ISSN 2249-6343
International Journal of Computer Technology and Electronics Engineering (IJCTEE)
Volume 2, Issue 4, July 2012
Intelligence Photo-Detector Light Switching
System (IPD- LSS)
M.A. Othman, M.M. Ismail, H.A. Sulaiman, M.H. Misran, M.A.M. Said

An intrinsic semiconductor has its own charge carriers and is
not an efficient semiconductor such as silicon. In intrinsic
devices the only available electrons are in the valence band,
and hence the photon must have enough energy to excite the
electron across the entire bandgap. Extrinsic devices have
impurities or dopants, where the ground state energy is closer
to the conduction band; since the electrons do not have as far
to jump, lower energy photons are sufficient to activate the
device. If a sample of silicon has some of its atoms replaced
by phosphorus atoms as impurities, there will be extra
electrons available for conduction. This is an example of an
extrinsic semiconductor. Photoresistors are essentially
photocells.
Photoresistors have many different types. Cadmium
sulphide cells can be found in many consumer items such as
camera light meters, street lights, clock radios, alarm devices,
outdoor clocks,solar street lamps and solar road studs.They
are also used in some dynamic compressors together with a
small incandescent lamp or light emitting diode to control
gain reduction and are also used in bed lamps.Lead sulphide
(PbS) and indium antimonide (InSb) Light Dependent
Resistors are used for the mid infrared spectral region. Ge:Cu
photoconductors are among the best far-infrared detectors
available, and are used for infrared astronomy and infrared
spectroscopy.
Abstract— In advancement and fabrication of highly reliable
active fiber optic components, a high capacity experimental
optical in fiber communications system has been designed and
set up in an environment approaching field conditions to test
the applicability of optical fiber transmission systems. The
photoresistor (SN-LDR-S) is the optical detector that can
perform the reverse function of light emitters which is they
convert optical signals back into electrical impulses that are
used by the receiving end of the fiber optic data, video or audio
link. The most common detector is the semiconductor
photodiode, which produces current in response to incident
light.
Index Terms— optical detector, photoresistor (SN-LDR-S),
semiconductor photodiode.
I. INTRODUCTION
A photoresistor or light dependent resistor (LDR) is a
resistor whose resistance decreases with increasing incident
light intensity; where, it exhibits photoconductivity. It can
also be referred to as a photoconductor or CdS (Cadmium
Sulfide) device, which is the material from which the device
is made and that actually exhibits the variation in resistance
with light level. Although CdS is a semiconductor, it is not
doped silicon. It is made of a high resistance semiconductor.
If light falling on the device is of high enough frequency,
photons absorbed by the semiconductor give bound electrons
enough energy to jump into the conduction band. The
resulting free electron (and its hole partner) conduct
electricity, thereby lowering resistance.
A photoelectric device can be either intrinsic or extrinsic.
II. INTELLIGENCE PHOTO-DETECTOR LIGHT SWITCHING
SYSTEM (IPD-LSS)
The main function of Intelligence Photo-Detector
Light Switching System (IPD-LSS) is able to turn on a switch
light automatically when the photo-detector unable to detect
the light ray in the detection area. In other words, this system
will switch off the light when exist of sun ray. Hence, it can
assist the consumer to use the electricity wisely.
This IPD-LSS is a system where can simplify the
switching system and automatically turn on or turn off the
light depend on the existence condition of sun ray. It makes
the switching system more convenient to the consumers. It is
an efficient system to control the light switching system and
it is constructed by combination of simple circuit design
which is Peripheral Interface Controller (PIC) , Light
Dependent Resistor (LDR),Voltage Regulator and Light
Emitting Diode (LED).
LDR are very useful especially in light or dark sensor
circuits. Normally the resistance of an LDR is very high,
sometimes as high as 1M ohms, but when they are
illuminated with light resistance drops dramatically.
Manuscript received July 16, 2012.
M.A.Othman, Centre for Telecommunication Research and Innovation,
Fak.Kej.Elektronik dan Kej. Komputer, Universiti Teknikal Malaysia
Melaka, Hang Tuah Jaya, 76100 Durian Tunggal, Melaka,
Malaysia,(azlishah@utem.edu.my), +6065552151, M.M. Ismail, Centre for
Telecommunication Research and Innovation, Fak.Kej.Elektronik dan Kej.
