This document presents a technical research on the development of a coin slot prepayment system for household electricity. It was conducted by three students from the University of Mindanao in partial fulfillment of the requirements for a Bachelor of Science degree in Computer Engineering. The study aimed to design and develop a coin slot prepayment system using a peripheral interface controller, wattmeter, and circuit breaker. It provides a convenient method for tenants in a boarding house to pay for electricity through coin slots and monitors their daily usage. The findings of the study include a bill of materials and costs for developing the system.

1. DEVELOPMENT OF A COIN SLOT PREPAYMENT SYSTEM FOR
HOUSEHOLD ELECTRICITY
A Technical Research
Presented to
The Faculty of Computer Engineering Department
University of Mindanao
In Partial Fulfillment
ofthe Requirement for the Degree
Bachelor of Science in Computer Engineering
Joebert S. Arquiola
Ismael M. Dampac
Dijie S. Osnan
August, 2012

2. APPROVAL SHEET
This technical research entitled “DEVELOPMENT OF A COIN
SLOT PREPAYMENT SYSTEM FOR HOUSEHOLD
ELECTRICITY”prepared and submitted by JoebertArquiola, Ismael
Dampac, and DijieOsnanhas been examined, accepted and is hereby
endorsed.
Engr. Rolieven P. Cañizares,MEP
Thesis Adviser
PANEL OF EXAMINERS
Approved by the committee on oral examination.
Engr. Randy T. Angelia, CpE
Chairperson
Engr. Esther Consuelo Tan, MEPEngr. Lynneth C. Sorronda,PECE
Member Member
Accepted in partial fulfillment of the requirements for the Degree of
Bachelor of Science in Computer Engineering.
Engr. Charlito L. Cañesares
Dean, College of Engineering
University of Mindanao

3. Abstract
The purpose of the study was to develop prepayment system electricity
by coin slot machine and notifies the daily usage of electricity. In addition, this
study provides paperless so the end users may pay as much as they want as
long as they have a positive balance and also this prepayment system will be
particularly implemented in a boarding house.
I. Introduction
Electricity is most needed and become more important because
everything in our world today depends on having the power to keep them
running and electricity services are essential for meeting all the basic human
needs. This study provides the customer with convenient method of paying for
the electricity, particularly for those on low incomes or who find it difficult to
pay the electric bill as a whole. The study would provide the customer
convenient method to pay their electricity bill, especially those on low incomes
or to those who find it difficult to pay the electric bill as a whole.Nowadays, a
number of apartments werestill implementing a mastered-metered form of
billing in which allocation of the payment is divided number of apartment
units. With this kind of setup, all consumers pay an exactly the same amount
regardless of the consumer’s income, capability to pay and level of
consumption, With then coin slot payment system, there will be no arrears to

4. collect and the tenant can control their budget for they can manage the use of
electricity according to their needs.
According to Robins (2010), more than half of all low-income families
with a mortgage have struggled to pay their electricity. Between 9 per cent and
11 per cent of households in the middle-income groups were similarly
struggling to pay their electricity bills. It was also found that low-income
households were more likely to seek help from their power supplier, as were
households with three or more occupants, since they used more electricity and
thus faced higher bills, or were renting or faced larger proportionate mortgage
repayments. The tribunal’s chief executive, Jim Cox, said it was clear low-
income households with financial commitments such as a mortgage were
finding it hard to keep up.
House Deputy Speaker Lorenzo Tañada said that the Philippines now
holds the unenviable record of having the highest cost of electricity in Asia,
beating Japan, Singapore and its more developed neighbors. In addition, at
P8.14 per kilowatt-hour, the price of electricity in the country is now the
highest in Asia that is why millions of Filipinos have been suffering from
spiralling costs of electricity and 14 million Filipino families have no
electricity in their homes (Diaz, 2011).
According to Davao Light and Power Company (2011), the new
distribution rates were being approved by the Energy Regulatory Commission
and covering the period July 1, 2011 to June 30, 2012. For residential
customers the average increase is P0.1942 per kWhr. The impact to a

