project report electronic design analog electronics ee2110e

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HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY

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PROJECT REPORT

Electronic Design/Analog Electronics (EE2110E)

Class code: 136277

Students list:

Trương Tuấn HuyStudent’s code: 20207159Class TE-E2 K65.

Nguyễn Giang NamStudent’s code: 20207165Class TE-E2 K65.

HANOI 2022.1

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY

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Trương Tuấn HuyStudent’s code: 20207159Class TE-E2 K65.

Nguyễn Giang NamStudent’s code: 20207165Class TE-E2 K65.

HANOI 2022.1

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3.2. Problem solving method...9

CHAPTER 4. CIRCUIT ANALYSIS...10

4.1. Circuit diagram...10

4.2. Working of the circuit...10

CHAPTER 5. TEST RUN AND CONCLUSION...12

5.1. Simulation...12

5.2. Real product...13

CHAPTER 6. FUTURE SCOPE...14

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CHAPTER 1. INTRODUCTION:

1.1 Introduction:

Light sensor alarm systems are widely used to detect changes in light levels andprovide an alert in response to those changes. In this project, we will bedesigning a light sensor alarm system using a photoresistor to detect changes inlight levels. The system will be designed to trigger an alarm when the light to atree is not available, providing a reliable means of detecting and responding tochanges in light.

The system will consist of a photoresistor that will be connected to a simplecircuit that includes a resistor and an alarm. The photoresistor will act as avariable resistor, changing its resistance depending on the amount of light itdetects. When the light level falls below a certain threshold, the resistance of thephotoresistor will increase, triggering the alarm.

The alarm can take different forms, such as a loudspeaker, flashing lights, or anotification sent to a smartphone or other device. The goal of the system is toprovide a simple and effective means of detecting changes in light levels andalerting the user when the light to their tree is not available. By doing so, thesystem can help ensure that the tree remains properly illuminated, even in theabsence of natural light.

1.2 Objective:

The objective of this project is to design and build a light sensor alarm systemthat will detect changes in light levels and trigger an alarm when the light to atree is not available. The system will use a photoresistor to detect changes inlight levels and will be designed to be simple, reliable, and effective. The alarmwill be triggered when the light level falls below a predetermined threshold,ensuring that the tree remains properly illuminated at all times. The project willdemonstrate an understanding of basic electronic circuits and sensors, as well asprovide a practical solution to the problem of ensuring proper lighting foroutdoor trees.

We will simulate the circuit using Proteus program.

1.3 Requirements of project:

In fact, in order to apply this circuit to detect the ability to light through of theled grow light, this circuit also has many uncertainties such as cost, components

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and weather conditions. So the requirement is to make a circuit that is not onlygood in price, but also works stably in all weather conditions.

Products made must be applied in good practice. In addition, it is also necessaryto ensure the aesthetics of the product.

Stable operation when the source changes.

The light must turn off at dawn and turn on automatically when the lightintensity drops to a certain extent. High sensitivity and stability. The circuit issimple and easy to customize.

The input signal is a light signal, namely the light hitting the photoresistor. Thissignal can change gradually over time (if it's sunlight) or suddenly (if it'sartificial light). The output signal is sound signal form buzzer. Non-functionalrequirements Compact, lifespan 1.5-2 years. Cheap price (about 60,000 VND).

1.4 Expected outcomes of project:

Our project can use the light sensor circuit to serve the purpose of lighting, hereare some typical products: Light sensor alarm systems are widely used infarming to detect changes in light levels that ensures plants grow gradually.Besides, our circuit can be also used in security system to recognize themovement at night which cause the change in light. The above products mostlyuse rechargeable batteries or solar energy, so the lifespan is not high, and ittakes time to charge, so making a light sensor circuit using direct power on thepower network is quite convenient and has a good lifespan, saving time, noneed to charge.

