ece 9 project document ation (final)

I. Title of the Project

DIGITAL COUNTDOWN TIMER

II. Rationale

The digital countdown timer device somehow queues with

the global competitiveness in the field of high technology.

The primary reason of its existence is for convenience of

people to life. Basically, it is not designed and created to

encourage people to become lazy, but to help them do

multitasking and lessen efforts in dealing things especially

today where there is an increasing demand of human attention

towards many varied things caused by the improving

technological trends.

A busy person tends to forget the other things he is

doing, thus, this project is also designed to address to this

particular problem of any person: forgetting about other tasks

because of being very busy. With the aid of the countdown

timer device, one just easily sets up an appliance to turn on

or off, as desired, in a chosen span of time, therefore,

minimizing his efforts in manually turning on or off the

appliance.

III. Introduction

Description of the Project

With the advent of technology, people nowadays think of

making their lives convenient. Everyone wants to make his

life more comfortable by just having everything to be easily

accessed. Answering to such want of the people, remote-control

has been invented for easy access on appliances or certain

electronic and electrical devices.

However, although, people have already been provided with

this tool to somehow reduce their efforts in operating

appliances, still, people want more and ask for more

convenience. The most common problem is that busy people tend

to forget on turning off their appliances because of the other

tasks they are doing. Hence, this project is designed to

respond to the need of a person for a certain device to

perform automatic power on or off of some appliances to avoid

leaving them operating and consuming electrical power, thus,

wasting energy and money too.

The invented device, Count Down Timer, is not limited to

automatic turning off of appliances but also its reverse. Its

application for instance is when a person would want to have

an appliance operating after a certain span of time. A

specific example would be when one would want his television

to turn on after five minutes expecting his favorite game show

will already air.

Review of Related Literature

The following review of a related literature is taken

from www.quasarelectronics.com. The project is specifically a

simple photographic timer.

The simple photographic timer is the first of a series of

timer kits based on the 3148 hardware platform. This is a

simple down timer with selectable preset times. At the end of

the selected time period the output goes ‘low’ for 2 seconds.

There are six (6) preset times: 60, 90 120, 300, 600 and

900 seconds (1, 1.5, 2, 5, 10 and 15 minutes).

Refer to the “3148 4-DIGIT TIMING MODULE” documentation

for details of hardware features, circuit description and

assembly instructions.

TIMER SPECIFICATIONS

Timing ranges60, 90, 120, 300, 600, 900

secs

Timing resolution 1/10 second

Inputs Start, Stop and Reset

Output

2 second active low Open

collector NPN transistor,

100mA @ 30V

Display4-digit 7-segment with decimal

point, 14mm RED LED

Supply voltage 9 to 12V DC

Supply current30 to 50mA, depending on the

number displayed.

Physical size 51mm x 66mm (2.0” x 2.6”)

Connection10-way right-angle SIL header

pins, 0.1” spacing

http://www.quasarelectronics.com/ds.htm#3148

OPERATING INSTRUCTIONS

The ‘power up’ default time is 60 seconds (the display

shows 60.0). Pressing the STOP button cycles through the other

preset time delays.

Pressing the START button starts the timer. The display

starts running down towards zero in tenths of a second. When

it reaches zero (0.0) the open collector output pulses low for

2 seconds and the timer then resets itself to the selected

time delay.

During the count down time, pressing the START button

again has no effect. Pressing and holding the STOP button

‘freezes’ the timer at its current value. Releasing the STOP

button then resets the timer to the previously selected time

delay, ready to start again.

At any time the timer can be reset via its RESET input.

The timer will reset to the previously selected time, ready to

start again.

Applications

This timer was developed after an inquiry from a hobbyist

who wanted a simple 60 second timer when printing photographs.

At the end of 60 seconds a beeper or buzzer would sound to

indicate ‘times up’.

After some discussion about other photographic uses it

was decided to add some extra ranges as well. We also decided

on an open collector style output rather than an on-board

buzzer. This enabled the kit to drive other devices such as

relays, making it more useful in other applications.

Open Collector Output. For more information about what an open

collector output is read the FAQ sheet at

www.quasarelectronics.com/ds.htm#3148.

Connecting to the Timer

A 10-way header strip provides external connection to the

timer, including power. All the inputs and the output are

organized as ‘pairs’ of pins, with each input or output having

a corresponding ground pin, as per the following diagram.

The ‘+’ sign indicates the actual input or output pin and

the ‘-’ sign indicates its associated ground pin.

Note: When using the output to switch a load (relay,

buzzer, etc) connect the load between the output pin and a

positive DC voltage. For example, if switching a 12V relay

connect the relay between the output pin and +12V.

