CHAPTER 1 THE PROBLEM AND ITS BACKGROUND INTRODUCTION Modern technology has brought a huge impact on the walk of life of many people in the globe. Paradigms of such advancement in technology are the gadgets like mobile phones and computers that make living a whole lot better than it was before. The researchers chose to be engrossed in the field of Electronics, specifically the realm of mobile phones that is undeniably one of the most commonly used devices of today’s generation. Recharging a mobile phone is one of the primary concerns of the people who use it in a daily basis. On this account, the researchers will deal with another means of recharging a mobile phone. Nowadays, there are several ways of charging that people can choose from at times they need to replenish their batteries. The charging protocol depends on the size and type of the battery being charged. Some battery types have high tolerance for overcharging and can be recharged by connection to a constant voltage source or a constant current source; simple chargers of this type require manual disconnection at the end of the charge cycle, or may have a timer to cut off charging current at a fixed time. Other battery types cannot withstand long high-rate over-charging; the charger may have temperature or voltage sensing circuits and a microprocessor controller to adjust the charging current, and cut off at the end of the charging period. A trickle charger provides a relatively small amount of current, only enough to counteract self-discharge of a battery that is idle for a long time. Slow battery chargers may take several hours to complete a charge; high-rate chargers may restore most capacity within minutes or less than an hour, but generally require monitoring of the battery to protect it from overcharge. (www.wikipedia.com, 2014)
Several types of battery chargers with various capabilities and features are already available in the market. The first type is the “simple charger” which works by supplying a constant DC or pulsed DC power source to a battery being charged. It does not alter its output based on time or the charge on the battery. Typically, a simple charger takes longer to charge a battery to prevent severe overcharging. Next is the “trickle charger”, which is typically a low-current (5–1,500mA) battery charger. It is generally used to charge small capacity batteries (2–30 Ah). Third is the “timer-based charger” which has its output terminated after a pre-determined time. Another type is the “intelligent/smart charger” which is a charger that can respond to the condition of a battery, and modify its charging actions accordingly. Also, it may monitor the battery's voltage, temperature or time under charge to determine the optimum charge current and to terminate charging. Furthermore, a “universal battery charger” is a heavy-duty automatic intelligent charging device that can be programmed with complex charging cycles specified by the battery maker. A “fast charger” makes use of control circuitry in the batteries being charged to rapidly charge the batteries without damaging the cells' elements. Most such chargers have a cooling fan to help keep the temperature of the cells under control. An “Inductive battery charger” use electromagnetic induction to charge batteries. A charging station sends electromagnetic energy through inductive coupling to an electrical device, which stores the energy in the batteries. This is achieved without the need for metal contacts between the charger and the battery. The eighth type is the “USB-based charger” that typically provides for a five-volt power supply which can also be used in phone charging. A “solar charger” converts light energy into DC current. And the last type is the “motion-powered charger” that charges batteries based on regular human motion. (www.wikipedia.com, 2014) Moreover, there are also some types of charging that the researchers consider as they delve in this research study. First is “charging by friction” which typically occurs when you rub one material 2
to another. Material losing electron is positively charged and material gaining electron is negatively charged. Amount of gained and lost electron is equal to each other. Next is “charging by contact” in which when a neutral object is touched by a charged object, charging of the neutral object will take place. In this process, a body with one type of charge produces the same type of charge on a conductor. And the last type is “charging by induction”. It refers to the movement of electrons to one part of an object by the electric field of an object. In this process, the opposite type of charge is produced. (www.sci-culture.com, 2014) Sometimes, when a mobile phone user is in a place where there's no outlet, like in a car in the middle of a traffic jam, charging a mobile phone is a complete hassle and can in turn bring the user’s life to peril. Perhaps the user has forgotten his charger and his friend offers to lend his or her charger, which he tries, only to find that doesn't fit his phone’s port. These several cases are the best examples of the possible significance of this study.
BACKGROUND OF THE STUDY Communication has become one of the basic needs of the people. One of the typical ways to get in touch with others is through mobile phones. With regard to this, the researchers have decided to conduct a research on the improvement of this realm of technology. Based on experiences, the battery life of a mobile phone is the primary concern when it comes to the limit on its usage. Since these gadgets are portable, their batteries often tend to run out of charge at times that users are not at home and they don’t have their phone’s charger with them. This circumstance drove the researchers to open an avenue for making mobile phone charging possible even without a need of the power grid.
