INPUT TRANSDUCERS

1. Thermostat – is a component of control system which senses the temperature of a system so that the systems' temperature is maintained near a desired setpoint. It maybe a control unit for heating or cooling system or a component part of a heater or airconditioner.ILLUSTRATION : The temperature setpoint must be set, once it is set, the temperature sensor sense the ambient/actual temperature and compare it to setpoint, once the actual setpoint has been reached, the sensor output controls the heating or cooling device.

2. Pressure Transducer - also known as pressure transmitter measures pressure, typically gases or liquids. It generates electrical signal as a function of the pressure imposed. It is commonly made of piezoelectric materials such as quartz.ILLUSTRATION : This is widely used in industrial manufacturing processes. Example are steam boiler machine. Steam pressure inside the vessel of boilers must be kept in critical attention in order not to explode due to exceeded steam pressure. It's the function of the pressure transducers to sense or monitor the pressure inside the vessel, once it reaches the pressure setpoint, the pressure transducers output controls the furnace in off position.

3. Photosensors - also known as Light Depending Resistor (LDR) is a light controlled variable resistor. The resistance decreases with increasing incident light intensity.ILLUSTRATION : Photosensor is made of high resistance semiconductor. In the dark, it can have a resistance as high as a few megaohms, while in the light, it has a resistance as low as a few hundred ohms.

4. Motion Sensor - is a device that detects moving objects. It is often integrated as a component of a system that automatically performs a task or alerts a user of motion in an area.ILLUSTRATION : Motion sensors form a vital component in security, home control, lighting control, energy efficiency, and factory automation.

5. Proximity Sensor - able to detect the presence of nearby objects without any physical contact.ILLUSTRATION : It emits an electromagnetic field and looks for a changes in the field or return signal.

6. Humidity Transducer - is a moisture-sensitive device that changes color when the indicated relative humidity is exceeded.ILLUSTRATION : Relative humidity is the ratio of the partial pressure of water vapor in an air-water mixture to the saturated vapor pressure of water at a prescribed temperature.

7. SONAR (Sound Navigation and Ranging) /Sound Transducer - is a sound transducer that uses sound propagation to navigate, communicate with or detect objects on or under the surface of the water.ILLUSTRATION : Passive and Active SONAR are the two types of technology.