AUTOMATIC TEMPERATURE BASED FAN CONTROLLER

ARDUINO UNO

The Arduino Uno is a microcontroller board based on the ATmega328 (datasheet). It has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz ceramic resonator, a USB connection, a power jack, an ICSP header, and a reset button. It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started.

The Uno differs from all preceding boards in that it does not use the FTDI USB-to-serial driver chip. Instead, it features the Atmega16U2 (Atmega8U2 up to version R2) programmed as a USB-to-serial converter. Uno board has a resistor pulling the 8U2 HWB line to ground, making it easier to put into DFU mode. Arduino board has the following new features:

• 1.0 pin out: added SDA and SCL pins that are near to the AREF pin and two other new pins placed near to the RESET pin, the IOREF that allow the shields to adapt to the voltage provided from the board. In future, shields will be compatible both with the board that use the AVR, which operate with 5V and with the Arduino Due that operate with 3.3V. The second one is a not connected pin, that is reserved for future purposes.
• Stronger RESET circuit.
• Atmega 16U2 replace the 8U2.

"Uno" means one in Italian and is named to mark the upcoming release of Arduino 1.0. The Uno and version 1.0 will be the reference versions of Arduino, moving forward. The Uno is the latest in a series of USB Arduino boards, and the reference model for the Arduino platform; for a comparison with previous versions, see the index of Arduino boards.

Figure: ARDUINO UNO A visual representation of the Arduino Uno board, showing its various pins and components, including digital I/O, analog inputs, power connectors, and the ATmega328 microcontroller.

POWER SUPPLY

The power supplies are designed to convert high voltage AC mains electricity to a suitable low voltage supply for electronic circuits and other devices. A power supply can by broken down into a series of blocks, each of which performs a particular function. A d.c power supply which maintains the output voltage constant irrespective of a.c mains fluctuations or load variations is known as “Regulated D.C Power Supply".

Figure: Block Diagram of Power Supply Illustrates a typical linear power supply setup, showing the flow from AC input through a transformer, rectifier, filter, and regulator to the DC output (Vout) connected to a load.

LCD DISPLAY

A model described here is for its low price and great possibilities most frequently used in practice. It is based on the HD44780 microcontroller (Hitachi) and can display messages in two lines with 16 characters each. It displays all the alphabets, Greek letters, punctuation marks, mathematical symbols etc. In addition, it is possible to display symbols that user makes up on its own. Automatic shifting message on display (shift left and right), appearance of the pointer, backlight etc. are considered as useful characteristics.

Figure: LCD A visual representation of a typical character-based LCD display, showing text like 'LCD display' and 'CONTROLLER'.

BUZZER

Digital systems and microcontroller pins lack sufficient current to drive the circuits like relays, buzzer circuits etc. While these circuits require around 10milli amps to be operated, the microcontroller's pin can provide a maximum of 1-2milli amps current. For this reason, a driver such as a power transistor is placed in between the microcontroller and the buzzer circuit.

TEMPERATURE SENSOR (LM35)

LM35 series sensors are precision integrated-circuit temperature sensors whose output voltage is linearly proportional to the Celsius temperature. The LM35 requires no external calibration since it is internally calibrated. The LM35 does not require any external calibration or trimming to provide typical accuracies of ±1/4°C at room temperature and ±3/4°C over a full -55 to +150°C temperature range.

The LM35's low output impedance, linear output, and precise inherent calibration make interfacing to readout or control circuitry especially easy. It can be used with single power supplies, or with plus and minus supplies. As it draws only 60 μΑ from its supply, it has very low self-heating, less than 0.1°C in still air.

Pulse Width Modulation

Pulse Width Modulation (PWM) is the most effective means to achieve constant voltage battery charging by switching the solar system controller's power devices. When in PWM regulation, the current from the solar array tapers according to the battery's condition and recharging needs Consider a waveform such as this: it is a voltage switching between 0v and 12v. It is fairly obvious that, since the voltage is at 12v for exactly as long as it is at 0v, then a 'suitable device' connected to its output will see the average voltage and think it is being fed 6v exactly half of 12v. So by varying the width of the positive pulse we can vary the 'average' voltage.

So, how do we generate a PWM waveform? It's actually very easy, there are circuits available in the TEC site. First you generate a triangle waveform as shown in the diagram below. You compare this with a d.c voltage, which you adjust to control the ratio of on to off time that you require. When the triangle is above the 'demand' voltage, the output goes high. When the triangle is below the demand voltage, the output goes low.

Diagram: Pulse Width Modulator Waveform Depicts a comparison between a triangle waveform and a DC voltage level. The output is shown as a square wave that switches high when the triangle wave is above the DC level and low otherwise, illustrating PWM generation.

