CN104883147A - Preamplifier of acoustic emission detector - Google Patents
Preamplifier of acoustic emission detector Download PDFInfo
- Publication number
- CN104883147A CN104883147A CN201510300683.7A CN201510300683A CN104883147A CN 104883147 A CN104883147 A CN 104883147A CN 201510300683 A CN201510300683 A CN 201510300683A CN 104883147 A CN104883147 A CN 104883147A
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- preamplifier
- inductance
- emission detector
- acoustic emission
- signal
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/45—Differential amplifiers
- H03F3/45071—Differential amplifiers with semiconductor devices only
- H03F3/45076—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier
- H03F3/45475—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier using IC blocks as the active amplifying circuit
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- Power Engineering (AREA)
- Amplifiers (AREA)
Abstract
The invention relates to a preamplifier of an acoustic emission detector. The preamplifier of the acoustic emission detector comprises an amplification portion, a power portion and a signal isolation portion. The preamplifier attached to the original PCI-1 type acoustic emission detector of an American physical acoustic corporation is powered by 28V direct currents of 0.2A; the frequency of the preamplifier ranges from 100KHz to 300KHz, a sensor port can be in a single-ended input mode or a differential input mode, and gain of the preamplifier can be 20dB or 40dB or 60dB and can be adjusted; the sensor port can be in the single-ended input mode when the preamplifier is used, in other words, signals are inputted into same-phase ends of sensors, and reversed-phase ends of the sensors are grounded; the secondary operational amplification is carried out by the amplification portion.
Description
Technical field
The present invention relates to acoustic emission detector preamplifier.
Background technology
Material by during deformation and fracture produce Elastic wave phenomenon be called acoustic emission (AcousticEmission is called for short AE), sometimes launch also referred to as stress wave.The voice signal launched by material contains the information of reflection material internal defect, character and state variation, and acoustic emission detection receives these signals exactly, carries out analyzing and processing to it, thus infers the change of material internal.Acoustic emission detection will be carried out in a certain frequency range, and this scope is called acoustic emission detection " frequency window ".
Aircraft external environment (as gas epidemic disaster, ultraviolet radiation, acid rain etc.) effect in process under arms, surface treatment and holiday, fifth wheel blocking osculum etc. all may cause local corrosion, the corrosion produced can affect materials microstructure structural behaviour, and produces fatigue crack.Find all kinds of defect in the very first time and defect detected and extent of injury assessment, for ensureing that the safe flight tool of aircraft is of great significance.The preamplifier bandwidth of acoustic current emission detector is 100 ~ 300KHz, and the low frequency characteristic that some are useful filters out, and the preamplifier for this reason designing a kind of low frequency characteristic seems particularly important.
Summary of the invention
The present invention devises a low frequency acoustic emission preamplifier, and its frequency is at 40KHz ~ 200KHz, and gain is 40dB.
The present invention relates to acoustic emission detector preamplifier, described acoustic emission detector preamplifier comprises amplifier section, power unit and signal isolated part;
Described primary sound emission detector adopts the PCI-1 type of American Physical acoustics company, and its subsidiary preamplifier is 28V direct current supply, and supply current is 0.2A; Frequency is at 100 ~ 300KHz, and sensor interface adopts single-ended and difference two kinds of input patterns, gain 20,40 and 60dB adjustable; In use adopt single-ended mode, i.e. transducer in-phase end input, end of oppisite phase ground connection; Described amplifier section adopts secondary amplifier.
Further, described power unit is the switch back-pressure circuit adopting MC34063 chip to form, the electric current of resistance (R5) control system, and electric capacity (C5) is used for arranging the switching frequency of DC chip; When 1 conducting of chip internal switch transistor T, electric current flows to ground through 1 pin of MC34063,2 pin and inductance (L2), inductance (L2) stored energy, when T1 disconnects, fly-wheel diode (D1) conducting, inductance (L2) exports negative voltage through fly-wheel diode (D1) to load; The inverting input (pin 5) of comparator monitors output voltage by external divider resistance (R6, R7).
