Design and Construction of a Time-Based Load Control System

Design and Construction of a Time-Based Load Control System Using Arduino Nano, RTC, LCD, and Set Buttons


Abstract

This project report details the design and construction of a time-based load control system using an Arduino Nano, Real-Time Clock (RTC) module, Liquid Crystal Display (LCD), and set buttons. The system is designed to automate the switching of electrical loads at predefined times, offering an efficient solution for energy management in both residential and industrial settings. The load control system ensures that devices are powered on or off according to user-defined schedules, which can be easily set and adjusted through the interface provided by the LCD and buttons. The system’s accuracy is ensured by the DS3231 RTC module, which maintains precise timekeeping even in the event of power interruptions. This report covers the design considerations, component selection, circuit design, software development, testing, and final implementation of the project.


Chapter 1: Introduction

1.1 Background of the Study

Automating the control of electrical loads based on time schedules is crucial for optimizing energy usage and reducing costs. Traditional methods of manual switching are not only inefficient but also prone to human error. A time-based load control system provides a reliable solution by automating the process, thereby ensuring that electrical appliances operate only when needed. The use of microcontrollers like the Arduino Nano, in conjunction with a Real-Time Clock (RTC), allows for precise control over timing, making it an ideal choice for such applications.

1.2 Problem Statement

Manual control of electrical loads can lead to inefficiencies, such as forgetting to turn off devices when not in use, leading to unnecessary energy consumption. There is a need for an automated system that can control the operation of these loads based on a predefined schedule.

1.3 Objectives of the Project
  • To design and construct a time-based load control system using Arduino Nano, RTC, LCD, and set buttons.
  • To provide a user-friendly interface for setting the on and off times for the loads.
  • To ensure accurate timekeeping and load control using the DS3231 RTC module.
  • To test the system for reliability and efficiency in controlling electrical loads.
1.4 Significance of the Project

The proposed system offers significant benefits in energy management by automating the control of electrical loads. It reduces the risk of leaving devices on unnecessarily, thus saving energy and reducing costs. The project is also significant in educational contexts, as it demonstrates the practical application of microcontrollers in real-world scenarios.


Chapter 2: Literature Review

2.1 Overview of Load Control Systems

Load control systems have been employed in various forms, ranging from simple mechanical timers to advanced programmable logic controllers (PLCs). However, the integration of microcontrollers like Arduino has simplified the design and increased the flexibility of these systems.

2.2 Microcontroller-Based Load Control

The use of microcontrollers in load control systems allows for precise control and easy customization. Arduino, in particular, has become popular due to its simplicity, open-source nature, and extensive community support.

2.3 Real-Time Clocks (RTC) in Automation

RTC modules like the DS3231 are widely used in automation projects to provide accurate timekeeping. The DS3231, with its temperature-compensated crystal oscillator, ensures time accuracy over a wide range of temperatures and conditions.

2.4 User Interface Design for Load Control Systems

The user interface is a critical aspect of any load control system, as it determines how easily users can interact with the system. The combination of LCDs and tactile buttons is a common approach, offering a straightforward method for users to input and adjust settings.


Chapter 3: System Design

3.1 System Overview

The time-based load control system comprises an Arduino Nano, DS3231 RTC module, a 16x2 LCD, and set buttons for user interaction. The system controls three relays, each connected to an electrical load, based on the time settings input by the user.

3.2 Component Selection
  • Arduino Nano: Chosen for its compact size, ease of programming, and sufficient I/O pins for the project requirements.
  • DS3231 RTC Module: Selected for its accuracy and reliability in timekeeping, essential for the precise control of loads.
  • 16x2 LCD: Used to display the current time and the on/off times set by the user.
  • Set Buttons: Tactile push buttons are used for navigating the menu and setting the on/off times.
  • Relays: Three relays are used to control the electrical loads, driven by the Arduino Nano based on the schedule.
3.3 Circuit Design


The circuit design involves interfacing the Arduino Nano with the DS3231 RTC, 16x2 LCD, and set buttons. The relays are connected to the digital output pins of the Arduino, with appropriate driver circuits to handle the relay coil current.

