ARID ZONE JOURNAL OF ENGINEERING, TECHNOLOGY & ENVIRONMENT
AZOJETE, June, 2019. Vol. 15(2):259-267

Published by the Faculty of Engineering, University of Maiduguri, Maiduguri, Nigeria.
Print ISSN: 1596-2490, Electronic ISSN: 2545-5818

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259

ORIGINAL RESEARCH ARTICLE

DESIGN AND IMPLEMENTATION OF AN ARDUINO BASED LIGHT DEPENDENT ALARM
SYSTEM

H. Ibrahim*, A. A. Mohammed and I. A. Aliyu
(Department of Computer Engineering, Kaduna Polytechnic, Kaduna, Nigeria)

*Corresponding author’s e-mail address: harunaebrahim@gmail.com

ARTICLE INFORMATION

Submitted 10 November, 2018
Revised 4 February, 2019
Accepted 10 February, 2019

Keywords:
Alarm
Arduino Uno
LDR
Microcontroller
Potentiometer

ABSTRACT
This paper is based on design and implementation of an Arduino
based alarm system which is capable of monitoring the
illumination of the surrounding automatically. Once the presence
or absence of light is detected accordingly, a control device is
activated which sends a sound alarm to a buzzer connected to the
output of the system. Waking up early from sleep has always
become a challenge most especially after a very hectic and busy
engagement during the previous day time, this makes waking up
early the next morning to meet up with the activities of the day a
challenge. The components used for carrying out this study
include Light Dependent Resistor, a control unit and an output
buzzer unit. The LDR works on the principle of change of
resistance based on the amount of luminous energy in its
environment at that moment of time, once an illumination is
detected, an Arduino Uno board was used to send a signal to the
buzzer that generates sound when the intensity of light increases.
The test conducted showed that the LDR resistance decreased as
illuminance on the LDR increased; the illuminance ranges at which
the buzzer was triggered was between 100-1000lux.

© 2019 Faculty of Engineering, University of Maiduguri, Nigeria. All rights reserve

1.0 Introduction
Advancement in technology has made all aspects of life simpler and easier thereby making
automated systems more preferred to manual systems (Nikhil, 2016). Automatic alarm systems
are designed to alert an individual or group of individuals at specified times. The alarm system in
this study uses sound and light devices. Researchers have worked on techniques for light
detection and sensing and had developed devices that offer excellent performance (Busari et al.,
2015). Light is an electromagnetic radiation within a certain portion of the electromagnetic
spectrum which is visible to the human eye and is responsible for the sense of sight (Effend et al.,
2014). The Light sensor is a passive device that converts light energy into electrical signal that
generates an output signal that is proportional to the intensity of the light (Mavrya et al., 2012).
The commonly used photo resistor is called Cadmium Sulphide Light Dependent Resistor (LDR).

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Ibrahim et al.: Design and Implementation of an Arduino Based Light Dependent Alarm System.
AZOJETE, Vol. 15(2):259-267 Print ISSN: 1596-2490, Electronic ISSN: 2545-5818, www.azojete.com.ng

Corresponding author’s e-mail address: harunaebrahim@gmail.com 260

Manual control of light is prone to errors and stressful. The introduction of automation and
remote management solution for detecting light illuminations is vital and can be achieved by
the used of programmed microcontroller. The alarm system in this article is designed to
automatically detect the presence and absence of light. A buzzer is triggered once light, with
illuminance between 100-1000lux, is detected.
Much effort and work have been done in this area of research but improvement on the
drawbacks of past works is necessary in order to have maximum performance of their
applications in domestic use which include: detection of the presence or absence of light, street
light switching, security systems and as a triggered alarm system. Some related works are
therefore discussed.
Isah et al. (2015) designed an automatic street light Control System. The work is based on
UA741 operational amplifier which is configured as a Schmitt trigger and a light dependent
resistor. During the day, the LDR senses enough illumination and the street light goes off and
comes ON when there is darkness. A transistor is used as switch to provide the switching
mechanism that activates the street lights. The transistor was not fully saturated and only
switched on DC loads. This design overcame the challenge of streetlight system using a timer
controller, and human intervention was completely removed. The drawback of this work is that
discrete components were used in its implementation: this requires using many circuit
components and thus not cost effective.
Similarly, an automatic street light control system was designed by Sakshee (2013). This work
exploits the working of a transistor, in saturation and cut-off region, to switch ON and OFF the
lights at the appropriate time with the help of an electromagnetically operated switch. It
operates on a 12V DC supply and a photoconductive device whose resistance changes in
proportion to light intensity. The work helped to reduce energy consumption, easy to operate
and has low cost. The major drawback of this work is that the ON and OFF timer controller
circuit is easily affected during sunny or rainy days.
Mustafa et al, (2013) proposed an automatic street light control system using PIC16F877A
microcontroller. In the work, two sensors were used which are an LDR and a photoelectric
sensor. The LDR is used to detect day/night time while the photoelectric sensor detects the
movements on the street. The microcontroller is used as a brain, to control the street light
system. The PIC16F877A microcontroller used is not as flexible as Arduino. Arduino hardware
components are cheaper in relation with the PIC microcontroller, and the programming
language is easy. Arduino needs no separate compiler and programmer, and it also has greater
academic applications because it is simple to learn. The objective of the study is to enable
waking up from sleep early easier so as to meet up with responsibilities such as dropping of
children in school and arriving in office on time a reality. With this study it makes meeting up
with such responsibilities a reality.