5. residential customer whose monthly usage is 175 kWhr is an increase in its
total distribution charges of P33.99/month. Including the effect of VAT and
franchise tax, the increase will be P0.2192 per kWhr or P38.37/month.
The proponents proposed to provide a convenient method of paying
electricity bill with budgeted amount of money. By the coin slot machine, the
tenant will not be more attentive in collecting monthly bills.
II. Objectives of the Study
This research study aimed to design and develop a coin slot prepayment
system for household electricity.
Specifically, the study was addressed:
1. To perform a function test
2. To present the cost of developing the system
III. Significance of the Study
Paying electricity bills every month can produce a problem especially to
those who have low income. In addition, some other community especially in
the squatters’ areas, most of the people who rented and lived there were just
using neighbourhoods’ mainline because they cannot afford to have their own
mainline. The development of a coin slot prepayment system for household
electricity was intended only to those who cannot afford the monthly electricity
bills as well as to those who used electricity when they need.
IV. Target Beneficiaries / Clients
This study benefited mostly the following:

6. End User.The output of this study helped them to avail electricity with
respect to their needs.
Tenant. The coin slot prepayment system in household electricity could
collect anytime the owner wants.
V. Review of Related Literature
This section presents different studies related to this applied research.
Circuit Breaker
Circuit breakers are a vital part of home safety. A basic understanding of
how a circuit breaker works will help you troubleshoot any electric problems
and help you determine when it’s time to call an expert (Pickett, 2012).
According to Harris (2011), the circuit breaker is an absolutely essential
device in the modern world, and one of the most important safety mechanisms
in your home. Whenever electrical wiring in a building has too much current
flowing through it, these simple machines cut the power until somebody can fix
the problem. Without circuit breaker (or alternative, fuses), household
electricity would be impractical because of the potential for fires and this
would be result from simple wiring problems and equipment failures.
Electricity
Electricity is a general term encompassing a variety of phenomena
resulting from the presence and flow of electric charge. These include many
easily recognizable phenomena, such as lightning, static electricity, and the
flow of electrical current in an electrical wire. In addition, electricity

7. compasses less familiar concepts such as the electromagnetic field and
electromagnetic induction (Bird, 2007).
Henderson (2012) said that a commercial power company charges
households for the energy supplied on a monthly basis. The bill for the services
typically states the amount of energy consumed during the month in units
of kWhr. This unit is a power unit multiplied by a time unit is a unit of energy.
A household typically pays the bill on the basis of the number of kWhr of
electrical energy consumed during the month. Thus, the task of determining the
cost of using a specific appliance for a specified period of time is quite
straightforward. The power must first be determined and converted to kW. This
power must then be multiplied by the usage time in hours to obtain the energy
consumed in units of kWhr. Finally, this energy amount must be multiplied by
the cost of electricity on a currency/kWhr basis in order to determine the cost in
a particular currency.
Infrared Sensor Circuit
According to Infrared (IR) Sensor (2012), this circuit is one of the most
basic and popular sensor modules. In electronics, this sensor is analogous to
human’s visionary senses which can be used to detect an obstacle which is one
of its common applications. In robotics, a group of such modules are used so
that a robot can follow a line pattern.
IR sensor circuitis a circuit that includes use of electronic devices that
emit or receive through the detection of radiation to experience some aspects of
the environment. Infrared (IR) sensor device normally used to detect the

8. temperature or the heat of an object and also the movement. When the sensor is
only intended to measure the level of infrared radiation only, not the other way,
then it is usually called a Passive Infrared (PIR) sensor.
Basically, that every object has or emits some form of thermal radiation.
Radiation is invisible to our eyes, but usually this is in the infrared spectrum.
For this reason,IR sensor circuitis required, which can receive and interpret
radiation can be detected in the spectrum (The Basic of IR Sensor Circuit,
2012).
Peripheral Interface Controller
According to Vysakh (2011), Peripheral Interface Controllers (PIC) is
one of the advanced microcontrollers developed by microchip technologies.
These microcontrollers are widely used in modern electronics applications. A
PIC controller integrates all type of advanced interfacing ports and memory
modules. These controllers are more advanced than normal microcontroller like
INTEL 8051. The first PIC chip was announced in 1975 (PIC1650). As like
normal microcontroller, the PIC chip also combines a microprocessor unit
called CPU and is integrated with various types of memory modules (RAM,
ROM, EEPROM, etc.), I/O ports, timers/counters, communication ports, etc.
PIC is the IC which was developed to control peripherals devices,
alleviating the load from the main CPU. Compared to a human being, the brain
is the main CPU and the PIC is equivalent to the nervous system (What is
PIC?, 2012).
Prepaid System

