University of Wyoming
Wyoming Scholars Repository
Honors Theses AY 15/16
Undergraduate Honors Theses
2016
Bicycle-Powered Charger
Alexandra N. Howell
University of Wyoming, ahowell8@uwyo.edu
Follow this and additional works at: http://repository.uwyo.edu/honors_theses_15-16
Recommended Citation
Howell, Alexandra N., "Bicycle-Powered Charger" (2016). Honors Theses AY 15/16. Paper 32.
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Bicycle-Powered Charger
Alexandra Howell
Design Team:
Alex Howell
Daylon Roitsch
Taylor Wollert
ME 4060
Systems Design
Final Written Report
Submission Date: May 11, 2016
Submitted To: Dr. Kevin Kilty
TABLE OF CONTENTS
Page
LIST OF FIGURES …………………………………………………………………… ii
LIST OF TABLES …………………………………………………………………….
ii
ABSTRACT …………………………………………………………………………...
1
INTRODUCTION …………………………………………………………………….. 1
SYSTEM DESIGN …………………………………………………………………....
6
TESTING ……………………………………………………………………………...
17
ECONOMICS AND COMMERCIAL VIABILITY ………………………………….
20
LIFE CYCLE ANALYSIS ……………………………………………………………
22
CONCLUSIONS ……………………………………………………………………… 24
APPENDICES:
1. FMEA …………………………………….........................................................
I
2. SolidWorks Drawings of the Support Frame.....…………………………….....
IV
3. SolidWorks Drawings of the Shaft System....………………………….……....
VII
4. Cost Analysis Table ……………………..…………………….…………........
XII
5. Test Results…………………………………………………………………….
XIII
6. Transistor Data Sheets………………………………………………………….
XIV
i
LIST OF FIGURES
Figure 1. Permanent magnet ATV magneto stator ……………………………………. 7
Figure 2. Visio model of a shunt regulator circuit ……………………………..……...
8
9
Figure 3. SolidWorks model of the assembly of the bicycle, support frame and
charging system …………………………………………….………………………….
Figure 4. Typical retail bicycle trainer ………………………………………………...
10
11
Figure 5. SolidWorks model of the designed support frame for the bicycle-powered
charger system ………………….……………………………………………………...
Figure 6. SolidWorks model of the shaft system ……………………………………...
12
Figure 7. Typical bicycle odometer setup ……………………………………………..
14
Figure 8. Integration of various sub-systems of the bicycle-powered charger system ..
15
Figure 9. Unified electronics and control sub-system integration …………………….
16
Figure 10. ATV magneto testing setup …..……………………………………………
18
Figure 11. Shunt regulated power supply testing results ……………………………...
19
24
Figure 12. Life cycle for a commercially produced version of the bicycle-powered
charger system …………………………………………………………………………
LIST OF TABLES
5
Table 1. Design constraints for each sub-system of the Bicycle-Powered Charger
system ………………………………………………………………………………….
Table 2. Shaft system outputs for various wheel sizes …..……………………..……... 13
Table 3. Estimated material and manufacturing costs for the final design of the
bicycle-powered charger system …..……………………….………………………….
21
ii
ABSTRACT:
Bicycles offer effective means of exercise and are popular forms of transportation. One
fault of the current use of bicycles is that the mechanical energy generated by a moving bicycle
is often wasted in the form of friction and expended heat. Wasted energy is troubling in the
modern world now that energy is deeply integrated into peoples’ everyday lives – one of the
most common energy consumers being small electrical devices such as cellphones. Our senior
design project addresses this issue via a bicycle-powered charger system designed to operate
similar to a normal commercial bicycle trainer while concurrently mitigating dependence on
outlet electrical energy for charging. The system is composed of the frame (trainer) and the
charging system. The trainer is based on a standard retail bicycle trainer to enable easy transition
from road use to stationary exercise use. The charging system will be capable of charging a 12 V
battery pack, which will then be able to charge multiple 5 V devices simultaneously. The bicycle
wheel sets into the trainer while resting against a rotor which spins the shaft connected to a
generator (a permanent magnet ATV magneto) which outputs a variable AC voltage RMS. This
AC output from the generator will pass through a shunt voltage regulator and a boost power
inverter, which connects to a removable battery pack capable of charging during system
operation and stores charge for use after operation. The prototype we create will utilize a
purchased trainer for design, but this prototype is intended to evolve into a commercial product.
We will discuss our design and estimate cost of a commercial product.
INTRODUCTION:
Global/Societal Context
Our bicycle-powered charger is more than a simple mechanical product. Based on the
needs of the end user, this product will address issues of physical, economic, and environmental
conditions. With various technologies now readily accessible to millions of people, physical
activity is no longer required. Since physical activity is no longer essential to survival, societies
have become lax in their amounts of daily physical activity, which poses potential health issues.
Our bicycle-powered charger will address this issue by encouraging our users to use their own
physical energy to quickly charge their electronic devices like cellphones and tablets. People
will be inclined to put in the effort to charge their devices using this method because of the other
two issues this product addresses: those of economic and environmental conditions. Our bicyclepowered charger offers a cost-effective way to provide the electricity for those devices in that it
can allow the users to decrease the amount of electricity they buy from commercial providers.
This may also directly and indirectly reduce further pollution of the environment by removing
some of the need for conventional electrical sources including coal, petroleum, and gasoline and
by promoting the use of bicycles. Each of these issues addressed by our bicycle-powered charger
prove it to be sustainable. Sustainability is essentially made up of three pillars: societal,
economic, and environmental. The physical activity provided by our bicycle-powered charger
may improve the social aspect of many peoples' lives while the lower consumption of traditional
1
electrical sources may reduce the economic burden on many people and may reduce further
environmental pollution.
