Memoria Electronica Engenheiras Final

7/28/2019 Memoria Electronica Engenheiras Final

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Electronics

TEMPERATURE SENSOR WITH LM35

TECHNICAL MEMORY

Team: Engenheiras

Authors: Raquel Rubin Sarbosa, Giovanna Misquita, Marta CamareroSanchez

Date: 05.06.2013


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The following project involves the construction of an alarm system temperature using basic

elements of electrical circuits in order to satisfy the customer s need. Three prototypes were

made in order to improve a specific aspect in relation to the previous prototype. In all circuits,

we used the Arduino microcontroller, in order to make the digital analog conversion circuit, and

thus create a backup system, so that in case that fails in analog system the customer can still

make full use of project tools.

The first prototype was made in order to satisfy the customers needs as soon as possible. The

second system was made so as to have a lower power consumption, thereby causing a savings to

the customer. The third prototype was made so as to have the best resolution, thus causing

higher fidelity measures and moreover a better detection of changes in degree of alarm, making

it more accurate.


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INDEX

OBJECTIVES ....................................................................................................................................... 3

1. INTRODUCTION ............................................................................................................................. 4

2. SYSTEM DESIGN PROTOTYPE 1 STANDARD ............................................................................ 6

3. SYSTEM DESIGN PROTOTYPE 2 BEST CONSUMPTION .......................................................... 12

4. SYSTEM DESIGNER PROTOTYPE 3 BEST RESOLUTION .......................................................... 15

5. SYSTEM FINAL VALIDATIONS AND DATASHEETS ........................................................................ 17

6. PROJECT ORGANIZATION ............................................................................................................ 25

7. COST ............................................................................................................................................ 26

8. CONCLUSIONS ............................................................................................................................. 28

9. REFERENCES ................................................................................................................................ 29

10. ANNEX ....................................................................................................................................... 30


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OBJECTIVES

The project has common goals like the following tasks:

Learning and familiarization with the use of microcontrollers and Labview virtual laboratory. Application of resources seen in the laboratory with the aim of improving specifications of a

system already implemented.

Use of average correction tools and elimination of random error. Learning about the projects and their control tools. Satisfy the wishes of a potential customer. Improve the overall vision of the project part of the division of tasks.


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1. INTRODUCTION

The main function of an engineer trained in any area, is the conduct and coordination of projects in

order to meet a need of a customer. The definition of a project is a realization of temporary

endeavor undertaken to create a product, service or result, which are typically authorized as a result

of a strategic consideration, which may be a market demand for a specific organizational need, the

request of a client, a technological breakthrough or even a legal requirement. Each project has a set

of phases that is called life cycle of a project, where in general, each phase has characteristics as

following:

Each project phase is marked by the delivery of one or more products, such as feasibilitystudies, cost study or functional prototypes.

At the beginning of each stage, set up the job to be done and those involved in theirimplementation.

The end of the phase is marked by a review of the product and project performance to date. The ability of the parties to alter the products of each phase is decreasing as the phase

progresses.

To help in the organizational structure of a project, there are several things you can take into

consideration in order to optimize time and resources. One of the most used tools to organize a

project that is called Microsoft Project is a project management tool produced by Microsoft, which

have focused on time management (dates, duration of the project, work calendar), Gantt Chart,

Model probabilistic network diagram, costs (fixed and non-fixed) and a range of reports. Overall, the

program is based on the model diagram network, which uses tables in the process of data entry,

allows the use of sub-projects and resources to group, filter and classification tasks. One of the things

that server in a way to be complementary to the project in Microsoft Project is the use of a Block

Diagram.

The block diagram is a graphical representation of a process model or a complex system. Through

connections and geometric figures, describes the relationships between each subsystem and the

information flow, that is, the graphic solution from the solution of a particular problem. The symbols

should be arranged in chronological order and with correct syntax to achieve the goal of solving the

problem. The diagrams use flowcharts to represent small parts of a large system with a focus on

logical process. In the case of the proposed project, block diagrams are of vital importance, since the

project is structured into discrete blocks and interconnected in a very direct way.

The project proposed by the client, is the construction of a simple alarm system that detects a rank

of temperatures between -50 and 50 degrees, through a specific temperature sensor (LM35) and

with the aid of a digital microcontroller (Arduino) besides the use of the tool Labview. Thus, the client

was aware of overheating or under-cooling a subsystem, thus avoiding a premature rupture of the

equipment.


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The measurement of temperature is not as simple as you can imagine at first. The mere fact that this

measure be made by an analog value and that will eventually be converted to a digital value, imply

several important factors in choosing the sensor. The sensor is no more than one transducer, or an

electronic device that converts a magnitude in another, where a temperature into an electrical signalin the form of tension. By the specifications and ease of use and connection to the Arduino, the

sensor used in the project was that the LM35 has a calibrated accuracy of 1 Celsius degree and a rank

of measurement ranges from -55 degrees to 150 degrees. The output is linear and each degree

Celsius equals 10mV. Furthermore, LM35 has the facility of not requiring additional circuitry for

external calibration impedance and low output makes this integrated circuit is easily installed in a

control circuit or in the case of the project developed by the staff, the microcontroller Arduino.

Microcontrollers are present in all products, and this microcontroller is just a computer, which

although not comparable to a desktop has several features in common with this device, including the

use of a central processing programs, the use of a RAM in which the variables are stored and input

and output devices. The microcontroller used in the project is the Arduino Board which is a

prototyping platform electronics free hardware, designed with a microcontroller Atmel single board

with support for input and output built and a programming language standard is essentially C / C + +,

where the goal is to create tools that are affordable, low cost, flexible and easy to use by students in

training, especially when you do not have to reach drivers more sophisticated and more complicated

tools. The Arduino is connected directly to Labview virtual environment.

The LabView (acronym for Laboratory Virtual Instrument Engineering Workbench) is a graphical

programming language. The main fields of application are the realization of LabView measurement

and automation. Programming is done according to the model data flow, which offers the

advantages this language for data acquisition and manipulation. In this system, the function blocks

are called virtual instruments, because each subprogram that can simply be run separately.

All these resources are fully utilized in the construction of the controller design temperature, in order

to obtain customer satisfaction and thus, aggregate maximum knowledge within electronics for

designers at the end of the course.


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2. SYSTEM DESIGN PROTOTYPE 1 STANDARD

For the implementation of this project we have followed the scheme showed below:

Figure 1. Blocks diagram prototype 1

In this part we are going to explain the process we have followed to do the analogical part. Here we

show the block diagram:

For the analogical block we have considered the process now explained:

First of all, it is important to say that all the elements of this prototype will be supplied with -5 Vand 5V.

Sensor: It is known that the sensors output voltage is between -500mV and 500 mV due to thefact that the temperature measured by it is between -50 and 50.In order to let the LM35 give

negative temperatures it is necessary to put a resistance of 18k, as said in the datasheet, which

goes from the output to ground. We can see it in our datasheet.


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Analog block: Two temperatures are fixed in order to set the alarm limits (lower and upper). Inour case, we have chosen as correct temperatures the ones which are from 26 to 30.

The entire analog block, which is made of two potentiometers, will be supplied with 5 V and all

the elements must be connected to the same ground. Firstly, the block receives the sensor

output voltage (in mV) which means the temperature divided by 100. For example, 26 0.260

V / 260 mV. The following step is to fix the temperature limits. So, we use two potentiometers

whom resistances are calibrated to obtain the limits in mV. 26 260mV 30 300mV. These

voltages will be called Vreference.

Once we have set the limits, its necessary to make a comparison between the sensors output

voltage and the potentiometers output voltage. The comparison is made this way:

o Two comparisons are needed in order to know if the sensors temperature is inside therange of the correct ones. The material used will be two operational amplifiers of the

TL074, shown in the datasheet.

o The first one will work like this. The positive entrance will receive the sensors voltageand the negative one will receive the voltage from the first potentiometer (the one

which fixes the lower limit 26). The AO makes a comparison between both voltages

and if the sensors temperature is higher than the one of reference the AO output is Vcc

(Vsupply5V). Otherwise, the output will beVcc (Vsupply -5V).

o The second AO will work like the one explained below although the sensors voltage willbe compared to the upper voltage limit (Vreference: 300mV).