Other Timing Modules

There are other firmware IC’s available for 3148:

1. 3148T2. Stopwatch with Pause function

2. 3148T3. 40KHz Auto Ranging Frequency Meter

3. 3148T0. Programmable Down Timer counting down in seconds

from a maximum of 10,000 sec

4. 3148T4 Programmable Down Timer counting down in minutes

from a max of 10,000 minutes

5. 3148T5 Programmable Down Timer counting down in hours

from a maximum of 10,000 hours

IV. Technical Aspect

A. Detailed Explanation of How the Project Works /

Operates

Digital countdown timer is based on a micro controller,

thus securing reliability and excellent operation under any

circumstances. It can be programmed to countdown up to 999

minutes and 59 seconds. When the timer starts counting, a

relay is activated. When this time reaches zero, the relay is

disabled. This can be used for automation and wherever a

reliable timer is needed. The heart of the circuit is a micro

controller from the 8050 family manufactured by Winbond

Microchip, the W78E51B. The time is displayed by 3 seven-

segment displays and it can take any value from 0 to 999

minutes and 59 seconds.

Crystal Y1 along with capacitors C1 and C2 form the

circuit that produces the 12 MHz reference signal. As you can

easily calculate, the 12 MHz frequency leads to a duty cycle

of 1μsec. This means that every command is executed in only

1μsec. The LM7805CV voltage regulator, the D1,D2,D3 and D4

diode and the C1, are supplying the necessary +5 Volts to the

micro controller, independent of the input voltage that can

vary from 9 to 15 Volts DC. The capacitor C2 makes the

regulator capable of responding to fast changes of the load

current, making sure that the circuit will be fed with the

proper voltage at any time. Transistor Q1, resistor R1 and

diode D5 drive the relay. Transistor Q1 acts like a switch.

Diode D5 protects the transistor from the inductive voltage

that occurs at the relay terminals every time it’s activated.

Resistor R1 limits the base current and is responsible for the

switching operation of the transistor.

Visualization of the microcontroller’s output is done

through three 7-segments displays. Transistors Q3, Q4, Q5, and

resistors R6 to R13 form the network that is driving the

displays. These three transistors act as switches driven by

the voltage (0 or 5V) that appears at the microcontroller’s

pins 1 to 8 that are programmed to operate as outputs. Every

time that a transistor is “on” the relevant display is active

and displays the contents of its seven segments (A, B, C, D,

E, and F and decimal point). The displays get the data from

the IC and display it in decimal mode e.g. numbers from 0 to

9. In order to reduce the communication lines from the IC to

the displays from 32 to 12, we have to make sure that when a

display is active, the rest two must be set off. This time-

sharing is an easy job for a device like the W78E5iB. One

should expect the brightness of the LEDs to be low using this

method of operation, but using the Q3 to Q5 transistors and

calculating the value of the R6 to R13 resistors carefully, we

achieve the highest brightness possible.

Electrical Specification

Supply Voltage:220 Volts AC +/- 10%, 60 Hertz,

single phase

Surge Protection: MOV 220V

Compatible Load Types:

Standard appliances up to 15 Amps

and incandescent lights up to 800

watts

Power Plug: 2-pin

Controlled Outlet: 2-pin

Minimum Load: No minimum load required

Maximum Load:

15 Amps (for resistive loads);

800 Watts (for incandescent

loads)

Device power

requirement:9-VDC to 15-VDC 500mA

PUSHBUTTON OPERATION

Programming controls: 2 pushbuttons: Start/Select, Reset

S2 Reset

Reset to zero

Start programming

S1 Select/Start (control)

Set minutes and seconds

Set seconds and tenths up to 999 minute.

B. Parts List

PARTS / COMPONENT DESCRIPTION

IC = W78E51B

W78E51B is an 8- bit microcontroller which

can accommodate a wider frequency range

with low power consumption. It contains 4k

bytes flash EPROM, 128 bytes RAM, & TWO

16-bit timer/counter.

IC = NEC 2561 High Density Mounting Type Photocoupler

Q1, Q2 = C1815

Transistors are tiny electrical devices

that they can amplify an electrical signal

and they can switch on and off, letting

current through or blocking it as

necessary.

NPN 0.4 W 60V 0.15A (TO-92) ECB

Q3, Q4, Q5 = A1015 PNP 400mW 50V 150mA 80MHZ (TO-92) ECB

Q6 = LM7805CTPositive Voltage Regulator 1.5A, 5V (TO-

220)

R1=22k, R2=2.2k,

R3 to R5 =1.5k, R6

to R13=130 ohm,

R14 to R23=2.2k,

R24 to R25=2.2k,

R26=470ohm,

R27=10k, R28=4.7k,

R29=680ohm

An electronic device use for resisting an

energy or electron flow

D1, D2, D3, D4, D5

1N4001

1A 50V (DO-41 plastic)

Diode Rectifier. An electronic device with

two wires or terminals. A rectifier allows

electrical current to flow through in only

one direction and is used for converting

alternating current into direct current.