9. According to Burns (2010), consumers of electricity these days now
have the option on having their electricity put on prepaid or post-paid plans.
Prepaid plan on electricity is where consumers deposit first or pay in advance
to be able to use electricity while post-paid plan is when a consumer pays for
his or her electricity after using it. For them to use more electricity they can just
simply load their accounts again and by loading their accounts regularly, they
also eliminate the possibility of being disconnected from the electric company.
An electric meter that has the capability to load the purchased energy, to
display real time information on how the load is being consumed, and to give a
warning that the load is close to zero providing positive buffer before
electricity is automatically disconnected. All prepaid meters should have an
average accuracy of as close as possible to the condition of zero error before
they are placed in service. Also, an electric service using a prepaid metering
system designed to allow a residential customer to purchase credit and then use
electricity until such time as the credit is exhausted (Republic Act No. 9136,
2008).
Relay
A relay is a switch that is electrically controlled. A device can enable
large signal from a smaller signal, it is like passing signals between two or
more different electronic circuit. This device is incorporated with a
electromagnet and 3 small metals. One of the small metals is movable and
normally pulled by a spring to connect on one of the 2 other metals. If the
electromagnet is saturated with a signal current the magnet will now pull the

10. moving metal and overpowering the spring, wherein the movable metal will
change it contact to the other metal from its normal contact state (Daintith,
2004).
Wattmeter
The wattmeter is an instrument for measuring the electric power (or the
supply rate of electrical energy) in watts of any given circuit. The instrument
which measures electrical energy in watt hours (electricity meter or energy
analyzer) is essentially a wattmeter which accumulates or averages readings;
many such instruments measure and can display many parameters and can be
used where a wattmeter is needed: volts, ampere, apparent instantaneous
power, actual power, power factor, energy in kWh over a period of time, and a
cost of electricity were being consumed (Chisholm, 1991).
Watt meters are often designed around dynamometer meter movements,
which employs both voltage and current coils move a needle. In general
construction, the instrument resembles a Siemens electrodynamometer
(Wattmeter design, 2009).
VI. Scope and Delimitations
This study focused in the way of paying electricity bills through coin
slot machine. In this system, the proponents used peripheral interface controller
as a brain system, wattmeter for reading the electricity and circuit breaker for a
connection between the device and electricity provider. The installation of
device is in the mainline together with the connection of each room, a coin slot
machineand LCD.

11. The testing of the device will be done using three rooms only. Also, a
drop of coins per transaction is limited to 12 drops. The value of one kilowatt-
hour in standard counting of wattmeter is more or less 600 revolutions of its
disc and the price of one kilowatt-hour is based from the Davao Light
company. However, the proponents lessen the 600 revolutions into 10
revolutions equal to 1 kilowatt-hourfor demonstration purposes only. Below 1
kilowatt-hour, the system will automatically disconnect the corresponding
room.
VII. Methods
Presented in this section are the process, diagrams, sketch, and the
overall design of the device.
The block diagram describes the whole process of the device. As you
turn on the device the PIC will perform the program. It will be the one to
control the circuit that will automatically connect or disconnect the main lines
connection to every room. The menu for the rooms, balance of wattage, and the
dropped coins will be displayed in the LCD as also being controlled by the
PIC. The sensors that are attach to every room electric meter will be the one
who will count the number of revolutions and send it automatically in the main
PIC and will communicate to the other PIC so that the system will know when
to cut the connection.

