CN201562008U - Milliampere meter - Google Patents
Milliampere meter Download PDFInfo
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- CN201562008U CN201562008U CN2009202559768U CN200920255976U CN201562008U CN 201562008 U CN201562008 U CN 201562008U CN 2009202559768 U CN2009202559768 U CN 2009202559768U CN 200920255976 U CN200920255976 U CN 200920255976U CN 201562008 U CN201562008 U CN 201562008U
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Abstract
A milliampere meter comprises a sampling unit, a signal conversion unit, a central processing unit, a display control unit and a power supply circuit. The power supply circuit supplies power to the milliampere meter; the signal output from the sampling unit is transmitted to the central processing unit after signal conversion; the display signal output from the central processing unit is displayed through the display control unit; and the external control signal of the display control unit is transmitted into the central processing unit. The sampling unit comprises a magnetic loop and a Hall device unit arranged in the magnetic field formed by a magnetic loop. The signal conversion unit comprises a V/F conversion circuit. A to-be-tested current generates magnetic field in the magnetic loop, which is converted to a voltage through the Hall device unit; and the obtained voltage is converted to a pulse signal through the V/F conversion circuit, and the pulse signal is input into the central processing unit. Compared with the prior art, the milliampere meter solves the problems in the prior art, and can be used for sampling micro-current.
Description
Technical field
The utility model belongs to the surveying instrument field of instrumentation technology, specifically is a kind of milliampere of stopwatch.
Background technology
At present in the radiation technique field, how to detect the tube current of X-ray machine be an engineering problem always in non-intervention, this tube current comes down to a moment (short then several milliseconds, long then five or six seconds) DC current, common pincers type multimeter is to be difficult to detect, mainly contain two reasons, the one, common split-core type meter can only be measured the current signal of interchange, and direct current is just powerless; The 2nd, because digital multimeter adopts the A/D sample mode of double integrator, the low basic reaction of sampling rate is not come, and data also do not show, electric current has not had, and owing to be continuous sampling, so data can not continue to show, when treating that electric current does not have, show zero again.Solve this two problems so must develop special-purpose instrument.
Summary of the invention
In order to solve the above-mentioned problems in the prior art, the utility model proposes a kind of new milliampere stopwatch, concrete technical scheme is as follows:
A kind of milliampere of stopwatch comprises sampling unit, signal conversion unit, CPU (central processing unit), shows control unit, power circuit.Power circuit provides power supply for this milliampere stopwatch; The signal of described sampling unit output imports CPU (central processing unit) into behind signal conversion unit; The shows signal of CPU (central processing unit) output shows by showing the control unit; The external control signal of described apparent control unit imports CPU (central processing unit) into.Described sampling unit comprises magnet ring and hall device unit, and the hall device unit is located in the magnetic field of magnet ring formation; Described signal conversion unit comprises the V/F change-over circuit; Tested electric current produces magnetic field in magnet ring, be magnitude of voltage by the hall device cell translation; The magnitude of voltage that obtains converts pulse signal to by the V/F change-over circuit again, and pulse signal is imported described CPU (central processing unit).
Also comprise storer, storer connects CPU (central processing unit).
Sampling unit also comprises sampling resistor and switch; The output terminal of the output terminal of described sampling resistor and hall device unit is connected two input ends of described switch respectively, and the output terminal of switch connects the input end of V/F change-over circuit.
Described hall device unit comprises differential amplifier circuit and two the first Hall device A spares that size is the same, direction is opposite and the second hall device B; The described first hall device A is connected the input end of differential amplifier circuit with the output of the second hall device B; The output terminal of differential amplifier circuit is the output terminal of hall device unit.
Described V/F change-over circuit is a voltage controlled oscillator.
Described CPU (central processing unit) is to be the circuit of core with the arm processor.
Described apparent control unit comprises keyboard and display.
Also comprise communicating circuit, communicating circuit is connected with the data I/O end of CPU (central processing unit).
Communicating circuit comprises RS232 change-over circuit and USB change-over circuit.
Compared with prior art, the utility model has solved problems of the prior art, can be used for the sampling of little electric current, and for example non-intervention detects the tube current of X-ray machine.
Description of drawings
Fig. 1 is a schematic block circuit diagram of the present utility model;
Fig. 2 (a) is the utility model hall device unit construction principle synoptic diagram;
Fig. 2 (b) is the utility model hall device element circuit principle schematic;
Fig. 3 is the profile synoptic diagram of embodiment;
Fig. 4 is the electrical schematic diagram of embodiment.
