CN102395064A

CN102395064A - Miniature frequency-modulation wireless microphone with one battery

Info

Publication number: CN102395064A
Application number: CN2011103069166A
Authority: CN
Inventors: 刘喆
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-10-12
Filing date: 2011-10-12
Publication date: 2012-03-28

Abstract

The invention relates to a miniature frequency-modulation wireless microphone with one battery. The wireless microphone consists of a power supply DC, an audio signal input circuit, a transistor bias circuit and a high-frequency oscillation and transmission circuit, wherein the audio signal input circuit consists of an electret microphone MIC, a resistor R1 and an electrolytic capacitor C1; the bias circuit consists of a negative-positive-negative (NPN) type transistor BG1, a capacitor C2 and a resistor R2; and the high-frequency oscillation and transmission circuit consists of the NPN type transistor BG1, a capacitor C3, high-frequency oscillation coils L1 and L2, a negative feedback capacitor C4, a negative feedback resistor R3, a coupling capacitor C5 and a transmission antenna AT. The invention has the advantages that: one miniature frequency modulation wireless microphone is manufactured by using 11 discrete components, so that the aims of simple circuit structure of the frequency modulation wireless microphone, stable high-frequency oscillation frequency, low power consumption, low cost and the like are fulfilled; and a transmission distance of the wireless microphone is about 30 m, and when the power supply DC adopts a power supply of 6 V, the transmission distance of the wireless microphone can be more than 100 m.

Description

Miniature frequency modulation wireless microphone with a batteries

Technical field

The invention belongs to electronics and communication technique field, relate to a kind of miniature frequency modulation wireless microphone of usefulness one batteries.

Background technology

The present invention adopts single battery, single NPN transistor, through the frequency of oscillation of change high-frequency oscillating circuits, thereby the frequency of oscillation modulation is become frequency-modulated wave.Because of circuit only uses a NPN transistor, the involving and disturb fewly of level before and after circuit receives makes that the frequency of oscillating circuit is more stable, is suitable for the signal transmission that fidelity such as wireless headset is had relatively high expectations, and can be used for fields such as classroom instruction.Evidence: the present invention only makes a miniature frequency modulation wireless microphone with 11 common discrete components, has realized that frequency modulation wireless microphone circuit structure is simple, and higher-order of oscillation frequency stabilization, little power consumption, making are easily and target such as with low cost.The transmitting range of the miniature frequency modulation wireless microphone of single battery is about 30m, and when power supply DC used the 6V power supply instead, the transmitting range of frequency modulation wireless microphone can reach more than the 100m.

Below specify the correlation technique content that the miniature frequency modulation wireless microphone of this usefulness one batteries relates in manufacturing process.

Summary of the invention

Goal of the invention and beneficial effect: the present invention adopts 11 common discrete components to make a miniature frequency modulation wireless microphone, has realized that frequency modulation wireless microphone circuit structure is simple, and higher-order of oscillation frequency stabilization, little power consumption, making are easily and target such as with low cost.The transmitting range of the miniature frequency modulation wireless microphone of single battery is about 30m, and when power supply DC used the 6V power supply instead, the transmitting range of frequency modulation wireless microphone can reach more than the 100m.

Technical characterictic: with the miniature frequency modulation wireless microphone of a batteries, form, it is characterized in that by power supply DC, audio signal input circuit, transistor bias circult, the higher-order of oscillation and radiating circuit:

Audio signal input circuit: form by Electret condenser microphone MIC, resistance R 1, electrochemical capacitor C1; The end of the output D connecting resistance R1 of Electret condenser microphone MIC and the positive pole of electrochemical capacitor C1; The metal shell end S of Electret condenser microphone MIC links to each other with circuit ground GND; The anodal VCC of the other end connection circuit of resistance R 1, the negative pole of electrochemical capacitor C1 connects the base stage of NPN transistor BG1;

Transistor bias circult: be made up of NPN transistor BG1, capacitor C 2, resistance R 2, the base stage of NPN transistor BG1 connects an end of capacitor C 2 and an end of resistance R 2, the anodal VCC of the other end connection circuit of the other end of capacitor C 2 and resistance R 2;

