insert the end of the wire through the hole shown in figure O. For our project, you
will want to strip approximately ¼ of an inch of insulation off of each side of a
piece of wire. Therefore, make sure that ¼ of an inch of the wire goes through the
hole to the other side of the stripers. Then apply a slight pressure on the wire
striper’s handles so that the wire striper presses slightly against the wire. Finally,
pull the wire out of the hole while still griping the handles firmly. The wire should
have a bare section approximately ¼ of an inch long.
Hole for wire
13
(Figure O)
QUICK CIRCUIT RUNDOWN
The primary outcome of creating this circuit will be a circuit that performs
and displays a count of how many switches are turned to the “on” position.
Although this is a relatively simple task, many electronic components are used in
order to carry out this task. Our wiring and circuit configuration is greatly
simplified via the use of premade chips. The start of the circuit begins with the
nine volt battery. As we encounter in our daily lives, batteries come in
predetermined voltages designed for specific tasks. For this particular project we
need to make sure that the source of voltage will be great enough to perform our
desired task and therefore we have chosen a nine volt battery to power the
circuit. However, this voltage is a little excessive for the chips that we will be
integrating into the circuit. With this in mind, power will first reach the five volt
regulator. As power is fed through this device, the voltage is stepped down to five
volts from the initial nine volts.
With a safe voltage established, the power in the circuit will be fed to the 8count dip switch. Our goal here is to provide power to three different switches
that will determine our display on the seven segment display unit. As power
leaves the five volt regulator, the power will be split into three parallel segments
with each segment containing a wire that hooks up to one of the three switches.
This will ultimately allow us to control our “count” as the displayed number will
be that of how many switches allow power to flow through them (they are
considered “on”). After three of the eight switches on the dip switch are hooked
up to the incoming power source, wires from the other end of the switches will be
connected to three different inputs on the four bit adder chip. The adder chip that
the circuit requires can actually add together binary numbers of up to four digits.
For our purpose, however, we will only need to concern ourselves with the first
bits (least significant bits) in the numbers to be added and the adder’s initial
carry. The initial carry to an adder chip is usually zero, but for our task, this is an
exception. To see more information on the full adder chip see the title labeled
“Four Bit Adder” within the description of parts section of this manual.
14
In essence, the full adder will ultimately create for us a binary number
representing the number of switches that are in the “on” position. However, we
are not done here for we must take this newly created binary number and display
it as a number that is more familiar to us (a decimal number). With this in mind,
the newly created binary number (which will already be in BCD) is sent to a BCD
to seven segment decoder chip. In a general sense, BCD is a hybrid number
representation that represents a number in binary but is represented in a form
that is more familiar to a human being. To expand farther on BCD and the BCD to
seven segment converter chip, please refer to the title labeled “BCD to Seven
Segment Converter Chip” found in the description of parts section of this manual.
Once this BCD number representation reaches this chip, the number (represented
as a specific combination of 1s and 0s) is converted into seven different outputs.
Each individual output is for one segment of the seven segment display unit. The
chip takes the BCD number and creates outputs that will help us to visualize this
number in a decimal system representation by creating new signals for a display
unit. Now, in order to hook our circuit up to a visual display, all we need to do is
take the outputs from the BCD to seven segment converter chip and hook the
corresponding outputs up to the corresponding inputs on the display unit. This is
what is accomplished next in the circuit.
Simply enough, the seven outputs of the BCD to seven segment decoder
chip are hooked up to the display unit directly without having to do any additional
planning. For example, we would take a wire segment and run it from the output
labeled “a” on the converter chip to the input labeled “a” on the seven segment
display. If all connections are made correctly, we will have a circuit that takes
electrical signals/charge coming from a set of switches and converts these signals
into a viewable decimal number representation. Any combination of only one
switch turned “on” should display a 1 on the seven segment display. Similarly, any
combination of two switches turned “on” should display a 2. All three switches
turned “on” should produce a visible 3. This circuit can also be expanded to
produce a count of a larger set of switches. For example, we could utilize all of the
switches on the 8-count dip switch and have a count of up to eight on the seven
segment display. However, with the types of components used in this design,
15
more adder chips and wiring would be required to complete this task. The circuit
design shown and demonstrated in this manual is only one of many ways to
construct this basic circuit design. The design shown here is the most intuitive for
individuals inexperienced in logic design. Below is a brief flowchart that shows the
general process of the circuit.