Embodiment
The utility model is described in further detail below in conjunction with accompanying drawing and embodiment.
A kind of milliampere of stopwatch (as Fig. 1) comprises sampling unit, signal conversion unit, CPU (central processing unit), shows control unit and power circuit.Power circuit provides power supply for this milliampere stopwatch; The signal of described sampling unit output imports CPU (central processing unit) into behind signal conversion unit; The shows signal of CPU (central processing unit) output shows by showing the control unit; The external control signal of described apparent control unit imports CPU (central processing unit) into.Described sampling unit comprises magnet ring and hall device unit, and the hall device unit is located in the magnetic field of magnet ring C formation; Described signal conversion unit comprises the V/F change-over circuit; Tested electric current produces magnetic field in magnet ring, be magnitude of voltage by the hall device cell translation; The magnitude of voltage that obtains converts pulse signal to by the V/F change-over circuit again, and pulse signal is imported described CPU (central processing unit).
Also comprise storer, storer connects CPU (central processing unit).
Sampling unit also comprises sampling resistor and switch; The output terminal of the output terminal of described sampling resistor and hall device unit is connected two input ends of described switch respectively, and the output terminal of switch connects the input end of V/F change-over circuit.
Described hall device unit comprises differential amplifier circuit and two the first hall device A that size is the same, direction is opposite and the second hall device B; Described first hall device is connected the input end of differential amplifier circuit with the output of second hall device; The output terminal of differential amplifier circuit is the output terminal of hall device unit.
Described V/F change-over circuit is a voltage controlled oscillator.
Described CPU (central processing unit) is to be the circuit of core with the arm processor.Arm processor connects timing generator circuit and obtains the benchmark sequential, and this circuit can adopt ripe crystal oscillator.
Described apparent control unit comprises keyboard and display.Also comprise communicating circuit, communicating circuit is connected with the data I/O end of CPU (central processing unit).Communicating circuit comprises RS232 change-over circuit and USB change-over circuit.
In this example, voltage controlled oscillator is selected the AD654 chip for use, has linearity height, and single power supply uses characteristic of simple.Work in the negative polarity mode.Processor is selected 32 ARM7 of PHILIPS for use, has volume little, and is low in energy consumption, online programming, the characteristics that function is strong.Keyboard is selected the mode of single line Interrupt Process for use, shows to use special-purpose LCD display, and the SPI interface is simple and practical.Storer is selected eeprom chip for use, and the power down data are not lost.Communicating circuit comprises USB (adopting existing mature technology) and two kinds of communication modes of RS232 (adopting SP232 is the circuit of core).Switch adopts dial switch.Described differential amplifier circuit is often seen in the prior art, is not further limited at this.
Principle of the present utility model is as follows:
1. the little DC techniques of two hall device difference measurements.
The conductor of tested energising produces magnetic field around it, two sizes of placement are the same in magnetic field, the hall device that direction is opposite,
Shown in Fig. 2 (a), C is the conductor at tested electric current place among the figure, and the first hall device A and the second hall device B export one positive one negative voltage signal, amplifies through difference to have overcome earth magnetism, the influence of temperature drift.The voltage of output is proportional to the size of electric current.Such as 1mA=1mV.Shown in Fig. 2 (b), because electric current is very faint, the magnetic field intensity of generation is little, so circuit is selected high precision for use, and the discharge circuit of low drift.
2. counting mode is measured the MAS Integral Technology.
Under the A/D mode, no problem when measuring regular waveform, measure the area of each fritter, addition just obtains total MAS then, but when the jagged waveform of measurement, error is just big.Adopt the V/F mode just to can solve this problem.Voltage signal is after testing given voltage controlled oscillator work, as 1V=100KHz.If mA is big, then the pulse of oscillator output is just many, and the time is long, and then counting is many, has not so just relied on sampling rate, as long as the linearity of voltage controlled oscillator is good, just can accurately measure the value of MAS, need not to calculate its value.Electric current such as X-ray machine is 100mA, time is 100mS, actual mAs value should be 100mA*0.1s=10mAs, no matter be that to get involved also be that non-intervention is measured, ultimate current is converted into voltage and a such relation is arranged is 1mA=1mV, and 100mA=100mV=10kHz, 0.1s have then produced 1000 pulses, radix point is exactly the mAs value hundred demonstrations, and apparent resolution is 0.01mAs.
3. integral type designing technique.
Adopt the utility model, can combine with non-intervention (promptly adopting the hall device unit sampling) getting involved (promptly adopting the sampling resistor sampling), be subjected to the control of dial switch (being switch), sensor and main frame are combined, need not other being used of instrument and meter, as shown in Figure 3.
