Data Acquisition System is a group of various devices that are combined in an orderly fashion to perform necessary operations on relevant data. Usually a data acquisition system is an assembly of sensors/transducers, signal conditioners, data conversion, data handling, data processing units, multiplexing circuits, data transmission, data storage and data display systems.
Measurements & Instrumentation
What is Thermal Imaging (or Thermography)? Working Principle, Block Diagram & Applications
Thermal imaging or thermography is a technique of scanning the infrared radiation emitted from an object. The collected information is processed and a graphical output showing the temperature distribution across the object is provided. It is possible to measure temperature which lies between – 20° C to +1500° C. The elements of the thermal imaging system are shown in figure 1.
What is Laser Doppler Anemometer? Working Principle, Construction, Diagram & Applications
Working Principle of Laser Doppler Anemometer
Laser Doppler Anemometer or Laser Doppler velocimetry (LDV), works on the principle of Doppler effect. It states that whenever a laser beam passes through the moving fluid, frequency shift takes place in the light scattered by the small particles present in that fluid. This shift in the frequency of the beam is directly proportional to the velocity of the fluid flow.
What is Turbine Flow Meter? Working Principle, Construction, Diagram & Applications
Figure 1: Turbine Flow Meter.
Working Principle of Turbine Flow Meter
The permanent magnet attached to the body of rotor is polarized at 90° to the axis of rotation. When the rotor rotates due to the velocity of the fluid (V) the permanent magnet also rotates along with the rotor. Therefore a rotating magnetic field will be generated. which is then cut by the pick-up coil. Due to this A.C. voltage pulses are generated whose frequency is directly proportional to the flow rate.
Measuring range: Accurate flow measurement overa wide flow range = 0.1 to 50,000 gallons/mm. Sizes = 6.35 mm to 60 mm.
What is Hall Effect Transducer? Working Principle, Diagram & Applications
Hall Effect Transducer works on the principle that whenever a thin plate of conducting material carries current in presence of transverse magnetic field, an e.m.f is produced between the opposite edges of the thin plate conductor which is given by,
What is Magnetic Recorder? Working & Diagram
Magnetic recorders are the type of analog recorders in which the data is recorded on a thin magnetic tape or wire. A magnetic recorder records the signals of high frequency and reproduces the recorded data in electrical form. The data that is recorded through magnetic recorder can be replayed or reproduced any number of times whenever required.
What is Photoconductive Cell? Working, Symbol, Characteristics & Applications
In certain semiconductor materials, when light falls on them, their electrical resistance varies. If constant voltage is applied to such conductor, the current varies as the amount of light falling on it varies (because resistance varies). These semiconductors are known as photoconductive cells or photoresistor or light dependent resistors (LDRs).
What is Moving Coil Microphone? Working, Diagram, & Applications
Moving Coil Microphone works on Faraday’s law of electromagnetic induction, which states that, “when a conductor moves in a magnetic field, it cuts the flux line and an emf is generated.” Therefore, Electro-dynamic microphones are also called as Electro-magnetic microphones.
Fig. 1: Moving Coil Microphone
What is Carbon Microphone? Working, Diagram, & Applications
Carbon microphone consists of a thin moving diaphragm, used as primary (first) transducer, which senses the sound pressure waves and convert them into displacement of diaphragm. Moving diaphragm is connected to a capsule having flexible bellows to allow compression or expansion. A capsule containing granules of carbon acts as a secondary transducer in this microphone. The device is externally powered by a constant voltage source (battery). Therefore, carbon microphone is not a self-generating type instrument, like Electro-dynamic microphone (Fig. 1).
Fig. 1: Carbon Microphone.
What is Hair Hygrometer? Working, Diagram, & Applications
Hair hygrometer is a type of absorption hygrometer, which works on the principle that, “change in moisture content causes change in physical and chemical properties of certain materials”, such as, human hair, animal membrane, wood, paper etc. As human hairs are used in this hygrometer, this type is called as hair hygrometer.