CN2098775U

CN2098775U - Circuit for avoiding microphone from producing noise

Info

Publication number: CN2098775U
Application number: CN 91219168
Authority: CN
Inventors: 严进发
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-07-25
Filing date: 1991-07-25
Publication date: 1992-03-11

Abstract

The utility model relates to a circuit for avoiding microphone from producing noise, comprising the normal phase detection circuit of a microphone, the reversed phase detection circuit of the microphone, a normal phase amplifier, a reversed phase amplifier, a balanced output regulating circuit, a power amplifier and an acoustic horn, wherein, the normal phase detection circuit of the microphone sends the signal of a sound source to the normal phase amplifier after detecting the sound source, the normal phase detection circuit of the microphone adjusts the balanced output between the signal of the sound source and the signal of an adjacent sound source detected by the reversed phase detection circuit of the microphone through the reversed phase amplifier, and then the signal is amplified by the power amplifier and broadcast by the acoustic horn. Therefore, the interfere of noise is relieved, and the aim of avoiding noise is obtained.

Description

Circuit for avoiding microphone from producing noise

The utility model is a kind of circuit arrangement that prevents the microphone generating howling, You Zhiyi utilizes positive-negative phase microphone detecting circuit, detect the mode of propaganda directed to communicate source of sound and near source of sound jointly, reach signal and check and balance and offset or the effect of compacting, (split form the positive antiphase source of sound perceptron) just as the human body ear in the head both sides.

The microphone loudspeaker of commonly using is to receive the sound source signal of propagandaing directed to communicate with a microphone, promptly exports loudspeaker to and sounding after amplifying via amplifier, this mode very easily produces howling, especially heal when big in volume, will heal obviously, this is that diffusion because of sound after the sound horn causes the positive feedback, repetition is picked up via microphone, amplifying circuit is produced due to the positive phase oscillation, therefore produce howling, when volume increases, feedback quantity is bigger, and the situation of therefore uttering long and high-pitched sounds is more serious; This kind vicious circle phenomenon can slightly be improved it by strengthening microphone body directive property.Subtract it slightly, then effect is limited, can't restrains the generation of howling fully.Given this, so the inventor concentrates on studies, wish to find a kind of complete design, make the generation that to restrain howling, make the effect of megaphone can more attain perfection, finally Providence doesn't let down a man who does his best, after going through research for a long time, realize about the human body ear each one (just as microphone positive and negative each one) and the principle of face one (just as loudspeaker) and success develop this circuit design, by this, can reach the purpose of eliminating howling fully, and the volume of megaphone can be risen at utmost, and be the following new milestone of history rewriting of megaphone.

Combine it, the main purpose of the utility model ties up in a kind of circuit arrangement that prevents the microphone generating howling is provided, and by the restraining function of just anti-phase two groups of circuit, and can reach the purpose that promotes tonequality, volume.

For structure, feature and other purpose that can more deep clear the utility model, referring now to accompanying drawing describe in detail as after.

Description of drawings:

Fig. 1 is the structure calcspar of the utility model.

Fig. 2 is the embodiment circuit diagram of the utility model.

Label declaration:

1 keynote source, 11 positive microphone detecting circuits

12 positive amplifiers, 2 secondary sources of sound

21 anti-phase microphone detecting circuit 22 inverting amplifiers

3 balance output regulation circuits, 4 power amplifiers

5 loudspeaker

C1, C2, C3, C4, C5, C6, C7, C8 capacitor

R1, R2, R3, R4, R5, R6, R7, R8 resistor

SR1 variable resistor IC1 integrated circuit

IC2 integrated circuit M1 positive microphone

The anti-phase microphone of M2.

See also shown in Fig. 1 square, the utility model system is made up of positive microphone detecting circuit 11, positive amplifier 12, anti-phase microphone detecting circuit 21, inverting amplifier 22, the institutes such as balance output Circuit tuning 3, power amplifier 4 and loudspeaker 5; Wherein, keynote source 1 is the sound of propagandaing directed to communicate, pick up via positive microphone detecting circuit 11 and to detect, after giving positive amplifier 12 to do the signal amplification, reach again balance output Circuit tuning 3, and via after power amplifier 4 amplifications, make and to promote loudspeaker 5 and sound, at this moment, near the back coupling sound 2 of source of sound can be picked up by anti-phase microphone detecting circuit 21 inspections, and inverting amplifier 22 is given in it transmission, deliver to again balance Circuit tuning 3, make the signal with positive amplifier 12 outputs, produce the effect that positive negative potential offsets, because of balance output Circuit tuning 3 when adjusting, system's tendency positive amplifier 12 output end signals here, therefore, the positive and negative effect of offseting is very small, and when howling produces, the output of inverting amplifier 22 increases suddenly, also just form and effect that positive amplifier 12 output end signals offset more greatly, so, Just be cancelled before howling not yet is completed into, so continuous being under the state of pining down can be reached the state that prevents the howling generation, and can reach the effect that promotes the megaphone volume.

See also shown in Figure 2, be the circuit diagram of embodiment, wherein, microphone M1 is responsible for picking up the inspection sound of propagandaing directed to communicate, and transfer to by integrated circuit (IC) 1, resistor R 2, R3, R4, R5 and capacitor C1, C2, C3, C5, positive microphone amplifying circuit that C7 constituted, produce positive current potential amplification effect; In addition, pick up the back coupling sound passed back of inspection loudspeaker, and, produce anti-phase current potential amplification effect by integrated circuit (IC) 2, resistor R 1, R6, R7, R8 and capacitor C4, anti-phase microphone amplifying circuit that C6 constituted via microphone M2; The output of these two groups of amplifiers is connected on the two ends of variable resistor SR1, and takes out the signal of balance output by the centre cap position, transfers to power-amplifier stage again and puts output by force, promotes sound horn; Because variable resistor SR1 when adjusting, is tendency positive amplifier out this side, therefore, when howling takes place, will produce bigger traction suppression, and howling is cancelled, making also not to have howling and to produce under big volume output state.

Take a broad view of the above, the utility model is one with just anti-phase being used for reaching and restraining the design that the megaphone howling takes place of offseting, this kind mode is initiative in existing megaphone system, and do not see any publication earlier, the record that does not also have the public publication sale, and its effect brilliance meets the necessary and sufficient condition of practicality, is the utility model of tool innovation and practical value.

Claims

1, a kind of circuit arrangement that prevents the microphone generating howling, it is characterized in that this circuit arrangement comprises: positive microphone detecting circuit, positive amplifier, anti-phase microphone detecting circuit, inverting amplifier, balance output regulation circuit, power amplifier and loudspeaker; Wherein, positive microphone detecting circuit can pick up examines the sound of propagandaing directed to communicate, and will pick up the signal of back, transmission is given the positive amplifier and is done to amplify output, and reaches one of balance output regulation circuit end, in addition, anti-phase microphone detecting circuit can pick up inspection back coupling sound, and the signal that will pick up, transmission is given inverting amplifier and is done to amplify output, and reaches holding in addition of balance output regulation circuit; Through the balance output regulation circuit two signals are done the balance adjustment again and take out the utter long and high-pitched sounds signal of electric current of real nothing; This kind utilizes one group of inverting amplifier of one group of positive, and produces the state of braking counteracting by the balance output regulation circuit, but autobalance is restrained the abnormal current that is produced when uttering long and high-pitched sounds, and makes the state that does not also have the howling generation when big volume is exported that reaches.