During use, under intervening mode, tested electric current obtains sampled voltage through a sampling resistor; Under non-intervening mode, tested electric current produces magnetic field in magnet ring, detects the size of electric current and with the output of the form of voltage by hall device.The revolving dial switch is selected one of two kinds of voltages to deliver to voltage-controlled oscillator circuit and is produced the pulse signal that frequency is directly proportional with size of current.
Claims (9)
1. a milliampere stopwatch comprises sampling unit, signal conversion unit, CPU (central processing unit), shows control unit and power circuit; Power circuit provides power supply for this milliampere stopwatch; The signal of described sampling unit output imports CPU (central processing unit) into behind signal conversion unit; The shows signal of CPU (central processing unit) output shows by showing the control unit; The external control signal of described apparent control unit imports CPU (central processing unit) into, it is characterized in that described sampling unit comprises magnet ring and hall device unit, and the hall device unit is located in the magnetic field of magnet ring formation; Described signal conversion unit comprises the V/F change-over circuit; Tested electric current produces magnetic field in magnet ring, be magnitude of voltage by the hall device cell translation; The magnitude of voltage that obtains converts pulse signal to by the V/F change-over circuit again, and pulse signal is imported described CPU (central processing unit).
2. according to claim 1 milliampere of stopwatch is characterized in that sampling unit also comprises sampling resistor and switch; The output terminal of the output terminal of described sampling resistor and hall device unit is connected two input ends of described switch respectively, and the output terminal of switch connects the input end of V/F change-over circuit.
3. milliampere stopwatch according to claim 1 and 2 is characterized in that described hall device unit comprises differential amplifier circuit and two first hall devices that size is the same, direction is opposite and second hall device; Described first hall device is connected the input end of differential amplifier circuit with the output of second hall device; The output terminal of differential amplifier circuit is the output terminal of hall device unit.
4. according to claim 3 milliampere of stopwatch is characterized in that described V/F change-over circuit is a voltage controlled oscillator.
5. according to claim 3 milliampere of stopwatch is characterized in that described CPU (central processing unit) is is the circuit of core with the arm processor.
6. according to claim 3 milliampere of stopwatch is characterized in that described apparent control unit comprises keyboard and display.
7. according to claim 3 milliampere of stopwatch is characterized in that also comprising storer, and storer connects CPU (central processing unit).
8. according to claim 3 milliampere of stopwatch is characterized in that also comprising communicating circuit, and communicating circuit is connected with the data I/O end of CPU (central processing unit).
9. according to claim 8 milliampere of stopwatch is characterized in that communicating circuit comprises RS232 change-over circuit and USB change-over circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009202559768U CN201562008U (en) | 2009-11-30 | 2009-11-30 | Milliampere meter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009202559768U CN201562008U (en) | 2009-11-30 | 2009-11-30 | Milliampere meter |
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| Publication Number | Publication Date |
|---|---|
| CN201562008U true CN201562008U (en) | 2010-08-25 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN2009202559768U Expired - Fee Related CN201562008U (en) | 2009-11-30 | 2009-11-30 | Milliampere meter |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103901382A (en) * | 2014-03-26 | 2014-07-02 | 孙家林 | Calibration detection device for time ampere meter |
| CN106997003A (en) * | 2017-06-09 | 2017-08-01 | 郑州云海信息技术有限公司 | It is a kind of to realize the lossless system for exempting to tear measurement open of server power supply electric current |
| CN108459193A (en) * | 2018-04-04 | 2018-08-28 | 北京智芯微电子科技有限公司 | Alternating current measuring device |
-
2009
- 2009-11-30 CN CN2009202559768U patent/CN201562008U/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103901382A (en) * | 2014-03-26 | 2014-07-02 | 孙家林 | Calibration detection device for time ampere meter |
| CN103901382B (en) * | 2014-03-26 | 2016-07-06 | 孙家林 | A kind of calibration detection apparatus of time current table |
| CN106997003A (en) * | 2017-06-09 | 2017-08-01 | 郑州云海信息技术有限公司 | It is a kind of to realize the lossless system for exempting to tear measurement open of server power supply electric current |
| CN108459193A (en) * | 2018-04-04 | 2018-08-28 | 北京智芯微电子科技有限公司 | Alternating current measuring device |
| CN108459193B (en) * | 2018-04-04 | 2020-09-11 | 北京智芯微电子科技有限公司 | Alternating current measuring device |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20100825 Termination date: 20101130 |