Automatic temperature controlled FAN

              Automatic temperature controlled FAN

  

Abstract:

Here is a circuit through which a fan can be linearly controlled automatically, depending on the room temperature. The circuit is highly efficient as it uses digital temperature sensor temperature measurement. Alternatively, the same circuit can be used for automatic temperature controlled AC power control. In this circuit, the temperature sensor used is a DS1820 having precision of 0.5ºC.

The microcontroller does the above job. It receives the signals from the sensor, and this signal is operated under the control of software which is stored in ROM. Microcontroller AT89c2051 continuously monitor the temperature sensor, When temperature reaches to some threshold value it switches on the fan.

Parts of the Systems:

1        Sensor: We will use DS1820 digital temperature sensor, which will give us digital output. It gives the temperature value in Centigrade scale.

2.      Micro controller: We are using micro controller 8051 to implement the overall system. Temperature sensor will be connected to any of the IO pin.

3.      AC Control: We will use a relay to control FAN. This relay is connected to the IO pin through triggering mechanism of a transistor.

8051 Microcontroller:
We will use 8051 microcontroller to build this system.
The 8051 architecture provides many functions (CPU, RAM, ROM, I/O, interrupt logic, timer, etc.) in a single package

• 8-bit ALU, Accumulator and 8-bit Registers; hence it is an 8-bit microcontroller
• 8-bit data bus – It can access 8 bits of data in one operation
• 16-bit address bus – It can access 216 memory locations – 64 KB (65536 locations) each of  RAM and ROM
• On-chip RAM – 128 bytes (data memory)
• On-chip ROM – 4 Kbyte (program memory)
• Four byte bi-directional input/output port
• UART (serial port)
• Two 16-bit Counter/timers
• Two-level interrupt priority
• Power saving mode (on some derivatives)

Programming Language: Embedded C

Sensors: DS1820 Digital temperature sensor.

Output:  On reaching threshold value switch on the FAN.

Algorithm:

1.      Switch off the FAN

2.      Get data from sensor.

3.      Calculate current temperature.

4.      If more than threshold switch on the FAN else switch off the FAN

5.      Go to step 2

 

Hardware Block Diagram: