CN202143205U

CN202143205U - Amplitude-modulated wave wireless microphone

Info

Publication number: CN202143205U
Application number: CN201120282434U
Authority: CN
Inventors: 刘喆
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-07-28
Filing date: 2011-07-28
Publication date: 2012-02-08
Anticipated expiration: 2021-07-28

Abstract

The utility model belongs to the field of electronic technology and wireless communication and relates to an amplitude-modulated wave wireless microphone. The amplitude-modulated wave wireless microphone is composed of a direct current (DC) power supply DC, an audio signal pick-up circuit, an audio signal first level amplifying circuit, an audio signal second level amplifying and negative feedback circuit, an amplitude-modulated wave oscillating and emitting circuit and a frequency stabilization circuit. At present, a great number of wireless microphones of a frequency modulation type exist, but common amplitude modulation radios are mostly used by social users so that popularization of the amplitude-modulated wave wireless microphone is urgent. The amplitude-modulated wave wireless microphones play an important role in situations of meetings, music teaching and the like. The amplitude-modulated wave wireless microphones can turn sound signals into amplitude modulation radio signals to be emitted, and after the common amplitude modulation radios receive the radio signals, the amplitude-modulated wave is reproduced into sound signals to be played. Oscillation frequency of the amplitude-modulated wave wireless microphone is stable, frequency is not easy to deviate, the biggest emitting radius is approximately 9 m, and nearby radios can not be disturbed. The amplitude-modulated wave wireless microphone does not need externally connected emitting antennas and is favorable for users to use.

Description

The amplitude-modulated wave wireless microphone

Technical field

The utility model belongs to electronic technology and radio communication field, is about a kind of amplitude-modulated wave wireless microphone.

Background technology

In recent years; Various e-magazines have been published the circuit of a lot of frequency modulation type wireless microphones successively; Their great majority all are directly to be added to transistor base to the audio signal of input to modulate; The junction capacitance between transistor c-b changes the output frequency that changes high-frequency generator in the high-frequency oscillating circuits through changing, thereby realizes the frequency-modulated wave that is modulated into to frequency of oscillation, through high frequency frequency selection circuit and amplifying circuit; At last by antenna to external radiation, this is the general operation principles of most frequency modulation wireless microphones.And society go up the user maximum be the ordinary amplitude modulation broadcast receiver, this just gives to popularize and uses the amplitude-modulated wave wireless microphone that great convenience is provided.The utility model circuit design is complicated a little oscillator; The itself modulating characteristic is better; Can produce the amplitude-modulated signal that frequency is relatively concentrated; Such signal is more much higher than the radio signal fidelity that modulates with other method, and in fact in fact the described amplitude-modulated wave wireless microphone of the utility model is exactly a seat minitype medium wave radio station.

The amplitude-modulated wave wireless microphone closes in fields such as meeting, music teachings all can bring into play great role.It becomes the am radio signal to voice signal and emits, and after being received by the ordinary amplitude modulation broadcast receiver, again the amplitude-modulated wave reduction is become voice signal and plays back.The stable difficult race frequency of the utility model frequency of oscillation, emission maximum radius are about 9m, therefore can not disturb near broadcast receiver.This wireless microphone need not external transmitting antenna, greatly facilitates user's use.

Evidence: the utility model uses all that common discrete component has realized that amplitude-modulated wave wireless microphone circuit structure is simple, circuit production is easy, with low cost and little power consumption, purpose such as be easy to popularize.Below specify the relevant manufacturing technology of this amplitude-modulated wave wireless microphone.

The utility model content

Goal of the invention and beneficial effect: at present the wireless microphone of frequency modulation type is a lot, but society go up the user maximum be the ordinary amplitude modulation broadcast receiver, be the task of top priority so promote the use of the amplitude-modulated wave wireless microphone.The amplitude-modulated wave wireless microphone closes in fields such as meeting, music teachings all can bring into play great role.It can become the am radio signal to voice signal and emits, and after being received by the ordinary amplitude modulation broadcast receiver, again the amplitude-modulated wave reduction is become voice signal and plays back.The stable difficult race frequency of the utility model frequency of oscillation, emission maximum radius are about 9m, therefore can not disturb near broadcast receiver.This wireless microphone need not external transmitting antenna, greatly facilitates user's use.The utility model purpose is to have overcome most on the market frequency modulation wireless microphones and exists the circuit structure complicacy, uses many disadvantages such as element is many.

