CN102724601A

CN102724601A - Single-tube frequency modulation wireless microphone

Info

Publication number: CN102724601A
Application number: CN2012102230121A
Authority: CN
Inventors: 刘昭利
Original assignee: Individual
Current assignee: Individual
Priority date: 2012-07-01
Filing date: 2012-07-01
Publication date: 2012-10-10

Abstract

The invention belongs to the technical field of electron and communication and relates to a single-tube frequency modulation wireless microphone which is composed of a 1.5 V battery, an audio signal input circuit, a transistor bias circuit, a high frequency oscillation circuit and a transmitting circuit. The single-tube frequency modulation wireless microphone adopts one battery and one non-protein nitrogen (NPN) transistor and achieves frequency-modulated wave by changing oscillation frequency of the high frequency oscillation circuit. By means of the fact that only one NPN transistor is used by the circuits, the circuits cannot be involved and disturbed by a front level and a rear level so as to enable the frequency of the high frequency oscillation circuit to be very stable. The single-tube frequency modulation wireless microphone is suitable for audio signal transmission of wireless earphones and the like with high-fidelity requirements and can assist teachers to give lessons at a lecture hall or can be used for recreational activities of karaoke and the like. The single-tube frequency modulation wireless microphone has the advantages of being simple in circuit structure, stable in high frequency oscillation frequency, small in power consumption, low in manufacturing cost and the like. Transmitting distance of the single-tube frequency modulation wireless microphone reaches 25 meters.

Description

Single tube frequency modulation wireless microphone

Technical field

The invention belongs to electronic technology and communication technique field, is about a kind of single tube frequency modulation wireless microphone.

Background technology

The present invention adopts single battery, single NPN type triode, realizes frequency-modulated wave through the frequency of oscillation that changes high-frequency oscillating circuits.Because of circuit only uses a NPN type triode,, make that the frequency of high-frequency oscillating circuits is highly stable so circuit can not receive involving and disturbing of front and back level.The present invention is suitable for the audio signal transmission that fidelitys such as wireless headset are had relatively high expectations, and can in lyceum, assist teachers' instruction or be used for recreations such as Karaoke.Single tube frequency modulation wireless microphone has characteristics such as circuit structure is simple, and higher-order of oscillation frequency stabilization, transmitting range reach 25 meters, power consumption is few, making is originally low.When DC power supply was used the power supply of two batteries instead, the transmitting range of single tube frequency modulation wireless microphone can reach more than the 80m.

Below specify single tube frequency modulation wireless microphone of the present invention related correlation technique content in implementation process.

Summary of the invention

Goal of the invention and beneficial effect: the present invention adopts single battery, single NPN type triode, realizes frequency-modulated wave through the frequency of oscillation that changes high-frequency oscillating circuits.Because of circuit only uses a NPN type triode,, make that the frequency of high-frequency oscillating circuits is highly stable so circuit can not receive involving and disturbing of front and back level.The present invention is suitable for the audio signal transmission that fidelitys such as wireless headset are had relatively high expectations, and can in lyceum, assist teachers' instruction or be used for recreations such as Karaoke.Single tube frequency modulation wireless microphone has characteristics such as circuit structure is simple, and higher-order of oscillation frequency stabilization, transmitting range reach 25 meters, power consumption is few, making is originally low.When DC power supply was used the power supply of two batteries instead, the transmitting range of single tube frequency modulation wireless microphone can reach more than the 80m.

The circuit working principle: single tube frequency modulation wireless microphone is made up of Electret condenser microphone MIC and 1 element such as NPN type triode, and high-frequency oscillating circuits is made up of peripheral cells such as NPN type triode VT1, higher-order of oscillation coil L1, capacitor C 4, capacitor C 5.Electret condenser microphone MIC becomes voice signal into audio signal; Be coupled to the base stage of NPN type triode VT1 through electrochemical capacitor C1; Tone currents is modulated high frequency self-sustained oscillation voltage, through the high-frequency signal of ovennodulation through capacitor C 6, by transmitting antenna AT to external radiation.The direct current biasing resistance of NPN type triode VT1 is resistance R 2, and resistance R 3 is formed the adding that exchanges negative-feedback circuit, can make the more stable work of NPN type triode VT1.Higher-order of oscillation coil L1 and oscillating capacitance C5 are determining frequency of oscillation, f=1/2 π, and the adjustment higher-order of oscillation coil L1 number of turn or spacing can change higher-order of oscillation frequency.Resistance R 1 is the supplying resistance of Electret condenser microphone MIC.