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CHAPTER 2. OVERALL DESIGN

OP-AMP IC ANDTRANSISTOR

ACTIVE ANDRESET IC PHOTORESISTOR

BUZZER ANDBUTTON

SOURCE

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CHAPTER 3. CIRCUIT DESIGN

For this light sensor alarm system, a photoresistor and a buzzer have beenchosen as the primary components. A photoresistor is a simple, inexpensive, andeffective type of light sensor that changes its resistance in response to changesin light levels. This makes it an ideal choice for detecting changes in light levelsand triggering an alarm when the light falls below a certain threshold. Thebuzzer, on the other hand, is a compact and easy-to-use component that providesan audible alert when triggered. This makes it a suitable choice for alerting theuser when the light to their tree is not available. Additionally, buzzers are widelyavailable, easy to interface with, and can be powered by a variety of sources,making them a versatile component for many different types of projects. Bychoosing a photoresistor and a buzzer for this light sensor alarm system, we cancreate a simple and effective solution for ensuring proper lighting for outdoortrees. So we decided to choose a LDR and HXD buzzer.

 Choose the source:

The HDX buzzer chosen for this light sensor alarm system has a specifiedvoltage range of 4V to 8V, which means that it requires a voltage within thisrange to operate effectively. However, in order to ensure that the buzzer hasenough voltage to operate reliably and with sufficient volume, a 9V source hasbeen selected for the system. While a voltage outside of the specified range maycause damage to the buzzer or reduce its lifespan, in this case, the 9V sourceprovides a small margin of safety while still falling within the buzzer'srecommended operating range. Additionally, 9V batteries are widely available,

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easy to use, and relatively inexpensive, making them a convenient choice forportable or standalone projects like this one. By choosing a 9V source for theHDX buzzer, we can provide the system with the necessary voltage to operateeffectively while still maintaining a reasonable level of safety and convenience.

 Choose an OP AMP:

An op amp IC358 has been chosen for this light sensor alarm system to controlthe flow of current and ensure that the buzzer is only activated when thephotoresistor detects a certain level of light. Op amps are highly versatile andwidely used electronic components that can be configured in a variety of waysto perform different functions. In this system, the op amp is used as acomparator, comparing the voltage output of the photoresistor with a referencevoltage set by a voltage divider circuit. When the voltage output of thephotoresistor falls below the reference voltage, the op amp output goes high,allowing current to flow to the buzzer and triggering the alarm. Conversely,when the voltage output of the photoresistor is above the reference voltage, theop amp output remains low, preventing current from flowing to the buzzer andensuring that the alarm is not triggered. By using an op amp as a comparator inthis way, we can create a reliable and precise control mechanism for the lightsensor alarm system.

 Choose a transistor:

1. Voltage and current requirements: The BC547BP transistor can handle amaximum voltage of 45V and a maximum current of 100mA, whichshould be sufficient for many low-power circuits.

2. Gain: The BC547BP transistor has a typical beta (h ) value of 200, whichfemeans it can provide a significant gain to the signal being amplified. Thiscould be useful in circuits that require amplification, such as audioamplifiers or oscillator circuits.

3. Cost and availability: The BC547BP is a widely available and affordabletransistor, making it a popular choice for many hobbyists and DIYelectronics projects.

4. Other characteristics: The BC547BP transistor is a general-purpose NPNtransistor, which makes it suitable for a wide range of applications. It alsohas a low noise level and a fast switching speed, which could bebeneficial in certain circuits.

To calculate the parameters of the BC547BP transistor in your circuit, we use the following formulas:

Emitter-Base voltage (Vbe):Vbe = V - 0.7Vbb6

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Where 0.7V is the threshold voltage of the Emitter-Base junction.With a value of V = 9V, we have:bb

Vbe = 9V - 0.7V = 8.3VEmitter-Base current (Ib):

Ib = (V - V ) / Rbb beb

With a value of V = 8.3V and R = 220Ω, we have:beb

Ib = (9V - 8.3V) / 220Ω = 3.1mACollector-Base current (Ic):Ic = β x Ib

Where β is the current gain factor of the BC547BP transistor.

According to the datasheet of BC547BP, the average calculated value of β isabout 200. However, this value may fluctuate depending on each specifictransistor. Therefore, to accurately calculate I , you need to determine thecspecific β value of the transistor in your circuit.

Assuming you have determined the specific β value of the transistor in yourcircuit to be 150, we have:

Ic = 150 x 3.1mA = 465mACollector-Emitter voltage (Vce):Vce = V - (I x R )cccc

With a value of V = 9V, I = 465mA, and R = 10,000Ω, we have:ccccVce = 9V - (465mA x 10,000Ω) = 3.5V

 Choose NE555

The NE555 is a popular integrated circuit that is widely used as a timer oroscillator in electronic circuits. In our circuit, we needed a component that couldreset the buzzer without the need to unplug the power source. The NE555provides a convenient solution to this problem as it can be configured in avariety of ways to provide a timing function, including a one-shot ormonostable mode. By using the NE555 as a reset switch, we can ensure that thebuzzer is reset and ready to sound again without interrupting the power source.