Komputer, Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, 76100
Durian
Tunggal,
Melaka,
Malaysia,(muzafar@utem.edu.my),
+6065552154, H.A.Sulaiman, Centre for Telecommunication Research and
Innovation, Fak.Kej.Elektronik dan Kej. Komputer, Universiti Teknikal
Malaysia Melaka, Hang Tuah Jaya, 76100 Durian Tunggal, Melaka,
Malaysia,(asyrani@utem.edu.my), +6065552150, M.H. Misran, Centre for
Telecommunication Research and Innovation, Fak.Kej.Elektronik dan Kej.
Komputer, Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, 76100
Durian Tunggal, Melaka, Malaysia,(harris@utem.edu.my), +606555204.
M.A.M.Said, Centre for Telecommunication Research and Innovation,
Fak.Kej.Elektronik dan Kej. Komputer, Universiti Teknikal Malaysia
Melaka, Hang Tuah Jaya, 76100 Durian Tunggal, Melaka,
Malaysia,(maizatul@utem.edu.my), +6065552041.
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ISSN 2249-6343
International Journal of Computer Technology and Electronics Engineering (IJCTEE)
Volume 2, Issue 4, August 2012
For example, when a light level of 1000 lux (bright light) is
directed towards it, the resistance is 400R (ohms). While,
when a light level of 10 lux (very low light level) is directed
towards it, the resistance has risen dramatically to 10.43M.
The IPD-LSS circuit is operate when a 9 Volt battery is
supply to the voltage regulator (LM7805) and the LM 7805
will provide 5 Volts to the PIC as well as the LDR. When the
light level is low the resistance of the LDR is high. This
prevents current from flowing to the input of the PIC.
Consequently the PIC detect a input in low level and turn on
its output. Hence, the LED is turn on. However, when light
shines onto the LDR its resistance falls and current flows into
the input of the PIC and then the turn off its output.
Consequently, the LED is turn off. The preset resistor can be
turned up or down to increase or decrease resistance, in this
way it can make the circuit more or less sensitive.
Figure 3: Flow Chart of the System Implementation
III. RESULTS AND DISCUSSIONS
In photoresistor, several advantages and disadvantages.
For advantages, they are completely dependent on how much
light they receive. This means that external forces will not
interfere with the devices that they are connected to. A
photoresistor is also very simple because it is merely a
semiconductor with a conductive pathway connected to one
end in order to transfer a current from the semiconductor to
the external device that it is powering.They are small enough
to fit into virtually any electronic device and are used all
around the world as a basic component in many electrical
systems. Also, photoresistors are simply designed and are
made from materials that are widely available, allowing
hundreds of thousands of units to be produced each year.
They allow less power to be used in many different kinds
of lights. They help lights last much longer. They can be
trigged by several different kinds of triggers, which is very
useful for motion lights and security systems. They are also
very useful in watches and cars so that the lights can turn on
automatically when it becomes dark. There are a lot of things
that light dependent resistors can do. For disadvantages,
photoresistors cannot detect low light levels and may not
work in certain conditions or circumstances. Photoresistors
are also slow to respond to new levels of light and may take
up to several seconds to recognize the change. This is because
electrons are still moving through the semiconductor and take
a few seconds to slow down or speed up.
Figure 1: IPD-LSS Circuit Schematic
Figure 2: IPD-LSS PCB Layout
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ISSN 2249-6343
International Journal of Computer Technology and Electronics Engineering (IJCTEE)
Volume 2, Issue 4, July 2012
The controller PIC16F877A also gives some advantges
and disadvantages in this cicuit. Each pin is only shared
between two or three functions so it’s easier to decide what
the pin function (other devices have up to 5 functions for a
pin). This controller also built in oscillator with selectable
speeds where it has an easy entry level and not so expensive
to buy. But for this controller there still some advantages and
limitation. This controller has no internal oscillator so need
an external crystal of other clock source. For RAM access,
register-bank switching is required to access the entire RAM
of many devices. In addition, operations and registers are
not orthogonal; some instructions can address RAM
and/or immediate constants, while others can only use the
accumulator. The hardware call stack is not addressable, so
preemptive task switching cannot be implemented. Other
than that, software-implemented stacks are not efficient, so it
is difficult to generate reentrant code and support local
variable. Since the LDR is sensitive with the intensity of
light, therefore for future advance system, we can apply this
project into house application which is powered via
photovoltaic system to optimum the battery usage. Besides
that, we also can apply this project into load light application
to minimum the electricity usage.