  • Power Supply: The system is powered by a 5V DC supply, with separate power rails for the Arduino and relays to avoid interference.
  • LCD Connection: The LCD is connected in 4-bit mode to save I/O pins, with the RS, E, and data pins connected to digital pins on the Arduino.
  • RTC Connection: The DS3231 RTC module communicates with the Arduino via the I2C bus, using the SDA and SCL pins.
  • Button Interface: The set buttons are connected to digital inputs on the Arduino, with pull-up resistors to prevent floating inputs.
3.4 Software Design

The software for the load control system is written in C++ using the Arduino IDE. The program is structured into several key functions:

  • Setup Function: Initializes the hardware components, including the RTC, LCD, and relays.
  • Main Loop: Continuously checks the current time from the RTC and compares it with the user-set times to control the relays.
  • Menu System: Allows the user to navigate through the interface, set the on and off times, and save these settings to the EEPROM.
  • Time Setting: Handles the input from the set buttons to adjust the time settings displayed on the LCD.
3.5 Flowchart

The flowchart below outlines the overall logic of the system, from initialization to the control of the relays based on the set times.

Include flowchart here


Chapter 4: Implementation

4.1 Assembly and Construction

The system is assembled on a PCB, with the Arduino Nano and other components soldered into place. The LCD is mounted on the front panel, with the set buttons placed adjacent for easy access. The relays are mounted on a separate board to isolate them from the low-voltage control circuitry.

4.2 Testing

The system is tested by setting various on and off times for the loads and observing the operation of the relays. The accuracy of the RTC is verified by comparing the displayed time with a reference clock.

4.3 Calibration

Calibration involves ensuring the RTC is correctly set and the relays switch at the precise times set by the user. Adjustments are made in the software to account for any delays or discrepancies.

4.4 Troubleshooting

Common issues encountered during testing include incorrect button debounce handling, relay chattering, and timing mismatches. These are addressed through software adjustments and hardware modifications, such as adding capacitors to the relay driver circuits.


Chapter 5: Results and Discussion

5.1 Performance Evaluation

The system successfully controls the loads based on the set times, with the RTC providing accurate timekeeping. The LCD and buttons offer an intuitive interface for setting the schedule, and the relays operate reliably without significant delays.

5.2 Advantages of the System
  • Energy Efficiency: By automating the control of loads, the system reduces unnecessary power consumption.
  • User-Friendly Interface: The use of an LCD and buttons makes it easy for users to set and adjust the on/off times.
  • Scalability: The system can be expanded to control more loads or integrate with other automation systems.
5.3 Limitations
  • Limited Load Capacity: The system is designed for small to medium loads, and additional measures are needed for controlling higher power devices.
  • Manual Time Setting: The current design requires manual setting of the time, which could be automated in future versions using network synchronization.
5.4 Future Work

Future improvements could include adding a Wi-Fi module for remote control and monitoring, as well as integrating a real-time operating system (RTOS) for more complex scheduling and load management tasks.


Chapter 6: Conclusion

This project successfully demonstrates the design and construction of a time-based load control system using an Arduino Nano, DS3231 RTC, LCD, and set buttons. The system offers a practical solution for automating the control of electrical loads, contributing to energy efficiency and cost savings. The project also serves as a valuable learning experience in microcontroller programming, circuit design, and system integration.


References

  1. Banzi, M., & Shiloh, M. (2020). Getting Started with Arduino: The Open Source Electronics Prototyping Platform. Maker Media, Inc.
  2. Monk, S. (2019). Programming Arduino: Getting Started with Sketches. McGraw-Hill Education.
  3. Floyd, T. L. (2020). Digital Fundamentals. Pearson Education.
  4. Hummel, C. (2019). Arduino Projects for Dummies. John Wiley & Sons.
  5. Myke, P. (2018). Programming the Arduino: Next Steps: Going Further with Sketches. McGraw-Hill Education.

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Blue Based Home Automation System

 ABSTRACT

This Project presents the overall design of Home Automation System (HAS) with low cost and wireless remote control. This system is designed to assist and provide support in order to fulfill the needs of elderly and disabled in home. Also, the smart home concept in the system improves the standard living at home. The main control system implements wireless Bluetooth technology to provide remote access from PC/laptop or smart phone. The design remains the existing electrical switches and provides more safety control on the switches with low voltage activating method. The switches status is synchronized in all the control system whereby every user interface indicates the real time existing switches status. The system intended to control electrical appliances and devices in house with relatively low cost design, user friendly interface and ease of installation. Due to the advancement of wireless technology, there are several different of connections are introduced such as GSM, WIFI, ZIGBEE, and Bluetooth. Each of the connection has their own unique specifications and applications. Among the four popular wireless connections that often implemented in HAS project, Bluetooth is being chosen with its suitable capability. Bluetooth with globally available frequencies of 2400Hz is able to provide connectivity up to 100 meters at speed of up to 3Mbps depending on the Bluetooth device class.