Background
Bicycles are a popular means of maintaining physical wellness and health. They are also
a useful form of transportation for commute (short trips ranging from approximately 0-5 miles)
and recreation (short and long trips ranging from 0-100 miles). Many people choose to bike as a
means of reducing their ecological footprint, which is particularly useful in large cities where
emissions tend to be concentrated. Many advancements have been made in internal combustion
engines (vehicles) to reduce emissions such as hydrocarbons, carbon monoxide, particulates,
nitrogen oxides, and carbon dioxide. Hydrocarbons, carbon monoxide, particulates and the
various nitrogen oxides are toxic to human health, can cause acid rain and foul odors, and, in
concentration, form ozone regions or photochemical smog in large cities. In moderate levels,
carbon dioxide is not toxic to human health but is still considered a greenhouse gas and is a
promoter of climate change.1
In the United States, vehicles are the second largest contributor to carbon emissions at
2
27%. Most modern internal combustion engines are equipped with a catalytic converter which
substantially decreases the emissions of these compounds. The flaw with these devices, however,
is that they do not operate efficiently if they are cold. It can take up to ten miles of driving for the
catalytic converter to reach steady state conditions. Statistics show that approximately half of all
the fuel used in the United States is used for trips less than ten miles. Furthermore, most of these
short trips occur during commutes in large cities, where emission reductions are even more
critical. For example, 70-90% of all hydrocarbon emissions in the U.S. stem from these trips
alone.3 Hence, those individuals who regularly use a bicycle for transportation are significantly
contributing to reductions in the human footprint.
Additionally, a vast majority of the population relies on cellphones and other electronic
devices for communication and entertainment. The “charge” for such devices is the electrical
energy supplied by power companies which is transported to the user through electrical outlets.
These power companies contribute to emissions through the production of this energy. Thirty
percent of all the carbon in the United States comes from power company emissions; they are the
largest contributor in the country.4 Based on data gathered from the individual members of this
project and their advisor, iPhones and similarly small electronic devices consume as much as 5
W at peak power while most laptops range between 30 and 40 W. A chart of the data detailing
1
Pulkrabek, W. W. (2004). Engineering fundamentals of the internal combustion engine. Upper Saddle River, NJ:
Pearson Prentice Hall.
2
Wollums, C., Burke, I., Coddington, K., Godby, R., Minier, A., & Reavey, R. (2016, April 4). A Conversation on
the Clean Power Plan’s Impact in Wyoming: Understanding the Challenges and Opportunities. Panel presented at
University of Wyoming, School of Energy Resources Panel Presentation in Wyoming Union Family Room,
Laramie, WY.
3
Pulkrabek, 2004.
4
Wollums et al., 2016.
2
these results is shown in Appendix 5. As such, for a person charging a 5 W cellphone every night
out of the week, the yearly peak power consumption is approximately 1.8 kW. In 2014, the
United States consumed 3,764,700 kilowatt-hours of electricity; 1,407,208 kilowatt-hours were
used purely in the home.5 Small electronics, primarily cellphones, account for approximately 2%
of electricity usage in the home due to charging necessities.6 Hence, those electronics consume
approximately 28,144 kilowatt-hours every year.
From this background knowledge, the overall goal of our bicycle-powered charger
system is to harness the mechanical energy generated by a stationary bicycle via a trainer and use
it to power everyday electronic devices. Such a design enables the user to continue using or
begin the habit of using their bicycle for transportation, thus addressing the issue of vehicular
pollution. The purpose of this bicycle-powered charger system is to charge various small
electronic devices (typically 5 V). Thus, the usefulness of such a product is twofold. Not only
will it promote less vehicular travel, it will also reduce reliance on power companies, which, in
turn, may reduce the emissions from the two of the highest emission sources in the United States.
Also, the system will be able to fulfill the basic electronic charging needs of the average
person who can maintain between 50 to 80 rpm7. It will consist of a bicycle (provided by the
user), a support frame, a shaft system (to connect the bicycle tire to the generator), a generator, a
unifying circuit (composed of an AC/DC convertor, voltage regulator, and buck boost power
inverter), a battery pack, and a display (to inform the user of the status of their workout and the
storage unit). The system will accommodate any standard adult sized bicycle. A system diagram
for this plan is listed in Appendix 5.
Several main objectives and various design considerations were generated to address the
goals of this design. Detailed considerations are provided in the following section. The
objectives include: increase user desirability, ensure system integrity, reduce overall cost, and
provide various charge capabilities.
User Desirability: The first objective, increase user desirability, will be accomplished by
ensuring the product has pleasing aesthetics, is relatively easy for the consumer to assemble and
to use, is economically viable for the consumer, and meets specific safety standards. The
aesthetics portion will focus on reducing the bulkiness of the system and making the surfaces of
the system clean and smooth with pleasing color tones so that the final product is attractive and
marketable to our users. Use of the system will be designed to be relatively easy for the
consumers by making it to be light-weight and able to smoothly integrate adult bicycles ranging
from 24 to 29 inches in tire diameter. To ensure the system is commercially viable, the system
5
U.S. Energy Information Administration. SAS Output. Retrieved April 18, 2016, from
http://www.eia.gov/electricity/annual/html/epa_01_01.html
6
McAllister, J., & Farrell, A. E. (n.d.). Power in a Portable World: Usage Patterns and Efficiency Opportunities for
Consumer Battery Chargers (pp. 11-107-11-118, Publication). University of California, Berkeley. Retrieved
April/May, 2016, from
http://www.eceee.org/library/conference_proceedings/ACEEE_buildings/2004/Panel_11/p11_10/paper
7
Web. 9 Dec. 2015. <http://www.ontherunevents.com/ns0060.htm>.
3
must cost between $200 and $400 at retail. A section on safety is described in detail in the
System Design section.
System Integrity: The second objective, ensure system integrity, will be accomplished through
design and testing. The support frame will be wear and shock resistant, and structurally sound;
the charging system will be robust and effective in charging outputs; the display will be accurate
and long lasting while displaying relevant information to the user such as distance, instantaneous
and average speed, heart rate, calories burned, and the charge status of the users’ small
electronics.
Overall Cost: The next objective, reduce overall cost, will be accomplished by utilizing the best
available materials at the lowest price. Specifically, the budget for the prototype is $700, which
was provided by University of Wyoming, Department of Mechanical Engineering associate
professor Dr. Kevin Kilty.
Charge Capabilities: The last objective, providing various charge capabilities, will be
accomplished by converting the variable AC voltage RMS output from the generator into
consistent DC voltage which can then be applied to three outlet options. One outlet will be
utilized to directly charge small electronic devices. A second outlet will be used to charge a
removable 12 V lead-acid battery with multiple USB 5 V charge outlets. The last output will be a
resistor to ground so that, in the case that some of our users are unable to generate sufficient
voltage to sustain the first two options, they will still have some resistance to the pedals and the
voltage that they do generate is still dissipated through the charging system
Design Considerations
Our bicycle-powered charger will have many design considerations, which fall under the
basic categories of Manufactural, Environmental, and Ergonomic. Health and safety will be
considered throughout the design. The underlying considerations and constraints for each
category are summarized in Table 1.
