Light sensitive timer

8/7/2019 Light sensitive timer

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LEADER:

Jeremy Bryan Gamboa

ASSISTANT LEADER:

Glicelle Mendoza

MEMBERS:

Kezziah Josh Arcega Ross Vincent Martin

Patricia-Ann Marcelo Carl Angelo Mariano

Jaime Garcia Erwin OrtoyoMa. Angelica Concepcion Chille Gapido

Archielyn Quejada Cherrina Gabriel


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TABLE OF CONTENTS

Abstract 1

Research Plan . 2

Introduction . 6

Results and discussion .. 13

Conclusions .. 17

Recommendations . 18

Bibliography .. 19

Acknowledgement .. 19


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ABSTRACT

Measuring time accurately is hardly a possible thing to do. This is aproblem encountered by stuents and researching facilities. Especially when

the lesson is about motion, time is very essential.

There is a device that we already used- the freefall apparatus. However, as

the name suggests, it can only measure freefall. So, the backbone of our study

is built on the concept of making of making a device that can measure timeaccurately.

To achieve this project goal, we used handful of devices that performspeculiar acts. First is the LDR, which dramatically decreases its resistance

from a 100K value when it is dark. Following is the transistor, a three

terminated device which has many functions.

What we did is to tap/stop button of the stopwatch and replaced it with a

circuit disregarding the push button of the stopwatch. Then, we made a fed

through circuit of he LDR to make an easier flow of electricity,.

Before we got it working, we did 3 experiments and failed once, on the

second one. The first test is the series connection to test our hypothesis aboutthe LDR as a light sensor. Next is the failing experiment, the parallel

connection. What we did to resolve the problem is to use transistor, the last

experiment.

After 3 experiments, our project is ready to take datas and we found the

efficiency of the project. Although there are weaknesses and limitation, the

versatility of the project makes it a good laboratory equipment, since it can be

used a freefall, kinematics, circular and even projectile.

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Research Plan

Exp. 1

SERIESCONNECTION

MATERIALS:

LDR or Light Dependent Resistor

LED

3V Battery

Wires

OBJECTIVE:

To test if the LDR will work the same way we think. The resistance of the LDR

varies proportionally to the intensity of light, so flashing light in the LDR will light up

the LED.

Exp. 2

PARALLELCONNECTION

Materials:

2 LDR

2 LED

3V Battery

Wires

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O

BJECTIVE:

This time, We want to know how the LDR will react if connected in parallel

connection. The set up is the same as the series connection except that an additional line

of connection is added to the circuit. The results shows a bright light from the LED as we

expected in a parallel connection. When we focused light in one of the LDR the light

dims.

Exp. 3

THETRANSISTOR

MATERIALS:

LDR

LED

3V Battery

Wires

Transistor

OBJECTIVE:

The aim of this test is to see if transistor can resolve the failure of

the parallel experiment.

The main purpose of the use of transistor is to reverse the function of the LDR. In the

series Connection experiment, The LED lights up when theres light. We prepared two

diagrams for the transistor circuit, one for the PNP transistor and another one for the

NPN. The availability of materials let us to use the NPN diagram.

The good things is we succeed in our task, with 3 trials for testing the 3 terminals

of the transistor


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3

Research Plan

PROCEDURE:

FOR THE LIGHT SENSOR

1. On a 1"x1" PCB, draw the layout of the schematic diagram.

2. Prepare the PCB for the femi chloride solution (we used a ready made PCB, so thispart is not necessary in our project).

3. Solder the LDR in its place.

4. Solder a 1 1/2" long solid or stranded wire on each of the terminal of the LDR.

5.Make a connection for the wires and the two terminal jacks. Be sure that theconnection is series.

6. Prepare a casing for the light receptors.Make a small box (preferably, with dimentions2"x2"x1") and poke two holes for the terminal jacks. Just make an opening for theentrance of the light.

7. Adjust the LDR in a way that it will get more light from the transmitter. Once it isdone, make another one of this, but this time, label the two terminals C and G.

PROCEDURE:

FOR THE JUNCTION BOX (CIRCUIT)

1. Prepare a 1"x1" PCB. Sketch the diagram in it.

2. Study the diagram. Notice that you can usually divide the circuit into two lanes. Focus

first on the bottom one and read schematics.

