1. The Invictus Initiative Study Lamp: Engineering A Brighter Future
Engineering Senior Design, Spring 2015
Naomi Gaunavinaka, ME; Matthew Minuti, ME; Arianna Vierczhalek, ME
Purpose
Background
Energy Input Analysis
Circuitry
Complete Design
Injection Molded ABS
plastic enclosure keeps
internal components safe
and dry.
3 V solar cell provides 0.21 W
of power in peak sunlight.
700 mAh Nickel Cadmium
battery is rechargeable and
can obtain over 1000
charge/discharge cycles.
Plastic insert holds the battery
and printed circuit board in
place. PCB is secured by two U-
shaped snap-fits and is
mounted on a slight reflector,
which LED will protrude
through.
Acrylic lens has a 50
mm diameter and a
visible light
transmission of 92%.
Plastic housing
features an annular
snap-fit to secure top
and bottom parts
together.
Average Daily
Solar Insolation
(Wh/m2)
Daily Equivalent
Peak Sun Hours
Percent of Battery
Charge Per Day
Using 3V Solar
Cell
Battery Amp-
hours after 1 Day
of Charge from 3V
Solar Cell (Ah)
January 5867 5.867 83.60% 0.59
February 6165 6.165 87.85% 0.61
March 5963 5.963 84.97% 0.59
April 5316 5.316 75.75% 0.53
May 5179 5.179 73.80% 0.52
June 5420 5.42 77.24% 0.54
July 5308 5.308 75.64% 0.53
August 5567 5.567 79.33% 0.56
September 5860 5.86 83.51% 0.58
October 5649 5.649 80.50% 0.56
November 5313 5.313 75.71% 0.53
December 5726 5.726 81.60% 0.57
Annual Average 5611 5.611 79.96% 0.56
Acknowledgements: Dr. Wenzhong Gao,
Dr. Ronald DeLyser, Mahesh Manandhar,
Cody Clickner, Michal Kmita
The product that was requested by The Invictus Initiative is a
portable, rechargeable lamp for primary and secondary school
students that can withstand the climate and environmental
conditions of Kenya, Africa. The purpose of this design is to create
an affordable lighting solution to be used by students, which does
not require an electric power input in order to charge or operate.
For students in rural farming towns of Kenya, education is their
primary opportunity to make their way out of these impoverished
communities and have the hope of creating a better life for
themselves and their families. Students with high enough test
scores are offered the opportunity to receive a government
funded higher education. However, there are a number of
obstacles that students face in achieving high enough test scores.
The biggest obstacle for most students is the energy poverty that
exists in this region of Kenya, which prevents students from
having bright enough light by which they can complete their
homework after the sun has set. To complete schoolwork at night
kerosene lamps may be used, but these emit a dim light that is
hard to study by and kerosene fuel is expensive and not reusable.
This is the problem that The Invictus Initiative Study Lamp
attempts to solve.
Solar energy was determined to be the best means of charging the
study lamp for its ability to recharge a battery over a long period
without a constant or repetitive energy input by the user.
Injection molded
enclosure and
insert: $2.16
NiCd Battery: $0.68
Battery Contacts:
$0.24
PCB: $0.39
Acrylic Lens: $0.25
Solar Cell: $0.50
Aluminum Stand:
$0.19
Total Cost for 1 Lamp*: $5.47
Switch: $0.435
Circuit Components:
$0.63
Table 1: Monthly Energy Analysis of 3 V Solar Cell For Use In Sigomere, Kenya
3 V, 70 mA Solar Cell
• Produces 0.21 W in peak sun
conditions.
Battery Charge Circuit
• Blocking diode protects against
reversal of current from the
battery to solar cell.
• Uses three 10 Ohm resistors in
parallel with 2 1N4001 diodes.
• Charges the battery with 61 mA
of current at nearly 1/10
Current for optimized charging.
Nickel Cadmium battery
• Rechargeable.
• 1.2 V, 700 mAh.
• Over 1000 charge/discharge
cycles when trickle charged.
Synchronous Boost Regulator
• Boosts 1.2 V input from battery
to 3.4 V output to power LED.
• Can operate from battery
voltage as low as 0.65 V.
• Accomplishes high efficiency by
integrating low resistance N-
Channel Boost switch and
synchronous P-Channel switch.
• Integrated Circuit minimizes
external components.
LED
• CCT of 4000K (White neutral
light).
• 121 lumens per Watt.
• 3 V forward voltage.
Figure 1: Battery Discharge Characteristic for Study Lamp
and Other Typical Discharge Rates
Introduction
The development of the most effective design was limited by
functional requirements, which were established at the beginning
of the design process. Some of the primary functional
requirements that drove the design process are as follows:
 The product shall mechanically generate energy or collect
solar energy for power.
 The product shall include an energy storage medium.
 The product shall produce light to last for a minimum of 30
uninterrupted minutes.
 The product shall convert stored mechanical or solar energy
into usable electricity.
 The product shall be compact.
 The light source shall produce a reading light of 200 lux.
 The product shall be able to collect the total amount of energy
needed within a maximum of 8 hours.
Multiple different mechanisms of energy input were explored and
developed. However, the solar lamp was determined to be the
only option that could operate for 30 uninterrupted minutes
without significant user input and time.
Image courtesy of The Invictus Initiative website
Figure 4: Custom Printed Circuit Board During Testing
Figure 3: Synchronous Boost Circuit Schematic
Figure 2: Battery Charge Circuit Schematic
 Battery discharged through LED for 5 hours.
 Sharp decrease in brightness observed after 88 minutes.
• Compact design with a depth of 26.14 mm.
• Total product diameter under 10 cm.
• Inseparable annular snap-fit protects internal
components from dust and water and keeps
children from accessing electrical
components.
• Holes on top of lamp allow for either a
hanging or standing fixture to be attached.
• Pressing on the lens from the bottom side of
the lamp enables the pushbutton switch to
turn the lamp on and off.
• Switch is protected internally from damage or
excessive force.
• Battery is secured in place with battery clips
and a compact fit between top and bottom
plastic pieces.
Key Design Features
*Lamp pricing was calculated for a mass production quantity of 10,000 per client’s request.
Energy Output Analysis
Aluminum stand
allows for adjustable
light dispersion angle
and may be
disconnected at base
for ease of hanging
the lamp.