Table 1. Design constraints for each sub-system of the bicycle-powered charger system.
4
Item
Support
Frame
ATV
Magneto
Battery
Pack
Unified
Electronics
Display
Considerations
Must support standard retail bicycles (focusing
on wheel sizes) and be useable for a range of
riders from the 95% male to the 5% female
Must generate power required for 12V
charging system
Must store 12V DC and have multiple
removable charge outlets
Must increase/decrease input voltage to meet
battery voltage requirements
Other Constraints
Weight, Size, Strength, Safety,
Cost, Aesthetics, Ease of Use
Must show calories burned, distance covered,
current speed, and charge accumulated
Weight, Durability, Safety,
Readability, Ease of Use, Cost
Size, Level of Resistance, Cost
Longevity of Charge Cycles,
Safety, Cost
Compatibility, Safety, Cost
Regarding manufacturability, we had to consider several constraints relating to the
materials we would be using. The material used for the support frame must be able to be welded,
and shaped all the while without hindering its structural integrity; the material must be able to be
polished or painted to meet our aesthetic objectives; and the material should be available and
inexpensive to meet our economic objectives. In our case, we have opted for aluminum and steel
materials for the majority of the design system components.
Environmental constraints to reduce environmental pollution must also be considered.
For instance, if powder coating is used instead of spray painting on the support frame, the
volatile organic compounds released into the atmosphere is reduced, the risk of cancer from
contact is decreased, and the probability of fire is lessened since powder coating is less
flammable.8 Also, powder coating has a much longer lifespan than spray painting which means
the environment will be effected less often.9 Further effect to the environment due to
manufacturing may be reduced by limiting the amount of manufacturing necessary. Since our
bicycle charger requires only two major components, the support frame and the charging system,
which can both be easily handled by a single adult without mechanical aid in most cases, the
amount of manufacturing will be minimal. From an operation standpoint, by using a system
which utilizes energy from a person exercising, we reduce the use of power from conventional
sources (coal, petroleum, and gasoline) and, thereby, reduce the environmental impacts which
typically accompany such sources.
Our ergonomic constraints allow our product to work for the larger population of
consumers while also helping to seek out product data from various regulatory agencies. The
larger population of consumers considered must be limited by age and health level ranges in
order to allow our bicycle-powered charger to be built to the highest of safety levels while still
remaining low in cost. These safety levels will be achieved by following the design codes of
several different regulatory agencies including the Consumer Product Safety Commission and
8
"How Is Powder Coat Better than Spray Paint?" Seattle Powder Coat. Seattle Powder Coat, 2012. Web.
<http://www.seattlepowdercoat.com/why_not_just_spray_paint>.
9
Ibid
5
the American Society for Testing and Materials. In addition, we may consider other agencies
which are deemed to be appropriate after further design and testing of our current bicyclepowered charger system. The codes from the different agencies will allow our design to be
monitored during the testing phase.
The constraints explained above must all be considered in order for our bicycle-powered
charger to be feasible. In essence, our bicycle-powered charger must be low-cost, structurally
sound, small, up-to-code, safe, and durable.
SYSTEM DESIGN:
Generator
The power output was one of the greatest concerns of the design team. The generator
should be able to quickly and efficiently charge all small electronics requiring approximately 5
watts. Ideally, the design team would like the generator to be capable of fully charging or
partially charging some larger applications like tablets and small laptops that can require
anywhere from 15 to 30 watts. The design team determined that a stepper motor or an alternator
would be appropriate generators for the bicycle-powered charger system. Knowing this, the
design team decided to use an ATV magneto, which was already available, for the prototype so
that testing could begin. The ATV magneto originated from another senior design team (Baja)
and was missing both the rotor and an appropriate cover. The rotor was purchased and the cover
was designed by the team for manufacture in the University of Wyoming Engineering shop
(hereafter referred to simply as the shop). Additionally, a custom shaft was designed and
manufactured to connect the generator to a PVC roller spun by the rear wheel of the consumers’
bicycles. It was expected that the magneto would be a 12-V, three-phase, eight-magnet, twooutput, AC voltage RMS generator. The two voltage outputs were the charging output used to
charge the battery of the ATV and the spark plugs outlet used for the ignition of the ATV. The
charging output would be used for this project design, which would output a variable AC voltage
RMS. There was some concern by the team that this generator would have too high of a
resistance for our users to exercise with. The team decided that if this was discovered to be true
after testing, two of the magnets and their windings would be removed to reduce the overall
resistance of the magneto. The ATV magneto obtained by the design team is shown in Figure 1.
6
Figure 1: Permanent magnet ATV magneto stator.
Energy Storage and Charging Capabilities
A 12 V lead-acid battery was chosen for our energy storage outlet. We intended it to be
able to function attached to the system during exercise and separate from the system for use at a
later time or location. Allowing this separation was necessary for individuals wishing to utilize
their produced energy on-the-go. In addition, the lead-acid battery pack would be capable of
charging multiple devices at once, including the display. With the battery being 12 V, it would
be capable of charging multiple devices simultaneously since the team found that most small
electronic devices charge and operate at 5 V. We intended the battery to be one of three outlets
with the other two outlets being direct charge to small electronic devices and a resistor. The
resistor was necessary to produce some resistance for exercise in case the individual using the
system did not produce enough voltage for either of the other two outlets.
In order to connect the ATV magneto to our three outlets, we had to design a unified
electronics and control circuit composed of a micro-processor and shunt regulator. The microprocessor would guide the voltage to the desired outlet. Specifically, the micro-processor would
be programmed to direct the voltage to the three desired outputs of the design with the preference
being to directly charge the users’ electronics first, then, once those devices were fully charged,
to the battery, and, lastly, to a resistor to ground. Figure 2 shows an example diagram of the
shunt regulator we would utilize.
7
Testing Port
AC Terminal
+ DC Terminal
Resistor 1
Capacitor
Bridge Rectifier
Zener Diode
Transistor
Resistor 2
AC Terminal
- DC Terminal
Figure 2: Visio model of a shunt regulator circuit. This would convert the variable AC
voltage output of the ATV magneto to a constant DC voltage.