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3. Insert a piece of wire in a hole in the end of the PCB. Add another wire connected inseries with the wire. Place anotherwire in series with the wires but keep them fromtouching each other. This will serve as the line for the light sensors.

4. Solder it and place, then add a resistor with value 1k ohm in series with the lineconstructed.

5. On the top lane, do the same procedure as in the bottom lane, just replace the resistorwith a transistor. The transistor must touch the junction between the resistor and the gapin the bottom lane (see the diagram for details).

6.Make sure that the transistor is NPN type. If so, connect the two line is in parallel witheach other. Label it with A, B, C, D, E and F (see the diagram).

PROCEDURE:

JUNCTION BOX (THECASE)

1. Prepare a small box, with preferred size 3 1/2" x 3 1/2" x 1 1/2" of any size.

2. Puncture eight holes in it for the terminal jacks. Label each holes A, B, C, D, E, F, G

and G.

3. Lay-out the box. The preferred locations of the terminal jacks are shown. The orderspecified in the diagram should be regarded, but the location or where the holes are pokedis not that considerable.

4. The two G terminals should be connected with each other. Connect the terminals in the

junction circuit and junction box of the same labels. Keep the box tightly closed.

* For the stopwatch, tap the start/stop line of the circuit. The circuit shouldstart and stop the watch disregarding the push button. Label the two terminalsF and E.

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Introduction

A) BACKGROUND OF THE STUDY

Almost all of the vehicles now a days are having a vehicular accident

because of not minding about over speeding. Over speeding is defined as

driving fastly or some what we call exceeding of thespeed from the given limit

that can cause harm to the driver. Passenger and some innocent human

beings. All over the world, we always hear news about road accidents that the

only reason is over speeding, if this will not be resolved as soon as possible,

many lives will be gone and the number of accidents will continue to increase

every year. So, as a concerned student of this society, we thinked of a device

that might help reduce the number of operators that are having over

speeding and also to prevent vehicular accidents.

Besides over speeding, the other target market of this project is the different

schools nationwide-especially on science laboratories. Because as we face the

reality, not all the schools have a device that can use for their experiments.

For example, on our school, our device is only for free falling objects and the

time that we gathered is not accurate because it needs human intervention to

stop and also it cannot measure kinematics and projectile motions.

B) STATEMENTOF THEPROBLEM

1. GENERALOBJECTIVE

Nowadays theres no any device that can measure different speed. Theres

a specific device in measuring the speed of a human, an animal, and also

theres a device in measuring the speed of cars, so its too expensive if youre

going to buy all of that devices. Thats why our group decided to make a

device that can measure different speeds and at the same time giving anaccurate time.

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C) SIGNIFICANCE

The one who will be benefit by using our invention was theschool(nationwide) because, students might learn more by the use of

technology. Having or using this will help to improve the quality of the study.

It can also use in measuring the speed and the time of free fall, kinematics,

and projectile motion.

Not only the school will be benefit by our invention but also in sports that

deals with speed, like marathon. In marathon, when the runner heared the

sound from the gun its time to them to start running but in reality light

travel faster than sound, so its more applicable to use the light as the go

signal rather than the sound coming from the gun. From now on, we donthave to use gun anymore because we now have device that can give an

accurate time.

D) SCOPE AND LIMITATIONS

Our inventionshas a limitation likethe other inventions out there. Here are

the following limitations of our projects.

A)In using our invention theres nothing that will block the laser except for

the object that were going to measure the speed, because if something willblocked the laser the timer will start at wrong time.

B)Our device is not applicable to use in a far distances because the timer

wont work. You can still use it in measuring in far distances but you have to

change the wire and put a longer wire on it.

C)The temperature might affect the resistance of the timer, higher the

temperature around the timer ,higher the resistance of the timer and if the

timer has a high resistance it wont stop. Our device must located on a place

with room temperature only.

D.REVIEWOF RELATED LITERATURE

PHOTORESISTOR

A photoresistor, light dependent resistor (LDR) or cadmium sulfide (CdS)

cell is a resistor whose resistance decreases with increasing incident light

intensity. It can also be referred to as a photoconductor.

