Week 8

Week 8

Aim : Preparation for making proposal report

Result:
To make a proposal report, all the research must be conducted to show the full operation of the project. All of the main components use for this project are:

Thermocouple Sensor

            A thermocouple is a junction between two different metals that produces a voltage related to a temperature difference. Thermocouple is a widely used type of temperature sensor for measurement and control and can also be used to convert heat into electric power. They are inexpensive and interchangeable, are supplied filtered with standard connectors and can measure a wide range of temperatures. The main limitation is accuracy: system errors of less than one Kelvin (K) can be difficult to achieve. I have done doing a room temperature sensor in previous semester by using thermocouple in subject measurement and instrumentation 2.

           

Thermostat

            A thermostat is a device of a control system which senses the temperature and maintained in a temperature required. The thermostat can switching heating or cooling devices on or off, or regulating the flow of a heat transfer fluid as needed, to maintain the correct temperature. A thermostat may be a control unit for a heating or cooling system or a component part of a heater or air conditioner. Thermostats can be constructed in many ways and may use a variety of sensors to measure the temperature. The output of the sensor then controls the heating or cooling apparatus. A thermostat may switch on and off at temperatures either side of the setpoint the extent of the difference is known as hysteresis and prevents too frequent switching of the controlled equipment.

Early technologies included mercury thermometers with electrodes inserted directly through the glass, so that when a certain (fixed) temperature was reached the contacts would be closed by the mercury. These were accurate to within a degree of temperature.

                    

Circuit diagram for thermostat.

Passive Infrared Sensor (PIR)

           

PIR sensors allow you to sense motion, almost always used to detect whether a human has move in or out of the sensor range. They are small, inexpensive, low-power, easy to use and don’t wear out. For that reason, they are commonly found in appliances and gadgets used in homes or businesses. They are often referred to as PIR, “Passive Infrared”, “Pyroelectric”, or “IR motion” sensors.

Basic stats:

§  Size: Rectangular

§  Output: Digital pulse high (3V) when triggered (motion detected) digital low when idle (no motion detected). Pulse lengths are determined by resistors and capacitors on the PCB and differ from sensor to sensor.

§  Sensitivity range: up to 20 feet (6 meters) 110° x 70° detection range

§  Power supply: 3V-9V input voltage

Plan next week:
Constructing the block diagram and also the operation flowchart.