Since the generator utilizes variable output AC voltage, a bridge rectifier is placed at the
beginning of the circuit shown in Figure 2. The bridge rectifier acts to convert AC voltage to DC
voltage. 10 The various other electronic components are added as controls to achieve a constant,
useful voltage. Resistor 1 is one ohm and functions to decrease the current further. The 490
micro-fared capacitor stores the excess energy that the users may produce and releases is steadily
back into the system. The Zener diode, a key component to the circuit, regulates the voltage. It
accomplishes this by operating at its breakdown voltage – the voltage which remains constant
within a specified range of current.11 For our application, we selected a 5.1 V Zener diode with
an operating range of 10 to 100 mA. Resistor 2 is around 70 ohms to reduce the amount of
current that passes through the Zener diode. To reduce the current output to the various outlets,
the NPN transistor is used. This transistor operates by turning on when a small amount of current
passes through its base terminal (the node between the Zener diode and Resistor 2). When on, the
transistor allows large current to pass through its collector terminal (the top side of the circuit
shown in Figure 2) to its emitter terminal (the bottom side of the circuit shown in Figure 2).12
The data sheet on the specific transistor used for this example shunt regulator is available in
Appendix 7.
As a final component for charging, a boost power converter may be necessary to step up
the voltage produced to 13.4 volts if the user does not produce enough voltage to charge the
battery. The boost power converter selected is a switched mode converter that utilizes an nchannel MOSFET as the switching mechanism. When the MOSFET is switched on, an inductor
10
"Technical Article: How a Motorcycle Charging System Works." ElectroSport. Web. 1 Dec. 2015.
<http://www.electrosport.com/technical-resources/technical-articles/how-motorcycle-charging-system-works>.
11
Kuhn, K. A. (2013, April 7). Zener Diode Voltage Regulators (Publication). Retrieved April/May, 2016.
12
S. (2012). Transistor NPN animation. Retrieved May 11, 2016, from
https://www.youtube.com/watch?v=aVJrTMuzlL4
8
is used to store energy. When the MOSFET switches off, the combined input voltage and
inductor voltage supply the load (battery) and charge a capacitor. The MOSFET then switches
back on to store more energy while the capacitor discharges and supplies an almost constant
voltage to the load. 13
Support Frame
The support frame is meant to hold both the rear tire of the users’ bicycle and the roller,
shaft and generator system. The setup of the frame containing these two modules is shown in
Figure 3 from various viewpoints.
Figure 3: SolidWorks model of the assembly of the bicycle, support frame and charging system.
Two support frames were analyzed during the initial design process of the bicyclepowered charger system: one purchased specifically for the prototype and one designed for the
final commercial product. The first frame was necessary due to some very sophisticated and,
therefore, time-consuming components of the designed frame and also the inability of the shop to
perform the heat treating necessary for welding aluminum. A typical retail bicycle trainer, shown
in Figure 4, was reverse engineered for the designed support frame.14 The dissipater on the retail
trainer provides resistance to the bicycle user and prevents the pedals from “running away” from
13
14
Eric Coates. “Boost Converts.” Learn About Electronics: Power Supplies. (2016). Web. 10 May 2016.
"Bicycle Trainer - Google Search." Bicycle Trainer - Google Search. Web. 9 Dec. 2015.
9
the user. The dissipater was not included in the designed support frame due to the prediction that
the ATV magneto would have sufficient resistance to warrant its exclusion.
Figure 4: Typical retail bicycle trainer. Since a member of the group has one of these
trainers, the design will be modeled after this trainer.
A SolidWorks drawing of the final design of the support frame is shown in Figure 5 with
a further breakdown of all the sub-assembles used in this design available in Appendix 3. It was
decided to construct this frame mainly of 1020 aluminum alloy due to its lightweight compared
to typical steel retail trainers. A 1020 aluminum alloy assembly is less than half the weight of a
steel assembly. To verify this, the designed support frame’s weight was first calculated for
aluminum and then for steel. The aluminum frame was 16.35 lbs. while the steel frame was
38.31 lbs. The components altered for this calculation included the back and front uprights, the
floor pieces, and the covers. To fulfill the design objective of accommodating a range of bicycles
between 24 and 29 inches in wheel diameter involved the incorporation of height adjustments
into the design and may require the user to level their bicycle. Commercial products are available
for such purposes. The frame in question will be designed to be structurally sound no matter if
the user takes the measures to level his/her bicycle or not.
10
Figure 5: SolidWorks model of the designed support frame for the bicycle-powered charger system. This model is comprised
of the final assembly and three sub-assemblies, as shown in Appendix 3. Among the sub-assemblies are the two top structures which
are alike except for the wheel supports. One wheel support is designed for increased stability for the user while adjusting the
lateral position of the bicycle.
11
For the prototype, the support frame was not manufactured exactly as described in Figure
5. Instead, a retail aluminum trainer was purchased by the team and modified to meet the team’s
specifications. This action was decided upon for several reasons, the most prominent of which
was the lack of aluminum heat treating abilities in the shop. Without proper heat treatment, the
attachment method of choice, welding, would reduce the stiffness of the aluminum to make it
structurally unsound during the welding process. Another reason for purchasing a pre-built
trainer for the initial prototype was time restrictions. The shop had many demands on its time,
including graduate level projects, and the team was informed that construction of the designed
support frame would be queued until further notice, significantly delaying the testing stage. Due
to these dilemmas, the design team elected that purchasing a trainer and modifying that trainer
for the design was a viable alternative.
Shaft System
Figure 6 depicts the SolidWorks model of the shaft system. It is composed of a shaft
connected to the ATV magneto and a larger cylinder (roller) supported by two pillow-block
bearings located where the dissipater is on retail trainers. The rear wheel of the users’ bicycle
will rest against the large cylinder and allow transfer of the wheel rotation to shaft rotation. The
design team chose a diameter of 4 inches for the cylinder because that diameter would likely
accommodate all the desired tire sizes and also increase the ratio between the roller and the tire.
The shaft system is adjustable to accommodate 24″ to 29″ tires.
Figure 6: SolidWorks model of the shaft system.
The shaft was constructed from steel, the cylinder was constructed from PVC, and the frame
connection components were constructed from aluminum. Each piece was built according to the
12
SolidWorks model specifications and utilized available materials in the shop. SolidWorks
drawings for each part can be found in Appendix 3. An outer aluminum shield will be added to
the final product to reduce the risk of injury to the user. The calculated outputs for applying
various wheel sizes to the shaft system are available in Table 2 below. The output speed of the
average user was estimated to be three wheel rotations per second, disregarding wheel diameter.
A range of metric tire diameter sizes similar in range to that chosen by the design team was also
analyzed. The bicycle chosen for testing, provided by one of the members of the design team,
had a tire diameter of 700 mm x 25 mm.