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A photoresistor is made of a high resistance semiconductor. If light falling on

the device is of high enough frequency, photons absorbed by the

semiconductor give bound electrons enough energy to jump into the

conduction band. The resulting free electron (and its hole partner) conduct

electricity, thereby lowering resistance.

A photoelectric device can be either intrinsic or extrinsic. An intrinsic

semiconductor has its own charge carriers and is not an efficient

semiconductor, e.g. silicon. In intrinsic devices the only available electronsare in the valence band, and hence the photon must have enough energy to

excite the electron across the entire bandgap. Extrinsic devices have

impurities, also called dopants, added whose ground state energy is closer to

the conduction band; since the electrons do not have as far to jump, lower

energy photons (i.e., longer wavelengths and lower frequencies) are sufficient

to trigger the device. If a sample of silicon has some of its atoms replaced by

phosphorus atoms (impurities), there will be extra electrons available for

conduction. This is an example of an extrinsic semiconductor.

PRINTED CIRCUIT BOARD

Printed circuit board, or PCB, is used to mechanically support and electrically connect

electronic components using conductive pathways, tracks or signal traces etched from

copper sheets laminated onto a non-conductive substrate. It is also referred to as printed

wiring board (PWB) or etched wiring board. A PCB populated with electronic

components is a printed circuit assembly (PCA), also known as a printed circuit board

assembly (PCBA).PCBs are inexpensive, and can be highly reliable. They require much more layout effort

and higher initial cost than either wire wrap or point-to-point construction, but are much

cheaper and faster for high-volume production.Much of the electronics industry's PCB

design, assembly, and quality control needs are set by standards that are published by the

IPC organization.

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WIRE

A wire is a single, usually cylindrical, string of metal. Wires are used to bear

mechanical loads and to carry electricity and telecommunications signals. Wire is

commonly formed by drawing the metal through a hole in a die or draw plate. Standard

sizes are determined by various wire gauges. The term wire is also used more loosely to

refer to a bundle of such strands, as in 'multistranded wire', which is more correctly

termed a wire rope in mechanics, or a cable in electricity. History

In antiquity, jewellery often contains, in the form of chains and applied decoration, large

amounts of wire that is accurately made and which must have been produced by some

efficient, if not technically advanced, means. In some cases, strips cut from metal sheet

were made into wire by pullingthem through perforations in stone beads. This causes thestrips to fold round on themselves to form thin tubes. This strip drawing technique was in

use in Egypt by the 2nd Dynasty. From the middle of the 2nd millennium BC most of thegold wires in jewellery are characterised by seam lines that follow a spiral path along the

wire. Such twisted strips can be converted into solid round wires by rolling them between

flat surfaces or the strip wire drawing method. The strip twist wire manufacturing method

was superseded by drawing in the ancient Old World sometime between about the 8th

and 10th centuries AD. There is some evidence for the use of drawing further East prior

to this period. Square and hexagonal wires were possibly made using a swaging

technique. In this method a metal rod was struck between grooved metal blocks, or

between a grooved punch and a grooved metal anvil. Swaging is of great antiquity,

possibly dating to the beginning of the 2nd millennium BC in Egypt and in the Bronze

and Iron Ages in Europe for torches and fibulae.

Twisted square section wires are a very common filigree decoration in early Etruscan

jewellery.

In about the middle of the 2nd millennium BC a new category of decorative tube was

introduced which imitated a line of granules. True beaded wire, produced by

mechanically distorting a round-section wire, appeared in the EasternMediterranean and

Italy in the seventh century BC, perhaps disseminated by the Phoenicians. Beaded wire

continued to be used in jewellery into modern times, although it largely fell out of favour

in about the tenth century AD when two drawn round wires, twisted together to form

what are termed 'ropes', provided a simpler-to-make alternative. A forerunner to beadedwire may be the notched strips and wires which first occur from around 2000 BC in

Anatolia.

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Wire was drawn in England from the medieval period. The wire was used to make wool

cards and pins, manufactured goods whose import was prohibited by Edward IV in

1463The first wire mill in Great Britain was established at Tintern in about 1568 by the

founders of the Company ofMineral and Battery Works, who had a monopoly onthisApart from their second wire mill at nearby Whitebrook,[5] there were no other wire

mills before the second half of the 17th century. Despite the existence of mills, the

drawing of wire down to fine sizes continued to be done manually.

