CN106841736B - Automatic resonant capacitor matcher suitable for three-dimensional magnetic characteristic measurement system - Google Patents

Abstract

The invention relates to an automatic resonant capacitor matcher suitable for a three-dimensional magnetic characteristic measurement system. The automatic resonant capacitance matcher comprises three capacitance matchers and a singlechip control unit; the capacitance matcher comprises n basic units connected in parallel, wherein each basic unit comprises a capacitance, an electronic switch and two single-pole double-throw switches; the electronic switch is connected with the capacitor in series, the other end of the electronic switch is connected with the fixed point of the first single-pole double-throw switch, and the other end of the capacitor is connected with the fixed point of the second single-pole double-throw switch; each single pole double throw switch has two movable contacts. The invention designs a circuit connection method capable of automatically realizing series-parallel connection of capacitors, which can flexibly control the series-parallel connection of the capacitors without human intervention.

Description

Automatic resonant capacitor matcher suitable for three-dimensional magnetic characteristic measurement system

Technical field:

the invention relates to magnetic property testing equipment of a soft magnetic material, which is suitable for automatic matching of resonance capacitors of a three-dimensional magnetic property flexible excitation system, can realize accurate calculation and matching of the resonance capacitors under different excitation conditions, and simplifies manual calculation and operation flow.

The background technology is as follows:

the three-dimensional magnetic characteristic system of the soft magnetic material can comprehensively measure magnetic characteristics such as hysteresis and loss of the material. The three-dimensional magnetic characteristic test system mainly comprises a main measuring device with three orthogonal axes, a high-performance power amplifier, a multi-channel differential amplifying circuit, a digital signal processing unit and the like. The main magnetic circuit of the three-dimensional tester consists of a space orthogonal magnetic pole and a magnetic yoke, and is an important component of an excitation system. The exciting part mainly amplifies the exciting signal by means of a power amplifier, generates exciting current on an exciting coil and generates a magnetic field to finish magnetic characteristic measurement. Because the excitation signal is an alternating signal, the impedance of the excitation coil is increased along with the increase of the experimental excitation frequency, so that excitation is difficult, the power efficiency can be reduced only by means of power amplification excitation, and the power factor is small. In order to compensate reactive current of the exciting coil, resonant matching capacitors with different specifications are arranged.

When the existing test system is used for measuring specific frequency, a system power supply is required to be turned off, corresponding matching resonance capacitance is calculated according to coil inductance and exciting frequency, and then corresponding capacitance is selected through a manual switch, so that the operation is complex, and the experimental efficiency is greatly reduced. The structure schematic diagram of the traditional resonant capacitor (namely, the capacitance matcher) is shown in fig. 1, and is formed by connecting a plurality of basic units in parallel, wherein each basic unit is formed by connecting a capacitor A and a pulling switch B in series, and whether the capacitor is connected into a parallel circuit or not is controlled. When the corresponding capacitor is needed in the experimental process, the corresponding switch is required to be shifted, and the capacitors with different specifications are connected in parallel, so that the experiment can be completed. The capacitor box calculates the capacitor to be connected in parallel every time the capacitor box selects the capacitor; in the circuit structure, all the capacitors can only be connected in parallel, so that the range of equivalent capacitance values is limited; the outside needs to set up toggle switch, and degree of automation is not high, influences experimental efficiency. Therefore, the design and manufacture of the novel automatic capacitive resonance matcher has important significance in saving experimental time, simplifying experimental steps and improving experimental efficiency.

Disclosure of Invention

The invention aims at overcoming the defects of the traditional matching resonant capacitor box and provides an automatic resonant capacitor matcher suitable for a three-dimensional magnetic characteristic measurement system. The invention changes the pulling sheet switch into an electronic switch based on the traditional capacitance box, adds an oblique capacitance series passage between adjacent capacitances, and adds two electronic switches to control the adjacent capacitances, and gives out an electronic switch signal through a singlechip to control the current flow direction, thereby achieving the purpose that the capacitances can be connected in series and in parallel.

The technical scheme of the invention is as follows:

the automatic resonant capacitance matcher suitable for the three-dimensional magnetic characteristic measurement system comprises three capacitance matchers and a singlechip;

wherein, three capacitance matchers are respectively connected with the singlechip.

