Transducer PDF

Transducers the collective term used for both Sensors and Actuators Sensors can be used to sense a wide range of different energy forms such as movement, electrical signals, radiant energy, thermal or magnetic energy, etc devices that perform a...

Transducers the collective term used for both Sensors and Actuators Sensors can be used to sense a wide range of different energy forms such as movement, electrical signals, radiant energy, thermal or magnetic energy, etc devices that perform an “Input” function they “sense” a physical change in some characteristic that changes in response to some excitation, for example, heat or force, and covert that into an electrical signal. Actuators can be used to switch voltages or currents. devices that perform an “Output” function used to control some external device, for example, movement or sound. Sensors Active Sensor require an external power supply to operate – called an excitation signal - which is used by the sensor to produce the output signal. self-generating devices because their properties change in response to an external effect Passive Sensors does not need any additional power source or excitation voltage. generates an output signal in response to some external stimulus. Analog Sensors produce a continuous output signal or voltage which is generally proportional to the quantity being measured. physical quantities such as Temperature, Speed, Pressure, Displacement, Strain, etc  Digital Sensors produce discrete digital output signals or voltages that are a digital representation of the quantity being measured produce a Binary output signal in the form of a logic “1” or a logic “0”, (“ON” or “OFF”). only produces discrete (non-continuous) values which may be outputted as a single “bit”, (serial transmission) or by combining the bits to produce a single “byte” output (parallel transmission). Accelerometer a electromechanical device that measures the vibration, or acceleration of motion of a structure It is based upon Newton’s Second law of motion acceleration of a body is directly proportional to, and in the same direction, as the net force acting on the body and inversely proportional to its mass. That mechanical energy is detected as acceleration and is converted into a proportional amount of electric signal which is used for the measurements. Capacitive MEMS Accelerometer detects acceleration by exploiting the movement fo a seismic mass, resulting in a capacitance change between parallel plates mechanically suspended by clamped beams used mostly in mobile devices Piezoresistive Accelerometer it measures the resistance changed by the force applied on the material used in automotive crash testing, safety air-bags & traction control system testing, etc Piezoelectric Accelerometer contains a Piezoelectric quartz crystal which produces an electric charge or output under acceleration when it detects or measures vibration. used in cell phones, vibration sensors, guitar pickups, etc.  Touch Sensor it is a tactile sensor that is sensitive to touch, force or pressure. mostly common used in smartphones and robotics. when there is a contact or pressure on the sensor, it opens up a circuit which allows current to flow through. Piezoelectric Piezoelectric effect: generating electric charge from mechanical stress. Direct effect: charge from deformation; converse effect: deformation from electric field. Asymmetrical crystal structures, like quartz, enable piezoelectric properties. Strain Gauge/Load Cell measure deformation by changing electrical resistance load cells convert force into an electrical signal using strain gauges they are commonly used in weighing systems, force measurement, structural health monitoring, testing and quality control, prosthetics, and rehabilitation equipment. Linear Variable Differential Transformer (LVDT) a type of electrical transformer used for measuring linear displacement (position) comprises a cylindrical coil assembly and a movable core The coil assembly includes a primary coil and two secondary coils symmetrically spaced. a type of electrical transformer used for measuring linear displacement (position) comprises a cylindrical coil assembly and a movable core The coil assembly includes a primary coil and two secondary coils symmetrically spaced. LVDT uses Industrial Automation: LVDTs are used in automation systems for precise control of machinery.  Aerospace: Utilized in aircraft systems for monitoring control surfaces and landing gear positions. Civil Engineering: Used in structures to measure deflections and deformations, ensuring safety and integrity. Medical Devices: Applied in medical imaging and diagnostic equipment for accurate positioning. Wind Speed Sensor measure the speed of wind. They play a vital role in weather monitoring, environmental studies, and various industrial applications. Anemometers (cup & propeller) use wind to spin, speed converted to electrical signal. Ultrasonic anemometers use sound waves to measure wind speed and direction. Hot-wire anemometers measure wind by how much it cools a heated wire. Water Flow Sensor Measures the rate of flow of liquids Uses mechanical and electronic subsystems to measure fluid Operation Water flows through a motor/turbine mechanism. Rotations generate a voltage proportional to the flow rate. Rain Sensor Used to notice water drops and rainfall Includes two parts: a sensor pad and sensor module Has two outputs: analog and digital  Operation The rain sensor’s sensing pad has copper traces acting as a variable resistor. Water on the pad changes its resistance inversely to the amount present. More water means better conductivity and lower resistance. Less water results in poorer conductivity and higher resistance. Barometric Pressure Sensor also known as pressure transducers measure the pressure exerted by the atmosphere They play a crucial role in various fields, including weather forecasting, navigation, and consumer electronics. Manometer measuring instrument used to determine the pressure of a fluid, such as air or water Consists of a tube connected to an indicator device that displays the pressure on a graduated scale precise monitoring and control of pressure to ensure proper and safe operation Manometer In environmental studies, manometers measure atmospheric pressure and other environmental gases, contributing to weather forecasting and environmental protection efforts. In scientific research and educational laboratories, manometers measure the pressure of gases in experiments. This helps in studying gas laws and understanding various physical phenomena. In aviation, manometers (altimeters) measure air pressure to determine altitude, which is critical for navigation and safety. Thermal Transducers It is a device that converts thermal energy into other physical quantities such as mechanical energy, pressure, electrical signals, and etc.  