Automatic light with pressure sensorLISTPreface...............3Part 1. Introducing the idea and determining specifications of the product..41.1. Analysis of demand and necessity of product ...41.2. The reason for choosing topic51.3. Products already on the market.51.3.1. Product 151.3.2. Product 251.3.3. Product 361.4.Specifications of the product.......61.4.1.Functionality ...6 1.4.2.Technical standards of product6 1.4.3 Non-functionality 7Part 2. Analysis of function and making plan...72.1. Analysis of function..72.1.1. Sub- Function 1 .82.1.2. Sub- Function 2 ..82.1.3. Sub- Function 3...82.1.4. Sub- Function 4...82.2.Making plan...8Part 3. Choosing technical method ...93.1.Diagram of the product 93.2. Components, architecture circuit 10 3.2.1 Choose the method for each block11 3.2.2 Architecture..12Part 4. Design circuit144.1 Design for every block.....144.2 Working principle for whole system16 4.3 Dependence of light intensity on resistance....18 4.4 Detemine V0, consuming power..18Part 5. Implement..18Part 6. Testing...19Part 7. Conclusion20Part 8. References.20

PREFACE

The main consideration in the present field of technologies are automation, power consumption and cost effectiveness. Automation is intended to reduce man power with the help of intelligent systems. Power saving is the main consideration forever as the source of the power (Thermal, Hydro ,Solar etc.,)are getting diminished due to various reasons. The main aim of the project is automatic power saving system with light dependent resistor (LDR) and pressure sensor. We want to save power automatically instead of doing it manually. So in villages, towns, etc. We can design intelligent systems for the usage of lights. Smart Light Technology is an eco friendly system as it helps in reducing light pollution.

We would like to thank most sincerely to Mr.Nguyen Duc Minhwho dedicated guidance, detailed explanations to help us complete this assignment. Not only about specialized knowledge, he also instructs us so much about practical knowledge in life: soft skills, listening, team work and presentations.

During the making of the report we have attempted very high but our knowledge is still limited due to some objective factors. We sincerely hope that teachers will help to facilitate with comments as well as criticisms to our report to make it more complete.

We're pleased to thank!

Part 1. Introducing the idea and determining specifications of the product .

1.1. Necessity and demand of the product.Street lighting is one of the important parts of a house or a citys infrastructure where the main function is to illuminate the area during dark hours of the day.Previously, the number of streets and houses in the town were very small. Therefore, the street lamps and light bulbs are relatively simple but with the development of urbanization, the number of streets and houses increases rapidly as a result of which the number of light bulbs and lamps has also increased in number.Hence more electric energy is required to illuminate these lights.But in the present time, electricity is wasted at houses due to not switching off unnecessary light bulbs.Earlier the light systems were operated manually and the street lamps glows through-out the night time even though there is no traffic in the street which is nothing but wastage of energy. Due to these reasons, so we need smart light technology, a system which can automatically sense the visible light and motion in the relevant place, and thereby reducing the wastage of electricity. This saved power can be used for some other cases.With the increase of modern technology, humans have become more busy in their lives. With the tired head after busy work and with the lack of time the probability of forgetting simple thingshave become more.(Ex: Forgetting to switch off the light when leaving the room etc.) But any way, since every household likes to have a less electricity consumption bill, they will turn to Smart light technology which in a way gives a demand to our product.

1.2. The reason for choosing the topic.With limited specialized knowledge, the design of a complex circuit is tough. So we chose a simple circuit, having product price matching to pockets of students.The common components can be easily found at electronics stores.The research, development and application of the Automatic light switch is fully consistent with the developing trend of Smart technology and will improve the quality of human life.1.3. Products already on the market. With the demand for Automatic light systems, there are similar products designed by some Vietnam manufacturers.They can be seen in the market with multiple categories, features and different prices. And their price is quite high compared to the cost of materials used. Let's go over some typical products.

1.3.1. Product 1 : Sai Gon Technology Company : Automated lightswitch with 12V Optical sensor Function: automated light switch using optical sensor Price : 200.000 VND

1.3.2. Product 2 : SH-D2 with infrared sensor: Function: automated light switch using infrared sensor Output: 100-240V/ 50-60 Hz Power: Bulb: 1000W Flourcent bulb: 350W Inductive distance: max 5m Price:about 1.000.000 VND

1.3.3. Product 3 : SH-D4 with body-infrared sensor Function : automated light switch used in staircases. Intelligent control by microprocessor chip Output: 220V/50-60Hz Power:Bulb: 1600W Flourcent bulb: 400W Time light: 15- 240 seconds Ambient temprature : 0-50C Price : about 1.000.000 VND

Estimated price of our product is 150.000 VND.

1.4. Specifications of product.1.4.1. FunctionalityOur products use 12DC source to provide for LED, and base on light intensity and pressure. The system automatically switch on light in suitable time when someone come in the twilight. It also means that if it is light or dark but no people, the light will not turn on.1.4.2. Technical standards of product.

