SU447607A1 - Device for measuring impedance diagrams of magnetostrictive transducers - Google Patents

Description

one

The invention relates to electroacoustics and can be brought in to measure the characteristics of electroacoustic transducers of the gynetostriction type according to the impedance diagram.

Devices are known for measuring impedance diagrams of electroacoustic transducers in a mode of varying the excitation frequency, comprising a linear voltage generator, a oscillating frequency generator, a measuring circuit including an electroacoustic converter, phase-sensitive detectors, and an indicator.

however, when measuring transducers, especially of low Q, using a known device, the dynamic impedance circle of the transducer is distorted into a loop-shaped curve, which reduces the accuracy of measurements of impedance diagrams.

Distortion circumference of dynamic impedance and single-turn magnetostrictive transducers

(L is due to the fact that the impedance of the clamped transducer undergoes significant changes in the narrow frequency band

 (a) is of an inductive nature and, therefore, variable in proportion to the frequency. Impedance) is included as an addend in the expression for the total impedance 2 nkf) H2, (0 (}. Known device

does not divide H.n. (f) n iq (f},

5 which leads to large errors with strong changes of -A (f)

Jh

In the case of measurements in a wide band.

The purpose of the invention is to increase

0 measurement accuracy impedance diagrams of converters of small q.

For this, the proposed device contains a subtractive device (BP, one input of which is connected to

the output of the phase-sensitive detector, which forms a voltage proportional to the reactive component of the input impedance of the converter, the other is connected to a linearly changing voltage generator, and the output is connected to one of the indicator inputs.

The drawing shows a block diagram of the proposed device.

The device contains a linearly varying generator 1, a oscillating frequency generator 2, a measuring circuit 3, a phase-sensitive detector, generating a voltage proportional to the active component of the input impedance, a subtractor B, a phase-sensitive detector 5, generating voltage, proportional reactive component of the input impedance of the two-coordinate indicator.

The device works as follows.

The linearly varying voltage from generator 1 as a modulating one is fed to oscillator frequency generator 2. In the generator 2, two orthogonal voltages of the oscillating frequencies are formed, which are fed to the inputs of the phase-sensitive detectors 4 and 5 as reference ones. In addition, one of the orthogonal voltages is fed to the measuring circuit 3, the output of which relieves a voltage proportional to the input impedance of the Znf converter that goes to the other inputs of the detectors 4 and 5. The voltage is proportional to the active component of the full input impedance

the converter, from the output of the detector 4, is fed directly to one of the inputs of the two-coordinate indicator 7, and the voltage proportional to the reactive component of the input impedance, from the output of the detector 5 to one of the inputs of the subtractor b, to the other input of which linearly variable voltage generator 1, the amplitude of which can be adjusted. As a result of subtracting from the output of the subtracting device, a voltage proportional to the reactive component of the dynamic impedance of the tested converter is applied to the corresponding input of the indicator 7.

THE INVENTION A device for measuring the impedance diagrams of magnetostrictive transducers in the mode of continuous variation of the excitation frequency, comprising a generator of a linearly varying voltage,

a oscillating frequency generator, a measuring circuit including a magnet, an axis-of-rotation converter, phase-sensitive detectors and an indicator, characterized in that, in order to improve the measurement accuracy of impedance diagrams of low-Q converters, it contains a subtractive device (an input whose one input is connected to the output of the phase-sensitive detector forming the voltage is proportional to the reactive component of the input impedance of the converter, the other one is connected to the generator of linearly live voltage, and stroke associated with zhODNim inputs of an indicator.