(Circuit Operation Flowchart)
16
PARTS LIST
Bellow is a table listing all of the parts that you will need to complete the switch
counting circuit. The parts may to be ordered through the Jameco web site at
www.jameco.com. Simply use the red parts numbers listed in the table below to
order the corresponding parts. The parts number can be copied and pasted into
the Jameco web site’s search bar. The total cost listed in the table does not
include shipping costs. Expect to pay approximatly $10.00 in shipping fees, as they
may vary.
PARTS TABLE:
Part
Part Number
Quantity
Needed
Cost of
Part/Parts
Seven segment
display unit
334880
1
$0.99
750 Ohm resistor
661474
$5.00
Breadboard
20758
100 (must purchase
in sets of 100)
1
$15.95
100 feet 22 gauge
wire
Five volt regulator
36856
1
$7.95
51262
1
$0.29
Nine volt battery
198731
1
$2.09
Nine volt battery
clip
22 gauge wire
stripper
Full adder chip
109154
1
$0.29
JE-2022C-R
1
$4.49
48063
1
$2.19
47811
1
$3.95
696917
1
$1.29
BCD to seven
segment chip
8- position dip
switch
Total cost:
Part Image
$44.48
17
CIRCUIT CREATION WALKTHROUGH
A. Getting Started
Listed are the corresponding segments of the breadboard that will be
referenced and concepts that you will need to become familiar with in order
to place connections on the breadboard.
1. This manual is based off the specified breadboard indicated in the parts list
section of this manual. All grid locations are based off this type of Jameco
brand breadboard.
2. To make things simpler, you will be using the right side of the breadboard only
with regards to the two colored middle columns (the red and blue lines in the
middle of the breadboard).
3. The breadboard is laid out in a grid-like fashion with Columns A-J and rows 163. In this manual, a port refers to a specific grid location where a wire is to be
connected into the breadboard. If you are instructed to place the end of a wire
in A-14, for example, you should place the end of the wire in the port that is
located under column A and within row number 14 as shown in figure 1.
4. The column of pins along the blue line in the middle of the breadboard will be
used for placing ground connections (see figure 1).
5. The column of pins next to the red line in the middle of the breadboard will be
used to make connections to power (also see figure 1).
6. As another example, if you are instructed to place the end of a wire in the 6th
row of ground, you should place the wire in the column of connections next to
the blue line in row 6 as shown in figure 1. Note that you will have to count the
rows differently for the case of
the ground and power columns
since these columns are ordered
differently than those to the very
right and left of the breadboard.
(Figure 1)
18
B. Connecting the Five Volt Regulator
1. Find and remove the five volt regulator (shown in figure 2)
from packaging.
2. The five volt regulator has three prongs. Place the regulator in
3.
4.
5.
6.
7.
the breadboard so that its three prongs are plugged into
(Figure 2)
column C and rows 5, 6, and 7. The black square on the
regulator should be facing left towards the center of the breadboard
(reference figure 4 as needed).
Next, use the pair of stripers (see figure 3) to cut a wire approximately 1 ½
inches in length (the stripers also have a cutting section).
Using the pair of wire stripers, take off approximately ¼ of an inch of
insulation off both ends of the newly cut wire. From now on, all wires are to
be striped to this length on both ends when you are prompted to strip a
wire in this manual.
Place one end of the wire in the 5th row of ground and the other end of the
striped wire in port E-6 (Column E and row 6).
Cut another piece of wire 1 ½ inches long, strip both ends of the wire as in
step number 4, and place one end of the wire in row 5 of power and the
other end in port D-7.
The resulting setup should look like the one shown in figure 4. Note that
your wires may be longer (and some of them should be). The wires are
shorter in the figures in order to make viewing the image easier.
(Figure 4)
(Figure 3)
19
C. Connecting the 8-Position Dip Switch
1. Locate and remove the 8-count dip switch from its
packaging (See figure 5).
2. The dip switch has 16 prongs total with eight prongs on
3.
4.
5.
6.
7.
8.
each side of the switch. Insert the chip into the breadboard
(Figure 5)
vertically so that one line of prongs is in column E and the
other is in column F. Both sides of the prongs should be contained in rows
11-18 and the side of the 8-position dip switch that says “open” should be
closer to the middle of the breadboard (see figure 7 as a reference).
Next, cut three pieces of wire approximately 1 ¼ inches in length and strip
both ends of each individual wire.