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Arid Zone Journal of Engineering, Technology and Environment, June, 2019; Vol. 15(2):259-267
Print ISSN: 1596-2490, Electronic ISSN: 2545-5818, www.azojete.com.ng

Corresponding author’s e-mail address: harunaebrahim@gmail.com 261

2. Materials and Methods
2.1 Design of the Arduino-Based Alarm System
The Arduino based alarm system using light sensor is designed in four working units which are
the power supply unit, the LDR, the controller and the buzzer. The units are connected together
to form a functional hardware system. The power supply unit powers the complete system. The
second unit is the Photo-sensor known as the Light Dependent Resistor (LDR). The LDR
resistance changes with the intensity of light. The LDR gives out an analog voltage when
connected to VCC (5v), which varies in magnitude and is directly proportional to the intensity of
the input light on it. The third unit is the Arduino UNO which serves as the Control Unit. The
Arduino, with its inbuilt ADC (Analog to Digital converter) converts the analog voltage (from 0-
5V) into digital voltage. Thus, when there is sufficient light in its environment or on the surface
of the LDR, the converted digital values are read from the LDR through the Arduino. The buzzer
is the last unit: it is connected to the Arduino pin and produces sound as it is programmed.
When the LDR detects a light beyond a certain threshold, the Arduino triggers the buzzer and a
sound is produced, but turned off when the intensity of light decreases. Figure 1 shows the
block diagram of the system and its component units.

Figure 1: Block Diagram of an Arduino Based Alarm System.

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Ibrahim et al.: Design and Implementation of an Arduino Based Light Dependent Alarm System.
AZOJETE, Vol. 15(2):259-267 Print ISSN: 1596-2490, Electronic ISSN: 2545-5818, www.azojete.com.ng

Corresponding author’s e-mail address: harunaebrahim@gmail.com 262

2.2 The Software System
In order to enable that the controller function appropriately, software that models the system
operation is designed and implemented using C language. The flowchart is shown in Figure 2.

Figure 2: The System flowchart.

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Arid Zone Journal of Engineering, Technology and Environment, June, 2019; Vol. 15(2):259-267
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2.3 The Hardware Design
The system hardware is implemented as shown in the Figure 3:

Figure 3: Circuit Diagram of an Arduino Based Alarm System
The voltage out across the LDR and the variable resistor is implemented as shown in figure 4.

Figure 4: Voltage Divider between LDR and Potentiometer.

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Ibrahim et al.: Design and Implementation of an Arduino Based Light Dependent Alarm System.
AZOJETE, Vol. 15(2):259-267 Print ISSN: 1596-2490, Electronic ISSN: 2545-5818, www.azojete.com.ng

Corresponding author’s e-mail address: harunaebrahim@gmail.com 264

Vout when light is detected;
Where:
RLDR is the resistance of the LDR, measured in ohm;
Vout is the output voltage from the voltage divider combination, measure in volt.

Vcc is the supply voltage , measure in volt.
Vout when light is not detected;
Vout = 4.95V
It was deduced that, when light is detected, the resistance of the LDR decreases with a
corresponding increase in voltage across the LDR as well as the variable resistor, and vice versa.
Figure 5 shows the light emitting resistor circuit.

Figure 5: The Series connection between The Miniature Indicator Light Emitting Resistor and a
Ballast Resistor.
The value of the current limiting resistor can be calculated from Figure 5. The formula is shown
below:

��im ���im �
�⢈Оᗐ⢈ 벨 ����
�⢈�� ⢈Оᗐ⢈�

(1)

��ૡ � 4.99 벨 �t��V

R

D

R

⢈ �
��� � ���

�
(2)

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Arid Zone Journal of Engineering, Technology and Environment, June, 2019; Vol. 15(2):259-267
Print ISSN: 1596-2490, Electronic ISSN: 2545-5818, www.azojete.com.ng

Corresponding author’s e-mail address: harunaebrahim@gmail.com 265

Where;
Vs � Power Supply Voltage

Vf � LEDforward voltage /Voltage drop across LED
I � Desired Current of LED

R � Current Limiting or Ballast ResistorDesired Current of LED
Note: Miniature Indicator LED (red LED) from the manufacturer datasheet has the following
parameters:

I � 2tmA
LED voltage � �.8V � 2V

Therefore, from equation (2), R is calculated as

R �
�5 � 2�V
2tmA

R � �5tΩ

The value of the current resistor needed to be connected in series to the Red LED is 150Ώ.
2.3 Construction of Arduino based light dependant alarm system
The construction of the hardware and packaging was carried out as shown in Figure 6 and 7
respectively.