The capacitance matcher comprises n basic units connected in parallel, wherein each basic unit comprises a capacitance, an electronic switch and two single-pole double-throw switches; the electronic switch is connected with the capacitor in series, the other end of the electronic switch is connected with the fixed point of the first single-pole double-throw switch, and the other end of the capacitor is connected with the fixed point of the second single-pole double-throw switch; each single-pole double-throw switch is provided with two movable contacts;

the parallel connection of the n basic units is specifically as follows: the second movable contact of the first single-pole double-throw switch of the kth stage is connected with the fixed point of the first single-pole double-throw switch of the next stage, and the first movable contact of the first single-pole double-throw switch of the kth stage is connected with the first movable contact of the second single-pole double-throw switch of the next stage; the second movable contact of the second single-pole double-throw switch of the kth stage is connected with the fixed point of the second single-pole double-throw switch of the upper stage, and the first movable contact of the second single-pole double-throw switch of the kth stage is connected with the first movable contact of the first single-pole double-throw switch of the upper stage; meanwhile, a second single-pole double-throw switch of the first basic unit is removed, and the other end of the capacitor A1 in the first basic unit is connected with a second movable contact in the second single-pole double-throw switch in the second basic unit and is connected with an output terminal E1; the first single-pole double-throw switch omitted in the last stage is connected with the second movable contact in the first single-pole double-throw switch in the upper stage basic unit, and is connected with an output terminal E2; e1 and E2 are respectively connected with the resonant inductance groups;

n=4 to 12, k is smaller than n;

in the basic unit, the electronic switch is a depletion type N-channel MOS tube, the source electrode of the MOS tube is connected with the capacitor, the drain electrode of the MOS tube is connected with the fixed point of the first single-pole double-throw switch, and the grid electrode leading-out signal wire of the NMOS tube is connected with the singlechip;

the single-pole double-throw switch is the same and is an electronic chip with the single-pole double-throw switch function, and the chip is provided with at least 6 terminals; wherein, three terminals are respectively used as a fixed point, a first movable contact and a second movable contact; the fourth terminal of the second single-pole double-throw switch chip is connected with the fourth terminal of the first single-pole double-throw switch chip of the previous stage, and the fourth terminal is led out to serve as a signal line Dk, and the Dk is connected with the singlechip.

The single pole double throw switch is preferably a MAX4644 chip.

The beneficial effects of the invention are as follows:

(1) The invention can realize the communication of computer data and a lower computer and control the change of the resonance capacitance value, has high degree of automation, and can greatly reduce the labor capacity and simplify the capacitance calculation.

(2) Compared with the traditional resonant capacitor matcher, when different experiments are carried out each time, the system is required to be closed, and the connection method of the resonant capacitor circuit is changed again. The invention does not need equipment to temporarily stop running, can switch the resonance capacitor in the experimental process, and ensures the continuity of the experiment.

(3) The invention designs a circuit connection method capable of automatically realizing series-parallel connection of capacitors, which can flexibly control the series-parallel connection of the capacitors without human intervention.

(4) According to the invention, through series-parallel connection of the capacitors, more than 100 equivalent capacitance values can be obtained, the selection range of resonant frequency in magnetic characteristic measurement is expanded, and more resonant capacitors can be selected in the intermediate frequency range in the magnetic characteristic experiment. Not only improves the resonance precision, but also saves the experiment cost and simplifies the manual calculation and operation flow.

Drawings

FIG. 1a is a conventional capacitive matcher connection unit; FIG. 1b is a schematic diagram of a conventional capacitive matcher circuit connection

FIG. 2a is a schematic diagram of a capacitive matcher connection unit of the present patent; FIG. 2b is a schematic diagram of a circuit connection of the capacitive matcher of the present patent;

FIG. 3 is a schematic diagram of a switch signal connection of a controlled switch of the capacitive matcher of the present patent;

FIG. 4 is a schematic diagram of a 40uF equivalent capacitive switch operation;

FIG. 5 is a schematic diagram showing the specific circuit connections of the kth stage basic unit;

FIG. 6a is a timing control signal of MAX 4644; FIG. 6b is a diagram of MAX4644 chip pins;

FIG. 7 is a schematic diagram of a three-dimensional magnetic property measurement system connected to the present patent;

fig. 8 is a diagram showing the operation steps of an automated resonant capacitor matcher suitable for use in the three-dimensional magnetic characteristic measurement system of the present invention.