C1 to C2 =

1000uF/16V,

C3 = 4.7uF/50V

Electrolytic capacitor is a device that

stores electrical charge, using a

positively charged surface and a

negatively charged surface with a gap

between them.

C4 to C5 = 30

pF,

C6 = 104pF

Ceramic capacitor is a filter capacitor or

condenser, the function is to filter or

smooth the rectified DC voltage produced by

the rectifier.

XTAL = 12 MHZ

The crystal is usually quartz, also has a

resonant frequency of its own, but optimum

performance is obtained when it is coupled

with an external capacitance.

YT5631BS

seven segment

LED display

0.8-inch Triple Digit, Seven Segment Display

LED = Red,

Green

Light Emitting Diode (Hi-Bright Diffused 5mm

20mA)

K1 (SPST Reed

Relay 12 Volt

DC Coil 5A

Mini PCB type)

Is an electromagnetic relay that is basically

electrically-control switch, it consists of a

coil that is energized to magnetize a

permeable iron circuit and actuate an

armature.

Miscellaneous / Other Parts:

Buzzer 12v

Push Button Switch

Toggle Switch

Illuminated Power Rocker Switch / Light

Plastic Case

Transformer – Input 220 volt / Output 12volt 500mA

(Step-down Transformer)

AC Socket Chassis-mounted

AC Cord with Plug

HC872 Plastic Case

PCB / Bolts

Fuse / Holder (quick active glass tube fuse)

C. Block Diagram

3 SEVEN-SEGMENTLED DISPLAY

PORT LATCH &SEVEN-SEGMENT

DRIVERS

CONTROL& INSTRUCTION

REGISTER

OSCILLATOR8-BIT

MICROCONTROLLERSYSTEM

D. Schematic Diagram

Detailed Schematic Diagram

E. PCB Layout

F. Applicability of the Project

This project can be regarded as having a definite

practicality since this device is very useful to the lifestyle

of people nowadays. As to humanity, this project is even

considered feasible since we are presently living in a world

of comfort through different electronic and computer gadgets,

thus, keeping us inattentive to other chores. Since this

device is digital in nature, it is also expected that the

timing is accurate compared to a mechanically-driven timer.

Hence, this project is applicable to the kind of living we

have now and the kind of technology we have nowadays.

V. Conclusion / Recommendation

Given the project above, encountering all the trials

during its construction, we have finally concluded that:

1. a timer is generally different from a stopwatch

because the later counts upward from zero for

measuring elapsed time while the former counts down

from a specified time interval,

2. a digital timer is more advantageous than a

mechanical timer since digital timers can achieve

higher precision because they are quartz clocks with

special electronics,

3. integrated circuits have made digital logic so

inexpensive that an electronic digital timer is now

less expensive than many mechanical and

electromechanical timers; individual timers are

implemented as a simple single-chip computer system,

similar to a watch; watch technology is used in

these devices, and

4. this project really helps busy people to (a)

integrate automation in his lifestyle so as to

decrease stress in exerting more efforts, (b) do

multitasking to save and maximize time, and (c)

conduct accurate timings in switching on or off or

in the operation of certain electrical devices.

With the above-stated conclusions, we, therefore,

recommend that:

1. this project should be advertised to public for the

aim of attracting electronic devices manufacturers

to venture on producing the product, and

2. this device should be improved to ensure safety and

maximum use and benefit of the product to the

consumers or buyers.

VI. Appendices

A. Data Sheets / Pin Configuration

(Also See Attached for other Pin Configurations)

A F B

CA1 CA2 CA3

E D C G

DP

NC

7 – SEGMENT PIN CONFIGURATIONCOMMON ANODE

B. Picture of the Project

C. Curriculum Vitae

C U R R I C U L U M V I T A E

JERRY

JALA

LEPORNIO

Age : 25

Address : P-5 Bilay, Butuan City

Contact Number : 09197924325

Citizenship : Filipino

Religious Aff. : Roman Catholic

Birth Date : December 31, 1982

Birth Place : Bilay, Butuan City

Father : Teodulo Lepornio

Mother : Arcadia Cabrera Jala

EDUCATION

College : Saint Joseph Institute of Technology

Butuan City

Degree : BS in Electronics Engineering (BSECE)