The higher-order of oscillation and radiating circuit: form by NPN transistor BG1, capacitor C 3, higher-order of oscillation coil L1 and L2, negative feedback capacitor C 4, negative feedback resistor R3 and coupling capacitance C5, transmitting antenna AT; The collector electrode of NPN transistor BG1 connects an end of capacitor C 3, the end of higher-order of oscillation coil L2 and an end of negative feedback capacitor C 4; The anodal VCC of the other end connection circuit of capacitor C 3; The end of another termination higher-order of oscillation coil L1 of higher-order of oscillation coil L2 and the end of coupling capacitance C5; The anodal VCC of the other end connection circuit of higher-order of oscillation coil L1; Antenna AT is penetrated in the other end sending and receiving of coupling capacitance C5, the emitter of another termination NPN transistor BG1 of negative feedback capacitor C 4 and the end of negative feedback resistor R3, and the other end of negative feedback resistor R3 links to each other with circuit ground GND.

Annexation in the composition of other circuit and the circuit between the element

The positive pole of power supply DC links to each other with circuit anode VCC, and the negative pole of power supply DC links to each other with circuit ground GND.

The circuit working principle: the miniature frequency modulation wireless microphone with a batteries changes voice signal into tone currents by Electret condenser microphone MIC; The high-frequency generator of being made up of NPN transistor BG1, higher-order of oscillation coil L1, L2 and capacitor C 3 again is modulated into FM signal and is radiated the space by transmitting antenna AT.Within this frequency modulation wireless microphone 30m scope, receive by FM wave band FM broadcasting broadcast receiver, and after broadcast receiver amplifies, be reduced into sound by the broadcast receiver loud speaker.Transmitting range is relevant with the operating current size of transmitting tube BG1, goes up the operating current that inclined to one side resistance R 2 can change NPN transistor BG1.

Description of drawings

Accompanying drawing 1 is the embodiment circuit working schematic diagram of the present invention's miniature frequency modulation wireless microphone that usefulness one batteries is provided.

Embodiment

According to shown in the accompanying drawing 1 with the circuit working schematic diagram and the description of drawings of the miniature frequency modulation wireless microphone of a batteries, and implement to realize the present invention according to the described components and parts specification requirement of embodiment.

The selection of components and parts and technical parameter thereof

When selecting NPN transistor BG1, require transistorized characteristic frequency fT, but the too high stability that can influence the circuit modulating frequency of characteristic frequency fT is selected power transistor among the 2SC9018 for use, requires β >=110 greater than 300MHz;

MIC is an Electret condenser microphone, and Electret condenser microphone MIC should select the microphone of two ends output type for use, and its drain D is an audio signal output end, connection circuit ground GND after the metal shell end of Electret condenser microphone links to each other with source S; It is output that FET is connected into drain D, helps improving the gain of output voltage of signals, and the sensitivity of Electret condenser microphone is increased; Require the shell ends S connection circuit ground GND of Electret condenser microphone MIC for the anti-interference that improves circuit; Electret condenser microphone sensitivity is high more, and the effect of wireless microphone is good more; It is CM-18W type (φ 10mm * 6.5mm) that Electret condenser microphone MIC can select model for use;

It is 1/8W metalfilmresistor or fixed carbon resister that resistance is selected power for use, and the resistance of resistance R 1 is 6K Ω; The resistance of resistance R 2 is 10K Ω; The resistance of resistance R 3 is 5.1 Ω;

C1 is an electrochemical capacitor, and capacity is 10 μ F/10V; C2 is an electric capacity of the dacron, and capacity is 0.033 μ F; C3 is a ceramic disc capacitor, and capacity is 8.2PF; C4 is a ceramic disc capacitor, and capacity is 18PF; C5 is a ceramic disc capacitor, and capacity is 47PF.