Bluetooth wireless connection enabled the system communicates with graphical user interface (GUI) on PC/laptop or smart phone without cable. The target home appliances are controlled by the system Main Control Board. In order improve the standard living in home, this system provides three different types of physical control methods to the Main Control Board. The first physical control method is by pressing on the modified Low Voltage Activating Switches. The conventional high voltages switches will be replaced by the modified 5 Volt push buttons as the activating switches. The low voltage switch eliminates the risk of dangerous electrical shock by wet hand. The second and third control methods are performed as wireless remote control to the appliances. The second control method is by clicking on Window GUI on PC/laptop by using mouse or touch pad. The system is directly installed beside the conventional electrical switches on the wall. The Bluetooth wireless connection enabled the system communicates with graphical user interface (GUI) on PC/laptop or smart phone without cable. The target home appliances are controlled by the system Main Control Board. In order improve the standard living in home, this system provides three different types of physical control methods to the Main Control Board. The first physical control method is by pressing on the modified Low Voltage Activating Switches. The conventional high voltages switches will be replaced by the modified 5 Volt push buttons as the activating switches. The low voltage switch eliminates the risk of dangerous electrical shock by wet hand. The second and third control methods are performed as wireless remote control to the appliances. The second control method is by clicking on Window GUI on PC/laptop by using mouse or touch pad. This method provides facility to the computer user to control the home appliances without walk to the switches on the wall. Third control method is done by Android GUI installed in Smart Phone. The user can easily touch on the screen of the phone to control the home appliances. This portable method is able to assist the disabled people who have problem with locomotion difficulty.

INTRODUCTION

Due to the advancement of wireless technology, there are several different of connections are introduced such as GSM, WIFI, ZIGBEE, and Bluetooth. Each of the connection has their own unique specifications and applications. Among the four popular wireless connections that often implemented in HAS project, Bluetooth is being chosen with its suitable capability. Bluetooth with globally available frequencies of 2400Hz is able to provide connectivity up to 100 meters at speed of up to 3Mbps depending on the Bluetooth device class.

The system is directly installed beside the conventional electrical switches on the wall. The Bluetooth wireless connection enabled the system communicates with graphical user interface (GUI) on PC/laptop or smart phone without cable. The target home appliances are controlled by the system Main Control Board. In order improve the standard living in home, this system provides three different types of physical control methods to the Main Control Board. The first physical control method is by pressing on the modified Low Voltage Activating Switches. The conventional high voltages switches will be replaced by the modified 5 Volt push buttons as the activating switches. The low voltage switch eliminates the risk of dangerous electrical shock by wet hand. The second and third control methods are performed as wireless remote control to the appliances. The second control method is by clicking on Window GUI on PC/laptop by using mouse or touch pad.

This method provides facility to the computer user to control the home appliances without walk to the switches on the wall. Third control method is done by Android GUI installed in Smart Phone. The user can easily touch on the screen of the phone to control the home appliances. This portable method is able to assist the disabled people who have problem with locomotion difficulty.

Advantages of Bluetooth based Home Automation

1.            The user can control his/her appliances without physical interface.

2.         It can be easily interfaced with other embedded micro chips like RF module, GSM module, PC because it is designed with a micro chip (AT89S52).

3.            It is reprogrammable.

4.            It makes the size of the system to be small.

Disadvantages of Bluetooth based Home Automation

1.          It is very expensive to buy or design.

2.          It requires programming which means not everybody can do the work.

3.          It has a particular distance that it can go.

 

BACKGROUND OF STUDIES

The present study relates to a Bluetooth based Home Automation device and pertains particularly to an improved the stress of starting and stopping your home appliances.

STATEMENT OF PROBLEMS

Bluetooth based Home Automation is a device good for banking hall, shopping mall, food joint, beer pallor, schools, hospital and many other places like that for controlling the appliances at those places. In the past, many types of equipment have been proposed but they have not functioned properly because of the deficiencies such as in ability to send information to far distance, how large the system maybe, non-reliability of the system and the cost of buying it.  