Table 2. Shaft system outputs for various wheel sizes. Operation was estimated to be three wheel
rotations per second to simplify calculations.
As may be observed from Table 2, the output may vary by approximately 300 rpm for the
various wheel sizes.
Display
The display will provide similar information to the user as most retail bicycle odometers
and will utilize the energy output of the design itself for operation. Specifically, the display will
inform the user of their speed, both instantaneous and average, and distance and the charge
accumulated in the battery while exercising. To increase interest in our consumer base, heath
statistics will also be added to the display, like calories burned and heart rate. A display of
particular interest to the team is a 132x132 Serial Color Graphic LCD. This display is taken from
the 6610 Nokia phones and may be purchased from gravitech.us for approximately $36. This
display is desired due to its aesthetics, simplistic use, and relatively inexpensive price.15 To
15
132x132 Serial Color Graphic LCD. (n.d.). Retrieved May 11, 2016, from http://gravitech.us/13secogrlcd.html
13
determine the speed and equivalent distance travelled by the user a typical bicycle odometer
setup will be utilized. A magnet or reflective tape will be placed into the spokes of the rear wheel
of the bicycle and a sensor will be mounted onto the frame of the bicycle. The sensor will record
the times the magnet or reflective tape passes in front of it and the display will show the
calculated speed and distance. An image of this system is provided below in Figure 7.
Figure 7: Typical bicycle odometer setup. This system is used for recording the speed and
distance of a moving bicycle. The odometer for the bicycle-powered charger will be mounted to
the rear wheel.
Since the design team will have no way of measuring the exact weight, height, sex, etc. needed
to calculate calories burned and heart rate, a range of these variables will be selected based on
our user base and the range of bicycle tire sizes used in this design.
System Integration
The system integrations of the components discussed in the previous sections is shown in
the system diagram displayed in Figure 8, where the support frame holds the bicycle with a user,
and the shaft system and connected generator. The generator then outputs to the unified
electronics and control charging system.
14
Figure 8: Integration of various sub-systems of the bicycle-powered charger system.
The system diagram of the unified electronics and control is shown in Figure 9. The variable AC
RMS voltage from the ATV magneto outputs into the bridge rectified of the shunt regulator
which mediates the charge for transfer throughout the rest of the charging system. The microprocessor then directs the charge to the three options of direct charge to the users’ electronics,
storage in the lead-acid battery and resistor to ground. A boost power inverter is needed for the
lead-acid battery, which also serves as the power source for the display for the system.
Figure 9: Unified electronics and control sub-system integration.
15
Project Budget
The project budget for the bicycle-powered charger was set at $700 and, therefore, the
prototype must cost less than this amount. The prototype budget was provided by mechanical
engineering associate professor Dr. Kevin Kilty. This budget objective will be accomplished by
economizing and designing the system so the best materials are obtained at the lowest overall
cost. As such, the incomplete permanent motorcycle magneto was acquired from the Baja design
team at no cost due to the multiple missing parts. Also, the designed support frame materials will
consist of durable, low cost aluminum and steel. To avoid construction fees, the assembly and
construction of the prototype is intended to be performed by the design team. A cost analysis
table for the bicycle-powered charger prototype is available in Appendix 4. Since commercial
viability is a desired outcome for this design project, an economic analysis on the projected final
design was performed by the team and will be discussed in detail later. The design team found
that the average market price of a bicycle trainer is between $200 and $400 and, hence, set the
target price of the final bicycle-powered charger product to fall within this range.
Safety
Safety for the user is a serious consideration for the design team. Most of the moving
parts of the final design of this system will be covered or partly covered (i.e. the generator, the
battery pack, the electrical circuitry and connections) according to American Society for Testing
and Materials (ASTM) standards. The risks posed by parts which cannot be covered or are
covered but still are not completely benign will be addressed by safety labels also according to
ASTM standards. Particularly, there will be warning and caution labels placed on the parts of the
system posing potential harm to the user and the user will be advised to keep the entire charging
system away from small children and pets, especially during operation. Some familiarity of the
user with bicycles and how to operate them safely must be assumed by the design team in order
to maintain the feasibility of this project. A Failure Mode and Effects Analysis (FMEA) for this
system and each of its individual components is provided in Appendix 1. The design team
deduced five areas which posed potential safety hazards to be: the support frame, the generator,
the shaft system, all the electrical components and the lead-acid battery. Hence, an FMEA was
done for each. The testing aspect of each of the FMEAs is likely to change as the design evolves
from the prototype to the final. The rankings of severity, probability, and detectability assigned
for these FMEAs are also included in Appendix 1.16
TESTING
16
FMEA Template. Web. 9 Dec. 2015. <http://www.lehigh.edu/~intribos/.../FMEA-template.xls>.
16
Frame
The frame used for prototype testing was purchased from MetalsDepot, a company out of
China, for $59.99. The frame was tested using a 700 mm x 25 mm testing bicycle (approximately
27 inch diameter) to ensure that it met the various size, weight, and stability requirements set by
the design team.
Results, Discussion and Recommendations
The design team found the frame to be able to accommodate bicycle tire sizes up to thirty
inches in diameter (this is total size of both the wheel frame diameter with the tire thickness
added), so the trainer met the size requirements. The strength and stability of the purchased
trainer was found to be suitable to support both the testing bicycle with a user and the prototype
charging system and, hence, was adequate for prototype testing.
The final design however would require significantly more testing as indicated in the
FMEA in Appendix 1. The final frame design generated by the design team would likely be
distributed to a contracted manufacturer (this was done for cost reasons as will be discussed in
the Economic Viability section). After the frame is manufactured, the design team would do
extensive testing on the yield, ultimate and stress limits of the system. The integrity of the welds
would be tested and, lastly, the stability of the system would also be tested on a variety of
various floor surfaces to ensure that the system remains stationary during use in all scenarios.
Shaft System
The shaft system was designed to attach to the purchased frame and to accommodate 24″
to 29″ tires. The shaft system was attached to the frame and the same 700mm x 25mm testing
bicycle was used to test its functionality and range.