AUTHOR’S PROFILE
Mohd Azlishah Othman was born on 21st October 1980 at Johor Bahru,
Johor, Malaysia. He received Degree Bachelor of Engineering in Electrical
Engineering (Telecommunication) from Universiti Teknologi Malaysia
(UTM) on 2003. In September 2005 he joined Universiti Teknikal Malaysia
Melaka (UTeM) as a Lecturer at Fakulti Kej. Elektronik dan Kej. Komputer
(FKEKK). He received his Master’s Degree in Computer and
Communication Engineering from University of Nottingham, UK on 2005
and continues his PhD in Electrical and Electronic Engineering in University
of Nottingham, UK from 2006 till now. His PhD thesis on the field of
Terahertz circuits and devices. Currently he is working on RF and
Microwave circuits and devices.
Mohd Muzafar Ismail was born on 5 August 1985, Raub, Pahang,
Malaysia. He received his first degree Bachelor of Engineering
(Electrical-Telecommunications) at Universiti Teknologi Malaysia (UTM)
on 2008. He got his Master’s Degree , Master of Engineering (Electronic
and Telecommunications) at UTM, 2010. Previously he worked as an
Electrical Engineer at Venture Technocom System Singapore before joining
Universiti Teknikal Malaysia Melaka as a lecturer on 2010 at Fakulti Kej.
Elektronik dan Kej. Komputer. His research currently focus on
Electromagnetics, Acoustic Engineering, Optical communication, and
Optimization.
Hamzah Asyrani Sulaiman was born on 28 Januari 1985, Jitra, Kedah,
Malaysia. He received his first degree Bachelor of Engineering (Computer)
at Universiti Teknologi Malaysia (UTM) on 2008. He got his Master’s
Degree , Master of Science (Computer Science) at UTM, 2010. He joined
Universiti Teknikal Malaysia Melaka as a lecturer on 2010 at Fakulti Kej.
Elektronik dan Kej. Komputer. His research currently focus on Computer
Graphics and Visualization/ Data Computation and Algorithm with Graphics
Processing Unit (GPU).
IV. CONCLUSION
At the end of this paper, we conclude that there are
differences
between photodiode (photodetector) and
photoresistor (photoconductor). Besides that, the
microcontroller as PIC16F877A can be used in this system
but have some limitation on it.
Mohamad Harris Misran was born on 29 February 1980, Kluang,
Johor, Malaysia. He received his first Degree Bachelor of Engineering
(Electronics) at University of Surrey, 2006. Then he continued his Master’s
Degree on Master of Engineering (Telecommunication) at University of
Wollongong, 2008. Then he joined Universiti Teknikal Malaysia Melaka as
a lecturer on 2008 at Fakulti Kej. Elektronik dan Kej. Komputer. Currently
his research on RF and Microwave circuits and Antenna Propagation.
APPENDIX
Appendixes,
if
acknowledgment.
needed,
appear
before
the
Maizatul Alice Meor Said was born on 26 Oktober 1982, Taiping,Perak,
Malaysia. She received Bachelor of Engineering (Electronics) at University
of Surreyon 2006. She received her Master of Engineering
(Telecommunication) at University of Wollongong, 2009 and she joined
Universiti Teknikal Malaysia Melaka as a lecturer on 2009 at Fakulti Kej.
Elektronik dan Kej. Komputer. Currently she is working on RF &
Microwave and Antenna propagation.
ACKNOWLEDGMENT
Authors would like to thank Universiti Teknikal Malaysia
Melaka for sponsoring this project and also for financing to
this journal.
REFERENCES
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John M. Senior, “Optical Fiber Communications Principles and
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[2]
Michael C. Brain, “Comparison of Available Detectors for Digital
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[3]
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[4]
Gerd Keiser, “Optical Fiber Communications”, Fourth Edition, 2010,
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[5]
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[6]
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