AIMS AND OBJECTIVES

The major objective of the project is to show the importance of a Bluetooth based Home Automation to every other type of automation system and solving the problems which other type of automation system may have caused to the users because of its en-efficiencies. There are many organizations that may have been looking for one way or the other to control their environment from a bit far distance So, our main aim in this project is to design a Bluetooth based Home Automation system.

 

SCOPE OF THE WORK

The scope of this project is based on good production and design, of a quality Bluetooth based Home Automation, Therefore, we covered everything necessary about the construction/implementation of a good, reliable and effective Bluetooth based Home Automation.


LITERATURE REVIEW

The aim of this chapter is to give the overview information about type of wireless technology nowadays. The best type of wireless is choose and suitable towards the problem identification. The comparison between all the types of wireless is done. Moreover, in this chapter, the explanations will focus more on radio frequency (RF). Nevertheless the review also discuss about the method to prevent frequency disturbance. Combination of reference from various sources such as journal, previous thesis and references book, the literature review has been carried out to collect information related to this project. Home automation or smart homes (also known as domotic) can be described as introduction of technology within the home environment to provide convenience, comfort, security and energy efficiency to its occupants [3]. With the introduction of the Internet of Things, the research and implementation of home automation are getting more popular [4]. Various wireless technologies that can support some form of remote data transfer, sensing and control such as Bluetooth, Wi-Fi, RFID, and cellular networks have been utilized to embed various levels of intelligence in the home [5]. The studies in [2, 6] have presented Bluetooth based home automation systems using Android Smart phones without the Internet controllability. The devices are physically connected to a Bluetooth sub-controller which is then accessed and controlled by the Smart phone using built-in Bluetooth connectivity. Researchers have also attempted to provide network interoperability and remote access to control devices and appliances at home using home gateways. [7] proposed mobile IP based architecture and its potential applications in Smart homes security and automation without any actual deployment and testing. Lately few researchers have also presented use of Web services, simple object access protocol (SOAP) and representational state transfer (REST) as an interoperable application layer to remotely access home automation systems. [8] Introduced a smart home management scheme over the Ethernet network based on XML SOAP standards. The drawback of using SOAP based Web a service is that it is complex and adds overhead to the client and server when parsing the message, resulting in slower operation and higher bandwidth.

 

Ultrasonic

Adler, et al, (1982), explains about how to make an Ultrasonic Remote Control for Home Receivers. Electromagnetic signaling systems can be designed to bridge the short distance involved, but their signals do not remain confined between the walls of buildings or apartments. Because the distance between receivers in adjacent apartments may easily be less than the viewing distance in a single large home, individual receivers must operate on different frequencies this is inconvenient in manufacture and installation.

 

Infrared

Maureen Kaine-Krolak, et al, (1995), studies about infrared to make an Introduction to Infrared Technology, Applications in the Home, Classroom, Workplaces and Beyond. Infrared technology increasingly present in mainstream applications, but there is several disadvantage by using the method, receiver and transmitter must be almost directly aligned. Main problem is the signal will lose if blocked by common material, people wall, plant and etc.

 

Xbee

Gill, K, et al, (2009), created about a Zigbee-Based Home Automation System. A ZigBee based home automation system and Wi-Fi network are integrated through a common home gateway as shown in Figure 2.1 . The home gateway provides network interoperability, a simple and flexible user interface and remote access to the system. This system demonstrates the feasibility and effectiveness of the proposed system. The ZigBee (IEEE 802.15.4) is a new technology that permits the implementation of Wireless Personal Area Networks (WPAN). It is very suitable for wireless sensor networks due to the very low power consumption. System allows home owners to monitor and control connected devices in the home, through a variety of controls, including a ZigBee based remote control, and any Wi-Fi enabled device which supports by Java. Lili, Y, Y.Shuang-Hua et al, (2006), research about the Safety and Security of Remote Monitoring and Control of intelligent Home Environments in Systems, Man and Cybernetics. Safety and security are two most important issues in the remote monitoring and control of intelligent home environments. The outdoor part is a mobile phone (or a PDA) equipped with a specially designed GUI (Graphic User Interface). The indoor part includes a broadband modem, a home portal (or called home server), and a wireless home network. The broadband modem maintains a permanent internet connection.


METHODOLOGY BLOCK DIAGRAM


The block diagram of the circuit shows principle of operation to achieve a desired output. The block diagram could also be said to be the circuit in a simplified form. It can also be explain as, the function of the circuit and shows component relationship with each other.