The making of circuit and subelement

The making of higher-order of oscillation coil L: higher-order of oscillation coil is divided into two sections coil windings; But around identical to requiring; Higher-order of oscillation coil L1 with ￠ 0.5mm enamelled wire on ￠ 5mm skeleton around 4 circles, higher-order of oscillation coil L2 is around 3 circles, scrapes off with pocket knife and plates tin behind the coat of paint at inductance coil two ends;

Transmitting antenna AT can use the long telescopic antenna of a 0.6m, or selects the long flexible conductor of 0.8m for use, and the end of transmitting antenna AT is welded on the printed circuit board (PCB), and the other end is stretched out naturally.

The debugging of circuit

The printed circuit board (PCB) correspondence position is inserted in the zinc-plated back of each component pin, and each components and parts pin should stay short as far as possible.Do not make higher-order of oscillation coil L1 and L2 distortion when noting welding.

Inspection printed circuit board (PCB) and welding quality should not have short circuit and empty, dry joint phenomenon earlier, can connect power supply then.With voltage between the base stage of universal instrument shelves of direct voltage measuring N PN transistor npn npn BG1 and the emitter should＞0.75V; With two terminal shortcircuits of higher-order of oscillation coil L1 once; Voltage should change to some extent between the base stage of NPN transistor BG1 and the emitter, and this explanation high-frequency oscillating circuits is started working.

Pull out the antenna of FM receiver, open FM receiver, with the transmitting antenna of frequency modulation wireless microphone near FM receiver; Slowly rotate the FM receiver tuning knob then, simultaneously to Electret condenser microphone MIC speech, be tuned to FM receiver receive till the voice signal sound; If FM receiver can not receive the signal of frequency modulation wireless microphone emission in tuning range, can suitably stretch or compress higher-order of oscillation coil L1, change the width of enamelled wire spacing, careful again tuning modulation broadcast receiver is until receiving voice signal clearly; Then draw back the distance between wireless microphone and the FM receiver gradually, up to distance when reaching 30m, still can receive clearly till the voice signal; Suggestion: in circuit debugging, the wireless microphone tranmitting frequency should be avoided the powerful f-m broadcast station frequency in the local fm band.

Claims

1. the miniature frequency modulation wireless microphone with a batteries is made up of power supply DC, audio signal input circuit, transistor bias circult, the higher-order of oscillation and radiating circuit, it is characterized in that:

The audio signal input circuit is made up of Electret condenser microphone MIC, resistance R 1, electrochemical capacitor C1; The end of the output D connecting resistance R1 of Electret condenser microphone MIC and the positive pole of electrochemical capacitor C1; The metal shell end S of Electret condenser microphone MIC links to each other with circuit ground GND; The anodal VCC of the other end connection circuit of resistance R 1, the negative pole of electrochemical capacitor C1 connects the base stage of NPN transistor BG1;

Transistor bias circult is made up of NPN transistor BG1, capacitor C 2, resistance R 2, and the base stage of NPN transistor BG1 connects an end of capacitor C 2 and an end of resistance R 2, the anodal VCC of the other end connection circuit of the other end of capacitor C 2 and resistance R 2;

The higher-order of oscillation and radiating circuit are made up of NPN transistor BG1, capacitor C 3, higher-order of oscillation coil L1 and L2, negative feedback capacitor C 4, negative feedback resistor R3 and coupling capacitance C5, transmitting antenna AT; The collector electrode of NPN transistor BG1 connects an end of capacitor C 3, the end of higher-order of oscillation coil L2 and an end of negative feedback capacitor C 4; The anodal VCC of the other end connection circuit of capacitor C 3; The end of another termination higher-order of oscillation coil L1 of higher-order of oscillation coil L2 and the end of coupling capacitance C5; The anodal VCC of the other end connection circuit of higher-order of oscillation coil L1; Antenna AT is penetrated in the other end sending and receiving of coupling capacitance C5, the emitter of another termination NPN transistor BG1 of negative feedback capacitor C 4 and the end of negative feedback resistor R3, and the other end of negative feedback resistor R3 links to each other with circuit ground GND.

2. the miniature frequency modulation wireless microphone of usefulness one batteries according to claim 1 is characterized in that: the positive pole of power supply DC links to each other with circuit anode VCC, and the negative pole of power supply DC links to each other with circuit ground GND.