Alarm system 1Once the analog block is finished it is necessary to know how the alarm system works. The

elements on which will be the alarm based are leds and their set resistances. In order to explain

it better, let us make an example divided into three parts.

1. If the temperature in the room is about 22, the sensors output voltage is of 220mV. One ledwill need to light because its under the lower limit. As we said before, this value will be

compared with the two limits. When 220mV enter into the first AO and are compared to

260mV, as 220mV < 260mV the AO output will be Vcc = -5V. In this case the led1 must light

itself. At the same time, the sensors voltage is being compared to 300mV , 220mV < 300mV

and the AO output will be -Vcc=-5V but in this case we dont want the led2 to light because it

could mean that the sensors value was inside the correct temperatures and thats not whatwe want to remark.


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2. If the temperature in the room is about 28, the sensors output voltage is of 280mV. In thiscase, none of the leds need to light because this value is in the correct range. When 280mV

enter into the first AO and are compared to 260mV, as 280mV > 260mV the AO output will

be Vcc = 5V. In this case the led1 must not light itself because the sensors value could be

inside the correct range. At the same time, the sensors voltage is being compared to 300mV,

280mV < 300mV and the AO output will be -Vcc=-5V and like the situation below we dont

want the led2 to light because it could mean that the sensors value was inside the correct

temperatures and thats not what we want to remark.

3. If the temperature in the room is about 35, the sensors output voltage is of 350mV. In thiscase the led2 must shine because the value is higher than the upper limit. When 350mV

enter into the first AO and are compared to 260mV, as 350mV > 260mV the AO output will

be Vcc = 5V. In this case the led1 must not light itself. At the same time, the sensors voltage

is being compared to 300mV, 350mV > 300mV and the AO output will be Vcc=5V but in this

case we want the led2 to light because it could mean that the sensors value has overtaken

the upper limit.

LED Sensor temperature Upper

limit

Led1

Led2

Its known that leds work like a diode and they light when the voltage that arrives to its anode is

greater than the one on the cathode and its shine depends on how many voltage arrives to it, but

also higher than the leds referencevoltage. If its set in direct polarization the leds voltage is 1.9V

(red) and 3.4V (green).

The led1 needs to be put into indirect polarization in order to shine only when the sensorstemperature is below the limit. In this case, the Vout will be Vcc and the led will work.

Otherwise, in the two other cases, the led wont shine because the output voltage wi ll be Vcc

and the led works in indirect polarization with negative voltages.

The led2 works the other way round. Analog Digital Block: In this part we are analyzing the fitting out of the analog signal in order

show it in Arduino/Labview. What we need to do is to convert the negative voltages into

positives because the Arduino only works in the [0, 5] V interval.


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The scheme that we are going to follow is this:

Figure 2. Analog Digital Block

First of all we are going to apply an Operational Amplifier which will plus to signals. It will be an

inverting AO, due to the fact that is the one explained in class and the output will be an interval

of voltages between 0 and -1. We have two different inputs, the two blue crosses in the

graph;the first one is the voltage (temperature) obtained by the sensor LM35 and the second one

is 500mV*. We have set this value because we want to change the negative values (from-500mV)

into positive ones, so Vmin: -500mV +500 mV= Vminnew=0V. If we apply an operational amplifier

with the corresponding resistances, R: 4k7, we will obtain an interval of voltages of [0, -1]V, as

said before. Now, we are in the green cross. In our case, 26 -0.780 V approximately.

Afterwards, as we want to obtain positive values, we need to invert the interval obtained and by

using another inverting AO. With R: 1k.

Once, we have all these process made we will obtain an output value between [0, 1]V Vsensor

in our case 0.780V, and it will be the input for the Arduino.

It is possible to create 500mV either by using a potentiometer or a voltage divider. In thiscase, we have chosen the second one because the potentiometer is very sensitive to any

touch and it changes its value easily. But the problem is that to sum 500mv we cant introducea simple voltage divider with RA: 400k and RB: 47k Its necessary to add a voltage follower in

order to avoid the resistance effects losses and keep the voltage value equally, real 500mV.

So the output is now at the second blue input.