3. Results and Discussions
Table 1 shows the testing of Arduino based alarm system. When the system was subjected to
darkness with the LDR having resistance of about 100KΩ, the light intensity is around 0lux and
the alarm is in off-state. With decrease in the resistance of the LDR, at about 1269Ω, the light
intensity begins to increase gradually to about 100lux and the alarm comes “ON”. The test
conducted shows the LDR resistance decreases as light intensity increases. The light illuminance
ranges at which the buzzer was triggered “ON” is between 100-1000lux. The result obtained is as
shown in a graph of resistance against light illuminance plot in Figure 8.

Figure 6: Construction of the System Figure 7: Packaging of the System

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Ibrahim et al.: Design and Implementation of an Arduino Based Light Dependent Alarm System.
AZOJETE, Vol. 15(2):259-267 Print ISSN: 1596-2490, Electronic ISSN: 2545-5818, www.azojete.com.ng

Corresponding author’s e-mail address: harunaebrahim@gmail.com 266

Table 1: Testing of the Arduino Based Alarm System.

S/N Light Illuminance (Lux) Resistance (Ώ) Buzzer

1 0 11 900.90 OFF

2 100 1269.18 ON
3 200 630.04 ON
4 300 547.10 ON
5 400 411.87 ON
6 500 342.09 ON
7 600 292.52 ON
8 700 264.66 ON
9 800 230.77 ON
10 900 212.04 ON
11 1000 190.30 ON

Figure 8: Result of plot for Resistance against Illuminance.

4. Conclusion
The Arduino based alarm system was built, tested and found to be working in conformity to the
design. It was found to be a versatile system capable of detecting the presence of light and
triggering the buzzer. The LDR resistance decreases (to about100Ώ) as incident of light falls on it
and increases (to about 10MΏ) in the dark. The range of illuminance at which the buzzer was
triggered was between 100-1000 lux. The alarm is triggered at about 6.45 a.m., which is in

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Arid Zone Journal of Engineering, Technology and Environment, June, 2019; Vol. 15(2):259-267
Print ISSN: 1596-2490, Electronic ISSN: 2545-5818, www.azojete.com.ng

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conformity with the mean time of getting out of bed. Such system can be produced locally with
a minimum circuit complexity, resulting in a technological tool of utility and economy suited to
the need of modern activities.

The implementation (construction) is built around an open-source electronics platform which is
based on an easy to use hardware and software. No need of a separate hardware
programmer/burner for loading/burning of program on to the microcontroller. The Arduino
software is easy to use for beginners and very flexible for advance users. It is recommended that
any other person working on this kind of design should make use of photodiode or
phototransistor so as to improve on the response time of the system and increase the resistance
needed to trigger the buzzer. A passive infrared (PIR) sensor can also be used to detect motion
when there is a variation of weather or light intensity.

References
Busari, A., Adebisi, O. and Akanji, O. 2015. Design and Implementation of a Microcontroller
Based Alarm Enabled Dark Activated Switch. International Journal of Engineering and Innovation
Technology, Ibadan, Nigeria, 4(12): 38-41

Effendi, M., Shayfull, Z. and Saad, M. 2014. Design and Implementation of an Alarm Reminder.
Locking Security System. International Journal of Electronics and Computer Science Engineering,
6(5): 465-472.
Isah, A., Oshoma, A. and Alexander, O. 2015, Design and Implementation of an automatic street
light Control System. International Journal of Emerging Technology and Advanced Engineering,
4(3): 318-329.
Mavrya, K., Singh, M. and Jain, N. 2012. Implementation of a Real Time Vehicle Tracking Using
GPS Technology. International Journal of Electronic and Computer Science Engineering, 4(4):
277-289.
Mustafa, E., Farij, A. and Abdalroof, A. 2013. Automatic street light control system using
microcontroller. Mathematical Methods and optimization Techniques in Engineering ISBN; 978-
960-474-339-1 pp 92 -96
Nikhil, K. 2016. Design and Construction of an IOT based Intelligent Home using Smart Devices.
International Journal of Innovative Research in Electrical Electronics and Instrumentation
Engineering, 4(6): 12090-12097

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