CN221042805U - Pre-amplifier circuit for free-field microphone - Google Patents
Pre-amplifier circuit for free-field microphone Download PDFInfo
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- CN221042805U CN221042805U CN202323084274.7U CN202323084274U CN221042805U CN 221042805 U CN221042805 U CN 221042805U CN 202323084274 U CN202323084274 U CN 202323084274U CN 221042805 U CN221042805 U CN 221042805U
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- 238000003199 nucleic acid amplification method Methods 0.000 claims abstract description 14
- 239000003990 capacitor Substances 0.000 claims description 51
- 230000000087 stabilizing effect Effects 0.000 claims description 23
- 230000005669 field effect Effects 0.000 claims description 21
- 238000001914 filtration Methods 0.000 claims description 17
- 230000009286 beneficial effect Effects 0.000 abstract description 2
- 230000010287 polarization Effects 0.000 description 5
- 239000000463 material Substances 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 239000004677 Nylon Substances 0.000 description 1
- 239000004809 Teflon Substances 0.000 description 1
- 229920006362 Teflon® Polymers 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 230000007274 generation of a signal involved in cell-cell signaling Effects 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
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Abstract
The utility model provides a pre-amplifier circuit for a free-field microphone, which comprises a signal filter circuit, a pre-amplification main circuit and a noise-removal voltage-stabilizing circuit, wherein the input end of the signal filter circuit is connected with the output end of an electret microphone, the output end of the signal filter circuit is connected with the input end of the pre-amplification main circuit, the output end of the pre-amplification main circuit is connected with the input end of the noise-removal voltage-stabilizing circuit, and the output end of the noise-removal voltage-stabilizing circuit is connected with the input end of a subsequent signal processing and amplifying circuit. The beneficial effects of the utility model are as follows: the ultra-weak electric signal output by the electret microphone can be initially amplified and then transmitted to a subsequent signal processing amplifying circuit for signal processing.
Description
Technical Field
The utility model relates to the technical field of circuits, in particular to a preamplifier circuit for a free-field microphone.
Background
Electret microphones are condenser microphones in which a polarized power supply is replaced with an electret that has been polarized by injecting electric charges in advance. Electret microphones are of two types, one is to use resident polymer film material as a vibrating diaphragm (vibration mode), and the vibrating diaphragm simultaneously plays the double roles of sound wave receiving and polarization voltage; the other is to make the back plate (back plate) of the electret material, which then only acts as a polarization voltage. The microphone has a simplified structure because it does not require polarization voltage. In addition, microphones with applied polarization voltages have been gradually replaced in sound recording and sound amplification and outdoor noise measurement because of their good electroacoustic characteristics.
The basic structure of the electret microphone consists of an electret film coated with metal, a metal electrode (called a back plate electrode) with a plurality of small holes, and a nylon isolation pad of tens of micrometers in between. Electrets are made of a specially selected and stable high temperature polymeric material (such as a very thin teflon film) that retains frozen charges thereon that create the necessary electric field when subjected to high voltage polarization. The frozen charge is kept in the electret, the total charge amount of the electret is unchanged due to the fact that a discharge loop is not arranged, the electret film is stable for thousands of years, polarized charges are distributed on the electret film, when the electret film is vibrated by sound waves to generate movement, the distance between two polar plates of the capacitor is changed, and therefore the capacitor is changed, and the charge amount on the electret is constant, and is known according to the formula q=cu: when C changes, the voltage U at the two ends of the capacitor is inevitably changed, so that an electric signal is output, and the conversion from sound vibration to electric signal generation is realized.
Currently, electret microphones are most commonly found in free field microphones. However, the capacitance between the electret diaphragm and the metal plate of the free-field microphone is relatively small, the output electrical signal is extremely weak, typically between 2 and 60pF, typically 10-12pF, depending on the microphone size, and thus its output impedance is very high (xc=1/2 pi fc), about several tens of megaohms or more, so that it cannot be directly connected to the amplifying circuit.
Disclosure of utility model
In order to solve the problems in the prior art, the utility model provides a pre-amplifier circuit for a free-field microphone, which solves the problems that an electret microphone applied to the free-field microphone in the prior art can not be directly connected with an amplifying circuit because an electric signal output by the electret microphone is extremely weak by arranging a signal filtering circuit, a pre-amplifying main circuit and a noise-removing voltage stabilizing circuit which are mutually matched in the pre-amplifier circuit of the free-field microphone.