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Figure 3. Voltage divider and voltage follower

Digital Block: This block is the only one that we have not design ourselves because we are usingan A/D converter, a microcontroller called Arduino.As said before, this boardmicrocontroller has

an analogical-digital converter inside. The A/D converter will transform the output of the later

block and then it is necessary to program the output of the Arduino by using its own programme

language, similar to C++. In order to make all the connections well we need to check the Arduino

pins connections.

1. The USB connects the Arduino and we need to use three pins of it. It is important to set heport serial, COM4 in our case.

2. The first one is AO Analog In) on which the analogical Vsensor will be entered. Like all theelements of a circuit, the Arduinos ground must be linked to the ground of our protoboard.Once it receives the Vsensor it needs to be programmed.

3. As we have added 500 mV we must deduct them because we want the display to show thetemperature.

4. The converter makes a mistake which is known: 0.00488V

Alarm system 2: Finally, the leds configuration needs to be made. In this case, we have decidedto light only a red led when the temperature is out of any of the two limits. So, once we have set

when should the leds shine we need to put the led on the protoboard, linked by 1k resistance.

The longer leg goes with the resistance and the other one goes with ground.

The code in Arduino is showed in in the Annex.

The last part of this Temperature Sensor Circuit is to watch the signal into LabView. This would also

let us to know the error and the accuracy of our system. Some important notes to be remarked are:

Never open Labview when Arduino is working because it will not run correctly. Change the . and , configuration to make the Arduino read points as decimals and not miles. Delete the sentences of Arduino which show letters because it will not understand anything.


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When we have launched Labview COM4 is se as the serial port and if we start the simulation, the

graph on the left shows us the temperature with the same interval time of Arduino. On the right, a

histogram appears and we can see how the noise affects our system. To know the resolution, it is

necessary to know the difference between the values measured. Although we will show all theinformation in the datasheet, the resolution was of 0.1.


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3. SYSTEM DESIGN PROTOTYPE 2 BEST CONSUMPTION

For the improvement of system consumption we have used the following scheme:

Figure 3. Blocks diagram prototype 2

The second prototype aims to get a lower consumption compared to electric current and hence

relative power, compared to the first prototype with correct operation.

The intention was to feed the entire first prototype only with the Arduino microcontroller instead of

using the (+5,-5)V power source .

Sensor: The sensor is now supplied by unipolar 5V. In this way, how it was explain before and it islinked to the 18k resistance in order to be able to give negative temperatures.

Conversion block: The system will be able to give negative temperatures we need to convert allof them into positive. Due to the fact that in this case we want to optimize the consumption we

will avoid using so much amplifiers and we will follow the next figure to give positive

temperatures, between 0 and 5V. The datasheet shows the following draw:


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Figure 4. Sensor datasheet

We need to use two diodes to let the sensor give to the circuit a positive tension with negatives and

positives temperatures. In this way, all the temperatures that go into the system are normalized by

0V and 5V.

Thus, the sensor continues to operate normally and reduce consumption, since it is no longer

necessary to use a voltage divider and two amplifiers, which at prototype One had the function of

transforming into positive, negative inputs to the application in the digital microcontroller.

! Changes in lower limit temperature of 35 degrees centigrade and the upper limit by 44 degrees in

order to make easy to realize how does the system works.

Analog Digital Block: Once we have the circuit fed and properly adjusted we need to use theprevious schema of prototype 1 to make the comparison between two voltages to turn the alarm

system properly specified. We are using now the LM224N which contains the same AOs thanTL074 but it can be supplied by 0 and 5 V, what we need due to the Arduino supply. By doing the

simulation, we have significantly reduced the total consumption.

Comparison Block: In comparison of the above figure, we have to compare the voltage out of thetemperature sensor and the voltage generated by potentiometer. For limitations of the

simulation program Proteus limits might not be compatible with the actually used, however, the

operation principle remains the same. Despite having changed into LM224N, the performance is

the same as the one of the first prototype.

Alarm system 1: it works equally than the first prototype. Digital block: The digital block consists only of the analog circuit power, reading the analog

values of temperature, and the conversion to digital LED lighting through digital programming.

The code in Arduino is showed in the Annex.

It can be observed that there are no significant changes between the code and the second initial

prototype. What distinguishes the two is the presence of lines of code for the added 500mV tension

of the first prototype. With these values used in analog and digital we can prove that consumption

improves significantly.

Alarm system 2: The same as the first and second prototype.


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Less consumption demonstration:

Use of resistances of high values as they present a lower consumption in relation to componentsof lesser value.

Use of pots with the highest value available, also to reduce the consumption of the system. Reducing the digital block, placing it with just one LED in forward parts. Thus, even using two

diodes consuming in order to put the system into unipolar power consumption remains the

smallest possible. Recalling that the power to the Arduino 5V is made, as it was with the power

supply before.

Measures of Consumption: In this prototype, the measures made are the same as the prototype 1,

with the difference that they are supply by Arduino. In this case, the most significant value is the

consumption. In the Prototype 1, the consumption was of 95mW and the second prototype has a

consumption of 16mW, proving that the prototype two is better than the first one.


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4. SYSTEM DESIGNER PROTOTYPE 3 BEST RESOLUTION

For the improvement of system resolution we have used the following scheme:

Figure 5. Diagram Blocks Prototype 3

In this third prototype what we are supposed to do is to get a better resolution and reliability in

comparison with the other two prototypes.

In the same way that in prototype two we feed the circuit with de Arduino microcontroller, in this

third part we are doing the same.

Sensor: Equally to the second prototype, the sensor is supplied by unipolar 5V. Conversion block: We need to convert all of the negative temperatures into positive. This part

doesnt change from the second prototype. Analog Digital Block: Using the LM224 and fed by the Arduino we make the comparison

between the two voltages to turn the alarm system properly specified.

Amplifier Block: In order to let all the n bits of the AD converter to be efficient, it is important touse all the entrance range, to adapt itself to the fullest to the AD converter. That is why we have

decided to put an amplifier of 5 dB because higher will saturate the AO. The resistances of the

non-inverting AO are these R1: 1k R2: 4k. This increases the accuracy because the

difference between the temperature measured by the multimeter and the Arduino are only 0.2

different.

Comparison Block: In comparison of the above figure, we have to compare the voltage out of thetemperature sensor and the voltage generated by potentiometer.

Alarm system 1: Works in the same way than in prototype 1 and 2.


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Digital block: Here is when we have done an important change. It consists reading the analogvalues of temperature and the conversion to digital LED lighting through digital programming.

We changed the code of the digital programming, as is shown in the annex.

As we want to reduce de random error caused by the 50Hz of the electric network of other

interferences, we have doing the mean of 1000 points given by the Arduino every 1ms.

Alarm system 2: The same as the other prototypes.Best resolution and reliability

By adding a block into Labview programme (mean) we have made the mean between 1000

temperatures got by the Arduino. This decreases the error giving us a resolution of 0.008. We can

proof it because the plot and histogram shows us very low variance between values given by

LabView. For example, the graph at environmental temperature goes from 26.792 to 26.802.

To ensure that we reaching a better resolution and reliability what we have done is to take 4

different values of temperature given by the Arduino 4 mean points) and compare with the

multimeter. In this way we have a graph were X coordinates are the Arduino values, and on Y

coordinates the multimeter values or viceversa. Once we have this, we compute de p value. To

know what is the p value we have used an online calculator.

As we obtained a p value of 0.002, we are improving the resolution and the reliability o f our data.

The improvement of accuracy has been explained before, in the Amplifier Block.


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5. SYSTEM FINAL VALIDATIONS AND DATASHEETS

Datasheet Prototype 1 Standard Model

Supply Amplifiers dual supply (TL074): Vcc = 5V andVcc = 5V Supply Temperature Sensor (LM35) : Vcc = 5V and Ground

Description

This circuit consists in an alarm system in order to alarm when the temperature is more than 30

degrees and lower than 26 degrees, all of them in Celsius scale. The amplifier is in dual supply with

5V and -5V, with an external voltage source.

Materials

This system was made with this list of components:

Resistors: 47K (1 unit), 400K (1unit), 18K (1unit), 1K (2 units), 4,2K( 1 unit), 4,7K (2 units). Amplifiers: TL074 (2 units with 4 amplifiers integrates in each one) Leds : Red Led (1 unit), Green Led (2 units) Potentiometer: Potentiometer 1K (2 units) Microcontroller: Integrated circuit Arduino (1 unit) Sensor: LM35 temperature se nsor (1unit)

PIN CONNECTIONS

TL074

SENSOR LM35


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LED RED AND LED GREEN

POTENTIOMETER

Electronic Values

Parameter Value

Supply Voltage (+) 5V

Supply Voltage ( -) -5V

Electric Current 19Ma

Consumption 95mW

Resolution 0,1 degrees


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Schematic Diagram (Proteus)

Datasheet Prototype 2 Best Comsumption

Supply Amplifiers single Supply (LM224n): Vcc = 5V Supply Temperature Sensor (LM35) : Vcc = 5V and Ground

Description


degrees and lower than 35 degrees, all of them in Celsius scale. This system has less consumption in

reference of the first prototype, descript in the datasheet one. The amplifier is single supply with 5V

and 0V, with an Arduino source of power.

Materials


Resistors: 18K (1 unit), 1k (4 units) Diodes: 1,5V (2 units) Potentiometers : 47k (2 units) Temperature Sensor: LM35 (1unit) Leds : Green Led (2 units), Red Led (1 unit) Amplifiers : LM224n (1 unit with 4 amplifiers integrates) Microcontroller : Integrated circuit Arduino (1 unit)


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PIN CONNECTIONS

LM224n

SENSOR LM35 (Single Supply)


POTENTIOMETER


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Electronic Values

Parameter Value

Supply Voltage (+) 5V

Supply Voltage (-) 0V

Ground

Electric Current 3,2mA

Consumption 16mW




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Datasheet Prototype 3 Best Resolution

Supply Amplifiers Single Supply (LM224n): Vcc = 5V Supply Temperature Sensor (LM35) : Vcc = 5V and Ground

Description


degress and lower than 35 degrees, all of them in Celsius scale. This system has the best resolution

between the 3 prototypes, descripts in the other two prototypes. The amplifier is simgle supply with

5V and 0V, with an Arduino source of power.

Materials


Resistors: 18K (1 unit), 1K (4 units), 4k (1 unit) Diodes: 1,5V (2 units) Potentiometers : 47k (2 units) Temperature Sensor: LM35 (1unit) Leds : Green Led (2 units), Red Led (1 unit) Amplifiers : LM224n (1 unit with 4 amplifiers integrates) Microcontroller : Integrated circuit Arduino (1 unit)

PIN CONNECTIONS

LM224n

SENSOR LM35 (Single Supply)


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POTENTIOMETER

Electronic Values

Parameter Value

Suplly Voltage (+) 5V

Supply Voltage (-) 0V

Electric Current 3,6mA

Consumption 18mW



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6. PROJECT ORGANIZATION

The following table has the total hours per each component of the group to do the Project:

Miembro del grupo Actividad Tiempo

Marta Camarero Initial planning

Report

Laboratory

Teacher consults

3 hours.

4 hours

15 hours

5 hours

Giovanna Misquita Initial planning

Report

Laboratory

Teacher consults

3 hours.

5 hours

16 hours

3 hours

Raquel Rubin Initial planning

Report

Laboratory

Teacher consults

3 hours

5 hours

14 hours

5 hours

Table 1. Work planning of the project.


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7. COST

The materials we have used during the implementation of this project are the ones listed in the

following tables. A part of the ones below we also needed the Protoboard ARISTON, wires and the

Arduino microcontroller, but this material was supplied by the teacher so we are not going to

consider these in the cost.

In the first prototype we used:

Material Model Quantity Price () Total price ()

Sensor LM35 1 0.835 0.835

U1 A.O, TL074, SL 2 0.71 1.42

R1 1 k 5 0.08 0.4

R2 4.7 k 3 0.08 0.24

R3 100 k 4 0.08 0.32

R4 47 k 1 0.08 0.08

Potentiometer 10k 2 0.29 0.58

Green LED 2 0.15 0.30

Red LED 1 0.11 0.11

Total cost 4.285

Table 2: Cost of the material used in prototype 1.