The specific embodiment is as follows:

the invention is suitable for an automatic resonance capacitance matcher of a three-dimensional magnetic characteristic measurement system, and the capacitance matcher is a basic composition. The capacitance matcher in the invention is to improve the basic unit of the traditional matcher, as shown in fig. 2a, a pulling sheet switch B is changed into a controllable electronic switch Bk, and two single-pole double-throw switches, namely a first single-pole double-throw switch Ck1 and a second single-pole double-throw switch Ck2, are added (the single-pole double-throw switch directly connected with the switch B is named as a first single-pole double-throw switch Ck1, the single-pole double-throw switch directly connected with a capacitor Ak is named as a second single-pole double-throw switch Ck 2), namely the electronic switch Bk is connected with the capacitor Ak in series, the other end of the electronic switch Bk is connected with the fixed point of the first single-pole double-throw switch Ck1, and the other end of the capacitor Ak is connected with the fixed point of the second single-pole double-throw switch Ck2, thereby forming the basic unit of the resonance capacitance matcher. The two movable contacts of the second single-pole double-throw switch Ck2 are respectively named as a first movable contact 1 and a second movable contact 2 for the first single-pole double-throw switch Ck 1.

The capacitive series-parallel control circuit (capacitive matcher) of this patent can be completed by connecting n basic units in parallel as shown in fig. 2 b: the second movable contact of the first single-pole double-throw switch Ck1 of the kth stage is connected with the fixed point of the first single-pole double-throw switch C (k+1) 1 of the next stage, and the first movable contact of the first single-pole double-throw switch Ck1 of the kth stage is connected with the first movable contact of the second single-pole double-throw switch C (k+1) 2 of the next stage; the second movable contact of the second single-pole double-throw switch Ck2 of the kth stage is connected with the fixed point of the second single-pole double-throw switch C (k-1) 2 of the previous stage, and the first movable contact of the second single-pole double-throw switch Ck2 of the kth stage is connected with the first movable contact of the first single-pole double-throw switch C (k-1) 1 of the previous stage; meanwhile, the second single-pole double-throw switch C12 of the first stage is removed, and the other end (opposite to the other end connected with the electronic switch B1 in the basic unit) of the capacitor A1 in the first basic unit is connected with the second movable contact 2 in the second single-pole double-throw switch in the second basic unit and is connected with an output terminal E1 to serve as an equivalent capacitor output pin; the other end of the electronic switch Bn is connected with a second movable contact 2 in the first single-pole double-throw switch in the basic unit of the previous stage, and is connected with an output terminal E2 to serve as an equivalent capacitance output pin; and (E1 is connected with the No. 4 pin of the second single-pole double-throw switch of the second stage unit, E2 is connected with the No. 4 pin of the first single-pole double-throw switch of the N-1 stage unit), thereby completing the control circuit of the capacitor series-parallel switch.

The number of the basic units may be 4 to 12. The number of the present invention is preferably 8.

The single-pole double-throw switch adopts an electronic chip with a single-pole double-throw switch function, and the chip is provided with at least 6 terminals; the invention adopts MAX4644 chip as single-pole double-throw switch, wherein, the pin of the chip is shown in FIG. 6b, the pin No. 2 and the pin No. 3 are the power supply pins of the chip, the pin No. 4 corresponds to the second movable contact 2 of the first single-pole double-throw switch Ck1 and the second single-pole double-throw switch Ck2, the pin No. 6 corresponds to the first movable contact 1 of the first single-pole double-throw switch Ck1 and the second single-pole double-throw switch Ck2, the pin No. 5 corresponds to the fixed point of the first single-pole double-throw switch Ck1 and the second single-pole double-throw switch Ck2, and the pin No. 1 is the control signal input pin of the single-pole double-throw switches Ck1 and Ck2 in the basic unit of the resonance capacitor matcher. In the kth-stage basic unit, a chip corresponding to the first single-pole double-throw switch Ck1 is a first single-pole double-throw switch chip Ck1, and a chip corresponding to the second single-pole double-throw switch Ck1 is a second single-pole double-throw switch chip Ck2. When the control signal output is low level (the logic value is 0) (i.e. the input of the No. 1 pin of the MAX4644 is low level), the dead point of the single-pole double-throw switch is conducted with the second movable contact 2, and the first movable contact 1 is suspended (i.e. the No. 5 pin of the MAX4644 is conducted with the No. 4 pin and the No. 6 pin is suspended); when the control signal output is high level (logic value is 1) (i.e. pin 1 of MAX4644 is input high level), the dead point of the single-pole double-throw switch is conducted with the first movable contact 1, and the second movable contact 2 is suspended (i.e. pin 5 of MAX4644 is conducted with pin 6 and pin 4 is suspended)). The pin 1 of the second single-pole double-throw switch chip Ck2 in the kth basic unit is connected with the pin 1 of the first single-pole double-throw switch chip Ck1 of the previous stage, and a serial control signal line Dk serving as the minimum bit is led out.