Technical characterictic: the amplitude-modulated wave wireless microphone, to form by DC power supply DC, audio signal pick-up circuit, audio signal one-level amplifying circuit, the amplification of audio signal secondary and negative-feedback circuit, amplitude-modulated wave vibration and radiating circuit, frequency stabilization circuit, its characteristic comprises:

The audio signal pick-up circuit is made up of Electret condenser microphone MIC, variable resistor RP and capacitor C 1; The annexation of element: the FET drain D among the Electret condenser microphone MIC connects the end of variable resistor RP; One end of the movable knee-joint capacitor C 1 of variable resistor RP, the metal shell end of Electret condenser microphone MIC links to each other with FET source S and circuit ground GND among the Electret condenser microphone MIC;

Audio signal one-level amplifying circuit is made up of NPN type triode VT1, resistance R 1, resistance R 2, resistance R 3, electrochemical capacitor C3 and capacitor C 2; Its annexation: NPN type triode VT1 base stage connects the other end of capacitor C 1 and an end of resistance R 1; The other end connection circuit ground GND of resistance R 1; The end of NPN type triode VT1 collector electrode connecting resistance R2 and an end of capacitor C 2; The anodal VCC of another termination DC power supply DC of resistance R 2, the end of NPN type triode VT1 emitter connecting resistance R3 and the positive pole of electrochemical capacitor C3, the negative pole connection circuit ground GND of the other end of resistance R 3 and electrochemical capacitor C3;

The audio signal secondary amplifies and negative-feedback circuit is made up of NPN type triode VT2, resistance R 4, resistance R 5, resistance R 6; Its annexation: the base stage of NPN type triode VT2 is with connecing the other end of capacitor C 2, an end of resistance R 4 and an end of resistance R 5; The anodal VCC of another termination DC power supply DC of resistance R 4; The other end connection circuit ground GND of resistance R 5, the end of the emitter connecting resistance R6 of NPN type triode VT2, the other end connection circuit ground GND of resistance R 6;

Amplitude-modulated wave vibration and radiating circuit are made up of NPN type triode VT3, resistance R 7, resistance R 8 and capacitor C 5, variable capacitance CP, oscillator coil L1 and frequency stabilization circuit; Its annexation is: the base stage of NPN type triode VT3 is with the end of connecting resistance R7, an end of resistance R 8 and an end of capacitor C 5; The anodal VCC of another termination DC power supply DC of resistance R 7; The other end of the other end of resistance R 8 and capacitor C 5 links to each other with circuit ground GND; The collector electrode of NPN type triode VT3 is with connecing the end of variable capacitance CP, the end of oscillator coil L1, and the other end of the other end of variable capacitance CP and oscillator coil L1 is with the anodal VCC that meets DC power supply DC.

Annexation in the composition of other circuit and the circuit between the components and parts

Element annexation in the frequency stabilization circuit: the collector electrode of a termination NPN type triode VT3 of capacitor C 4, the end of the other end connecting resistance R9 of capacitor C 4, the base stage of another termination NPN type triode VT3 of resistance R 9.

The circuit working principle: input audio signal was fed earlier on the variable resistor RP with corrective action before getting into NPN type triode VT1.Variable resistor RP high input impedance is Electret condenser microphone MIC or ceramic pick-up are directly separated.It has provided a suitable audio voltage gain, and the low-voltage audio signal of coming from Electret condenser microphone MIC directly promotes NPN type triode VT1.The emitter of NPN type triode VT2 is connected to the high frequency negative feedback loop in audio amplifier circuit, and NPN type triode VT2 also is the part as current source circuit.NPN type triode VT3 forms radio-frequency oscillator.This oscillator has many advantages, and oscillator coil L1 does not need tap, makes to make simply, and is easy to through regulating the control output signal strength.Regulate the amplitude of the input audio signal of Electret condenser microphone, can regulate its emissive porwer smoothly.

Description of drawings

Accompanying drawing 1 is the embodiment circuit working schematic diagram that the utility model provides an amplitude-modulated wave wireless microphone; For reducing the interference of electromagnetic signal to Electret condenser microphone MIC, require to use the Electret condenser microphone of two ends output type, the metal shell end of Electret condenser microphone MIC is with wherein the source S and the circuit ground GND of FET link to each other.

Embodiment

According to the circuit working schematic diagram and the description of drawings of amplitude-modulated wave wireless microphone shown in the accompanying drawing 1, and implement to realize the utility model according to the described components and parts specification requirement of embodiment.