Further, described signal isolated part adopts electric capacity (C7) and electric capacity (C8) isolated DC signal, and inductance (L1) and inductance (L6) isolate AC signal, the electric capacity of an about 100uF is accessed respectively at the end of inductance (L1) and inductance (L6), filter circuit is formed, every falling system alternating current component with inductance.。
Accompanying drawing explanation
Describe exemplary embodiment of the present invention in more detail by referring to accompanying drawing, above and other aspect of the present invention and advantage will become and more be readily clear of, in the accompanying drawings:
Fig. 1 is secondary amplifier principal diagram of the present invention intention;
Fig. 2 is the Bode diagram of amplifier of the present invention;
Fig. 3 is that MC34063 negative supply of the present invention produces circuit diagram;
Fig. 4 is phantom power supplied schematic diagram of the present invention.
Embodiment
Hereinafter, more fully the present invention is described now with reference to accompanying drawing, various embodiment shown in the drawings.But the present invention can implement in many different forms, and should not be interpreted as being confined to embodiment set forth herein.On the contrary, provide these embodiments to make the disclosure will be thoroughly with completely, and scope of the present invention is conveyed to those skilled in the art fully.
Hereinafter, with reference to the accompanying drawings exemplary embodiment of the present invention is described in more detail.
Preamplifier of the present invention forms primarily of amplifier section, power unit and signal isolated part: amplifier section is responsible for the amplification of small-signal, and the quality of its design directly affects the operating characteristic of amplifier; The power supply of preamplifier is responsible for by power unit, the quality of the quality of power supply also extreme influence preamplifier; Due to holding wire and the shared coaxial cable of power line of current preamplifier, signal isolated part is responsible for the signal of output and isolated from power to come.
1 amplifier section design
Primary sound emission detector adopts the PCI-1 type of American Physical acoustics company, and its subsidiary preamplifier is 28V direct current supply, and supply current is 0.2A; Frequency is at 100 ~ 300KHz, and sensor interface adopts single-ended and difference two kinds of input patterns, gain 20,40 and 60dB adjustable.There is the problems such as sensitivity is low, delay of response due to transducer in a differential mode, therefore in use adopt single-ended mode, be i.e. transducer in-phase end input, end of oppisite phase ground connection.Because amplifier gain in use procedure adopts 40dB, so the gain design of preamplifier is fixing 40dB gain by the present invention.
Because sensor signal is millivolt level, signal be amplified 40dB, and frequency at 30KHz ~ 200KHz, obviously to adopt single amplifier not realize, adopts secondary amplifier for this reason.First select a suitable voltage feedback type high speed amplifier, it adopts positive-negative power supply; There is high bandwidth, meet and amplify 100 times and undistorted at 100KHz.By comparing screening, adopt the amplifier chip NE5532 of TI, its operating voltage is ± 5V ~ ± 15V, and the bandwidth when-3dB reaches 10MHz, and slew rate is 240V/ μ s.In order to improve the gain bandwidth product of amplifier, design amplifies 10 times respectively at firsts and seconds, reach signal the most at last and amplify 100 times, because amplifying circuit exists certain loss, and the inexactness of resistance, make multiplication factor not to be accurate to 40dB, rear stage resistance R7 can be changed to adjustable resistance, realize the fine setting of multiplication factor, amplifying circuit schematic diagram as shown in Figure 1.
Adopt Multisim to emulate to it, it reaches 578KHz at the cut-off frequency of 37dB, meets design requirement completely.Fig. 2 is the baud curve chart of amplifier, and its effect is quite perfect as seen from the figure.