4th Year

Secondary : Bilay National High School

Bilay, Butuan City

1998-99

Elementary : Bilay Elementary School

Bilay, Butuan City

1994-95


JOE RANDY

BALANSAG

TABUNGAO

Age : 20

Address : Alubihid, Buenavista Agusan del Norte



Religious Aff. : Philippine Catholic (PECC)

Birth Date : September 13, 1988

Birth Place : Buenavista Agusan del Norte

Father : Jose Jagna Tabungao

Mother : Judith Hidalgo Balansag

EDUCATION


Butuan City


4th Year

Secondary : Buenavista National High School

Matabao, Buenavista Agusan del Norte

SY 2004-05, 1st Honorable Mention

Elementary : Saint Joseph Institute of Technology

Butuan City

SY 2000-01, 3rd Honors


KEITH MARVIN

ATEGA

DELGADO

Age : 20

Address : Cabadbaran City



Religious Aff. : UCCP

Birth Date : May 19, 1988

Birth Place : Oroquita City

Father : Wills Pagasian Delgado

Mother : Prosperity Mae Badajos Atega

EDUCATION


Butuan City


4th Year

Secondary : Mindanao Institute

Cabadbaran City

SY 2004-05

Elementary : Sapang Dalaga Elementary School

Sapang Dalaga, Misamis Occidental

SY 2000-01


VICTOR

LABADOR

GENZON

Age : 21

Address : Guinabsan, Buenavista Agusan del Norte

Contact Number :



Birth Date : Godofredo Genzon

Birth Place : Guinabsan, Buenavista Agusan del Norte

Father : Godofredo Genzon

Mother : Concordia Labador

EDUCATION


Butuan City

Degree : BS in Computer Engineering (BSCpE)

4th Year

Secondary : Guinabsan National High School

Guinabsan, Buenavista Agusan del Norte

SY 2004-05

Elementary : Lumboyan Elementary School

Guinabsan, Buenavista Agusan del Norte

SY 2000-01


CYRUS

YAO

CABALLES

Age : 19

Address : P-2, B-3 San Francisco Agusan del Sur




Birth Date : January 8, 1989

Birth Place : San Francisco Agusan del Sur

Father : Cesar Concerman Caballes Sr.

Mother : Virgilia Mabulay Yao

EDUCATION


Butuan City

Degree : BS in Computer Engineering (BSCpE)

4th Year

Secondary : San Francisco West Central Elem. School

San Francisco Agusan del Sur

SY 2004-05

Elementary : Agusan Sur National High School

San Francisco Agusan del Sur

SY 2000-01


ALVIN REY

BOYLES

ALEMANIA

Age : 19

Address : Km. 2 Baan Highway, Butuan City

Contact Number :



Birth Date : December 29, 1988

Birth Place : Baan Highway, Butuan City

Father : Sofronio Morales Alemania

Mother : Ma. Felema Luison Boyles

EDUCATION


Butuan City


4th Year

Secondary : Agusan National High School

Butuan City

SY 2004-05

Elementary : Riverside Central Elementary School

Baan, Butuan City

SY 2000-01

VII. Bibliography

www.keil.com/dd/dcs/datashts/nuvoton/w783057c.pdf

www.kitsrus.com/pdf/k148t4.pdf

www.cannonsports.com/Images_Internet/Internet_pdfs/

TIMERS_VOL22_LOW.pdf

www.hobbyprojects.com/c/counters_and_timer_circuits.html

www.educypedia.be/electronics./circuitsbysubject.htm

www.electronickits.com/kit/comple/timers/canuk247.htm

www.circuit-innovations.co.uk/timer.html

http://www.circuit-innovations.co.uk/timer.html

http://www.electronickits.com/kit/comple/timers/canuk247.htm

http://www.educypedia.be/electronics./circuitsbysubject.htm

http://www.hobbyprojects.com/c/counters_and_timer_circuits.html

http://www.cannonsports.com/Images_Internet/Internet_pdfs/TIMERS_VOL22_LOW.pdf

http://www.cannonsports.com/Images_Internet/Internet_pdfs/TIMERS_VOL22_LOW.pdf

http://www.kitsrus.com/pdf/k148t4.pdf

http://www.keil.com/dd/dcs/datashts/nuvoton/w783057c.pdf

Saint Joseph Institute of Technology

Butuan City

DOCUMENTATION OF DIGITAL

COUNTDOWN TIMER PROJECT IN ECE 9

Submitted to:

ENGR. CATHERINE M. VERALLO

Instructor

Submitted by:

LEPORNIO, JERRY J.

TABUNGAO, JOE RANDY B.

DELGADO, KEITH MARVIN A.

GENZON, VICTOR L.

CABALLES, CYRUS Y.

ALEMANIA, ALVIN REY B.

OCTOBER 2008

ece 9 project document ation (final)

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