Resistance Temperature Detector (RTD) Temperature sensors that operate on the principle of resistance change with temperature. Capitalizes on the fact that the electrical resistance of a material changes as its temperature changes. Its principle is that the electrical resistance of a metal changes with temperature. RTDs are widely used in industrial settings to monitor and control the temperature of processes, ensuring optimal operating conditions and safety. RTDs help maintain the desired temperature within heating, ventilation, and air conditioning systems by providing accurate temperature readings. Thermistor Also called as Thermally Sensitive Resistors It is a second class resistance thermometer utilizing elements made of semi- conducting material. Thermistors are temperature sensors that exhibit a significant change in resistance with a change in temperature. Difference Between Thermistor and RTD A thermistor is better for lower temperatures whereas RTDs are more suitable for higher temperatures Thermistors are highly sensitive and nonlinear RTDs are relatively insensitive but very linear Thermistors are cheaper then RTDs Thermocouple the most commonly used type of all the temperature sensor types popular due to their simplicity, ease of use, and their speed of response to changes in temperature, due mainly to their small size have the widest temperature range of all the temperature sensors from below -200 degrees C to well over 2000 degrees C.  are thermoelectric sensors that consist of two junctions of dissimilar metals, such as copper and constantan that are welded or crimped together. One junction is kept at a constant temperature called the reference (Cold) junction, while the other is the measuring (Hot) junction. When the two junctions are at different temperatures, a voltage is developed across the junction which is used to measure the temperature sensor TEG/TEC (Thermoelectric Generator/Cooler) part of Thermoelectric modules. TEG is used for Heat generation to produce electricity mainly used for Power generation. TEC is used to Transfer Heat from one electronic device to another, mainly used for cooling and heating applications. TEG uses the Seebeck effect and TEC uses the Peltier effect. TEG generates electricity by using heat, When heat is applied through a thermoelectric module it generates a DC current and voltage. TEC can work as a cooler or heater depending on the orientation of the DC supply, it works by transferring heat from one side to another. LM35 - Temperature Sensor LM35 is a temperature measuring device having an analog output voltage proportional to the temperature. It provides output voltage in Centigrade (Celsius). It does not require any external calibration circuitry. The sensitivity of LM35 is 10 mV/degree Celsius. As temperature increases, output voltage also increases. e.g. 250 mV means 25°C. It is a 3-terminal sensor and small IC used to measure surrounding temperature ranging from -55 °C to 150 °C. LM35 gives temperature output which is more precise than thermistor output. Bimetallic Thermostat  component made up of two strips of different metals that expand at different rates when heated. This unique property allows bimetallic strips to be used in various applications, including thermostats. operates by using a bimetallic strip made of two different metals that bend unequally with temperature changes, either breaking or completing an electrical circuit to control heating or cooling systems based on the desired temperature. Infrared Thermometer the infrared thermometer transmits radiation through a lens system to an infrared detector, transforming the energy into an electrical signal. can utilize optical filters to monitor a limited number of wavelengths, but other devices can measure a wide range of wavelengths. measures both infrared radiation and surface emissivity It features a lens that directs infrared light through the thermometer and into a thermopile, or detector, where they are concentrated. When using an infrared thermometer, you must consider the distance-to-spot ratio. This ratio compares the size of the measured area to the distance between the thermometer and the sample. Relative Humidity and Temperature Sensor(HTU21P) HTU21P(F) is a digital humidity and temperature sensor for OEM (Original Equipment Manufacturer) applications. This sensor provides calibrated, linearized signals in analog pulse width modulated (PWM) format. PWM signal runs on a base frequency of 120Hz, the data signal is provided on the SDA line. Pulling SCL high or low allows for switching between humidity and temperature, respectively. Pyrometer Also known as a radiation thermometer, is a type of remote sensing thermometer used to measure the temperature of distant objects. It operates by detecting the thermal radiation emitted by the object being measured. commonly used in various industries to monitor and control high temperatures, such as those found in furnaces and industrial processes. measures surface object temperatures without making physical contact with the object  pyrometer is a type of infrared thermometer