Results, Discussion and Recommendations
The custom shaft system’s effectiveness at transferring the rotational energy from the rear
bicycle tire to the generator was tested by pedaling the bicycle at a range of speeds produced by
the user. The shaft system was found to transfer all of the rotational energy from the tire to the
generator with no slipping for the whole range of speeds. However, there was some clunking and
movement between the shaft and the generator due to the shaft being designed with the wrong
taper. This could be eliminated by redesigning the shaft using more accurate and precise
measurement techniques. The slippage of the shaft system would need to be tested further once
the final generator has been designed and selected by the project team.
The adjustability of the shaft system was found to be easy and effective. It takes less than
a minute to adjust the shaft system to the tire size and it stays put once adjusted. The range of the
shaft system did not meet our objectives because it could only accommodate 24″ to 27.5″ tires.
The shaft system would need to be redesigned to accommodate tires up to 29″, but this would be
a simple task.
17
ATV Magneto Generator
The generator was tested once the frame, the roller and shaft and the magneto were all
assembled. The outputs of both the charging wires and the spark plug wires were tested using an
ammeter and an oscilloscope for various user cadences. The system assembled for testing is
shown in Figure 10.
Figure 10: ATV magneto testing setup. Included in the setup are the assembled bicycle
(700x25), support frame, shaft and generator sub-systems.
Results, Discussion and Recommendations
The design team found that the ATV magneto was a one-phase, 6 V generator, not a
three-phase, 12 V generator as previously assumed. Due to this misassumption, the design team
also found that the resistance of the generator was not sufficient to provide a high enough pedal
resistance to the user because the testing operator was moving the pedals at maximum speed with
ease. Hence, the operator was effortlessly maintaining a cadence of approximately 100 rpm
which surpasses the target range set by the design team of 50 to 80 rpm, the range of speeds an
average person can sustain. This cadence corresponded to a shaft rotational speed of 1800 rpm
which surpassed the predicted speed of the shaft system for a bicycle tire of a diameter of
approximately 27 inches. At this maximum speed, the output of the system was approaching 7 V
and the current was 2 amperes, resulting in a maximum power output of 14 W. (The output of the
spark plug wires was also measured and was found to be 140 V, but, since the design team knew
that the outlets were meant for spark ignition and would therefore have a very high resistance
and almost negligible current, other data was not gathered about the outputs for fear of
compromising the design team’s testing equipment.) Hence, the team found that the ATV
magneto, while helpful for prototyping of this project design, is not a suitable or adequate
generator for this system. It was a viable option to pursue because it is being manufactured as an
after product already and, although not powerful enough, it was useful in making the design team
aware of various issues and possible adjustments to the overall system to be made for the final
design. Hence, it is the suggestion of the design team that the final design should include design
18
of the generator by the team specifically for integration of this system, since there are not any
appropriate products currently being manufactured. The designed generator should meet the
specifications discussed (lightweight, reduced bulkiness, ease of use, safe for the user) while also
being able to generate 20 W or more during operation. Furthermore, the designed generator
should incorporate the additional resistance that the ATV magneto failed to adequately induce to
the user. If incorporating the added resistance into the final generator design jeopardizes the
integrity of the design, the design team suggests the consideration of adding the commercial
dissipater back into the system integration. However, adding this component back into the design
would greatly reduce the efficiency of the system.
Shunt Regulator
As a final test for our prototype, we analyzed the effect of our shunt regulator circuit on
the produced voltage. For this test, we represented the ATV magneto as a Thevenin equivalent
circuit with a standard 7 V RMS AC source and a one ohm resistor. By altering the load
resistance we were able to produce the load line shown in Figure 11.
DC VOLTAGE OUTPUT (V)
Load Line
10
9
8
7
6
5
4
3
2
1
0
0
0.2
0.4
0.6
0.8
1
AC (A)
1.2
1.4
1.6
1.8
Figure 11. Shunt regulated power supply testing results.
Results, Discussion and Recommendations
From the produced load line, we would be able to determine the optimum operating
conditions for specific loads placed on our system. With the output of the ATV magneto being
only 7 V RMS we would need to custom design a generator to produce more voltage for future
systems, as mentioned previously.
ECONOMICS AND COMMERCIAL VIABILITY
19
Hence, from the prototype testing results and discussion of possible future and final
design changes, the team performed an economic analysis to ensure that the final bicyclepowered charger product could be marketed to the consumers at a desirable price. Since the
design is mainly an integration of parts, the design team would purchase many of the necessary
components in bulk. Additionally, for the custom parts specifically designed by the team
(support frame, generator, shaft system), the designs would be sent to a contracted manufacturer
to be produced in bulk at wholesale. The shaft system, since it is a more complex design, would
be custom constructed at a local business to ensure the integrity of the system. With these
assumptions, the team estimated the total cost of each sub-assembly of the system and, therefore,
the total cost of the whole system, which can be viewed in Table 3. The final cost to the design
team shown in Table 3 is that of manufacturing and material costs only. It does not incorporate
labor costs for the integration of the system or for the necessary programming of the display.
20
Table 3: Estimated material and manufacturing costs for the final design of the bicycle-powered charger system. The total cost to the
design team is $164.06. Labor costs of assembly are not included in this economic analysis.
Integration and Manufacture Cost Analysis
Item
Quantity
Cost
Unified Electronics and Control
Item
Bridge Rectifier
1 V Power Resistor
400 mF Capacitor
75 V Power Resistor
5.1 V Zener Diode
Transistor
Total
1
2
1
1
1
1
$ 1.00
$ 3.95
$ 6.02
$ 1.69
$ 0.90
$ 2.90
$ 16.45
12 V Lead Acid Battery
Boost Power Inverter
Removable Battery Pack
Power Supply
Micro-processor
Charger
5 V USB
Total
1
1
1
1
1
1
1
1
1
$ 16.00
$ 2.50
$ 7.00
$ 2.50 Contracted Generator
$ 2.50
$ 2.50
$ 2.50
$ 35.50
$ 15.00 Contracted Frame
Charging System
Display
Quantity
Cost
Roller System
Shaft
Adujuster Brace
Bearing Base
Roller
Pillow Block Bearings
Shims
Bolts
Nuts
Washers
Set Screws
Total
1
1
1
1
2
2
4
4
8
2
$
$
$
$
$
$
$
$
$
$
$
4.94
12.13
2.78
3.98
12.69
2.47
4.54
0.68
2.56
0.34
47.12
Core
Windings
Encasing
Total
1 $
1 $
1 $
$
2.50
7.50
10.00
20.00
1 $
30.00
Frame Total
Total Integration Cost
1 $ 164.06
21
The total cost to the design team was found to be approximately $164 for manufacture
and material costs of the various sub-systems. Hence, the team could market this product in the
range of $300 to $400. This is a desirable price range to the consumers because most affordable
retail bicycle trainers are sold at prices in the range of $200 to $400 as outlined previously. Our
product could be sold in this range and also offers more to the consumers than just the frame.