FeaturesDescription

Input 12VDC source Light Pressure

Output Stable operation Light turn on in suitable time

Time lightAdjust following to demand of users

1.4.3. Non- functionality Small, neat High lifespan: about 2 years Friendly appearance Cheap price: 8$With this estimated price to sell in the market, most of Vietnamese workers can buy at least product for their family, and improve quality life. Moreover, we can use it for street light system, which is not only convenient but also saving national budget.

Part 2. Analysising of function and making plan.

2.1. Analysis of function.

Figure 1: Function diagram2.1.1. Sub- function 1: Convert light to voltage LDR( Light Detecting Resistor) is high sensitive to light. When there is more light, the pulses become faster, so resistance drops, against when there is less light, the resistance increases to very high. It can obtain following statistics: Bright resistance : 20k-45k. Dark resistance : 2000 k.When light fall on the LDR, circuit sends low signal, relay is off. When no light or weak light, circuit sends high signal. The relay will be energized and the armature of the relay will come to its normally open position. The circuit is gotten supply voltage.=>Switch the relay when VR7set time the light on following T=RC2.1.4. Sub- function 4: Switch on/off light

2.2. Making plan

OrderJobsDescriptionsTimeOutputImplementers

1Find out ideaFind and chose idea11/4-12/4/2015 (2 days)Automatic light with motion sensorAll of members

2Making plan- Divide work for each members- Making plan18/4/2015(1 day)

Job detailsThanh

3Describe our topic-Describe topic, creative and applicability

20/4-23/4/2015 (3 days)Slide and present for lecturersAll of member

4Estimated cost- Find out cost of components, and necessary tools2/5-3/5/2015 (2 days)- Cost estimation- Pay money

NganOshani

5Simulation- Draw schematic by proteus- Chose appropriate components

11/5-18/5/2015( 7 days)Finish simulationKim AnhHang

6Simulation in breadboard-Buy components-Test and repair22/5-24/5/2015(2 days)Circuit run well and stably

Kim AnhHang

7Perfecting product-Test product before lecture- Finish report28/5-10/6/2015( 2 days)- Good- Finish reportAll of members

Part 3. Choose the technical method

3.1.Block diagram

Figure 2: Block diagram

The first block is the source which supplies the energy for the whole circuit. The second block comprises of the switching circuit using LDR ; this block consists of relay, transistors ,resistors ,LDR . The LDR acts as the light sensor that senses visible light ; the switching circuit sends a HIGH signal when no light falls on the LDR and it sends LOW signal when light falls on the LDR . LDR is highly sensitive to light. The third block comprises of sensor which is basically a pressure sensor ; when pressure is sensed by this sensor it triggers the timer circuit . The fourth block which comprises of the 555 timer which is operated in mono-stable mode. Since the 555 timer is operated in mono-stable mode we will get a single pulse as the output in the output terminal of the 555 timer. The last block comprises of Lamp which is connected to the output terminal -3- of the 555 timer. The result of which the 555 timer will be triggered and the bulb will be glowing for a short period of time depending on the time constant, T = RC of the mono-stable mode circuit. 3.2. Components and Architechturea) Choose the suitable method for each block

The blocksMethodsCriteria for evaluatingChoose

ComplexityReliabilityCost

Source1.Pin 12V- Very simple, suitable for testing circuits-Use directly but no need to calibrate-Easy to run out of energy- Highreliability- Safe12000 VND

2.Source seft-designed using LM 8712 or IC 8705- Must construct the principle diagram, PCB-Easy to repair when something gets wrong- Unstable- Dangerous when testing products used directly by 220V25000 VND

The circuit using LDR1. The circuit seft designed- Must construct the principle diagram, PCB-Very simple to install- Have chance and experiment in making circuits- Stable- Safe- Easy to repair when something gets wrong30000VND

2.Use module available in the market using LM393- Use directly and simply without calibrating- Don't understand clearly about the circuit.- High reliability by LM393- Difficult to repair and replace components65000VND

Pressure sensor1. ButtonUse to stimulate the circuit1000 VND

2. Pressure sensorComplicated designRelatively stable

Delaying time block1. Self-made with IC 8051- Designed complexly with 39 terminals-Have to write algorithsm, code for 8051- Stable

2. Using IC 555 timer-IC 555 is programmed readily-IC 555 is designed simply with 8 terminals-Relatively stable3500VND

Display block1. led- Simple, effectiveLow stability350VND/a led

2. Bulb 220V- Need a relay connected to them

- Use 220V- Easy to break or burnt when moving6000-10000 VND

Completed diagram

Figure 3: Completed diagramb) Architechture Light Depentdent Resistor (LDR )

- LDRs or Light Dependent Resistors uses an active semiconductor layer ( Cadimi Sulfua Cds ) that is deposited on an insulating substrate. The semiconductor is normally lightly doped to enable it to have the required level of conductivity.- LDR are very useful especially in light/dark sensor circuits. Normally the resistance of an LDR is very high, sometimes as high as 1000 000 ohms, but when they are illuminated with light resistance drops dramatically.

