SU938116A1 - Non-magnetic media electroconductivity meter of self-excited generator type - Google Patents

Description

AUTOGENERATSM METER

(54) ELECTRICAL CONDUCTIVITY OF NONMAGNETIC MEDIA

The invention relates to a measuring technique and can be used for measuring the conductivity of non-magnetic media by non-destructive methods. A self-oscillating device is known that contains a dual-circuit measuring {N1-specific auto-oscillator with a frequency-assigning circuit with a stabilized piezoresonator and a parametric sensor in an external circuit, as well as an amplitude detector with an emitter follower at the input, an initial level compensation compensator, and a recording device. When monitoring the conductance of magnetic media, the amplitude signal removed from the internal circuit of the autogenerator is determined mainly by the magnitude of the reactance introduced into the eddy current sensor and does not depend much on the input active resistivity. With a large enough bore hole in the loop, the system has a high sensitivity Ul. The disadvantage of the device is the presence of an error associated with the effect of the change between the sensor and the sample on the instrument signal. The closest to the invention in technical superstore is a suspension bus; not | atomic 13M1A1 The unit is divided into reincarnation procedure 2. The disadvantage of the known vzmervtel is the high accuracy of the measurement, after which it is active. The aim of the invention is to improve measurement accuracy. The aim is to ensure that the autogenerator conductivity meter of non-magnetic media is equipped with two connected drains by field-effect transistors with opposite types of conductivities, connected by sources parallel to the inductance of the internal circuit of the autogenerator with opposite conductivities, connected to the inductance of the internal circuit of the auto-generator with the opposite conductivity types connected to the source of the dual-circuit auto-generator with the same conductivity type, and I had to use a 0-g; varicap parallel connected to the same inductance, with the point the varicap connection and the capacitor, and the gate of one field-effect transistor are connected through corresponding resistors and with the emitter of the single-circuit auto-oscillator transistor, and the gate of the second field-effect transistor is connected via a resistor to the output of the amplitude detector of the two-circuit autogenerator. The circuit diagram of the self-generator of the electrical conductivity of the non-magnet generator, is shown in the drawing. An auto-oscillator meter contains bipolar transistors 1 and 2, a system of two coupled circuits, consisting of capacitors 3-5, inductor 6 and eddy current transducer 7, two field-effect transistors 8 and 9 with opposite types of conductivities, varicap 1O, capacitor 11 , resistors 12–20, a quartz resonator 21, capacitors 22–26, two amplitude detectors 27 and 28, a dividing unit 29, and an AOR recording device. The dual-circuit auto-oscillator is performed on a transistor 1 with a quartz resonator 21 between the collector and the emitter of transistor 1. The internal circuit of this auto-generator, connected between the collector of transistor 1 and the positive terminal of the power source, contains a capacitor 3 and inductance 6. Through the capacitor 4 of the dual-circuit auto-oscillator through a capacitor 4 An external circuit, consisting of a capacitor 5 and an eddy current transducer 7, is connected to a capacitor divider, consisting of 5 capacitors 22 and 23, connected to an external circuit, as collector of the transistor 2 whose emitter is connected to the media at its capacitive divider. The emitter circuits of transistors 1 and 2 include the reshalers of the autoscene 17 and 18, respectively. Resistors 15 and 16, 19 and 2 form voltage dividers to apply a positive bias to the bases of transistors 1 and 2. Capacitors 24 26 are shunted by alternating current, resistors 17, 16, 19, respectively. Amplitude detector is connected to the internal loop of a double-circuit auto-oscillator with a quartz frequency stabilization. 27, the output of which is connected to the first input of the dividing unit 29. An amplitude detector 28 is connected to an external circuit, the output of which is connected to the second input of dividing unit 29. The output of dividing unit 29 is connected to registering device 30. Parallel to inductance 6, field-effect transistors 8 and 9 and series-connected capacitor 11 and varicap 10, connected to the emitter of transistor 2 of a single-circuit auto-generator, are connected by sources. The gate of the field-effect transistor 8 through a resistor 12 is connected to the output of the amplitude detector of a double-circuit self-oscillator. The gate of the field-effect transistor 9 through the resistor 13 is connected by the emitter of the transistor 2 of the single-circuit oscillator. Self-generator meter works as follows. When a non-magnetic medium is introduced into the field of the eddy-current transducer 7, its active and reactive resistances change, and the active resistance increases by an amount), and the reactive one decreases by an amount n. : / de, (ffJM 4gj (a) - resistance introduced into the external loop of the dual-circuit auto-generator; G - medium electrical conductivity. Increase of the active resistance of the external loop by Hz,) d (0) Increases the active and reactive resistances of the internal loop by G (ff ) and Hrl (G), respectively, and reducing the reactance of the external circuit by an amount ((5) leads to an increase in the active and reactive resistances of the internal loop by values) and, 1 (0 Amplitude signal of a single-circuit oscillator at bearing the field current sensor vortex conductive medium substantially determined by the amount Grna

The amplitude detector 27 of the dual-circuit auto-oscillator detects the signal, which is determined by the magnitude X (T.) The values of the impediments Hv1tO), vs-) C (5) ((G), which are interferences, compensate for by means of in the circuit of varicap 10 and field-effect transistors 8 and 9, which perform the functions of adjustable resistances, as follows.

When the Q-factor of the external circuit of the double-circuit auto-oscillator decreases, the voltage drop across the resistor 18 in the emitter circuit of transistor 2 decreases, hence the bias voltage on the varicap 1O increases, which leads to a decrease in the capacitance of the varicap connected in parallel with the internal circuit.

This increases the intrinsic frequency of the internal circuit, thereby compensating for the increment of reactance ((D), which is inductive in nature.

The increments of active resistances introduced) and Hz (b) are compensated by reducing the shunt effect on the internal resistance circuit of the drafts of field-effect transistors 8 and 9,

The characteristic of the pale-yellow transistor 8 is such that as the voltage across the gate increases, the source-drain resistance increases. The characteristic of the field-effect transistor 9 is inverse to the characteristic of the field-effect transistor 8. Thus, reducing the voltage drop across the resistor 18 leads to an increase in the source-drain resistance of the transistor 9, and, accordingly, to compensation V-5m ((;;).

Useful signal. (SG) is changed in accordance with the value, (((h) h which also causes the appearance of the interference hg ((J). This is used to compensate for the value ((3) by applying to the gate of the field-effect transistor 8 a voltage depending on L BUL with the output of the amplitude detector 27.

The degree of compensation of the values of X ((v BHtt P Py selection of resistors 14, 13 and 12, respectively.

After amplitude detectors 2.7 k28, analog signals proportional to bНДО and VKM are supplied to dividing unit 29

The voltage of which, the nponoiational ratio “(&) / J Q lno, goes to the recording device of the AOR. Taking into account that the withdrawal lines of eddy current transducers are close to direct when the gap between the sensor and the sample is changed, the value of bdCr (U –GEN.Sh) / Hetz (0). changes insignificantly.

An autogenerating conductivity meter for nonmagnetic media makes it possible to increase the measurement accuracy due to the introduction of adjustable resistance into its circuit.

Claims (2)

1. Authors svpetelsgvo USSR № 497537, cl. QO1N ЗЗ / ОО, 1973. 2. USSR author's certificate for application number 2727855 / 18-28, cl. GO1N 27 / O2, 1979 (prototype). guv