12. Input Process Output
KEY LCD
BUTTON
SENSOR PIC16F84A RELAY
[ROOM1] [ROOM1]
PIC16F877A
SENSOR PIC16F84A RELAY
[ROOM1] [ROOM2]
SENSOR RELAY
[ROOM1] PIC16F84A
[ROOM3]
Figure 1. Block Diagram of the System
VIII. Findings of the Study
In this section presents the results of the study
Item Description Qty. Unit Unit Price Amount
2n222 30 Pieces P4.50 P135
2X16 LCD 1 Piece P350 P350
3mm Transparent Acrylic 1 Foot P180 P180
4 Gang 2-Pin Connector 1 Piece P78 P78
4MHz Crystal Oscillator 4 Pieces P40 P160
Angled Aluminum 12 Feet P230 P230
Bolt & Screw 30 Pieces P1 P30
Bosny Spray Paint 1 Piece P75 P75
Boysen Flat Wall Paint White 1 Piece P175 P175
Boysen Quick Dry Paint Black 1 Piece P90 P90

13. Breaker 20 Ampere 1 Piece P270 P270
Bulb 3 Pieces P30 P90
Buttons 5 Pieces P15 P75
Capacitor 100uf 10 Pieces P2 P20
Capacitor 22pf 10 Pieces P1 P10
X. References
Bird, J. (2007).Electrical and electronic principles and technology (3rded.),
Newnes, ISBN0-978-8556-6
Burns, G. (2010). Prepaid and postpaid system for electricity. Retrieved
on June 7, 2012, from http://ezinearticles.com/?Prepaid-and-Postpaid-
System-for-Electricity&id=5396087
Chisholm, H. (1911). In Encyclopedia Britannica (vol. 29, pp. 202).
Huntingdon: Cambridge University Press.
Daintith, J. (2004). A dictionary of computing. Retrieved on December

14. 17, 2011, from http://www.encyclopedia.com/doc/1O11-relay.html
Davao light implements new distribution rates. (2011). Retrieved on January
15, 2012, from
http://www.davaolight.com/index.php?option=com_content&view=article&
catid=76%3Ajuly11&id=1085%3Adavao-light-implements-new-
distribution-rates&Itemid=116
Diaz, J. (2011). Phl power cost now highest in asia. Retrieved on January 14,
2012, from
http://www.philstar.com/Article.aspx?publicationSubCategoryId=66&article
Id=710471
Harris, T. (2011).How circuit breakers work.Retrieved on January 15, 2012,
fromhttp://electronics.howstuffworks.com/circuit-breaker.htm
Henderson, T. (2012).Electricity: Electric Circuits. Retrieved on May 27,
2012, from http://www.physicsclassroom.com/calcpad/circuits
Infrared (ir) sensor. (2012). Retrieved on May 28, 2012, from
http://www.engineersgarage.com/electronic-circuit/infrared-ir-sensor
Pickett, M. (2012).Understanding circuit breakers. Retrieved on January 15,
2012, from http://www.servicemagic.com/article.show.Understanding-
Circuit-Breakeers.14264.html
Republic Act No. 9136. (2008). Rules for prepaid retail electric service using a
prepaid metering system. Retrieved on June 1, 2012, from
http://www.erc.gov.ph/pdf/Draft%20Revised%20Rules%20for%20prepaid
%20service%2011.11.08.pdf
Robins, B. (2010). Low-income families, especially home buyers, struggle to
pay power bills. Retrieved on January 14, 2012, from
http://www.smh.com.au/lifestyle/life/lowincome-families-especially-home
buyers-struggle-to-pay-power-bills-20101216-18zqr.html
The basic of ir sensor circuit. (2012). Retrieved on May 28, 2012, from
http://www.hqew.net/circuit-diagram/IR-Sensor-Circuit_5884.html
Vysakh.(2011). Peripheral interface controller (pic). Retrieved on May 27,
2012, from http://www.circuitstoday.com/peripheral-interface-controller-pic
Wattmeter design. (2011). Retrieved on December 19, 2011, from
http://www.allaboutcircuits.com/vol_1/chpt_8/11.html
What is pic? (2012). Retrieved on January 14, 2012, from

15. http://piclist.com/images/www/hobby_elec/e_pic1.html