Wire is usually drawn of cylindrical form; but it may be made of any desired section by

varying the outline of the holes in the draw-plate through which it is passed in the process

of manufacture. The draw-plate or die is a piece of hard cast-iron or hard steel, or for fine

work it may be a diamond or a ruby. The object of utilising precious stones is to enable

the dies to be used for a considerable period without losing their size, and so producing

wire of incorrect diameter. Diamond dies must be rebored when they have lost theiroriginal diameter of hole, but the metal dies are brought down to size again by

hammering up the hole and then drifting it out to correct diameter with a punch.

USES

Wire has many uses. It forms the raw material of many important manufacturers, such

as the wire-net industry, wire-cloth making and wire-rope spinning, in which it occupies

a place analogous to a textile fiber. Wire-cloth of all degrees of strength and fineness ofmesh is used for sifting and screening machinery, for draining paper pulp, for window

screens, and for many other purposes. Vast quantities of aluminium, copper, nickel and

steel wire are employed for telephone and data wires and cables, and as conductors in

electric power transmission, and heating. It is in no less demand for fencing, and much is

consumed in the construction of suspension bridges, and cages, etc. In the manufacture of

stringed musical instruments and scientific instruments wire is again largely used. Among

its other sources of consumption it is sufficient to mention pin and hair-pin making, the

needle and fish-hook industries, nail, peg and rivet making, and carding machinery;

indeed there are few industries into which it does not enter.

Not all metals and metallic alloys possess the physical properties necessary to make

useful wire. The metals must in the first place be ductile and strong in tension, the quality

on which the utility of wire principally depends. The metals suitable for wire, possessing

almost equal ductility, are platinum, silver, iron, copper, aluminium and gold; and it is

only from these and certain of their alloys with other metals, principally brass and bronze,that wire is prepared.

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By careful treatment extremely thin wire can be produced. Special purpose wire is

however made from other metals (e.g. tungsten wire for light bulb and vacuum tube

filaments, because of its high melting temperature). Copper wires are also plated with

other metals, such as tin, nickel, and silver to handle different temperatures, providelubrication, provide easier stripping of rubber from copper.

TRANSISTOR

A transistor is a semiconductor device used to amplify and switch electronic signals. It

is made of a solid piece of semiconductor material, with at least three terminals for

connection to an external circuit. A voltage or current applied to one pair of the

transistor's terminals changes the current flowing through another pair of terminals.

Because the controlled (output) power can be much more than the controlling (input)power, the transistor provides amplification of a signal. Today, some transistors are

packaged individually, but many more are found embedded in integrated circuits.

The transistor is the fundamental building block of modern electronic devices, and is

ubiquitous in modern electronic systems. Following its release in the early 1950s the

transistor revolutionized the field of electronics, and paved the way for smaller and

cheaper radios, calculators, and computers, among other things.

RESISTOR

A resistor is a two-terminal electronic component having a resistance (R) that produces

a voltage (V) across its terminals that is proportional to the electric current (I) flowing

through it in accordance with Ohm's law:

V = IR

Resistors are elements of electrical networks and electronic circuits and are ubiquitous in

most electronic equipment. Practical resistors can be made of various compounds and

films, as well as resistance wire (wire made of a high-resistivity alloy, such as nickel-

chrome).The primary characteristics of a resistor are the resistance, the tolerance, the maximum

working voltage and the power rating. Other characteristics include temperature

coefficient, noise, and inductance. Less well-known is critical resistance, the value below

which power dissipation limits the maximum permitted current, and above which the

limit is applied voltage. Critical resistance is determined by the design, materials and

dimensions of the resistor.

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Resistors can be integrated into hybrid and printed circuits, as well as integrated

circuits. Size, and position of leads (or terminals), are relevant to equipment designers;resistors must be physically large enough not to overheat when dissipating their power.

STOPWATCH

A stopwatch is a handheld timepiece designed to measure the amount of time elapsedfrom a particular time when activated to when the piece is deactivated. A large digital

version of a stopwatch designed for viewing at a distance, as in a sports stadium, is called

a stopclock.

A typical mechanical analog stopwatch.