InputIntensity of light

Output- light resistance ( 20-45 K)- dark resistance (2M)

The maximum voltage150 V

Power consumption100 mW

Spectral peak540 mm

Ambitient temperature30-70 0C

IC 555

IC 555 is a component which is able to generate the pulse accurately. In our curcuit we use it to provide time delays.

Supply voltage (VCC)4.5 to 15 V

Supply current (VCC = +5 V)3 to 6 mA

Supply current (VCC = +15 V)10 to 15 mA

Output current (maximum)200 mA

Maximum Power dissipation600 mW

Power consumption (minimum operating)30 mW (5V), 225 mW (15V)

Operating temperature0-700C

Relay

A relay is an electrically operated switch. Many relays use an electromagnet to mechanically operate a switch, but other operating principles are also used, such as solid-state relays. Relays are used where it is necessary to control a circuit by a low-power signal (with complete electrical isolation between control and controlled circuits), or where several circuits must be controlled by one signal.

Input12 V

Rated load10A/250VAC/30VDC, 10A/125VAC/28VDC

Power consumption0.36W, 0.45W

Ambient temperature25-70C

Pull-in voltage( VDC)75%

Drop-out voltage( VDC) 10%

Weight10 grs

Operating Humidity45-85%RH

Part 4. Design the circuit.4.1.Design for every block4.1.1. Source

1st source2nd source

Supply energy for the the switching circuit using LDRSupply energy for the rest block

4.1.2.The switching circuit using LDR

Working principle: When light falls on the LDR, the resistance of the LDR will be low. So the voltage drops across the resistor R7 will be high. This keeps the transistor Q1 ON. The collector of Q1 is coupled to base of transistor Q2. So Q2 will be OFF and the relay is too. Hence the bulb will not glow even if there is any motion in the road. When night falls the resistance of the LDR increases to make the voltage across the R7 decrease below 0.6V . This makes the transistor Q1 OFF which in turn makes Q2 ON . The relay will be energized and the armature of the relay will come to its normally open position.

4.1.3.Pressure sensor

Metal plates

Working principle: When people come in, the pressure will connect 2 metal plates of pressure sensor, so the 9V- source will supply energy for the delay time block.

4.1.4.Delaying time block

Working principleWhen the 555 timer is operated, the output pulse ends when the voltage on the capacitor equals 2/3 of the supply voltage. The output pulse width can be lengthened or shortened to the need of the specific application by adjusting the values of R and C.The output pulse width of time t, which is the time it takes to charge C to 2/3 of the supply voltage, is given by:t = R.C.ln(3) = 1.1 RCwhere t is in seconds, R is in ohms (resistance) and C is in farads (capacitance).While using the timer IC in monostable mode, the main disadvantage is that the time span between any two triggering pulses must be greater than the RC time constant.

4.1.5.Displaying block

4.2. Working principle for whole system:

LDR

Led is offLight Intensity corresponding Vout

VR7< V0

Output 555 Timer = 0 FalseF

true

F > 0 False

Output 555 timer1Led is On True

4.3. Dependence of light on resistance

ParameterIntensity of lightResistance

Cell resistance10 lux20k

100 lux45k

Dark resistance10 lux after 10 sec2M (min)

4.4. Determine V0We calculate the circuit We have : V0= 0.84 V

Part 5. Implements

This is circuit which we simulated by proteus and perform in breadboard:

Picture 1. Simulation

Picture 2: Physical design

Part 6. TestingDemo video( Youtube link) https://www.youtube.com/watch?v=JVcuUBt3hI0We tested on this device and the results are good.

Picture 3. Testing

Part 7. ConclusionIf green forest is like "lungs" of the Earth, the Electronics and Telecommunications sector has created a communication network covering the entire world and reached out to the vast universe.Through work assignments subject "Introduction to electronics - telecoms '' helped us to take the knowledge we have learned into practice.Moreover, this also help us to have the opportunity to dig deeper into knowledge about the components and develop skills design, installation simple electronic circuits. Since then, we have the opportunity to try our best to design the simple electronics products, useful for everyday life.In today's life, the energy savings are so essential. We hope that this product can contribute to energy saving power. One more time, we would like to thank Mr. Nguyen Minh Duc has helped us to complete this product.Despite a lot of effort,knowledge is limited, time is limited. Therefore, our report was flawed they need to supplement and perfect. We are looking forward to get the help and the care from the teacher.

Part 8. References

Automatic Street Light with motion sensor(n.d), academia.edu, retrieved from http://www.academia.edu/7935630/Automatic_Street_Light_with_Motion_Sensor Minh Ha Motion Sensor Light Switch(n.d),REUK.co.uk - The Renewable Energy Website, retrieved from http://www.reuk.co.uk/Motion-Sensor-Light-Switch.htm Electronic Components Datasheet Search(n.d), Alldatasheet.com, retrieved from http://www.alldatasheet.com/view.jsp?Searchword=Datasheet%20bc107b&gclid=CNOY5Ijp4cUCFUxwvAodiroAgQ

Group 2Page 11