DC FAN

A fan is a powered machine used to create flow within a fluid, typically a gas such as air. A fan consists of a rotating arrangement of vanes or blades which act on the air. The rotating assembly of blades and hub is known as an impeller, a rotor, or a runner. Usually, it is contained within some form of housing or case. This may direct the airflow or increase safety by preventing objects from contacting the fan blades. Most fans are powered by electric motors, but other sources of power may be used, including hydraulic motors, handcranks, internal combustion engines, and solar power.

Mechanically, a fan can be any revolving vane or vanes used for producing currents of air. Fans produce air flows with high volume and low pressure (although higher than ambient pressure), as opposed to compressors which produce high pressures at a comparatively low volume. A fan blade will often rotate when exposed to an air fluid stream, and devices that take advantage of this, such as anemometers and wind turbines, often have designs similar to that of a fan.

Typical applications include climate control and personal thermal comfort (e.g., an electric table or floor fan), vehicle engine cooling systems (e.g., in front of a radiator), machinery cooling systems (e.g., inside computers and audio power amplifiers), ventilation, fume extraction, winnowing (e.g., separating chaff of cereal grains), removing dust (e.g. sucking as in a vacuum cleaner), drying (usually in combination with a heat source) and to provide draft for a fire.

BLOCK DIAGRAM

Figure: Block Diagram A schematic showing the interconnection of key components: Power Supply, DHT11 sensor, Switch, Arduino microcontroller, LCD display, Fan, Wi-Fi module, and a mobile App, indicating data flow and control.

SOFTWARE REQUIREMENTS

• Arduino
• Embedded C language

HARDWARE REQUIREMENTS

• LM 35
• ARDUINO
• DC FAN
• LCD
• Wi-Fi
• APP

WORKING

I used an LCD shield to display the current temperature and speed of the fan, but you can use the circuit without the LCD display. You also need to select the transistor by the type of fan that you use. In my case I used the well-known BD139 transistor and a 9V battery to provide power to the fan and transistor. The LM35 temperature sensor and red led are powered with 5V from the Arduino board. As you can see in the sketch on the first line I included the LiquidCrystal library (header) that includes useful functions to use when an LCD is connected to the Arduino board. Then I set the pins for the sensor, led and fan. The most important part is to set the variables tempMin and tempMax with your desired values. TempMin is the temperature at which the fan starts to spin and tempMax is the temperature when the red led lights warning you that the maximum temp was reached. For example if you set tempMin at 30 and tempMax at 35 then the fan will start spinning at 30°C and reach its maximum speed at 35°C. We store the temperature value in the temp variable and then use some if() functions to check if temp is lower than tempMin and if so let the fan OFF (LOW). The next if() is to check if temperature is higher than the minTemp and lower than the tempMax and if so then use the map() function to re-map the temp value from one value to another. In our case fanSpeed will have a value of 32 at tempMin and 255 at tempMax. These values are used to control the speed of the fan using PWM and the analog Write(). The fan LCD re-maps the temp to allow the display of fanSpeed in a 0 to 100% range so you can say that the speed of the fan is directly dependent of the LM35's temperature. When the temperature reaches the value set in tempMax the fan will be at its maximum spinning velocity and the LCD will display FANS: 100% even though the temperature might increase above tempMax. The rest of the explanation can be read in the comments area of the Arduino sketch. In the next project I will make a temperature protection circuit that will turn off the power of equipment when its temperature has reached a certain value.

In this work we are designing the temperature based speed controlled fan. The surrounding temperature is sensed by LM35 sensor the sensed signal is sent as voltage pulses to microcontroller ATMEGA 328P and converts into an electrical signal which is applied to micro controller. The micro controller on arduino drives the motor driver to control the fan. ESP8266 Wi-Fi module is interfaced with arduino by using UBIDOTS free cloud storage website it is possible to switch the fan using mobile phone or laptop. Firstly when the supply is given to arduino, ESP8266 Wi-Fi module is connected to the specified network and by using mobile, fan can be switched. When fan is turned ON using phone the fan starts running LM35 sensor senses the surrounding temperature and according to temperature it controls the speed of the fan as specified in the arduino program.

Application

Temperature based fan speed controller is useful for cooling the processor in the laptops and personal computers “more efficiently". Generally fan in laptop comes with only two or three possible speeds. So it results in more power consumption. The fan designed in this project, has different values of speed according to temperature change. This can be also used in small scale industries for cooling the electrical/mechanical equipment. The whole circuit except motor and fan can be manufactured on a single PCB, and it can be used for temperature based control operations.