In the second prototype we needed:

Material Model Quantity Price () Total Price ()

Sensor LM35 1 0.835 0.835

U1 A.O, LM224 1 0.96 0.96

R1 1 k 3 0.08 0.24

R2 10 k 2 0.08 0.16

Potentiometer 47 k 2 0.28 0.56

Green LED 4 0.15 0.60

Red LED 1 0.11 0.11

Total cost 3.47

Table 3: Cost of material used in prototype 2.


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For the third prototype we used:

Material Model Quantity Price () Total Price ()

Sensor LM35 1 0.835 0.835

U1 A.O, LM224 1 0.96 0.96

R1 1 k 4 0.08 0.32

R2 2,2 k 2 0.08 0.16

R3 10 k 2 0.08 0.16

Potentiometer 47 k 2 0.28 0.56

Green LED 4 0.15 0.60

Red LED 1 0.11 0.11Total cost 3.7

Table 4: Cost of the material used in prototype 3.


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8. CONCLUSIONS

When finished doing the project, the team Engenheiras believes that it has complied project

objectives, since the product presented to the client meets everything that was asked to the

beginning of quadrimester.

Also useful was a project of the organizational point of view, since we realize how much the initial

planning and fair division of tasks facilitates the work not only professional, as time management and

composition overall project.

Another factor was valid observed evolution in relation to the handling of laboratory instrument,

including multimeter, Labview and Arduino, including functions of circuit analysis. Moreover, there

was enhancement of the tool Proteus and FilterPro, in which team members were already

familiarizer at least partially.

The detection of useful tools to improve a circuit were used wisely, according to previous

experiments conducted in the discipline what comes in accordance with the proposal of learning. The

use of a diode in different polarizations, the correct use of the greed of the circuit when concepts in

conjunction with operational amplifiers, showing a total control of the team in relation to the project

and its utility in relation to customer request.

In general, it may also be noted that the concepts have been applied use of resistances greater for

lower consumption and moreover the use of amplifiers for decreasing frequencies of unwanted noise

to the circuit, concepts that have already been worked in the laboratory.

At most, we believe that the project was important both to better absorb the concepts workthroughout the course, but also at the point where working issues important to the labor market,

such as managing time and design, and the frequent use of a third language.


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10. ANNEX

1. Arduino figure

Image 1. Arduino

2. Arduino code 1st prototype

intpinoSensor = 0; //pinlinked to Vsensor LM35 (portaanalogica 0)

intvalorLido = 0; //Vsensor

floattemperatura = 0; //valorLidoconvertedintotemperature

#define LED_G 2

#define LIMITE 30

#define LIMITE2 26

voidsetup() {// Configuration of output pins

pinMode(LED_G, OUTPUT); // Initializingleds values

digitalWrite(LED_G, LOW);

Serial.begin(9600); //Initialize Serial comunication

}voidloop() {

valorLido = analogRead(pinoSensor);

temperatura = (temperatura - 0.500); // Deduct the 500mV to know Treal

temperatura = (valorLido * 0.00488); // 5V / 1023 = 0.00488 (ADaccuracy)

temperatura = temperatura * 100; //Convertsmilivoltsinto celcius, andeach 10mV are equal to a 1 celcius


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Serial.print(Temperatura actual: );Serial.println(temperatura);if (temperatura > LIMITE || temperatura < LIMITE2)

{//Turn on the green led

digitalWrite(LED_G, HIGH);

}

else

{digitalWrite(LED_G, LOW); // Turn off the green light

}

// Showing interval time

delay(500);

}

3. Arduino code 2nd prototypeintpinoSensor = 0; //pinlinked to Vsensor LM35 (portaanalogica 0)



#define LED_G 2#define LIMITE 35

#define LIMITE2 44





}voidloop() {

valorLido = analogRead(pinoSensor);






}

else


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{

digitalWrite(LED_G, LOW); // Turn off the green light

}


delay(500);

4. Arduino code 3rd prototypeintpinoSensor = 0; //pinlinked to Vsensor LM35 (portaanalogica 0)



#define LED_G 2

#define LIMITE 35

#define LIMITE2 44





}

voidloop() {valorLido = analogRead(pinoSensor);


temperatura= temperature/5.4; / divided by the gain





}

else

{digitalWrite(LED_G, LOW); // Turn off the green light

}


delay(500);

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Memoria Electronica Engenheiras Final