Furthermore, this product, if used regularly as discussed in the ensuing life cycle assessment
section, could significantly reduce our users’ dependence on electrical power generation plants
and, therefore, reduce their monthly and yearly electricity household costs. Consequently, our
product is desirable in that it offers a way to accelerate health and exercise, and reduce
dependence on power plant generation and, correspondingly, residential costs all at an affordable
upfront price.
LIFE CYCLE ASSESSMENT
A commercially produced version of our bicycle-powered charger would have
several stages in its life cycle: raw material extraction and production, sub-system construction,
sub-system integration, operation, and afterlife. At each stage, we analyzed the environmental
impacts and human impacts. For the first stage, raw material extraction and production, we
focused on the primary materials used for the custom-built components – aluminum and steel.
The other materials were not considered due to their small amount relative to aluminum and steel
and to reduce the complexity of this assessment. For the environmental impacts, aluminum
extraction and production produces perfluorocarbons, polycyclic aromatic hydrocarbons,
fluoride, sulfur dioxide, and carbon dioxide, all of which are greenhouse gases.17 Another
environmental impact comes from the produced sulfur dioxide in the form of acid rain which, as
is known, can harm plant life.18 Steel production has a very small impact on the environment due
to the large emphasis on reusing or recycling its residuals.19 The human impacts associated with
aluminum and steel stem from similar areas as the environmental impacts. For aluminum, the
polycyclic aromatic hydrocarbons are considered carcinogenic and so have the potential to cause
cancer.20 Another human impact comes from the released sulfur dioxide which can contribute to
difficulty breathing, respiratory illness, and aggravated cardiovascular disease of an individual if
it is found in large concentrations.21 The people most likely to feel these effects are children, the
17
Aluminum - The Environmental Literacy Council. (2015). Retrieved from http://enviroliteracy.org/specialfeatures/its-element-ary/aluminum/
18
Ibid.
19
Fact sheet: Steel industry by-products. (2014, October). Retrieved from
https://www.worldsteel.org/publications/fact-sheets/content/01/text_files/file/document/Fact_Byproducts_2014.pdf
20
Toxic substances portal - polycyclic aromatic hydrocarbons (PAHs). (2014, August 28). Retrieved from
http://www.atsdr.cdc.gov/toxfaqs/tf.asp?id=121&tid=25
21
Sulfur Dioxide (SO2). (2016, February 22). Retrieved from https://www3.epa.gov/airtrends/aqtrnd95/so2.html
22
elderly, and people with existing respiratory conditions.22 Additionally, the acid rain resulting
from sulfur dioxide emissions can have an effect on humans by corroding structures such as
buildings.23 With enough acid rain, the structural integrity of a building could become
significantly reduced and thereby increase the safety risk to humans.
The environmental and human impacts from sub-system construction would stem from
the need for heat-treatment of the support frame but also a small amount could come from the
construction of the shunt regulator circuit discussed previously. For the shunt regulator circuit,
each individual electrical element was connected by lead soldering. Lead can negatively impact
the developing nervous system in adolescents and reduce the memory and learning capabilities
of individuals.24 This is not a significant risk, however, since the electrical components will be
covered to avoid electrical injury. Sub-system integration, however, would not result in any
significant environmental impacts since we would primarily use bolts to integrate each subsystem. Similarly, there would be very little negative environmental and human impacts from the
operation stage since our bicycle-powered charger is designed to be operated by a person
exercising. The only residuals in that stage would be the respiration and perspiration from the
individual and some amount of heat due to the inevitable inefficiency in mechanical to electrical
energy conversion. We predict that an average user would operate the system for approximately
144 hours per year – three hours per week. More testing would show the full effect of our system
on the environmental impacts associated with charging small electronic devices. With
modifications to our generator, we could reduce the potential amount of heat produced. The
largest impacts to humans at that stage would be the dual benefits of improving health due to
exercise and the charging voltage produced via our system.
The afterlife, as the final stage in the life cycle of a commercially produced version of our
bicycle-powered charger, would have very little environmental and human impacts. This is due
to the design of our bicycle-powered charger. By limiting the variety of materials used and
integrating the subsystems using bolts, we enabled our system to be easily separated into its subsystems thereby allowing easy reuse of sub-systems or recycling of materials. Aluminum is very
recyclable.25 Steel, also, is very recyclable.26 By reusing and/or recycling the subsystems and
materials from used bicycle-powered chargers, we can essentially eliminate the negative
environmental and human impacts from the first two stages: raw material extraction and
production and sub-system construction. A life cycle diagram of a commercially produced
version of our bicycle-powered charger is shown in Figure 12.
22
Sulfur Dioxide (SO2). (2016, February 22). Retrieved from https://www3.epa.gov/airtrends/aqtrnd95/so2.html
Ibid.
24
Striebig, B. A., Ogundipe, A. A., and Papadakis, M. (2016). Engineering applications in sustainable design and
development (First ed.). Boston, MA: Cengage Learning.
25
Aluminum - The Environmental Literacy Council. (2015). Retrieved from http://enviroliteracy.org/specialfeatures/its-element-ary/aluminum/
26
Fact sheet: Steel and raw materials. (2014, October). Retrieved from
https://www.worldsteel.org/publications/fact-sheets/content/00/text_files/file0/document/fact_raw
materials_2014.pdf
23
23
Raw Material
Extraction and
Production
• Aluminum
• Steel
Sub-system
Construction
• Support Frame
• Shaft System
• Shunt Regulator
Sub-system
Integration
• Completed Bicycle-Powered
Charger
Operation
• Human Exercise
• Electrical Device Charging
Afterlife
• Recycle
• Reuse
Figure 12: Life cycle for a commercially produced version of the bicycle-powered
charger system. At each stage, energy input is required and some form of residuals (by-products)
are released.
CONCLUSIONS
With successful design and completion of this bicycle-powered charger system, the
possibility for a healthier population with a lower environmental footprint becomes greater.
Improved health will come from more physical exercise due to increased cycling. It has been
found that cycling has positive psychological effects and boosts productivity in the workplace.27
A lower environmental footprint will come directly from increased bicycle usage. This system
will encourage an increased usage of bicycles because, as users become more familiar with the
system and realize its potential, they will enjoy operating it more. This may lead individuals to
opt for bicycle transportation rather than vehicular transportation for short-distances, which is
made possible by the easy transition from stationary use to road use.
