CN2265655Y

CN2265655Y - Active electrodynamic microphone

Info

Publication number: CN2265655Y
Application number: CN 96217779
Authority: CN
Inventors: 王月明
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-07-22
Filing date: 1996-07-22
Publication date: 1997-10-22
Anticipated expiration: 2006-07-22

Abstract

The utility model relates to a microphone which adopts the basic structure of a moving-coil type microphone. The utility model is formed by additional arrangement of a multi-turn coil B and a 3 V electric supply class-A amplifying circuit. The utility model not only has the advantages of the moving-coil type microphone, but also has the unique advantages of increased low frequency, expended frequency response, increased sensitivity, reduced amplitude distortion, simple circuit and stable working performance.

Description

Active moving-coil microphone

The utility model relates to a kind of moving-coil microphone, specifically is a kind of acoustical-electrical transducer spare of being made up of sound film, voice coil loudspeaker voice coil, permanent magnet, soft iron and shell.

The most frequently used moving-coil microphone is to drive voice coil loudspeaker voice coil cutting magnetic line in permanent magnet field by the vibration of sound film at present, acoustic energy is changed into the device of electric energy.Its sound construction, working stability, low price, applied range, but also exist some shortcomings, such as: the permanent magnetic field of moving-coil microphone is to be set up by a permanent magnet, and because of reasons such as service time are permanent, field intensity will weaken, and sensitivity will reduce; The vibration of sound film is subjected to air drag and reaches the fixedly traction action of voice coil loudspeaker voice coil tension force, and amplitude is compressed, and causes the large-signal amplitude distortion; The induced electromotive force that voice coil loudspeaker voice coil vibration produces is in frequency response range, and along with frequency rises and increases, the low frequency amplitude is little; Effect of inertia reduces the high frequency response ability during vibration of sound film.

The purpose of this utility model is: provide a kind of and have highly sensitively, can promote the amplitude of low frequency signal, the high-performance microphone that frequency response is wide.

Concrete technical scheme of the present utility model is: close around one group of multiturn coil B on the permanent magnet of moving-coil microphone in-core, and 3 volts of power supply Ec of moving-coil microphone voice coil loudspeaker voice coil one termination negative pole, another termination electrochemical capacitor of voice coil loudspeaker voice coil C negative pole, the positive pole of C and two resistance R ₂, R ₂An end and NPN type triode BG ₁Base stage link R ₂The negative pole of another termination Ec, R ₁The other end and an end and the Ec positive pole of coil B link, the magnetic field that the electric current that flows into coil B is produced is consistent with the magnetic direction of permanent magnet, the other end of coil B and positive-negative-positive triode BG ₂Emitter link BG ₁Collector electrode and BG ₂Base stage link BG ₁Emitter and an adjustable resistance W slide head link the termination BG of W ₂Collector electrode, another termination Ec negative pole of W, the W two ends are microphone output.

Operation principle of the present utility model is: pass through R ₁And R ₂Be BG ₁, BG ₂Provide the positive bias operating voltage, BG ₁With BG ₂Straight coupling constitutes the Class A amplifying circuit, and the signal of telecommunication is exported by the W two ends from the negative pole and ground input of capacitor C.Be characterized in: coil B (5) is BG ₁Inductive load, be again BG ₂Perceptual negative feedback resistor, and can be by magnetic coupling x and voice coil loudspeaker voice coil formation positive feedback loop; Adjustable resistance W is BG ₂Load, again the part be BG ₁Negative feedback resistor.

Special-effect of the present utility model is: the intensity that former magnetic field is strengthened in the magnetic field that the direct current composition among the coil B (5) produces, can improve sensitivity, and play the effect of magnetizing; Coil B (5) is BG ₂Perceptual negative feedback resistor, low frequency signal is had castering action; Variation magnetic field that tone currents among the coil B (5) produces and voice coil loudspeaker voice coil magnetic coupling form positive feedback loop, make large-signal increase the weight of to amplify and reduce the signal amplitude distortion, can make voice coil loudspeaker voice coil produce the effect that induced current is subjected to Ampere force again, slacken voice coil loudspeaker voice coil inertia, the widening frequency band response.

Fig. 1 is the utility model structural representation;

Fig. 2 is the utility model amplifier circuit figure;

Fig. 3 is that one of the utility model is implemented illustration;

1 is the sound film among the figure, the 2nd, and voice coil loudspeaker voice coil, the 3rd, cylinder type hollow soft iron shell, the 4th, cylindrical permanent magnet, the 5th, coil B, the 6th, amplifier, the 7th, microphone enclosure, the 8th, mains switch.