The electronic switch Bk is composed of a depletion type N-channel MOS tube (NMOS tube), a source electrode is connected with a capacitor, a drain electrode is connected with a fixed point (No. 5 pin) of the first single-pole double-throw switch chip Ck1, and a grid electrode leading-out signal wire of the NMOS tube is used as Fk and is connected with a pin of the singlechip. And the minimum parallel control bits of the Bk switch are formed into F1-F8 parallel control signal lines side by side according to the serial number sequence, and the F1-F8 parallel control signal lines are connected into pins of the singlechip PA0-PA 7. When the control signal of Fk is at a high level (logic value is 1) (the grid electrode of the NMOS tube inputs the high level), the switch is conducted; when the control signal of Fk is low (logic value is 0) (the gate of the NMOS transistor inputs low), the switch is turned off.

The controllable capacitor series-parallel switch control circuit shown in figure 3 is formed. Fig. 5 shows the actual circuit connection of the kth stage basic unit. Thereby completing a capacitance matcher connection.

Fig. 4 shows the operation state of the switch when the 40uF equivalent capacitance is realized. At this time, F1-F8 input control signals 0x07, and D1-D7 input control signals 0x01. The electronic switches B1 and B2 are closed, the fixed points (pins No. 5) of the first single-pole double-throw switch chip C1 and the second single-pole double-throw switch chip C2 are closed on the first movable contact 1 (pin No. 6), at the moment, the 57uF capacitor and the 10uF capacitor are connected in parallel and then connected in series with 99uF, and the final capacitance value is 40uF.

Taking 8 basic units of the resonant capacitor matcher as an example, the output ends of the capacitor series-parallel control circuit are E1 and E2, and are connected with a resonant inductance group of the three-dimensional magnetic characteristic measurement system. All Ck1 and Ck2 single-pole double-throw switches in FIG. 3 are identical and are electronically controlled single-pole double-throw switches, and MAX4644 chips are adopted as the single-pole double-throw switches in the invention.

The minimum bit serial control signal line Dk of the 8 basic units sequentially forms a D1-D7 serial control signal line (the last-stage control signal has no next stage, so there is no D8 signal line, but the last bit is always 0 in order to be considered in operation), and is connected with the PA8-PA14 pin of the singlechip.

The invention relates to an automatic resonant capacitance matcher suitable for a three-dimensional magnetic characteristic measurement system, which comprises a three-dimensional magnetic characteristic measurement system, three resonant inductance groups, three resonant capacitance matchers and a single chip microcomputer control unit, wherein the three resonant inductance groups are arranged on the adapter;

wherein, three excitation coil windings in the three-dimensional magnetic characteristic measurement system, every excitation coil winding links to each other with a resonance inductance group, and every resonance inductance group links to each other with a resonance capacitance matcher, and three resonance capacitance matcher links to each other with singlechip control unit respectively, and singlechip control unit still directly communicates the interface with the serial ports of three-dimensional magnetic characteristic measurement system.

As shown in fig. 7: the three-dimensional magnetic characteristic measurement system is provided with three exciting coil windings corresponding to the exciting directions of the X axis, the Y axis and the Z axis. The exciting coil windings in each direction are matched with the capacitance values of the output in the capacitance matchers through the corresponding resonant inductance groups, so that three capacitance matchers are required to be corresponding. The capacitance matcher connected with the X-axis inductor is called an X-axis resonance capacitance matcher; the capacitance matcher connected with the Y-axis inductor is called as a Y-axis resonance capacitance matcher; the capacitance matcher connected to the Z-axis inductance is referred to as a Z-axis resonant capacitance matcher.

The singlechip control unit comprises a singlechip. The specific model of this embodiment is stm32f103ze.