The timing functions are traditionally controlled by two buttons on the case. Pressing the

top button starts the timer running, and pressing the button a second time stops it, leaving

the elapsed time displayed. A press of the second button then resets the stopwatch to

zero. The second button is also used to record split times or lap times. When the split

time button is pressed while the watch is running, the display freezes, allowing the

elapsed time to that point to be read, but the watch mechanism continues running to

record total elapsed time. Pressing the split button a second time allows the watch to

resume display of total time.

Mechanical stopwatches are powered by a mainspring, which must be periodically wound

up by turning the knurled knob at the top of the watch.

Digital electronic stopwatches are available which, due to their crystal oscillator timing

element, are much more accurate than mechanical timepieces. Because they contain a

microchip, they often include date and time-of-day functions as well. Some may have aconnector for external sensors, allowing the stopwatch to be triggered by external events,

thus measuring elapsed time far more accurately than is possible by pressing the buttons

with one's finger. The first digital timer used in organized sports was the Digitimer,

developed by Cox Electronic Systems, Inc. of Salt Lake City Utah (1971). It utilized a

Nixie-tube readout and provided a resolution of 1/1000 second. Its first use was in ski

racing, but was later used by the World University Games inMoscow, Russia, the U.S.

NCAA, and in the Olympic trials.

The device is used when time periods must be measured precisely and with a minimum

of complications. Laboratory experiments and sporting events like sprints are good

examples.

The stopwatch function is also present as an additional function of many digitalwristwatches, cell phones, and portable music players.

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Results and discussions

Part 1 resistance readings

The LDR`s resistance changes with the change in luminous intensity. Higher intensitybears lower resistance, and this characteristic became the subject of our study. The

changing resistance value of the LDR will make way for the possibility of the project, but

to what extent does the resistance value change with light intensity?

To answer this question, we tested our LDR under a series of lights with different light

intensity. Below is a graph showing the relationship of resistance and light intensity.

Light source intensity resistance

1.5 V led .08 cd 87,665

Dimmer flashlight 1 cd 21,321

Dimmer flashlight 3cd 9,747

Dimmer flashlight 5 cd 568

Spotlight 18 cd 117

Based on the graph, we can see the inverse relationship between the two variables. In this

set up, we can see that change in the resistance comes with a change of light intensity.

The ldr depends on the light, so it is clear that the independent variable is the light

intensityand the dependent variable is the LDR`s resistance.

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Part 2 voltage readings

Now that we have a calculated and measured table for the resistance, we must test how it

affects the voltage in the circuit. Following the formula V=IR and I is constant, it is very

predictable that the voltage changes indirectly with the resistance. However, we needaccurate results in this experiment and further tests are needed. In this case, we used a 3V

battery for the input voltage. Below is a table for the results of the experiments:

Resistance Output voltage

87,665 3.42x10 V

21,321 1.40x10 V4,747 3.07x10 V

568 5.28x10 V

117 0.025 V

Since the input voltage is constant, the table is comprised only of the resistance and the

output voltage. The formula is right, and our predicted outcome matches the result.

On this part, the dependent variable is the voltage, since it depends on the resistance

given by the LDR

Part 3 LED experiment

This experiment`s target is to show the effect of variable resistance to a LED in the

circuit. Our expected outcome is the same as the voltage experiments. The light emitted

by the LED depends on the amount of voltage pushing the current to flow.

For the experiment, we used a LED, a 3V battery LDR and a dimming flashlight for the

varying light intensity.

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The set up for the experiment is a series connection of the components and a flashlight

directed towards the LDR. Switching the lights causes changes with the LED`s light.

As expected, the LED dims with the darker surrounding based on the results of part 2

experiment.

We tested this set up in a toy with a push button, since the stopwatch functions the same

way as the toy is. We simply just tapped the wires of the push button to the circuit, and

the toy activates with the presence of light.

Part 4 parallel connection

Following the earlier experiments, it is clear that the push button will function in the

presence of light, preferably a laser light. However, this is not our project needs. The

principle that our project holds is the activation of the switch with the light from theemitter is blocked. We need a circuit that turns off when there is light, and activates when

there is a focused light.

