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These transducers are most frequently used for calculating different physical quantities like pressure, vibration, temperature, force, and displacement. • They can be used for measuring various physical quantities like temperature, pressure, displacement, force, vibrations etc. Thus, the output signal of the pulse width counter will be a digital output that is proportional to a change in the sensed physical parameter. In other words, the phase angle could be some angle other than 90°, as desired. A transducer (23) for producing a digital output signal proportional to a change in a sensed physical parameter includes first and second pairs of series-connected resistors (24, 25 or 26, 28). In another aspect, the invention provides an improved method of producing a digital output signal proportional to a change in a sensed physical parameter, which method comprising the steps of: providing a first pair of series-connected resistors; providing a second pair of series-connected resistors; arranging the resistors such that the electrical resistance of at least one of the resistors is variable in response to a change in the sensed parameter; applying a first exciting alternating voltage at a particular frequency across the first pair; applying a second exciting alternating voltage at the same frequency across the second pair; the first and second exciting voltages having identical waveforms (i.e., as to general waveshape and frequency), but being shifted relative to one another by a constant phase angle (φ); vector-summing the voltage existing at a point between the resistors of the first pair with the voltage existing a point between the resistors of the second pair to provide a vector-summed output signal; and counting the time difference between the occurrence of a distinguishing event (e.g., a zero crossing) of the vector-summed signal and the occurrence of a like distinguishing event of the exciting voltage referred to; thereby to provide a digital output signal proportional to the change in the sensed physical parameter. DPS300 User Switchable Pressure Range, Volts or Current Output Low DP Sensor From a structure point-of-view, this appears to be, in large part, a conventional LVDT, albeit operated in a reverse manner. a counter operatively arranged to count the time difference between the occurrence of a distinguishing waveform event of said vector-summed signal and the occurrence of a like distinguishing waveform event of the exciting voltage referred to; whereby said time difference count will be a digital output signal proportional to the change in said sensed physical parameter. More particularly, two separate exciting signals, of identical waveform but shifted 90° from one another, are supplied to two separate coils. The currents induced in the driven coils are reflective of the relative position of the core member, and the output signals of the driven coils are analog values of the driving signal. A possible approach, utilizing well known prior art, would typically be to start with the conventional d.c. signal output of a strain-gage bridge excited from a d.c. source, and to generate a pulse-width modulated waveform in the conventional way by summing the bridge output signal with a reference triangular wave to shift its zero crossing time. The circuit o/p can be directly adjusted against the input value. Your email address will not be published. It is a passive transducer that means it requires external power for operation. of the vector-summed signal and the occurrence of a like distinguishing event of the exciting voltage referred to; whereby the count of the time difference will be a digital output signal proportional to the change in the sensed physical parameter. Summing point 18 also receives a triangular wave from triangular reference generator 19. 2 wire 4-20mA or 3 wire 0-20mA: 1. 14. The resistive transducer element works on the principle that the resistance of the element is directly proportional to the length of the conductor and inversely proportional to the area of the conductor. Accordingly, the general object of this invention is to provide an improved transducer for indicating a change in a sensed physical parameter. 16. 10. The process of variation in resistance is widely used in the industrial applications. 7. There has recently been developed an "inverted" LVDT, dubbed a linear variable phase transducer ("LVPT"). For example, the first and second excitation means are shown as being sine wave generators. This output time count is inherently a digital value. DPS Low Differential Pressure Transmitter 4. of the vector-summed signal with the occurrence of a like distinguishing event of the exciting voltage being counted to produce a digital output signal. These transducers work in both primary as well as secondary. The phase comparator is arranged to sense and determine the phase of the vector-sum signal with respect to the reference waveform. That physical parameter may possibly be strain, and one or more of the resistances may be in the form of electrical strain gauges. MOOG INC., NEW YORK, Free format text: Pressure transducers with a transmitter current output signal e.g. 4. In the preferred embodiment, that phase angle is 90°. If any system component produces an analog output signal, this signal must first be converted to its digital equivalent, before it may be integrated in the control scheme. The capacitive transducer consists of two parallel metal plates that are separated by the dielectric material such as air. Owner name: (e.g. The slider moves horizontally. We are familiar with the equation of capacitor which is given as In a normal capacitor, the distance between the two plates is fixed, but … Sine wave generators 31 and 32 are operatively arranged to generate identical alternating waveforms (i.e., either sine waves, cosine waves, triangular waves, sawtooth waves or any other alternating waveform having a repetitive zero crossing) of like function and frequency. The sliding contacts are placed on the resistive element. MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE, Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. For example photovoltaic cell in which light energy is converted into electrical energy. Resistive sensors are among the most common in instrumentation. This transducer is shown as having four independently-variable electrical resistances 11, 12, 13, 14, respectively, operatively arranged in a bridge. A strain gauge measures the external force (pressure) applied to a fine wire. Capacitive Transducer. A resistive transducer is mainly used in the calculation of temperature, displacement, pressure, force. The measurement of the physical quantity is quite difficult. The summing point output will provide a vector-summed output signal, as shown by the associated waveform diagram, which illustrates the resultant vector sum 34 of two equal signals, and a similar resultant 34' for unequal inputs, and the associated phase angles φ and φ'. Transducer - MCQs with answers Q1. While analog strain gage transducers have been widely applied for many years, it is believed that no one has recognized the desirability of providing a simple output-signal analog-to-digital conversion, accomplished in much the same way that a variable-phase transducer can be digitized. Other types of devices include variable-phase output signal devices, such as resolvers. These offer the attractive possibility of providing a direct digital output signal by counting the time delay represented by the relative phase shift. together with the specification, and are to be considered a portion of the entire written description of this invention. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). LVITs, Linear Variable Inductive Transd­ucers, which have been around for more than 30 years, are relatively low cost, contac­tless position sensing devices that utilize eddy currents developed by an inductor in the surface of a conductive movable element that is mechan­ically coupled to the moving object whose position is being measured. However, this is not invariable. When combined with basic electronic circuitry, the sensor detects the change in presence or proximity of ferrous objects. These transducers are usually used as the secondary transducers, where the output from the primary mechanical transducer acts as the input for the variable resistance transducer. Accordingly, it would generally be desirable to provide an accurate transducer that is sensitive to a physical parameter, and that directly produces a digital output. Q7. Figure 1 By using one of the fixed connections and the sliding connection a resistive element may be made whose effectively length varies with the position of the slider, but whose resistivity and cross-section area remain constant. 9.  It is also known as Linear Variable Differential Transducer. A second excitation means, such a second sine wave generator 32, is operatively arranged to apply a second alternating exciting voltage at the same frequency across the second pair of resistors 26, 28. ρ – the resistivity of the conductor in materials in ohm meter. The resistive transducers are also known as resistive sensors or variable resistance transducers. While analog strain gauges have been widely applied for many years, the reliability and performance of semiconductor strain gauges has now increased to the point where they may now be used for many critical sensing applications. FIG. Save my name, email, and website in this browser for the next time I comment. A – cross-section area of the conductor in meter square. 4,134,065, 4,297,698 and 4,282,485. The voltages between the resistors of each pair are vector-summed. With parenthetical reference to the corresponding parts, portions or surfaces of the disclosed embodiment, merely for purposes of illustration and not by way of limitation, the inventive transducer (23) is adapted to produce a digital output signal proportional to a change in a sensed physical parameter. A method as set forth in claim 10 and further comprising the additional step of comparing the phase angle of the vector-summed output signal with the phase angle of either exciting voltage and for producing a pulse-width-modulated square-wave output signal at the excitation frequency. A method as set forth in claim 10 wherein said waveform is a sine wave. This does not occur in all circumstances. to understand the working principle, consider a conductor rod. A transducer as set forth in claim 1 wherein the amplitudes of said exciting voltages are the same. The present invention relates generally to the field of transducers, and, more particularly, to an improved transducer that is arranged to produce a digital output signal in response to a change in a sensed physical parameter, and to an improved method of operating such a transducer. Alibaba.com offers 1,104 variable resistive load bank products. When the mechanical element whose displacement is to be calculated is moved, then it will change the flux path’s permeance which is generated from the circuit. The primary transducer changes the physical quantities into a mechanical signal, and secondary transducer directly transforms it into an electrical signal. Unless otherwise indicated, the terms "inwardly" and "outwardly" refer to the orientation of a surface relative to its axis of elongation, or axis or rotation, as appropriate. Alternatively, they may be modulated as a function of the time difference associated with some other distinguishing events. •The variable resistance transducers are also called as resistive transducers or resistive sensors. 2 is a block diagram of an improved variable-phase resistive transducer, generally indicated at 23. The change in resistance is measured by the ac or dc measuring devices. Resistive Type of Sensors - Their Analysis and Applications Debasmit Das 10115039 Batch : E3 2. simply refer to the orientation of the illustrated structure as the particular drawing figure faces the reader. The linear variable differential transformer (LVDT) (also called linear variable displacement transformer, linear variable displacement transducer, or simply differential transformer) is a type of electrical transformer used for measuring linear displacement (position). The resistive transducer can work both as the primary as well as the secondary transducer. A first excitation means, such as a sine wave generator 31 is operatively arranged to apply a first alternating exciting voltage at a particular frequency across the first pair of resistors 24, 25. This EzEd Video explains Resistive Transducers The circuit Consists of Slider to give Zero output and Full output. The electrical resistance of at least one of these resistors is variable in response to a change in the sensed parameter. Figure 1 illustrates a simple strain gauge. 6. The improved transducer broadly includes: a first pair of series-connected resistors (24, 25); a second pair of series-connected resistors (26, 28), the electrical resistance of at least one of the resistors being variable in response to a change in the sensed parameter; first excitation means (31) for applying a first exciting alternating voltage at a particular frequency across the first pair; second excitation means (32) for applying a second exciting alternating voltage at the same frequency across the second pair; the first and second exciting voltages having identical waveforms (i.e., as to general waveshape and frequency), but being shifted relative to one another by a constant phase angle (φ); summing means (33) for vector-summing the voltage existing at a point between the resistors of the first pair with the voltage existing at a point between the resistors of the second pair to provide a vector-summed output signal; and a counter (36) operatively arranged to count the time difference between the occurrence of a distinguishing event (e.g., the point at which the waveform reaches or crosses zero, etc.) Circuitry, the drawing indicates that All four resistances are variable voltage between resistors 13, is... 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