Place one of the wires into ports GND-8 (this represents the 8th row under
the ground column) and A-11, one wire into ports GND-9 and A-12, and one
wire into ports GND-10 and A-13. When port locations are specified
In pairs of two (as in with this step), this means that one end of an
individual wire goes into one port while the other end
of the wire goes into the other port. It does not matter
which end of an individual wire goes into what port as
long as both of the wire’s bare ends occupy the pair of
port locations.
(Figure 6)
Locate and unpack three 750 Ohm resistors (see figure 6).
Place one resistor in ports G-3 and G-11, one resistor in ports H-3 and H-12,
and one resistor in ports J-3 and J-13.
Cut and strip a wire 1 ¾ inches long and place one end of the wire in the 1st
row of power and the other end in port F-3.
Your circuit should look like the one in figure 7.
(Figure 7)
20
D. Connecting the Full Adder
1. Locate and unpack the full adder chip shown in
figure 8. The number on the chip should read
HD74LS83AP to decipher it from the other chip. This
number can be found on top of the chip.
2. The full adder chip contains 16 pins just as with the 8
-position dip switch and contains two rows of 8 pins on
(Figure 8)
each side of the chip. Locating rows 21-28, place the chip
vertically with each row of 8 pins going into columns E and F and the hole
on the full adder chip facing the dip switch. The hole is the semi-circle
segment missing out of the chip. See figure 10 for a picture of the chip’s
alignment. You may have to bend the chip’s pin connections slightly in
order to get the chip to fit into the breadboard.
3. Cut six pieces of wire approximately 1 ¼ inches long and strip the ends of
each wire.
4. Place one end of each of the six wires in the ground column in rows 16, 17,
18, 19, 21, and 22.
5. Place the other ends of the wires currently occupying rows 16, 17, 18, 19 of
the ground column into ports A-21, A-22, A-23, and A-24 respectively (in
this order!).
6. Place the other ends of the wires currently occupying rows 21 and 22 of the
ground column into ports A-27 and A-28 respectively.
7. Cut and strip another segment of wire about 1 inch in length and put one
end of the wire in the 20th row of power and the other end in port A-25.
8. Cut and strip a wire 1 ¾ inches in length and connect one end to the 25th
row of ground and the other end to port F-31.
9. Next, cut and strip three wires 1 ½ inches in length and one wire 1 ¼ inches
in length.
10. Of the three 1 ½ inch long wires, place one wire in ports J-21 and J-31, one
wire in ports I-22 and I-31, and one wire in ports H-23 and H-31.
11. Take and place the 1 ¼ inch wire into ports G-25 and G-31.
21
12. So far, your connections should appear as shown in figure 9 (an image is
shown here because the next image will be harder to visualize).
13. Cut and strip three wires 2 ¼ inches in length.
14. With these three wires, place one wire in ports G-13 and G-27, one wire in
ports I-12 and I-26, and one wire in ports H-11 and H-24.
15. Your circuit should look like the one shown in figure 10. The image may not
be easy to follow. In essence, the only difference between figure 9 and
figure 10 is that there are now three additional wires running from the 8count dip switch to the full adder chip in figure 10.
16. From here on out, the circuit will only get messier and thus it will become
increasingly harder to find an incorrect connection made when the overall
circuit does not work. Make sure to double check all of your connections up
to this point to make sure that all wires are connected to their correct port
locations.
(Figure 9)
Semi-circular hole
(Figure 10)
E. Connecting the BCD to Seven Segment Chip
1. Locate and unpack the BCD to seven segment converter
chip shown in figure 11. The number on the chip should
read HD741S48P to decipher it from the full adder chip.
2. Again, the BCD to seven segment chip has two rows of 8
pins. Align the chip vertically and place both rows of pins in
columns E and F with the semi-circular hole facing the binary
(Figure 11)
22
adder chip. The chip should be contained in rows 33-40 (see figure 12 as a
reference).
3. Cut and strip three wires about 1 ¼ inches in
length.
4. Place one of the three wires in each of the
following pair of port locations: GND-27 and A-34,
GND-31 and A-38, and GND-32 and A-40.
5. Next, cut and strip a wire 2 inches in length and
place the wire in ports POW (power)-26 and G-33.
6. Cut and strip another 2 inch piece of wire, placing it
in ports B-26 and B-33.
7. Cut and strip two more wires roughly 1 ¼ inches
long.
8. Place one of the wires in ports H-28 and H-32 and
the other wire into ports G-32 and D-32.