Or first hypothesis is to use parallel connections of 4 LDR`s and a resistor with a high

value. Our trial is that when one of the 4 resistors exposed to light is blocked, the current

will have no choice but to take the path with the high resistance, the one with the resistor

(1K ). The extreme high resistance prevented the flow of current however current also

did not passed through the 1K resistor. Sad to say, but our project didnt worked.

Part 5 transistor

To solve the problem left by the failed parallel connection experiment, we decided to use

a transistor. There are two main types of transistor, the PNP and the NPN type. The only

difference is the sequence of the positive and negative terminals, where P is positive and

N is negative. However, the applicable type is not yet known so we have to conduct tests

to figure it out. We prepared two diagrams for each of the transistors. We first used the

one for the NPN type.

We still encountered problems, as different terminals of the transistors will have major

effects to the project. To transfigure the right set up, we switched the places of the

emitter, base and collector. It took us three trials to get the desired result a table below

shows results gotten from the experiments if these terminals are connected to the positive

terminal:

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emitter The emitter is the one connected to the

positive terminal of the loop. We got

the desired result in this set up.

Base Actually, we just wasted time doing

this. We didnt get the right outputs.collector It didnt worked when this is connected

to the positive terminal, but reversed

connection made the circuit functional

but not the same way we want it to be.

Based on the experiments, the transistor should be a NPN type and the emitter terminal of

the transistor should be the one connected to the positive terminal.

Part 6 LED experiment 2

The success of the last experiment immediately made a way for the project. We

performed the earlier LED experiment replacing the circuit with the new devised circuit.

The objective of the experiment is to switch off the LED with the presence of light. It is

the reverse function of the earlier experiments, and we hope this will succeed.

To our surprise, we got the LED turned off when we focused light to the LDR. This

means that decreasing the resistance prevents the flow of current to other lines in thecircuit, and the desired results of the experiments are now in our hands.

Part 7 stopwatch test

Now, we are ready to install the light sensor circuit to the stopwatch. It has two light

sensors. Blocking one of them starts the circuit and blocking again another one stops the

stopwatch. We got it working, and we tested the difference of time measured between

two timers manually operated and our project.

distance Our timer Person A Person B

10 cm 0.51 0.80 0.56

20 cm 0.69 0.73 0.72

30 cm 1.19 1.24 1.17

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The difference is obvious in the set experiments, but we strongly believe in the accuracy

of our timer since it uses speed of light and electronics.

Conclusions

We created a product that measures time. There are many of these things, but

our project offers accuracy. The optoelectronics applied made this possible

and functional.

Although there are certain limitations such as weakness of foreign light

obstructions and unable to time transparent objects, we still offer versatility.

This product offers capability to measure freefalling objects, linear and on

some occasions, projectiles.

The sensor is much sharper than a human eye, and the switching functions aremuch faster than human reflex. In short, accurate time can be measured with

this device, a function that only a few apparatuses could offer.

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RECOMMENDATIONS

The light sensitivity of our project offers a great advantages over manualstopwatch operation. Aside from laboratory works and study aids, this project

can be used in test driving cars. This can also be used by athletes by giving the

time it took to travel a given distance. Our project can also be used in

freeways to monitor speed limits.

For variation, you can separate the stopwatch from the switch circuit to beinstalled to other system. This may be applied to the lightning system of our

homes to save electricity. If installed in a stove playing the sensors across theheating coil, it can serve as an automatic electric stove. You can install this in

an electric extension to control it with a light sense, switching it off and on

through a distance.

Other importat application of our project is for the security system. This c an

be turned into an alarm system, or to a camera that captures images of thosewho interfered the light source.

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BIBLIOGRAPHY

Boylestal, Robert, electronic devices and circuit theory. Cainta, Rizal. Jemma, Inc.

1900

ACKNOWLEDGEMENT

Our group wants to thank all of those people who supported us to finish this project.

Of course to our group mates who contributed efforts, cooperation and financial needs to

make this project possible.

We also want to thank the family of our some group mates who let us see their effort in

entertaining us to their houses and prepared snacks for us. Kezziah and Carls family.

We would like to express our thanks to our teachers who became supportive and believes

in our capability that we can do this output.

Above all, our Lord who gave us enough knowledge, strength and ability to execute this

performance.

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PHOTOS

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Light sensitive timer

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