2 power unit designs
Due to amplifier NE5532 employing ± 15V Power supply, so need to provide a negative supply.Negative supply can be obtained by transformer, also can pass through DC-DC circuit.Simple by transformer, but bulky, and be not suitable for miniaturization, so usually adopt DC chip to obtain, the present invention selects the DC chip MC34063 commonly used.MC34063 has the controlled oscillator of the pedestal generator of temperature self-compensation function, comparator, duty ratio, can be used for booster converter, buck converter, reverser, only needs a small amount of external component.
Fig. 3 is the switch back-pressure circuit adopting MC34063 chip to form.The electric current of resistance R5 control system, C5 is used for arranging the switching frequency of DC chip, and more P cock frequency is higher for electric capacity.When 1 conducting of chip internal switch transistor T, electric current flows to ground through 1 pin of MC34063,2 pin and inductance L 2, inductance L 2 stored energy.When T1 disconnects, because the electric current flowing through inductance can not suddenly change, therefore, sustained diode 1 conducting.Now, L2 exports negative voltage through D1 to load.Like this, as long as the time constant of the operating frequency relative load of chip is enough high, load just can obtain continuous direct voltage.The inverting input (pin 5) of comparator monitors output voltage by external divider resistance R6, R7, its output voltage Uo=1.25 (1+R7/R6), only relevant with R6, R7 numerical value by the known output voltage of formula, because 1.25V is that reference voltage is invariable, if R6, R7 resistance is stablized, Uo also stablizes.
3 signal isolated part designs
The power supply of preamplifier can adopt external power supply form to power, can also by illusion Power supply.External power supply is powered and is had the advantage of signal low frequency characteristic good (as shown in Figure 2), is also the power supply plan of early stage preamplifier.But this type of power supply also has deficiency, and each exactly preamplifier needs independent external power supply to power, if passage is more, in the longer situation of measuring distance wiring move very inconvenient.And phantom power supplied principle is as shown in Figure 4, signal and power sharing coaxial cable, C7 and C8 isolated DC signal, and L1 and L6 isolates AC signal.C7 and C8, except adopting polar capacitor, also can adopt polarity free capacitor, such as 102 or 104 etc.
Inductance L 1 and L6 are used for the signal of the system that excludes, and need the electric capacity accessing an about 100uF respectively, form filter circuit with inductance, every falling system alternating current component at the end of L1 and L6.Electric capacity wherein added by L1 end as shown in Figure 3, be C9, and the electric capacity be connected with L6 is due in data acquisition board, so do not mark.The value of L1 and L6 directly affects the operating characteristic of amplifier, and when getting 1mH, the low frequency of signal is by the about 20KHz of frequency, and the inductance increasing L1 and L6 can reduce the low frequency of signal by frequency, and it is 1mH that the present invention gets L1 and L6, meets system requirements.
4 system performance testings
The preamplifier left end of design is the input of signal, and right-hand member is through amplifying signal output.Whole preamplifier is tested, in order to ensure the accuracy measured, signal input part replaces calibrate AE sensor by signal generator, the circuit of test right-hand member design as shown in Fig. 4 right-hand member, wherein L6 end connects+28V DC power supply, the negative terminal of oscilloscope input termination C8, forms a complete Measure Channel.
28V DC power supply is provided to system by inductance L 6 and coaxial cable, when signal generator input amplitude is the sinusoidal signal of 20mVpp, this preamplifier output is tested respectively under the frequency of 40KHz, 100KHz, 200 KHz, 300KHz, oscillographic output waveform also demonstrates the correctness of hardware designs, meets designing requirement originally completely.
The foregoing is only embodiments of the invention, be not limited to the present invention.The present invention can have various suitable change and change.All any amendments done within the spirit and principles in the present invention, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (3)
1. acoustic emission detector preamplifier, is characterized in that:
Described acoustic emission detector preamplifier comprises amplifier section, power unit and signal isolated part;
Described primary sound emission detector adopts the PCI-1 type of American Physical acoustics company, and its subsidiary preamplifier is 28V direct current supply, and supply current is 0.2A; Frequency is at 100 ~ 300KHz, and sensor interface adopts single-ended and difference two kinds of input patterns, gain 20,40 and 60dB adjustable; In use adopt single-ended mode, i.e. transducer in-phase end input, end of oppisite phase ground connection; Described amplifier section adopts secondary amplifier.