The utility model is described in further detail below in conjunction with accompanying drawing:

As shown in Figure 1: close around one group of multiturn coil B (5) on the permanent magnet (4) of the moving-coil microphone core that sound film (1), voice coil loudspeaker voice coil (2), soft iron (3) and permanent magnet (4) are formed, coil B (5) two ends are drawn outside the shell in the soft iron shell with flexible conductor, this microphone core is inserted in the empty cabin of microphone enclosure (7) head, put power supply Ec and amplifier (6) at the microphone enclosure middle part, mains switch (8) is set on the microphone enclosure arm, and output line is drawn in the microphone bottom; Amplifier circuit as shown in Figure 2; 3 volts of power supply Ec of voice coil loudspeaker voice coil one termination negative pole, another termination electrochemical capacitor of voice coil loudspeaker voice coil C negative pole, the positive pole of C and two resistance R ₁, R ₂An end and NPN type triode BG ₁Base stage link R ₂The negative pole of another termination Ec, R ₁The other end and an end and the Ec positive pole of coil B link, the magnetic field that the electric current that flows into coil B is produced is consistent with the magnetic direction of permanent magnet, the other end of coil B and positive-negative-positive triode BG ₂Emitter link BG ₁Collector electrode and BG ₂Base stage link BG ₁Emitter and an adjustable resistance W slide head link the termination BG of W ₂Collector electrode, another termination Ec negative pole of W, the W two ends are microphone output.Also can set up ringing circuit as shown in Figure 3 on this basis, be convenient to check the silent that amplified before the large-scale meeting.When the general test-run a machine inspection of people at present amplifies the sound, facing to the microphone air blowing or with finger tapping microphone outer cover, cause microphone sound film to be subjected to powerful the impact often, the as easy as rolling off a log sound film that makes is impaired, also brings some discordant noises to the meeting-place.After installing ringing circuit additional, can set up a test-run a machine knob, after turning round by this, can produce the melodious the tinkle of bells of a kind of harmony, both can check the silent that amplified, can inform that again participant's meeting begins.Ringing circuit selects for use Shanghai scientific popularization publishing house to publish, and Hao Hongan writes " 555 integrated circuit practical circuit collection " book, and the 43rd page of Fig. 3 .3 circuit if set up the active passive change over switch again, also can use as general moving-coil microphone under the passive situation.K in the accompanying drawing 3 ₁Be test-run a machine knob open in usual, K ₂Be dpdt double-pole double-throw (DPDT) active passive change over switch, K ₃Be the single-pole single-throw(SPST mains switch.Use when active, with K ₂Push active shelves, K _2-1The non-earth terminal of voice coil loudspeaker voice coil is inserted input amplifier C negative pole, K _2-2Non-ground wire of output and BG ₂Collector electrode connects, closed mains switch K ₃, microphone is active amplification output, turns round K by test-run a machine ₁, ringing circuit work; Use when passive, with K ₂Push passive shelves, voice coil loudspeaker voice coil non-ground-end and amplifying circuit disconnect, output non-ground-end and BG ₂Also disconnect, pass through K _2-1And K _2-2Voice coil loudspeaker voice coil is directly exported, and microphone is not for there being the output of amplification.

Claims

1. an active moving-coil microphone is made up of moving-coil microphone core, amplifier and shell; It is characterized in that: close around one group of multiturn coil B on the permanent magnet of moving-coil microphone in-core, 3 volts of power supply Ec of moving-coil microphone voice coil loudspeaker voice coil one termination negative pole, another termination electrochemical capacitor of voice coil loudspeaker voice coil C negative pole, the positive pole of C and two resistance R ₁, R ₂An end and NPN type triode BG ₁Base stage link R ₂The negative pole of another termination Ec, R ₁The other end and an end and the Ec positive pole of coil B link, the magnetic field that the electric current that flows into coil B is produced is consistent with the magnetic direction of permanent magnet, the other end of coil B and positive-negative-positive triode BG ₂Emitter link BG ₁Collector electrode and BG ₂Base stage link BG ₁Emitter and an adjustable resistance W slide head link the termination BG of W ₂Collector electrode, another termination Ec negative pole of W, the W two ends are microphone output.