B1-B8 are the lower 8 bits of the 16-bit switch control signal data, and D1-D7 are the upper eight bits of the 16-bit switch control signal data. The 16-bit switch control signal data is used as a capacitor series-parallel switch control signal, and is connected with a 16-bit pin of stm32 (for example, an X-axis resonance direction switch control signal data is connected with PA0-PA15, a Y-axis resonance direction switch control signal data is connected with PB0-PB15, and a Z-axis resonance direction switch control signal data is connected with PC0-PC 15), so as to drive the MOSFET switches B1-B8 and MAX4644 in FIG. 3 to be turned on or turned off.

The electronically controlled single pole double throw switch refers to a controlled three-terminal switch device, which can control the opening and closing direction of the switch by giving a logic level signal (0 or 1) to a control terminal, and can change the flow direction of current in a circuit. Taking MAX4644SOT23-6 chip as an example, the pin 1-IN end of the chip is a control end interface, which can change the opening and closing direction of the switch. The pins No. 4 and No. 6 are movable contacts, and the pin No. 5 is a fixed point. The program flow chart is shown in fig. 5, and the control end of the three-dimensional magnetic characteristic measurement system sends serial data through the serial port according to the communication protocol shown in the second table. The singlechip analyzes the data format to obtain the functional word instruction and the capacitance value data. And judging and configuring the resonant capacitance of the X axis, the Y axis or the Z axis according to the functional word. And looking up a table according to the capacitance value data to obtain the switch action potential. The singlechip outputs action potential and controls the switch to be turned off, thus completing the series-parallel operation of the capacitor. And the singlechip returns an ACK signal to inform the singlechip of finishing the action potential.

The automatic resonant capacitance matcher suitable for the three-dimensional magnetic characteristic measurement system can realize automatic operation through a control program during operation. The control program is written in the language C and downloaded to the singlechip, and mainly realizes two functions. Providing a protocol for communication with an upper computer; and secondly, controlling corresponding switching actions according to the capacitance value transmitted by the upper computer to realize series-parallel operation of the capacitor, thereby obtaining an equivalent capacitance value. The specific algorithm is that the corresponding relation between the equivalent capacitance provided by the first table and the control signal of the singlechip is written into the ROM in a two-dimensional array mode, the capacitance data sent by the upper computer through the serial port is analyzed, the closest equivalent capacitance is traversed and inquired, and the singlechip outputs the switching action corresponding to the equivalent capacitance.

Step one: fig. 1 is a schematic diagram of a three-dimensional magnetic characteristic measurement system, wherein an upper computer sets excitation frequency and excitation coil inductance, and a calculated capacitance value is transmitted to a lower computer through a serial port to analyze data.

Step two: the signal amplified by the power amplifier is added on the exciting coil and resonated with the resonance matching capacitor to generate exciting current, so that magnetic fields are generated in three directions to finish three-dimensional magnetic characteristic measurement. The lower computer analyzes the upper computer electronic value data, and obtains the action value of the switch through table lookup.

Step three: under the control of the lower computer, the three resonant capacitors are switched in series and parallel.

Step four: and starting three-dimensional magnetic characteristic measurement experiment operation to obtain three-dimensional magnetic characteristic data.

Step five: the upper computer inputs the frequency of the next experiment, and the system automatically starts from the step without manual interference.

The related software or program involved in the operation of the automatic resonant capacitor matcher suitable for the three-dimensional magnetic characteristic measurement system is known in the prior art, and can be easily written and realized by a person of ordinary skill in the art according to the composition of the device and the operation steps. In a plurality of basic units of the capacitor series-parallel switch control circuit, the selection of the capacitor in each unit is determined by the test frequency and the excitation inductance selected by the three-dimensional magnetic characteristic measurement system, and the test frequency and the excitation inductance are determined by the formula

The basic capacitance value is determined.

Measuring inductance L of resonant inductor in system according to three-dimensional measurement characteristics, and typical excitation frequency f to be determined experimentally according to formula

Capacitances of 99uF, 57uF, 10uF, 9uF, 3uF, 1uF, 0.5uF, 0.1uF were determined. Taking these 8 typical capacitors as examples, table one represents a partial capacitance value which can be realized through serial-parallel operation, and when a certain capacitance value is needed, the partial capacitance value corresponds to a control signal which should be output by the singlechip. The control signal F is a parallel control signal line F1-F8 and is connected with a pin corresponding to the singlechip. The control signal D is a series control signal line D1-D7 with D8 constant at 0 (D8 has no specific circuit connection, default set to 0). D1-D7 are connected with pins corresponding to the singlechip. The data in the table is required to be written into the memory by the singlechip and is used as an important part of the table look-up program of the singlechip.