2. acoustic emission detector preamplifier as claimed in claim 1, is characterized in that:
Described power unit is the switch back-pressure circuit adopting MC34063 chip to form, the electric current of resistance (R5) control system, and electric capacity (C5) is used for arranging the switching frequency of DC chip; When 1 conducting of chip internal switch transistor T, electric current flows to ground through 1 pin of MC34063,2 pin and inductance (L2), inductance (L2) stored energy, when T1 disconnects, fly-wheel diode (D1) conducting, inductance (L2) exports negative voltage through fly-wheel diode (D1) to load; The inverting input (pin 5) of comparator monitors output voltage by external divider resistance (R6, R7).
3. acoustic emission detector preamplifier as claimed in claim 1 or 2, is characterized in that:
Described signal isolated part adopts electric capacity (C7) and electric capacity (C8) isolated DC signal, and inductance (L1) and inductance (L6) isolate AC signal, the electric capacity of an about 100uF is accessed respectively at the end of inductance (L1) and inductance (L6), filter circuit is formed, every falling system alternating current component with inductance.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510300683.7A CN104883147A (en) | 2015-06-04 | 2015-06-04 | Preamplifier of acoustic emission detector |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510300683.7A CN104883147A (en) | 2015-06-04 | 2015-06-04 | Preamplifier of acoustic emission detector |
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| CN104883147A true CN104883147A (en) | 2015-09-02 |
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| CN201510300683.7A Pending CN104883147A (en) | 2015-06-04 | 2015-06-04 | Preamplifier of acoustic emission detector |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111696690A (en) * | 2020-06-22 | 2020-09-22 | 中国核动力研究设计院 | Wide-temperature radiation-resistant adjuster for detecting acoustic emission signals of reactor |
| CN113970596A (en) * | 2021-10-12 | 2022-01-25 | 湖南大学 | Stress wave extraction device and method suitable for power device |
| CN114354765A (en) * | 2021-12-02 | 2022-04-15 | 中国核电工程有限公司 | Single-channel acoustic emission signal acquisition device for nuclear power station |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20040178806A1 (en) * | 2003-03-10 | 2004-09-16 | Foreman Donald S. | Micropower apparatus for low impedance measurements |
| CN103471765A (en) * | 2013-09-06 | 2013-12-25 | 北京遥测技术研究所 | Underwater dynamic pressure sensor signal conditioning circuit |
-
2015
- 2015-06-04 CN CN201510300683.7A patent/CN104883147A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20040178806A1 (en) * | 2003-03-10 | 2004-09-16 | Foreman Donald S. | Micropower apparatus for low impedance measurements |
| CN103471765A (en) * | 2013-09-06 | 2013-12-25 | 北京遥测技术研究所 | Underwater dynamic pressure sensor signal conditioning circuit |
Non-Patent Citations (1)
| Title |
|---|
| 王银玲等: "基于FPGA的声发射检测仪的设计", 《仪器研制》 * |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111696690A (en) * | 2020-06-22 | 2020-09-22 | 中国核动力研究设计院 | Wide-temperature radiation-resistant adjuster for detecting acoustic emission signals of reactor |
| CN113970596A (en) * | 2021-10-12 | 2022-01-25 | 湖南大学 | Stress wave extraction device and method suitable for power device |
| CN114354765A (en) * | 2021-12-02 | 2022-04-15 | 中国核电工程有限公司 | Single-channel acoustic emission signal acquisition device for nuclear power station |
| CN114354765B (en) * | 2021-12-02 | 2024-06-14 | 中国核电工程有限公司 | Single-channel acoustic emission signal acquisition device for nuclear power station |
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