3
With this proposed research, they can conveniently recharge their phone’s battery whenever there are other mobile phones with enough charge to be transferred to it. Furthermore, its primary purpose is for emergency purposes. An example that they can lay down with this is when users are stranded in a certain place and their phone’s battery runs out of charge, they can use other phones to recharge their phone’s battery through the use of the product of this research.
THEORETICAL FRAMEWORK In this study, the researchers will make use of important theories and principles to come up with the desired outcome of this research. First on the list is Electron transfer (ET) which is one of the most ubiquitous and fundamental phenomena in Chemistry, Physics, and Biology. Non-radiative and radiative ET are found to be a key elementary step in many important processes involving isolated molecules and supermolecules, ions and excess electrons in solution, condensed phase, surfaces and interfaces, electrochemical systems and biology, and in solar cells, in particular (www.wiley.com, 2014 ). This is the primary theory the will help the researchers in the stretch of this study. Since mobile phone charging is their research topic, it will deal with the transfer of electric charge and how this will work for their study and eventually for their prototype.
This study will also deal with “amplification” which is the increase in the strength of current, voltage, or power by mechanical or electronic means (www.definitions.net, 2014). This principle will also be of great help to the researchers for there will be a need to amplify the possible input to a level required for a mobile phone to actually charge up.
4
CONCEPTUAL FRAMEWORK
Figure 1 Paradigm of the Study Input: - sufficiently charged phone Process: - charge transfer - amplification Output: -recharged phone
Figure 1 shows how the circuit the researchers will produce. The input of the circuit would be the current from the charged phone. This will be taken from the headset port of the phone giving charge. This current will pass through the interface device which amplifies the input current up to the value suitable for the benefitting phone to recharge. The output current will be transferred to the benefitting phone to recharge its battery.
STATEMENT OF THE PROBLEM The main objective of this study is to construct an interface device that is capable of transferring stored charges from a charged phone to a phone in need of charge. The specific objectives of this study are as follows: 1. To design and construct an interface device that could amplify an extremely small value of current to a value suitable for a phone too recharge its battery 2. To determine the functionality of the interface device in terms of:
5
Current
Voltage
Voltage gain
Power
Power efficiency
Impedance
Significance of the Study
The main objective of the study is to be able to actualize another efficient way of recharging a mobile phone through intelligible research and experiments. 1. This study shall benefit many people who consider mobile phones as important aspects of their lives. Furthermore, this Interface device is expected to be a user-friendly device that everyone can make use of. 2. This study shall benefit the Electric companies for the users can save more electricity when using Interface device. The little amount of power can be used at its maximum level. 3. This study shall benefit the environment. There is no waste generated with this product and energy is conserved. 4. This study shall benefit the future researchers for this can help them to have a better idea.
6
SCOPE AND LIMITATION The coverage of this study will be limited only to the construction of the prototype of the interface device which is capable of transferring of electric charge from one phone to another. This is also limited only on the fabrication of the said device that can be used only by some types of cellular phones. The phone giving charge should have the capability of running an android application. This will be conducted in various related environments which may provide the means for us to bring this research study into an entity. The materials that will be used in this study are the following: cellular phones; amplifiers; connecting wires; current booster; The researchers can’t exactly specify the amount of electric charge that can be transferred in a specific time that they set. On the other hand, the packaging and marketing of the prototype of this study are beyond the scope of our research endeavour. Finally, this research will be conducted so as to be a basis for some other similar studies in the offing.
DEFINITION OF TERMS Amplifier - electronic equipment that increases strength of signals passing through it. (www.wikipedia.com) Audio Power - is the electrical power transferred from an audio amplifier to a loudspeaker, measured in watts.
7
Battery Charger - is a device used to put energy into a secondary cell or rechargeable battery by forcing an electric current through it. (www.wikipedia.com, 2014) Charge - there are two kinds of charge, positive and negative - like charges repel, unlike charges attract. - positive charge comes from having more protons than electrons; negative charge comes from having more electrons than protons. Charge Rate - is often denoted as C or C-rate and signifies a charge or discharge rate equal to the capacity of a battery in one hour. (www.wikipedia.com, 2014) Mobile Phone - any wireless telephone capable of operating while moving at any speed, battery powered and small enough to be easily carried by a person. Interface device – circuit that is between the mobile phones that do the process of transferring stored energy. Rectification – a process of converting alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction. Rectifier - a circuit capable of rectifying an alternating current to a direct current. Step Up DC – DC Converter – also known as boost converter. A DC to DC power supply with an output voltage greater than its input voltage. It is used to sustain the amount of voltage needed for the charging circuit to function.
8