AC INPUT AND RECTIFICATION

It is important that you choose the right transformer for your power supply. The transformer’s secondary voltage should not be much larger than the voltage of the diode; otherwise, energy will be wasted because the diode will be forced to dissipate heat. However, at the same time, the secondary voltage must not drop below the required minimum input voltage of the diode (typically 2 to 3 V above its output voltage) and in this project we used 220v to 12v and 500mA transformer. The rectification stage is usually preceded by a transformer, which is equipment that steps down phase voltage down to safer and lower levels that are more suitable for rectifier diode to handle. The transformer is composed of three important elements; a primary winding, a secondary winding, and a core structure. When the transformer has stepped down the voltage to the required level, the rectifier diodes are then used to convert the alternating current to dc voltage. There are half wave rectification and full wave rectification. In this work full wave rectification is employed.

 

FILTRATION

After rectification, the dc obtained is usually filled with ripples which are very harmful to the electronic devices that will use it especially the microcontroller. This calls for the filtration of the rectified output to produce a smooth voltage. The smoother the voltage the more lasting is the ICs. When a full wave or bridge rectifier is connected to a capacitor, the peak to peak ripple is cut in half. When a full wave voltage is applied to the RC circuit, the capacitor discharges half a cycle. Therefore, the peak-to-peak ripple is half the size it would be with a half rectifier. The peak –to- peak ripples voltage; 

VR = I, fC I = dc load current, f  - frequency, C - capacitance  

To get a good filtration, it is advisable to use a capacitor of voltage about twice the value of the expanded input voltage. In this work, a capacitor of 50V at 3300 µf was used. 

 

REGULATION

 After the stepping down the voltage using transformer, rectification by the rectifier and filtration by the capacitor, the voltage is ready to be used though the faithfulness of the voltage cannot be predicted. In order to make the voltage constant, a regulator is needed. A zener diode could be used for this purpose however, but in this work 7805 IC regulator was used.

 

 

MICROCONTROLLER UNIT

The microcontroller unit is made up of the crystal oscillator that is connected to the X1 and X2 which is pin18 and 19 of MCU, The Bluetooth module communicates with the 8051 using serial communication. Tx pin of the Bluetooth module is connected to Rx pin of the microcontroller (pin10) and Rx pin of the Bluetooth module is connected to Tx pin of the microcontroller. Output pin of the Bluetooth is connected to P3.0 and P3.1 of the microcontroller and the microcontroller is monitoring for low voltage that is zero at the pin and whenever an intruder crosses the sensor the pin will be low. The baud rate used for serial communication in this project is 9600. So the crystal needs to be exactly 11.0592 MHz for getting this baud rate. Port 2.0, Port 2.1, Port 2.2 and Port 2.3 of the microcontroller is used for controlling the loads.

Bluetooth Module (HC-05)

For the communication between mobile phone and microcontroller Bluetooth module (HC-05) is used. HC-05 is low power 1.8V operation and is easy to use with Bluetooth SPP (serial port protocol). Serial port Bluetooth module have a Bluetooth 2.0 +EDR (enhanced data rate), 3Mbps modulation with complete 2.4GHZ radio transceiver and base band. Using Bluetooth profile and android platform architecture different type of Bluetooth applications can be developed.

 

Relay

Relay is basically an electromagnetic switch which can be turn on and off by an applying the voltage across its contacts. In this project used a 12V 3-channel relay.

 

THE CIRCUIT DIAGRAM OF THE BLUETOOTH BASED HOME APPLIANCE CONTROLLER

DESCRIPTION OF COMPONENTS

The components used in the construction of this power failure alarm system are as follows.

TRANSFORMER

A transformer is a static device or machine that transfers electric power from one circuit to the other. It changes the size of alternating voltage by process of mutual induction between the two coils or windings, in accordance with Faradays law of electromagnetic induction. Its two coils or windings are separated electrically but magnetically they are linked together. A transformer plays a major role in electric power engineering and is a necessary part of the electric power distribution network.

The transformer is of two basic types, step-up transformer and step-down transformer; it has two coils namely the primary and the secondary coils. If the number of turns in secondary coil is greater than the primary it is a step-up transformer and if the secondary coil is less than the primary is known as a step-down transformer.

We made use of step-down transformer in this project to step down from 220v to 12v, The diagram of a transformer is as shown below.