The selection of components and parts and technical parameter thereof

MIC is an Electret condenser microphone; Electret condenser microphone MIC should select the microphone of two ends output type for use; Help improving gain of output voltage of signals and anti-interference; Wherein the drain D of FET is an audio signal output end, connection circuit ground GND after the metal shell end of Electret condenser microphone links to each other with the source S of FET.High more its effect of Electret condenser microphone sensitivity is good more, can select CM-18W type Electret condenser microphone MIC for use, and its sensitivity is divided into five retainings: redness is-66dB; Xiao Huang is-62dB that rheum officinale is-58dB Lan Sewei-54dB; White is greater than-52dB, and present embodiment is selected the white point product for use;

VT1 is a NPN type triode, selects model 2SC9014 for use, requires β >=150; VT2 and VT3 are NPN type triode, and selecting model for use is 8050, requires β >=110;

The resistance of resistance R 1 is used 100K Ω; The resistance of resistance R 2 is used 3.9K Ω; The resistance of resistance R 3 is used 2K Ω; The resistance of resistance R 4 is used 39K Ω; The resistance of resistance R 5 is used 8.2K Ω; The resistance of resistance R 6 is used 3K Ω; The resistance of resistance R 7 is used 18K Ω; The resistance of resistance R 8 and R9 is all used 15K Ω; The resistance of variable resistor RP is used 1M Ω;

The capacity of capacitor C 1, C2 is 0.22 μ F; Capacitor C 5 is all used the terylen electric capacity of 0.1 μ F; Electrochemical capacitor C3 uses capacity 47 μ F, withstand voltagely is 16V; The ceramic disc capacitor of capacitor C 4 usefulness 100PF; Range of capacity 150～300PF of variable capacitance CP;

DC power supply DC power consumption is a milliampere level, can select the 9V laminated cell for use.

The circuit debugging method

When making the circuit of this device, require circuit board to use high-frequency loss circlet epoxy resins plate.

Oscillator coil L1 is with No. 32 enamelled wires of international standard, and is flat around 40 circles on the ferrite bar of long 60mm, ￠ 5mm.Spacing through the oscillator coil L1 turn-to-turn in the adjustment circuit can be finely tuned frequency of oscillation.

The debugging of amplitude-modulated wave wireless microphone does not generally need professional electrical apparatus such as sweep generator, frequency meter, and this is that the utility model is made characteristics of success easily.

This machine quiescent current≤5mA, the operating current when emission state is general≤14mA, thereby can use for a long time.Do not use alternating current to be transformed into DC power supply, otherwise be prone to cause that circuit working is unstable.The audio signal of input should be greater than 10mV, otherwise will significantly influence transmitting power and transmitting range.

Turn on broadcast receiver, band switch should place the AM wave band, with the amplitude-modulated wave wireless microphone near broadcast receiver, slowly rotate the broadcast receiver tuning knob then, simultaneously to Electret condenser microphone MIC speech, be tuned to broadcast receiver receive till the voice signal sound.If broadcast receiver can not receive the signal of wireless microphone emission in tuning range; Can stretch or compress higher-order of oscillation coil L1 gently; Change the spacing of the turn-to-turn of enamelled wire coil; Adjust variable capacitance CP simultaneously, the frequency of careful tuning AM receiver again is until the voice signal clearly of receiving that on a certain frequency wireless microphone sends.Then draw back the distance between amplitude-modulated wave wireless microphone and the broadcast receiver gradually, reach >=during 9m, still can receive clearly till the voice signal up to distance.Attention wireless microphone tranmitting frequency in debugging should be avoided the frequency in the broadcasting station of local AM band.

Claims

1. an amplitude-modulated wave wireless microphone is made up of DC power supply DC, audio signal pick-up circuit, audio signal one-level amplifying circuit, the amplification of audio signal secondary and negative-feedback circuit, amplitude-modulated wave vibration and radiating circuit, frequency stabilization circuit, and its characteristic comprises:

The audio signal pick-up circuit is made up of Electret condenser microphone MIC, variable resistor RP and capacitor C 1; Its annexation: the FET drain D among the Electret condenser microphone MIC connects the end of variable resistor RP; One end of the movable knee-joint capacitor C 1 of variable resistor RP, the metal shell end of Electret condenser microphone MIC links to each other with FET source S and circuit ground GND among the Electret condenser microphone MIC;

Amplitude-modulated wave vibration and radiating circuit are made up of NPN type triode VT3, resistance R 7, resistance R 8 and capacitor C 5, variable capacitance CP, oscillator coil L1 and frequency stabilization circuit; Its annexation is: the base stage of NPN type triode VT3 is with the end of connecting resistance R7, an end of resistance R 8 and an end of capacitor C 5; The anodal VCC of another termination DC power supply DC of resistance R 7; The other end of the other end of resistance R 8 and capacitor C 5 links to each other with circuit ground GND; The collector electrode of NPN type triode VT3 is with connecing the end of variable capacitance CP, the end of oscillator coil L1, and the other end of the other end of variable capacitance CP and oscillator coil L1 is with the anodal VCC that meets DC power supply DC;

The collector electrode of a termination NPN type triode VT3 of capacitor C 4 in the frequency stabilization circuit, the end of the other end connecting resistance R9 of capacitor C 4, the base stage of another termination NPN type triode VT3 of resistance R 9.