The utility model provides a pre-amplifier circuit for a free-field microphone, which is arranged between an electret microphone in the free-field microphone and a subsequent signal processing amplifying circuit, and comprises a signal filtering circuit, a pre-amplifying main circuit and a noise removal voltage stabilizing circuit, wherein the input end of the signal filtering circuit is connected with the output end of the electret microphone, the output end of the signal filtering circuit is connected with the input end of the pre-amplifying main circuit, the output end of the pre-amplifying main circuit is connected with the input end of the noise removal voltage stabilizing circuit, the output end of the noise removal voltage stabilizing circuit is connected with the input end of the subsequent signal processing amplifying circuit, and an extremely weak electric signal output by the electret microphone can be sequentially filtered by the signal filtering circuit, amplified by the pre-amplifying main circuit, noise removed and stabilized by the noise removal voltage stabilizing circuit and then sent to the subsequent signal processing amplifying circuit for processing.
The utility model further improves, a field effect transistor Q1, a triode Q2, a resistor R4, a resistor R5 and a capacitor C2 are arranged in the pre-amplification main circuit, wherein the grid electrode of the field effect transistor Q1 is connected with the output end of the signal filtering circuit, the drain electrode of the field effect transistor Q1 is connected with the emitting electrode of the triode Q2 and the input end of the denoising voltage stabilizing circuit, the source electrode of the field effect transistor Q1 is connected with one end of the resistor R4, one end of the resistor R5 and one end of the capacitor C2, the base electrode of the triode Q2 is connected with the other end of the resistor R4 and the other end of the capacitor C2, and the collector electrode of the triode Q2 and the other end of the resistor R5 are grounded.
According to the utility model, a resistor R1, a resistor R7 and a capacitor C1 are arranged in the signal filter circuit, wherein one end of the capacitor C1 is connected with the output end of the electret microphone, the other end of the capacitor C1 is connected with one end of the resistor R7 and the grid electrode of the field effect tube Q1, the other end of the resistor R7 is connected with one end of the resistor R1, and the other end of the resistor R1 is grounded.
The utility model further improves, a resistor R2, a resistor R3, a capacitor C4 and a capacitor C6 are arranged in the denoising voltage stabilizing circuit, wherein one end of the capacitor C4 is connected with the drain electrode of the field effect transistor Q1, the emitter electrode of the triode Q2, one end of the resistor R3 and the input end of a subsequent signal processing amplifying circuit, the other end of the resistor R3 is connected with one end of the resistor R2 and one end of the capacitor C6, the other end of the resistor R2 is connected with one end of the resistor R1 and the other end of the resistor R7, and the other end of the capacitor C4 and the other end of the capacitor C6 are grounded.
According to the utility model, the model of the field effect transistor Q1 is 2SK208, and the model of the triode Q2 is BC857C.
According to the utility model, the resistance value of the resistor R4 is 120KΩ, the resistance value of the resistor R5 is 20KΩ, and the capacitance value of the capacitor C2 is 105uF.
According to the utility model, the resistance value of the resistor R1 is 100KΩ, the resistance value of the resistor R7 is 100MΩ, and the capacitance value of the capacitor C1 is 10uF.
According to the utility model, the resistance of the resistor R2 is 50KΩ, the resistance of the resistor R3 is 20KΩ, the capacitance of the capacitor C4 is 101uF, and the capacitance of the capacitor C6 is 4.7uF.
Compared with the prior art, the utility model has the beneficial effects that: the pre-amplifier circuit is provided with a signal filtering circuit, a pre-amplifying main circuit and a denoising voltage stabilizing circuit which are matched with each other, so that extremely weak electric signals output by an electret microphone can be sequentially filtered by the signal filtering circuit, amplified by the pre-amplifying main circuit, denoised and stabilized by the denoising voltage stabilizing circuit and then sent to a subsequent signal processing and amplifying circuit for processing, and extremely weak electric signals output by the electret microphone can be initially amplified and then transmitted to the subsequent signal processing and amplifying circuit for signal processing, and the problem that the extremely weak electric signals output by the electret microphone applied to the free microphone in the prior art cannot be directly connected with the amplifying circuit is solved.
Drawings
In order to more clearly illustrate the utility model or the solutions of the prior art, a brief description will be given below of the drawings used in the description of the embodiments or the prior art, it being obvious that the drawings in the description below are some embodiments of the utility model and that other drawings can be obtained from them without the inventive effort of a person skilled in the art.
Fig. 1 is a schematic block diagram of a preamplifier circuit for a free-field microphone in accordance with the utility model.
Detailed Description
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this utility model belongs; the terminology used in the description of the applications herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the utility model; the terms "comprising" and "having" and any variations thereof in the description of the utility model and the claims and the description of the drawings above are intended to cover a non-exclusive inclusion. The terms first, second and the like in the description and in the claims or in the above-described figures, are used for distinguishing between different objects and not necessarily for describing a sequential or chronological order.
Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the utility model. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments.
In order to make the person skilled in the art better understand the solution of the present utility model, the technical solution of the embodiment of the present utility model will be clearly and completely described below with reference to the accompanying drawings.