Tables two and three are communication protocol parts. In the patent, a single chip microcomputer needs to control three resonant capacitor matchers, and a single chip microcomputer program is used for distinguishing capacitor matching boxes (specifically an X-axis resonant capacitor matcher, a Y-axis resonant capacitor matcher and a Z-axis resonant capacitor matcher) in a certain direction according to functional words in one frame of communication data, calculating the capacitance data and outputting corresponding control signals. And programming according to the communication protocols of the second and third tables, and enabling the singlechip to communicate with the three-dimensional magnetic characteristic measurement system.

The first, second and third tables are specific details of the implementation of the single chip microcomputer program in fig. 8. The corresponding relation between the capacitance value and the output action potential of the singlechip PA, PB or PC port is exemplified in the first table. The second table defines the serial port data format. And a data format of information sent by the singlechip is defined in a table III.

Part of the resonance matcher can be provided with a capacitance value and a control signal

Form one

Communication protocol between upper computer and lower computer

Form two

Communication protocol between lower computer and upper computer

Form three

The invention is not a matter of the known technology.

Claims (2)

1. The automatic resonant capacitance matcher suitable for the three-dimensional magnetic characteristic measurement system comprises three capacitance matchers and a singlechip;

wherein, the three capacitance matchers are respectively connected with the singlechip;

the capacitor matcher is characterized by comprising n basic units connected in parallel, wherein each basic unit comprises a capacitor, an electronic switch and two single-pole double-throw switches; the electronic switch is connected with the capacitor in series, the other end of the electronic switch is connected with the fixed point of the first single-pole double-throw switch, and the other end of the capacitor is connected with the fixed point of the second single-pole double-throw switch, so that a basic unit of the resonant capacitor matcher is formed; each single-pole double-throw switch is provided with two movable contacts;

the parallel connection of the n basic units is specifically as follows: the second movable contact of the first single-pole double-throw switch of the kth stage is connected with the fixed point of the first single-pole double-throw switch of the next stage, and the first movable contact of the first single-pole double-throw switch of the kth stage is connected with the first movable contact of the second single-pole double-throw switch of the next stage; the second movable contact of the second single-pole double-throw switch of the kth stage is connected with the fixed point of the second single-pole double-throw switch of the upper stage, and the first movable contact of the second single-pole double-throw switch of the kth stage is connected with the first movable contact of the first single-pole double-throw switch of the upper stage; meanwhile, a second single-pole double-throw switch is not arranged in the first basic unit, and the other end of the capacitor A1 in the first basic unit is connected with a second movable contact in the second single-pole double-throw switch in the second basic unit and is connected with an output terminal E1; the last stage basic unit is not provided with a first single-pole double-throw switch, and the other end of the electronic switch is connected with a second movable contact in the first single-pole double-throw switch in the previous stage basic unit and is connected with an output terminal E2; e1 and E2 are respectively connected with a resonant inductance group of the three-dimensional magnetic characteristic measurement system;

n=4 to 12, k is smaller than n;

in the basic unit, the electronic switch is a depletion type N-channel MOS tube, the source electrode of the MOS tube is connected with the capacitor, the drain electrode of the MOS tube is connected with the fixed point of the first single-pole double-throw switch, and the grid electrode leading-out signal wire of the NMOS tube is connected with the singlechip;

the single-pole double-throw switch is the same and is an electronic chip with the single-pole double-throw switch function, and the chip is provided with at least 6 terminals; wherein, three terminals are respectively used as a fixed point, a first movable contact and a second movable contact; the fourth terminal of the second single-pole double-throw switch chip is connected with the fourth terminal of the first single-pole double-throw switch chip of the previous stage, and the fourth terminal is led out to serve as a signal line Dk, and the Dk is connected with the singlechip.

2. The automated resonant capacitor matcher for three-dimensional magnetic property measurement systems of claim 1 wherein said single pole double throw switch is a MAX4644 chip.

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