Week 8 (23 to 29/9/2012)

This week there was another briefing. The briefing was mostly about the proposal presentation. We were briefed about how to prepare before and during the presentation. I took note of the briefing and try to prepare my presentation the best that I could.

Week 7 (16 to 22/9/2012)

Still another week worth of research. In this week, I did some research on previous work of fans that don't use temperature controlled technology.

1) Axial-flow fans

An Axial flow pump or Fan is used to push fluid in a direction that is parallel to the shaft of the impeller. In comparison, a radial or centrifugal pump or fan would direct the fluid perpendicular to the axis of rotation. Axial pumps are sometimes termed propeller pumps owing to their similarity to the propeller of a boat. The difference, however, is that these pumps are usually shrouded in a casing to transmit fluids from one specific location to another. 

2) Centrifugal fan

A centrifugal fan is a mechanical device for moving air or other gases. The terms "blower" and "squirrel cage fan" (because it looks like a hamster wheel) are frequently used as synonyms. These fans increase the speed of air stream with the rotating impellers. They use the kinetic energy of the impellers or the rotating blade to increase the pressure of the air/gas stream which in turn moves them against the resistance caused by ducts, dampers and other components. Centrifugal fans accelerate air radially, changing the direction (typically by 90°) of the airflow. They are sturdy, quiet, reliable, and capable of operating over a wide range of conditions.

This is some of the research that I will put in the literature review section.

Week 6 (9 to 15/9/2012)

For this week, all the students were briefed on the details that must be made in the report and the marks given for each item. FYP calendar is also provided so that students can refer.

In this week I also took do research for the components in my project.

Temperature sensor

From the block diagram, the first part is the temperature sensor. The temperature sensor that will be used in this project is LM 35 temperature sensor. The LM35 series are precision integrated-circuit LM35 temperature sensors, whose output voltage is linearly proportional to the Celsius (Centigrade) temperature. The LM35 sensor thus has an advantage over linear temperature sensors calibrated in ° Kelvin, as the user is not required to subtract a large constant voltage from its output to obtain convenient Centigrade scaling. The LM35 sensor does not require any external calibration or trimming to provide typical accuracies of ±¼°C at room temperature and ±¾°C over a full -55 to +150°C temperature range.

The reason this project picked this temperature sensor is because low cost is assured by trimming and calibration at the wafer level. Also, 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 µA from its supply, it has very low self-heating, less than 0.1°C in still air. The LM35 is rated to operate over a -55° to +150°C temperature range, while the LM35C sensor is rated for a -40° to +110°C range (-10° with improved accuracy). 

 Motor Driver (Transistor N-MOSFET)

For the next part, this project will need a motor driver. The motor can be controlled by a switch, but the most common way to control a motor is through a transistor. This is because transistor can act as a switch too. Transistor is better when dealing with larger items (like a toy motor or washing machine). A transistor is incredibly useful because it switches a lot of current using a much smaller current. A transistor has 3 pins. For a negative type (NPN) transistor you connect your load to collector and the emitter to ground. Then when a small current flows from base to the emitter a current will flow through the transistor and the motor will spin.

There are two types of standard transistors, NPN and PNP, with different circuit symbols. The letters refer to the layers of semiconductor material used to make the transistor. Most transistors used today are NPN because this is the easiest type to make from silicon.

1) Arduino Microcontroller

As mentioned above, this project will use the microcontroller Arduino. Arduino is an open-source single board microcontroller. The reason this project picked this particular microcontroller is because the programming for it is more user friendly compared to other microcontrollers. For the Arduino hardware, the Arduino board consists of an 8-bit Atmel AVR microcontroller with complementary components to facilitate programming and incorporation into other circuits. An important aspect of the Arduino is the standard way that connectors are exposed, allowing the CPU board to be connected to a variety of interchangeable add-on modules known as shields. Some shields communicate with the Arduino board directly over various pins, but many shields are individually addressable via an I²C serial bus, allowing many shields to be stacked and used in parallel. Besides that, Arduino also pre-programmed with a boot loader which will make it easier to upload programs to the on-chip flash memory, while other devices need to use an external programmer.

So those components above are some that I will use for my project.

Week 5 (2 to 8/9/2012)

Another week of research. This time I'm doing a research on types of fan control. Of all the types of fan control, 2 of them picked up my interest



Thermostatic


In this style of fan control, the fan is either on or off. A system thermistor checks the temperature inside the chassis, and if it detects a temperature outside of range, it spins the fans up to maximum. When the temperature drops below a threshold again, the fans are turned back off. This control method reduces power requirements during periods of low usage, but when the system is operating at capacity, the fan noise can become a problem again.

Pulse-width modulation

Pulse-width modulation (PWM) is a common method of controlling computer fans. A PWM-capable fan is usually connected to a 4-pin connector (pinout: Ground, +12V, sense, control). The sense pin is used to relay the rotation speed of the fan and the control pin is an open-drain or open-collector output, which requires a pull-up to 5V or 3.3V in the fan. Unlike linear voltage regulation, where the fan voltage is proportional to the speed, the fan is driven with a constant supply voltage; the speed control is performed by the fan based on the control signal.

The control signal is a square wave operating at 25kHz, with the duty cycle determining the fan speed. Typically a fan can be driven between about 30% and 100% of the rated fan speed, using a signal with up to 100% duty cycle. The exact speed behaviour (linear, off until a threshold value, or a minimum speed until a threshold) at low control levels is manufacturer dependent.^[3]

The reason I'm interested in these 2 types of fan control is because they are relevant to my project

Week 4 (26/8/2012 to 1/9/2012)

This week I also do a research for the project. I surf the internet to do the research, like always. I did a research on the wind chill factor



Wind Chill Factor


Wind chill (often popularly called the wind chill factor) is the felt air temperature on exposed skin due to wind. The wind chill temperature is never higher than the air temperature, and the windchill is undefined at higher temperatures (above 10 °C [50 °F]). Humidity on the skin can result in a higher perceived air temperature, which is accurately termed the heat index (or humidex), and is used instead; note however that heat index figures do not include any reference to wind speed.