9. Cut a wire 2 inches in length, strip both of its ends,
and place it into ports C-32 and C-39.
10. Your circuit should look like the one in figure 12.
The gray wires represent the new wires added in
this section that run from the full adder chip to the BCD to
(Figure 12)
seven segment converter chip. Any other wire below the gray
wire connected to ports G-32 and D-32 is a new wire added within this section
(section E).
F. Connecting the Seven Segment Display Unit
1. Locate and unpack the seven segment display unit shown in figure 13.
2. The seven segment display unit has ten pins total with rows of five pins
at the top and bottom of the unit. Place the display unit horizontally so
that the two rows of five pins are contained in columns C and G and
contained within rows 45-49. The hollow decimal point on the seven
segment display (seen at the bottom right hand corner of figure 13)
(Figure 13)
23
should be closer to the middle of the breadboard relative to the other side of
the display. See figure 14 for the correct alignment.
3. Cut and strip four wires about 2 ¼ inches long.
4. Place one of the four wires in the following pairs of port locations: ports J-35
and J-45, ports J-34 and J-46, ports I-36 and I-48, and ports H-37 and H-49.
5. Cut and strip two wires approximately 2 ¼ inches long and place one of the
wires in ports G-39 and A-46 and the other wire in ports G-40 and A-45.
6. Cut and strip a long wire about 2 ½ inches in length and place it in ports G-38
and A-48.
7. Locate another 750 Ohm resistor and place it into
ports POW-40 and B-49.
8. Lastly, cut and strip a wire 1 ¼ inches long and
place it into ports GND-38 and A-47.
9. Your circuit should emulate the one shown in
figure 14. All of the wires to the right of the BCD to
seven segment display chip are the new wires
placed in this section except for the very top one
connecting the chip to power.
10. The overall circuit is shown in figure 15.
(Figure 14)
(Figure 15)
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G. Running the Circuit
1. Locate and unpack both the nine volt battery and the battery clip as show
in figures 16 and 17 respectively.
2. Snap the battery clip onto the nine volt battery. The wide metal connection
of the battery clip should fit onto the small node of the battery and the
small metal connection of the battery clip should fit into the wide metal
connection on the battery. The result should look similar to figure 18.
(Figure 16)
(Figure 18)
(Figure 17)
3. Strip off ¼ of an inch of insulation off of the battery clip’s red and black wire
ends, if the two ends of the wires are not already bare.
4. Place the end of the battery clip’s red wire into port A-7 and the end of the
black wire into port GND-1. The circuit is now
active.
5. On the 8-count dip switch, there is a side on the
switch that says “open.” Flip all eight of the white
(Figure 19)
switch levers so that the high end of the levers stick up
on the side labeled “open” (see figure 19).
6. The seven segment display should display an illuminated zero as shown in
figure 20.
(Figure 20)
25
7. Flip the first switch so that the high end of the
switch lever is away from the end labeled “open”
(see figure 21). The individual switch levers are
labeled 1-8 so be sure to flip the lever labeled “1.”
8. The display unit should illuminate a 1 as displayed in
figure 22.
(Figure 21)
(Figure 22)
9. Now flip the second switch (the switch labeled 2) so
that it’s lever matches that of switch number one (see
figure 23).
10. The display unit should illuminate a 2 as seen in figure 24.
(Figure 23)
(Figure 22)
(Figure 24)
26
11. Finally, flip the third switch lever so that it matches
up with the first two switches (see figure 25).
12. The seven segment display unit should display a 3 as
(Figure 25)
shown in figure 26. Any combination of only one switch
turned “on” should still display the number one and any combination of
two switches turned “on” should still display the number two.
(Figure 26)
27
GLOSSERY / INDEX
8-Count dip Switch- A device that consists of eight separate switches in a parallel
arrangement. Each individual switch can be connected separately and all eight
switches are not required to be connected to a circuit. (Page 6)
Battery- A battery is used to provide electrical power. A battery creates a
potential difference that forces electrons to flow through a conductor (a
substance that permits electrical flow). Electrical charge, more as a standard
convention, is said to flow from the positive end of the battery to the negative
end of the battery (ground). (Page 8)
BCD- BCD, or binary coded decimal, is a number representation that represents a
number in binary (1s and 0s) but is displayed in a context more familiar to
humans. (Page 7)
BCD to Seven Segment Converter- This device converts a number represented in
BCD (binary coded decimal) to an array of seven outputs for a seven segment
display unit. The outputs of the converter can then be directly linked to the
corresponding input locations on the seven segment display. (Page 7)
Breadboard- A device used to construct prototype circuits before implementing
them in a permanent situation. It contains many rows and columns of ports that
can be used to link wire connections to various electronic components.
Breadboards are limited to small-scale circuit creations. (Page 3)
Current- The flow of electrical charge in a circuit. It can be thought of as the rate
at which electrons move through the circuit. The unit used frequently for current
is the Amp. (Page 5)
Five Volt Regulator- A device that steps down the voltage in a circuit to a concise
five volts. This device is often used to safeguard various electrical components.
(Page 9)
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Four Bit Adder- The four bit adder takes 2 four digit binary numbers and adds
them together. The outputs of the adder are four sum bits/digits and an output
carry bit. The resulting number is the sum represented in binary notation.
(Page 4)
Ground- Refers to the lowest point of potential energy. On a battery, ground is
referred to as the negative end of the battery and is viewed (conventionally) as
the point to which electrical charge flows towards. (Page 9)
Ohm- A unit that measures resistance. (Page 5)
Power- Provided energy that creates current (flow of charge) within a circuit.
Power is also referred to as the positive end of a battery since it is the initial
starting point (in conventional terms) for electrical charge (or electrons) flowing
through a circuit. (Page 9)
Resistor- A resistor is a device used in circuits to limit the amount of current.
Resistors are imperative in protecting many electronic components from damage.
Resistance is measured in Ohms and can be determined on a resistor through its
colored band markings. (Page 5)
Seven Segment Display Unit- A device that takes inputs from a given circuit and
illuminates seven different segments in order to create a visual representation of
a symbol, digit, letter, etc. The device also has an additional segment for a
decimal point display. (Page 6)
Voltage- Voltage is the potential difference between two points. It can be thought
of as the pressure excreted on electrons (or charge) to move through a given
circuit. Electrons conventionally travel from a point of high potential energy to a
point of lower potential energy. (Page 8)
29
CREDITS
1) D. C. Giancoli, “Electric Currents and Resistance,” in Physics for scientists and
engineers, 4th ed. Upper Saddle River, NJ: Pearson Education, 2008, ch. 25, sec. 3,
pp. 657. (Reference for pages 5 and 24)
2) Jameco Electronics. (2012, November 8). [Online.] Available:
http://www.jameco.com/webapp/wcs/stores/servlet/StoreCatalogDisplay?storeI
d=10001&catalogId=10001 (Reference for pages 3, 4, 6-10, 13, 15, and 19)
3) J. A. Therrell. (2012, October 4). AGE DETERMINATION GUIDELINES: Relating
Children’s Ages To Toy Characteristics and Play Behavior. [Online]. Available:
http://www.cpsc.gov/BUSINFO/adg.pdf (Reference for page 2)
4) J. Hewes. (2012, October 12). Breadboard. [Online]. Available:
http://www.kpsec.freeuk.com/breadb.htm (Reference for pages 3 and 23)
5) M. M. Mano and M. D. Ciletti. Digital Design, 5th ed. Upper Saddle River, NJ:
Pearson Education, 2012. (Reference for pages 3, 7, 11, 23, and 24)
6) Yee, Kam. (2012, October 24). Personal Interview. (Reference for pages 1, 12,
and 13)
7) Yee, Kam. (2012, October 31). Digital Logic Design. [Online.] Available:
http://www.montgomerycollege.edu/faculty/~kyee/public_html/EE244/
(Reference for page 13)
8) S. A. Smith and B. Norris. (2012, October 4). Reducing the risk of choking
hazards: Mouthing behavior of children aged 1 month to 5 years. [Online].
Available: http://web.ebscohost.com.proxyum.researchport.umd.edu/ehost/pdfviewer/pdfviewer?sid=59647bfc-7563-413a89b1-ecd9cc58cb6c%40sessionmgr111&vid=2&hid=106 (Reference for page 2)
30
9) Small Bear Electronics LLC. (2012, October 9). Using a Solderless Breadboard.
[Online]. Available:
https://www.smallbearelec.com/HowTos/Breadboarding/BreadboardIntro.htm
(Reference for pages 3 and 23)
10) T. V. Roon. (October 12). 7-Segment Displays. [Online]. Available:
http://sentex.ca/~mec1995/tutorial/7seg/7seg.html (Reference for pages 6 and
24)
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