SU1224684A1 - Moisture meter - Google Patents

Abstract

This invention relates to a non-destructive testing technique. The accuracy of the humidity measurement is increased. The device contains a modulating signal generator (HMS) 1, a low frequency generator 2, a high frequency generator 3, a capacitive sensor 4, a capacitor 5, a voltage follower 6, two amplitude detectors (BP) 7 and 16, two amplifiers 8 and 18, two synchronous detectors 9 and 19, indicator 10, two controlled attenuators 11 and 12, two rectifying diodes 13 and 14, integrator 15 and a logarithmic converter (LP) 17. Anti-phase voltages of the GMC 1 with a repetition frequency affect the control inputs of the LF generator 2 and the generator HF 3 operating in standby mode. When exposed to trigger pulses, the low-frequency generator 2 and the high-frequency generator 3 produce electric oscillation packets of the same amplitude, which pass through attenuators 11 and 12 and combine to create a voltage modulated by Q frequency. When the high-frequency sensor 4 is excited, it conducts The bridge is reduced due to the dispersion of the dielectric constant of the liquid phase and is mainly determined by the dry weight of nit. The voltages are further rectified by BP 16, then logarithmized, and the variable component of the voltage of the LP 17 is amplified by the amplifier 18. The indications of the indicator 10 do not depend on the instability of the elements of the device. 1 il. (LU N5 4 O5 CX) 4

Description

I

This invention relates to a non-destructive testing technique.

The purpose of the invention is to improve accuracy.

The drawing shows a structural electrical diagram of a moisture meter.

The moisture meter contains modulating signal generator 1, low and high frequency generators 2.3, capacitive sensor 4, voltage repeater capacitor 6, first amplitude detector 7, first amplifier 8, first synchronous detector 9, indicator 10, first and second controlled attenuators 11.12, the first and second rectifying diodes 13, 14, the integrator 15, the second amplitude detector 16, the logarithmic converter 17, the second amplifier 18, the second synchronous detector 19.

The moisture meter works in the following way.

Anti-phase voltages of the generator 1 with a repetition rate affect the control inputs of the generators 2 and 3 operating in the standby mode. When exposed to pulses, the generators 2 and 3 produce electric oscillation packets of the same amplitudes of low and high frequencies that pass through the controlled attenuator 11, and the high frequency oscillations through the controlled attenuator 12. At the output of the attenuator, the 11 and 12 oscillations are combined, creating a voltage modulated by the frequency jJi.

When sensor 4 is excited by high-frequency oscillations, its permeability decreases due to the dispersion of the dielectric constant of the liquid phase and is mainly determined by the dry matter mass hp. . The voltages are further rectified by the amplitude detector 16, then the logs 4) are scanned. The variable component of the voltage of the logarithmic converter 17 is amplified by the amplifier 18.

Indicator 10 indications are equal

about .K,

be + gps

 Koh

224684

Where

IS

five,

at 35 20

thirty

40

45

To

50

 B w

the resulting device conversion factor; moisture mass

- moisture content of the material

ib -mc

From this it follows that the instrument readings do not depend on the instability of low and high frequency generators, controlled attenuators, and

Dr.

Claims (1)

Invention Formula A moisture meter containing a modulating signal generator, low and high frequency generators and a series-connected capacitive sensor and a capacitor, the voltage repeater, the first amplitude detector, the first amplifier and the first 25 synchronous detector, as well as an indicator that By the fact that, in order to improve the accuracy, the first and second controlled attenuators, respectively, connected between the outputs of the generators and high the first and second rectifying diodes, the integrator and the second amplitude detector connected in series, a logarithmic converter, the second amplifier and the second synchronous detector, and the input of the second amplitude detector, are connected to the outputs of the first and second attenuators, the output of the second synchronous detector. connected to the indicator; the integrator's input is connected to the output of the first synchronous detector; its output is connected to the control inputs of the first and second controlled attenuators through counter-switched rectifier diodes and the low frequency generator and the high frequency generator control inputs are connected to the antiphase outputs of the modulating generator signals and, respectively, with the first and second control inputs of the first and second synchronous detectors. Editor I. Casarda Compiled by R. Kuznetsova Tehred V. Kadar Proofreader M. Demchik Order 1943/42 Circulation 778 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4