As shown in fig. 1, the preamplifier circuit for the free-field microphone provided by the utility model is arranged between an electret microphone in the free-field microphone and a subsequent signal processing amplifying circuit, and comprises a signal filtering circuit, a preamplifier main circuit and a noise-removing voltage-stabilizing circuit, wherein the input end of the signal filtering circuit is connected with the output end of the electret microphone, the output end of the signal filtering circuit is connected with the input end of the preamplifier main circuit, the output end of the preamplifier main circuit is connected with the input end of the noise-removing voltage-stabilizing circuit, and the output end of the noise-removing voltage-stabilizing circuit is connected with the input end of the subsequent signal processing amplifying circuit. In this embodiment, the very weak electrical signal output by the electret microphone can be sequentially filtered by the signal filtering circuit, amplified by the pre-amplifying main circuit, and then sent to the subsequent signal processing amplifying circuit for processing after being denoised and stabilized by the denoise and stabilizing circuit, that is, the very weak electrical signal output by the electret microphone can be initially amplified and then transmitted to the subsequent signal processing amplifying circuit for signal processing.
As shown in fig. 1, a field effect transistor Q1, a triode Q2, a resistor R4, a resistor R5 and a capacitor C2 are arranged in the pre-amplification main circuit, wherein a grid electrode of the field effect transistor Q1 is connected with an output end of the signal filtering circuit, a drain electrode of the field effect transistor Q1 is connected with an emitting electrode of the triode Q2 and an input end of the denoising voltage stabilizing circuit, a source electrode of the field effect transistor Q1 is connected with one end of the resistor R4, one end of the resistor R5 and one end of the capacitor C2, a base electrode of the triode Q2 is connected with the other end of the resistor R4 and the other end of the capacitor C2, and a collector electrode of the triode Q2 and the other end of the resistor R5 are grounded; the model of the field effect transistor Q1 is 2SK208, and the model of the triode Q2 is BC857C; the resistance of the resistor R4 is 120KΩ, the resistance of the resistor R5 is 20KΩ, and the capacitance of the capacitor C2 is 105uF. In this embodiment, the pre-amplifying main circuit is configured to amplify the very weak electric signal output by the electret microphone filtered by the signal filtering circuit, so as to facilitate the subsequent signal processing by the signal processing amplifying circuit.
As shown in fig. 1, a resistor R7 and a capacitor C1 are arranged in the signal filter circuit, wherein one end of the capacitor C1 is connected with the output end of the electret microphone, the other end of the capacitor C1 is connected with one end of the resistor R7 and the grid electrode of the field effect transistor Q1, the other end of the resistor R7 is connected with one end of the resistor R1, and the other end of the resistor R1 is grounded; the resistance of the resistor R1 is 100KΩ, the resistance of the resistor R7 is 100MΩ, and the capacitance of the capacitor C1 is 10uF. In this embodiment, the signal filtering circuit is configured to filter a very weak electrical signal output by the electret microphone, and output the filtered very weak electrical signal to the pre-amplifying main circuit for amplification, so as to reduce a noise ratio in the signal.
As shown in fig. 1, a resistor R2, a resistor R3, a capacitor C4 and a capacitor C6 are arranged in the denoising voltage stabilizing circuit, wherein one end of the capacitor C4 is connected with the drain electrode of the field effect transistor Q1, the emitter electrode of the triode Q2, one end of the resistor R3 and the input end of the subsequent signal processing amplifying circuit, the other end of the resistor R3 is connected with one end of the resistor R2 and one end of the capacitor C6, the other end of the resistor R2 is connected with one end of the resistor R1 and the other end of the resistor R7, and the other end of the capacitor C4 and the other end of the capacitor C6 are grounded; the resistance of the resistor R2 is 50KΩ, the resistance of the resistor R3 is 20KΩ, the capacitance of the capacitor C4 is 101uF, and the capacitance of the capacitor C6 is 4.7uF. In this embodiment, the denoising voltage stabilizing circuit is used for denoising and stabilizing the very weak electric signal output by the electret microphone amplified by the pre-amplifying main circuit, so as to reduce the noise ratio in the signal and facilitate the subsequent signal processing and amplifying circuit to process the signal.
In the utility model, the signal filter circuit, the pre-amplification main circuit and the noise removal voltage stabilizing circuit are arranged in the pre-amplifier circuit of the free field microphone, so that the extremely weak electric signals output by the electret microphone can be sequentially filtered by the signal filter circuit, amplified by the pre-amplification main circuit, subjected to noise removal voltage stabilizing by the noise removal voltage stabilizing circuit and then sent to the subsequent signal processing amplifying circuit for processing, and the extremely weak electric signals output by the electret microphone can be primarily amplified and then transmitted to the subsequent signal processing amplifying circuit for signal processing, thereby solving the problem that the electric signals output by the electret microphone applied to the free field microphone in the prior art cannot be directly connected with the amplifying circuit.