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Additionally, the NE555 is a low-cost and widely available component, makingit an ideal choice for our circuit.

CHAPTER 4: COMPONENTS

4.1) Photoresistor:

_Photoresistor: is used to sense the presence of light.

_Photoresistor is an electronic component made of a special substance whose

resistance changes and decreases with the level of light. It is a linear, ohmic resistance.

non-Photoresistor is used as a light-sensitive sensor in detector circuits, for example in light meters when taking pictures, in circuits that determine the light and darklevels of the environment to activate automatic lighting switches.

Photoresistor is made of high impedance semiconductor and no junction. In the dark, photoresistors have resistances up to several (MΩ). When there is light, the resistance drops to a few hundred (Ω). The operation of photoresistors is based on the photoelectric effect in the mass of matter. When a photon with enough energy hits it, it knocks an electron out of the molecule, becomes free inthe mass, and makes the semiconductor a conductor. The degree of electrical conductivity depends on the number of photons absorbed.

Depending on the semiconductor, the photoresistor reacts differently to differentphoton wavelengths. Photoresistor reacts later than photodiodes, about 10ms, soit avoids rapid changes of light source.

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4.2) Op - Amp IC LM358:

_Op-Amp IC is used to amplify the signal from the LDR.

_An operational amplifier is a DC-coupled high gain electronic voltageamplifier. It is a small chip which has 8 pins. An operational amplifier IC isused as a comparator which compares the two signals, the inverting and non-inverting signal. LM358 is a dual-channel operational amplifier. It consists oftwo independent, high-gain, frequency-compensated operational amplifier. Toactivate the IC, we connect the power source with the Vcc and GND pin. Then,we provide two input voltage to the op-amp for comparision.

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4.3) Timer IC NE555:

IC 555 is monolithic timing circuit that gives precise and highly stable delays of time or oscillation. This IC can be used for where the temperature ranges from 0° to 70°C. The main function of this IC is to generate an accurate timing pulse. In the monostable mode, the delay of this IC is controlled by the external components like a resistor and capacitor. In the astable mode, both the duty cycle and frequency are controlled by two external resistors and one capacitor. In this project, we use it in the bi-stable mode. The circuit produces 2-stable state signals which are low and states. The o/p signals of low and high state signals are controlled by reset and activate the i/p pins, not by charging and discharging of capacitors. If a low logic signal is given to active pin, then the o/p of the IC circuit goes to high level. If the low logic signal is given to the RST pin, then the o/p of the circuit goes to the low level.

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4.4) NPN TRANSISTOR BC547

_A transistor is a semiconductor device accustomed to amplify or switchelectrical signals and power. It is composed of semiconductor material, typicallywith a minimum of 3 terminals for connection to an electronic circuit. A voltageor current applied to 1 pair of the transistor's terminals controls the currentthrough another pair of terminals. Because the controlled output power can beover the controlling input power, a transistor can amplify a signal.

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_N-P-N Transistor: It consists of one p-type material that is present between twon-type materials. N-P-N transistor is used to amplify weak signals to strongsignals. In NPN transistor, the electrons move from the emitter to collectorregion resulting in the formation of current in the transistor. This transistor iswidely used in the circuit.

BC 547 has three terminals: emitter, collector and base. It has two operation status: forward bias and reverse bias. In the status of the forward bias, the current can pass when the collector and emitter are connected. In the status of

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the revers bias, it acts as a disconnect switch and current cannot pass.

4.5) Potentiometer:

Potentiometer is used to adjust the sensitivity of the alarm.

A potentiometer is a manually adjustable variable resistor with 3 terminals. Twoterminals are connected to both ends of a resistive element, and the thirdterminal connects to a sliding contact, called a wiper, moving over the resistiveelement. The position of the wiper determines the output voltage of thepotentiometer. The potentiometer essentially functions as a variable voltagedivider. The resistive element can be seen as two resistors in series

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