SU822100A1 - Digital magnetic susceptibility meter - Google Patents

Description

The invention relates to devices for measuring magnetic quantities, and in particular to devices for measuring the magnetic susceptibility of rock samples in geophysical studies.

A known device for measuring magnetic susceptibility, containing series-connected generators. jq torus with inductor, time selector, digital counter, generator and frequency counter. This device uses the frequency method for determining tC by measuring the frequency (period) of a generator containing 15 LC circuits. A sample is placed in the inductor L. The frequency of the circuit (period) is measured when there is no sample in the coil \ 1d and if there is V ^. The quantity d 'is then calculated by the formula

- - 3.4

_4/0 2JTX 'wherein K - fill factor;

vj is the frequency of the circuit after removing the sample from the inductor with an additional measurement.

his

Frequencies V _o and Carried out the periods corresponding to them) are measured using a frequency meter G1].

The disadvantage of this device is the measurement error associated with the departure of the frequency V _o for the time interval between the measurements of Vo and V ₇ , and, in addition, the need to record the readings of the frequency meter after each measurement of the frequency (period) and then perform calculations by the formula.

The purpose of the invention is' improving the accuracy of measuring magnetic susceptibility.

This goal is achieved by the fact that in a digital magnetic susceptibility meter containing an LC generator with an inductive element, a time selector, a digital counter and an indicator connected in series, as well as a control unit connected to the control input of the temporary selector, a frequency multiplier and a signal conditioner are introduced, connected to the control unit associated with the control input of the digital counter, and a frequency multiplier is connected between the output of the LC generator and the input of the temporary selector.

In FIG. 1 is a block diagram of a digital magnetic susceptibility meter; in FIG. 2 - one of the design options of the signal conditioner.

The device consists of a series-connected LC-generator 1, the inductive element 2 of which has a volume of 3 for placing the test sample 4, a frequency multiplier 5, (temporary selector 6, digital counter 7 and indicator 8. Shaper 9 of the presence (absence) signal of the test sample 4 · β volume 3 of the inductive element 2 is connected to the input of the control unit 10. The control unit 10 is connected to the control inputs of the temporary selector 6 and the digital counter 7. Shaper 9 signal presence (absence) of the test sample 4 in the amount of 3 in productive element 2 consists (Fig. 2) of the holder 11, which contains the sample 4. The holder 11 has a rod 12 with a lamella 13. The guide 14 has contacts 15-18. Contacts 15 and 17 are connected to the terminal of the power source. connected to the anode of the thyristor 19, pin 18 is connected through a resistor 20 to the control electrode of the thyristor 19, the cathode of which is connected to a common bus through the resistor 21. The connection point of the cathode of the thyristor 19 with the resistor 21 is the output of the former 9.

The device operates as follows.

Initial state of the digital magnetic susceptibility meter! an alternating signal U is supplied from the output of the generator 1 to the input of the frequency multiplier 5. An alternating signal of frequency nV is supplied to the input of the temporary selector 6, where η. is the frequency multiplier. The rod 12 is extended from the guide 14, and the contacts 15-18 are open. The thyristor 19 is locked, from the output of the shaper 9 of the signal of the presence (absence) of the sample in volume 3, a zero signal is supplied to the input of the control unit 10. The temporary selector 6 is closed. The test sample 4 is in the holder 11.

Let at the initial moment of time t and the frequency of the generator U _o . When the Start button is pressed at this point in time, the control unit generates a pulse of duration> which is fed to the input of selector 6. Selector 6 is unlocked and a signal of frequency nV _{0 is} supplied to counter 7. An alternating signal pulses of frequency nVp are counted over time. After 1 ¾, the selector 6 is locked, the counter 7 remembers the number Нр = _о о пУа. Then, at time t ₄ , the test sample 4 is placed in the volume 3, the rod 12 enters the guide 14, and the lamella 13 sequentially closes the contacts 15-18. The thyristor 19 is unlocked at the moment when the test sample 4 is in the volume 3 of the inductive element completely (lamella 13 closes contacts 15-18). The distance between the contacts 15-18 and the length of the lamella 13 are selected accordingly. In this case, from the output of the shaper 9 to the input of the control unit 10 receives a voltage signal +. The control unit 10 generates two single signals: the first - a pulse of duration arrives at the control input of the selector 6, unlocking it for this time, the second - the signal goes to the control input of the counter 7, ensuring the automatic transition of the counter to the reverse counting mode. (subtraction). During the time 2 ^ occurs subtraction from the number N _o of n \ / _o. After 2¾, the selector 6 is locked, the counter 7 stores the number N ₂ = N ₀ -N ₄ = 't _p n (V ₀ -2V ₄ ).

When removing the sample 4 from the volume 3 at the time point, the rod 12 leaves the guide 14, the lamella 13 in this case sequentially opens the contacts 15-18. When the contacts 17 and 18 are opened, the thyristor 19 does not lock, because the resistor 21 is selected so that a current flows through the thyristor 19, more than the holding current. The thyristor 19 is locked only when the voltage + is removed from its anode + when the contacts 15 and 16 are opened, which corresponds to the removal of the entire sample 4 from the volume 3. At the same time, from the output of the shaper 9, a zero signal is supplied to the input of the control unit 10, and the control unit 10 generates two of a single signal :, the first is a pulse of duration arriving at the input of the selector 6, unlocks it for this time, the second is the signal arriving at the control input of the counter Ί and ensures the counter automatically switches to direct counting mode (tracking). Over time Ίο, the numbers Ν ₂ and N3 = ^ 0 n \ $ are added. After a while, the selector 6 is locked, and the counter 7 remembers the number Ν ₄ = Ν ₀ -Ν ^ + + · Ν · 3 = τρη (ν ₀ -2ν ₀ + v £), i.e. a value proportional to the # value of the test sample 4. The number N _{4 is} displayed on the indicator board 8. By pressing the Reset button, the circuit returns to its original state.

Claims (1)

1. Sat. Geophysical equipment, Nedra, 1973, no. 51, p. 23-26.