Magnetic transducer

K. Larsson, K. Kriz and D. Kriz, Magnetic transducers in biosensors and bioassays, Analusis, 27 (1999) 617-621. 

Coriolis flow meter Hot-wire anemometer Thermal mass flow meter Piezo-electric element Magnetic transducer... 

Application of magnetic fluids in ultrasonic non-destructive testing [1-3] opens the real perspectives for automation of the testing methods, based on the surface waves. This report presents the results of investigations aimed at the creation of the transducer of the surface waves for the automated control. The basic attention is drawn to the analysis of the position of the front meniscus of the contact liquid when the surface waves excite through the slot gap. 

The calculation on the base of solution (2) and experimental investigations have allowed to choose some constructions of magnetic systems for retaining of a magnetic fluid on the transducer surface for magnetic and non-magnetic materials. 

Double-magnet systems are the most convenient ones for transducers on non-magnet materials. In this case magnetic moments are the normal ones to a surface of the pattern and the opposite ones to the each other. The magnetic field fills the whole zone of the acoustic contact in such positions of... 

Figure 8-5 shows the main circuit diagram of a potential control rectifier provided with magnetic amplifiers (transducers). The chosen potential is set at the nominal value with a potentiometer. The actual potential is compared with this value, which corresponds to the voltage between a reference electrode and the protected object. 

Since acceleration is the second derivative of displacement, a piezoelectric accelerometer sensor with an integrator becomes a velocity transducer. This arrangement is gradually superseding the self-generating mo ing-coil velocity sensor (where a coil of wire moves relative to a magnetic field). 

A typical excitation system includes a voltage regulator, or exciter, protection circuits, and measurements transducers. If the terminal voltage decreases below rated value, the conU ol system increases the rotor cuiTent and thus the magnetic field as shown in Faraday s law, the generated voltage is thus forced up to the desired value. 

For general-purpose use below 1000 Hz, a transducer can be attached to a machine by a magnetic base. Even though the resonant frequency of the transducer/magnet assembly may distort the data, this technique can be used with some success. However, since the magnet can be placed anywhere on the machine, it is difficult to guarantee that the exact location and orientation is maintained with each measurement. Shows common magnetic mounts for transducers. 

When the development of a scientific field expands, the need for handbooks arises, wherein the information that appeared earlier in journals and conference proceedings is systematically and selectively presented. The sensor and actuator Held is now in this position. For this reason, Elsevier Science took the initiative to develop a series of handbooks with the name "Handbook of Sensors and Actuators" which will contain the most meaningful background material that is important for the sensor and actuator field. Titles like Fundamentals of Transducers, Thick Film Sensors, Magnetic Sensors, Micromachining, Piezoelectric Crystal Sensors, Robot Sensors and Intelligent Sensors will be part of this series. 

Even if nowadays, the MCT may be considered a primary thermometer only on a narrow temperature range, it is considered the best dissemination standard in the millikelvin range [56-59], In fact, the 3He melting pressure is a good thermometric property because of its sensitivity over three decades of temperature with a resolution A T/T up to 10 5 [56], The good repeatability, the insensitivity to magnetic fields up to 0.5 T [60] and the presence of temperature-fixed points allow for the control of possible shifts in the calibration curve of the pressure transducer. The usefulness of these fixed points is evident, considering that the ITS-90 is based just on the definition of fixed points. 

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