The above embodiments are preferred embodiments of the present utility model, and are not intended to limit the scope of the present utility model, which includes but is not limited to the embodiments, and equivalent modifications according to the present utility model are within the scope of the present utility model.
Claims (8)
1. A preamplifier circuit for a free-field microphone, disposed between an electret microphone in the free-field microphone and a subsequent signal processing amplifier circuit, characterized by: the signal filter circuit is characterized by comprising a signal filter circuit, a pre-amplification main circuit and a denoising voltage stabilizing circuit, wherein the input end of the signal filter circuit is connected with the output end of the electret microphone, the output end of the signal filter circuit is connected with the input end of the pre-amplification main circuit, the output end of the pre-amplification main circuit is connected with the input end of the denoising voltage stabilizing circuit, the output end of the denoising voltage stabilizing circuit is connected with the input end of a subsequent signal processing amplifying circuit, and an extremely weak electric signal output by the electret microphone can be sequentially filtered by the signal filter circuit, amplified by the pre-amplification main circuit, denoised and stabilized by the denoising voltage stabilizing circuit and then sent to the subsequent signal processing amplifying circuit for processing.
2. The preamplifier circuit for a free-field microphone according to claim 1, wherein: the pre-amplification main circuit is internally provided with a field effect tube Q1, a triode Q2, a resistor R4, a resistor R5 and a capacitor C2, wherein the grid electrode of the field effect tube Q1 is connected with the output end of the signal filtering circuit, the drain electrode of the field effect tube Q1 is connected with the emitting electrode of the triode Q2 and the input end of the denoising voltage stabilizing circuit, the source electrode of the field effect tube Q1 is connected with one end of the resistor R4, one end of the resistor R5 and one end of the capacitor C2, the base electrode of the triode Q2 is connected with the other end of the resistor R4 and the other end of the capacitor C2, and the collecting electrode of the triode Q2 and the other end of the resistor R5 are grounded.
3. The preamplifier circuit for a free-field microphone according to claim 2, wherein: the signal filtering circuit is internally provided with a resistor R1, a resistor R7 and a capacitor C1, wherein one end of the capacitor C1 is connected with the output end of the electret microphone, the other end of the capacitor C1 is connected with one end of the resistor R7 and the grid electrode of the field effect tube Q1, the other end of the resistor R7 is connected with one end of the resistor R1, and the other end of the resistor R1 is grounded.
4. A preamplifier circuit for a free-field microphone according to claim 3, characterized by: the noise-removal voltage stabilizing circuit is internally provided with a resistor R2, a resistor R3, a capacitor C4 and a capacitor C6, wherein one end of the capacitor C4 is connected with the drain electrode of the field effect tube Q1, the emitter electrode of the triode Q2, one end of the resistor R3 and the input end of a subsequent signal processing amplifying circuit, the other end of the resistor R3 is connected with one end of the resistor R2 and one end of the capacitor C6, the other end of the resistor R2 is connected with one end of the resistor R1 and the other end of the resistor R7, and the other end of the capacitor C4 and the other end of the capacitor C6 are grounded.
5. The preamplifier circuit for a free-field microphone according to claim 4, wherein: the model of the field effect transistor Q1 is 2SK208, and the model of the triode Q2 is BC857C.
6. The preamplifier circuit for a free-field microphone according to claim 5, wherein: the resistance value of the resistor R4 is 120KΩ, the resistance value of the resistor R5 is 20KΩ, and the capacitance value of the capacitor C2 is 105uF.
7. The preamplifier circuit for a free-field microphone according to claim 6, wherein: the resistance value of the resistor R1 is 100KΩ, the resistance value of the resistor R7 is 100MΩ, and the capacitance value of the capacitor C1 is 10uF.
8. The preamplifier circuit for a free-field microphone according to claim 7, wherein: the resistance value of the resistor R2 is 50KΩ, the resistance value of the resistor R3 is 20KΩ, the capacitance value of the capacitor C4 is 101uF, and the capacitance value of the capacitor C6 is 4.7uF.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202323084274.7U CN221042805U (en) | 2023-11-15 | 2023-11-15 | Pre-amplifier circuit for free-field microphone |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202323084274.7U CN221042805U (en) | 2023-11-15 | 2023-11-15 | Pre-amplifier circuit for free-field microphone |
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| Publication Number | Publication Date |
|---|---|
| CN221042805U true CN221042805U (en) | 2024-05-28 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202323084274.7U Active CN221042805U (en) | 2023-11-15 | 2023-11-15 | Pre-amplifier circuit for free-field microphone |
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| Country | Link |
|---|---|
| CN (1) | CN221042805U (en) |
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- 2023-11-15 CN CN202323084274.7U patent/CN221042805U/en active Active
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