27
Heesch, Kristiann C., Billie Giles-Corti, and Gavin Turrell. "Cycling for Transport and Recreation: Associations
with Socio-economic Position, Environmental Perceptions, and Psychological Disposition." Preventive Medicine:
29-35. Print.
24
Appendix 1: FMEA
Figure A1.1: Failure Mode and Effects Analysis of the bicycle-powered charger system where potential failure stems from five areas:
the generator, the support frame, the shaft system, the electrical components collecting and directing the charge outputted by the
generator, and the lead-acid battery. These were then ranked based on the severity of a failure if it were to occur, the probability of a
failure occurring and the detectability of a failure or imminent failure to the users. Descriptions of the rankings of the severity,
probability and detectability are shown in Tables A1.1-A1.3.
I
Table A1.1: Ranking of the severity to both the users and the system if a failure were to occur.
Effect
SEVERITY of Effect
Ranking
Very high severity ranking when a potential failure mode
Hazardous without
10
warning
affects safe system operation without warning
Hazardous with
warning
Very high severity ranking when a potential failure mode
affects safe system operation with warning
9
Very High
System inoperable with destructive failure without
compromising safety
8
High
System inoperable with equipment damage
7
Moderate
System inoperable with minor damage
6
Low
System inoperable without damage
5
Very Low
System operable with significant degradation of performance
4
Minor
System operable with some degradation of performance
3
Very Minor
System operable with minimal interference
2
None
No effect
1
Table A1.2: The ranking of various probabilities of failures of a system
PROBABILITY of Failure
Very High: Failure is almost inevitable
High: Repeated failures
Moderate: Occasional failures
Low: Relatively few failures
Remote: Failure is unlikely
Failure Prob Ranking
>1 in 2
10
1 in 3
9
1 in 8
8
1 in 20
7
1 in 80
6
1 in 400
5
1 in 2,000
4
1 in 15,000
3
1 in 150,000
2
<1 in 1,500,000
1
II
Table A1.3: Ranking of the likelihood of the users detecting failure or imminent failure of the
system.
Detection
Likelihood of DETECTION by Design Control
Ranking
Design control cannot detect potential cause/mechanism and
Absolute
10
Uncertainty
subsequent failure mode
Very Remote
Very remote chance the design control will detect potential
cause/mechanism and subsequent failure mode
9
Remote
Remote chance the design control will detect potential
cause/mechanism and subsequent failure mode
8
Very Low
Very low chance the design control will detect potential
cause/mechanism and subsequent failure mode
7
Low
Low chance the design control will detect potential
cause/mechanism and subsequent failure mode
6
Moderate
Moderate chance the design control will detect potential
cause/mechanism and subsequent failure mode
5
Moderately High
Moderately High chance the design control will detect
potential cause/mechanism and subsequent failure mode
4
High
High chance the design control will detect potential
cause/mechanism and subsequent failure mode
3
Very High
Very high chance the design control will detect potential
cause/mechanism and subsequent failure mode
2
Almost Certain
Design control will detect potential cause/mechanism and
subsequent failure mode
1
III
Appendix 2: SolidWorks Drawings of the Support Frame
Figure A2.1: Back assembly of the complete bicycle charging system assembly consisting of a back floor support and two back
uprights to be fitted and bolted into covers welded onto the front uprights. The covers will allow the frame to fold up for greater
transportation ease for the user and, when set up, will place the front and back uprights approximately 60° apart.
IV
Figure A2.2: One of two top assemblies attached to the final frame design. Both top assemblies have adjustment abilities so that the
user can set their bicycle in the lateral plane anywhere they desire so that the system fits into the bicycle however is necessary for
operation. Both top assemblies are constructed from steel rather than aluminum for strength purposes. These steel top assemblies are
then connected the remainder of the aluminum frame by way of a hollow steel slotted piece designed to drop into the hollow part of
the top of the front uprights and bolted into place. This top assembly differs very slightly from the other top assembly in that the steel
wheel support is designed to offer more support than the other. The purpose of this variation is so the user can place the bicycle into
the frame and steady it while making adjustments using this top assembly and the other.
V
Figure A2.3: The other top assembly designed exactly like the other with the small wheel support variation and intended
primarily adjustment purposes and support of the bicycle after the final placement has been made.
VI
Appendix 3: Solid Works Drawing of the Shaft System.
Figure A3.1: The adjuster brace that allows the shaft assembly to adjust and accommodate different sized bicycle tires.
VII
Figure A3.2: This part connects to the frame and also to the pillow block bearings which support the shaft.
VIII
Figure A3.3: These parts act as shims to elevate the pillow block bearings off of the bearing base so that the roller has clearance.
IX
Figure A3.4: The roller goes on the shaft and rests against the bicycle tire. It uses friction to transfer the rotational energy from the rear
tire to the shaft and ultimately the generator.
X
Figure A3.5: The shaft is supported by the pillow block bearings and it supports the generator and the roller.
XI
Appendix 4: Cost Analysis Table
Table A4.1: Table showing costs to the design team for design, construction and integration of first prototype of the bicyclepowered charger system.
Item
Generator
Permanent magnets
Battery Pack
Power inverter
Bridge rectifier
Support Frame
Gear
Shaft
Bicycle Computer
Bicycle
Cost Estimate
$0
$40-80
$30 - $80
$10
$8
$3-$6
$13
$6
$11
$0
General Information
3 phase permanent magnet motorcycle magneto stator
Rotor (estimate, will be constructed in the shop)
12V NiMH/NiCd; Rechargeable;
Range from 1600mAh to 5000mAh
Buck-Boost system
Convert AC to DC
Aluminum Square Tube, cost per foot
Steel Plate, cost per square foot
6061 Aluminum, cost per foot
Odometer included
Used road bike
XII
Appendix 5: Test Results
Figure A6.1 shows the peak power consumption for various small household electronic
devices. Each member of the team participated in measuring their personal devices in order to
gather this data.
50
45
Peak Power (W)
40
35
30
25
44
40
35
25
24
20
15
10
5
8
7
5
5
3
3
2
2
0
Figure A5.1: Electronic device peak power consumption. Values were self-obtained from
personal electronics.
XIII
Appendix 6: Transistor Data Sheets
XIV
XV