Capacitor

A capacitor is capable of storing electrical charges. It has the ability to block direct current (D.C) while passing alternating current (A.C), that is, it can be used as a filter. All capacitors consist of two metal plates separated by an insulator. Capacitors are important components in the electronics and telecommunications industries. They are essential, for example, in radio and T.V receivers and in transmitter circuits. The earliest capacitor was invented -almost accidentally- by van musschen, in about 1746, and became known as a Leyden jar. (Nelkon and Parker, 1990.)

Further, it is an electronic component that stores electrical energy or charge. The capacitor is constructed with two electrode plate facing each other but separated by an insulating substance called the dielectric.   It store energy by separating +ve and -ve electrical   charges.   The   capacitance of a capacitor   is   given   by charge/voltage  C = Q/V.

And   it   is   measured   basically   in   farad   (f).   But   most   practical capacitors is rated in micro farads   (uf)   or pico farad   (pf).   The capacitance of a capacitor is generally very small, so unit ranges from microfarad (10A- 9 F) and Pico farad (10A-12 F) are used. There are different types of capacitor, which includes:

The table below shows the types of capacitor.

1.

Variable

2.

Electrolytic

3.

Fixed capacitor

4.

Trimmer

5.

Polarized

6.

Non polarized

Capacitor can be of fixed value, a dielectric or a variable capacitor, which has a making vane with dielectric as solid as air. The capacitors used in this project are electrolytic and capacitor is shown below.

Variable capacitor               Non variable capacitor

Microcontroller 

A microcontroller (also MCU or µC) is a computer-on-a-chip. A microcontroller (also microcontroller unit, MCU or µC) is a small computer on a single integrated circuit consisting of a relatively simple CPU combined with support functions such as a crystal oscillator, timers, watchdog timer, serial and analog I/O etc. It is a type of microprocessor emphasizing self-sufficiency and cost-effectiveness, in contrast to a general-purpose microprocessor (the kind used in a PC). In addition to all arithmetic and logic elements of a general purpose microprocessor, the microcontroller usually also integrates additional elements such as read-only and read-write memory and input/output interfaces. Microcontrollers are used in automatically controlled products and devices, such as automobile engine control systems, remote controls, office machines, appliances, power tools and toys. Microcontrollers are complete computer systems on a chip, typically combining an arithmetic logic unit (ALU), memory, timer/counters, serial port, input/output ports (I/O) and a clock oscillator.  

Microcontroller Advantages 

• Highly integrated and powerful – thousands of transistors on a single chip. • Can be used to replace a handful of discreet logic chips.

• Relatively easy to learn and implement.

• Easier to integrate into a design than discrete logic chips.

• Very low hardware cost possible 

• Many types and manufacturers available.

• Architectures and programming languages vary somewhat, but not completely, so what we learn about one microcontroller (µC) is good knowledge to apply to another one.

• Many different IC packages available (DIP8, SOIC-16 etc.) 

Microcontroller Disadvantages

• Microcontrollers are IC chips and need to be put on to a custom-designed PC board. This takes time and money, which may not suit all applications. 

Contrast this with an industrial automation PLC, which is a computer-in-a-box that contains simple screw terminals to connect power, communication and I/O.

• Programming microcontrollers requires a certain amount of skill and training. 

 • The programming and debugging software can be quite costly.

 

TRANSISTOR

The transistors were invented in 1947. The invention of transistors was a great improvement over the vacuum tube in computers because they are smaller, take less power to operate, usually cost less and are more rugged than the vacuum tube. Transistor are three-lead semi-conductor devices produced in variety of shape and size to accommodate such design in parameter as poor heat dissipation, break down voltage and cost some power transistors have an oval shape body with two mounted roles on either side.

Generally there are 2 types of transistors.

1.     Negative Positive Negative ( NPN )

2.     Positive Negative Positive ( PNP )

Concentrating on the bipolar transistor since it was employed in the circuit. The bipolar transistor is used in 3 broad areas of electronics.

1.     As a generator

2.     As a linear amplified to boast an electrical signal.

3.     As automatic switches devices

 

This semiconductor device is back-to front connection of P-N junction or front-to-front connection of P-N junction. The three terminal of the transistor include, the Emitter, Base and Collector.

The types of a bipolar transistor that exist are the PNP and the NPN where N denotes negative and P denotes positive. See the diagram below.

Bridge Diode

The diode is a two terminal that has anode and cathode region. On a diode, one can easily differentiate a positive terminal (anode) by the dark part of the diode while the side with white color is the cathode. The diode from the rectifier, form a junction between a sample of P-type and one of the N-type semiconductors. This combination possesses the property of a rectifier.

This semiconductor material allows the flow of current in   one direction.

 

Crystal Oscillator

This crystal is an electrical device which when energy is applied, emits pulses at a fixed frequency. One can find crystals of virtually any frequency depending on the application requirements. The more common crystal frequencies are 12 MHZ and 11.059 MHz with 11.059 MHZ the most common and that was the one used in this project. The crystal oscillator is unstable and has 11.095 MHz for clocking the microcontroller for 11.095 million times per second.

 

RESISTOR     

Figure 3.11 shows circuit symbol of a resistor.

A resistor is a two way terminal passive element, which provides voltage drop and help dissipate electrical energy and also provide a current limit in a circuit. They are   made   of resistive materials   such as magnesium, nichrome, Constantia, etc and enclose in a plastic case to prevent moisture Ralph, (1992). Resistors are unquestionably the most commonly used circuit components. They are designed to resist the flow of electrical current. The resistance values are measured in ohms, the values maybe indicate on the resistor. If the resistance is not indicated, the value of the resistor can be determined by observing the resistor color code table. The different types of resistors are; fixed and variable resistors. The value of resistor ranges from zero to infinity.

The knowledge of resistor (especially, fixed resistor) is very important in electronics designs.

The table shows the resistor colour code

Colour

1st band 1st figure

2nd      band 2nd figure

3rd       band multiplier

4th       band tolerance

Black

0

0

None

 

Brown

1

1

0

1%

Red

2

2

00

2%

Orange

3

3

000

 

Yellow

4

4

000

-

Green

5

5

00000

 

Blue

6

6

000000

 

Violet

7

7

0000000

 

Grey

8

8

0000000

 

White

9

9

00000000

 

Gold

-

-

 

5%

Silver

-

-

 

10%

No colour

-

-

 

20%

 












There are various shapes, sizes and voltages (0.25W and 0.5W) of resistors but the most employed type is the 0.25W.

DIODE/LED (LIGHT EMITTING DIODE)

A diode is a device, which is made from semiconductor material that allows current to flow in one direction; it blocks the current that tries to travel against the flow in a wire. These devices are often used in several electronic circuits that convert AC to DC. An LED is the alternative of the diode, once a current is applied to an LED; it emits light at a specific frequency. LEDs are utilized in varied applications like keyboards, hard disks, TV remote controls, and these devices are largely helpful as standing indicators in computers also as battery-operated electronics Transistor.

VOLTAGE REGULATOR

Voltage regulator is an electrical device which maintains the voltage of a power source within acceptable limits. To keep voltages within the recommended range, the voltage regulator is needed and it can be tolerated by the electrical equipment using that voltage. The image below shows the picture and circuit symbol of a voltage regulator.

References

1. Kortuem, G., Kawsar, F., Fitton., D., Sundramoorthy, V.: Smart objects as building blocks for the internet of things. Internet Computing, IEEE, vol. 14, no.1, 44--51 (2010)

2. Piyare, R., Tazil, M.: Bluetooth based home automation system using cell phone. In Consumer Electronics (ISCE), 2011 IEEE 15th International Symposium on, pp. 192-195.(2011)

3. Wikipedia. Home automation, http://en.wikipedia.org/wiki/Home_automation

4. Liu, Y.: Study on smart home system based on Internet of things technology. In Informatics and Management Science IV. vol. 207, W. Du, Ed., ed: Springer London, 73--81 (2013)

5. Al-Qutayri, M.A., Jeedella, J.S.: Integrated Wireless Technologies for Smart Homes Applications. In Smart Home Systems, M. A. Al-Qutayri, Ed., ed: InTech (2010)

6. Yan, M., Shi, H.: SMART LIVING USING BLUETOOTH-BASED ANDROID SMARTPHONE. International Journal of Wireless & Mobile Networks (IJWMN), vol. 5, no.5, pp. 65--72 (2013)

7. Park, B.: Mobile IP-based architecture for smart homes. International Journal of Smart Home, vol. 6, no.1, 29--36 (2012)

8. Perumal, T., Sulaiman, M.H., Sharif, K.Y., Leong, C.Y.: Development of an embedded smart home management scheme. International Journal of Smart Home, vol. 7, no.2, 15--26 (2013)

 

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