Technical characterictic: single tube frequency modulation wireless microphone, it is made up of 1.5V battery, audio signal input circuit, triode biasing circuit, high-frequency oscillating circuits and radiating circuit, and its characteristic comprises:

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 negative 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 positive pole of electrochemical capacitor C1 connects the base stage of NPN type triode VT1;

The triode biasing circuit: be made up of NPN type triode VT1, resistance R 2 and capacitor C 2, the base stage of NPN type triode VT1 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;

High-frequency oscillating circuits and radiating circuit: form by NPN type triode VT1, higher-order of oscillation coil L1, oscillating capacitance C5, capacitor C 3, negative feedback capacitor C 4, negative feedback resistor R3, coupling capacitance C6 and transmitting antenna AT; The collector electrode of NPN type triode VT1 links to each other with the end of the end of higher-order of oscillation coil L1, oscillating capacitance C5, an end of negative feedback capacitor C 4 and the end of coupling capacitance C6; The anodal VCC of the other end of higher-order of oscillation coil L1 and the other end connection circuit of oscillating capacitance C5; Antenna AT is penetrated in the other end sending and receiving of coupling capacitance C6; The emitter of NPN type triode VT1 links to each other with the end of the other end of negative feedback capacitor C 4, negative feedback resistor R3 and an end of capacitor C 3; The anodal VCC of the other end connection circuit of capacitor C 3, the other end of negative feedback resistor R3 links to each other with circuit ground GND;

1.5V the positive pole of battery links to each other with circuit anode VCC, the negative pole of 1.5V battery links to each other with circuit ground GND.

Description of drawings

Accompanying drawing 1 is the embodiment circuit working schematic diagram that the present invention provides a single tube frequency modulation wireless microphone.

Embodiment

According to the circuit working schematic diagram and the description of drawings of the wireless microphone of single tube frequency modulation shown in the accompanying drawing 1, 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

VT1 is a NPN type triode, selects middle power NPN type triodes such as 2SC9018 for use, requires characteristic frequency fT greater than 300MHz; But the too high stability that can influence the circuit modulating frequency of characteristic frequency fT; Require β >=110, also can select the high high-frequency triode of characteristic frequency fT for use, as: 3DG80 etc.;

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, and the available model of Electret condenser microphone MIC is the CM-18W type;

It is 1/8W metalfilmresistor or fixed carbon resister that resistance is selected power for use, and the resistance of resistance R 1 is 200 Ω; The resistance of resistance R 2 is 36K Ω; The resistance of resistance R 3 is 82 Ω;

C1 is an electrochemical capacitor, and capacity is 1 μ F/10V; C2～C6 is the high frequency Leaded Ceramic Disc Capacitor of good stability, and the capacity of C2 is 1000PF; The capacity of C3 is 68PF; The capacity of C4 is 6PF; The capacity of C5 is 36PF; The capacity of C6 is 6PF.

Circuit production main points and circuit debugging

The making of higher-order of oscillation coil L1: flat around 5 circle back tread flakings with the enamelled wire of ￠ 0.5mm on diameter ￠ 5mm spiral bit staight shank, plate scolding tin scrape off the coat of paint at coil two ends with pocket knife after;

Transmitting antenna AT can use 1 long 0.3m telescopic antenna, or selects the flexible conductor of long 0.5m for use, and the end of transmitting antenna AT is welded on the printed circuit board (PCB), and the other end is sagging naturally;

Before making, measure the performance of each element with universal instrument, each ceramic disc capacitor is preferably measured capacitance with capacitance meter; The infringement to triode of the static of NPN type triode VT1 when as far as possible reducing welding, heat is installed at last, and element is as far as possible near circuit board during plug-in mounting;

The mains switch SW of single tube frequency modulation wireless microphone places the position of " pass "; Universal instrument is placed " 10mA " shelves, two test pencils are received the two ends of mains switch, but the total current of measuring circuit; If operating current is about 10mA; Explain that circuit working is normal basically, if operating current is excessive or too small all undesired, answering has phenomenons such as error-free weldering, rosin joint, short circuit on the check circuit plate;

With voltage between the base stage of universal instrument shelves of direct voltage measuring N PN type triode VT1 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 type triode VT1 and the emitter, and this explanation high-frequency oscillating circuits is started working;

Pull out the antenna of FM receiver; Open the FM receiver mains switch, the transmitting antenna AT of single tube frequency modulation wireless microphone near FM receiver, is slowly rotated the FM receiver tuning knob then; Simultaneously to Electret condenser microphone MIC speech, be tuned to FM receiver receive till the voice signal;

If still can not receive sound in 88～108MH whole frequency, then should stir higher-order of oscillation coil L1 a little, only need push or dwindle the distance between the every circle of higher-order of oscillation coil L1 aside, careful especially during adjustment; If the degree of tightness of adjustment higher-order of oscillation coil L1 is not still proved effective, then should higher-order of oscillation coil L1 be welded the increase half turn or reduce half turn, the back higher-order of oscillation coil L1 that burn-ons again continues above-mentioned adjustment, until receiving voice signal clearly;

Then draw back the distance between wireless microphone and the FM receiver gradually, up to distance when reaching 25m, still can receive clearly till the voice signal;

Suggestion: when circuit debugging, the tranmitting frequency of single tube frequency modulation wireless microphone should be avoided the frequency of powerful f-m broadcast station in the local fm band.

Claims

1. single tube frequency modulation wireless microphone, it is made up of 1.5V battery, audio signal input circuit, triode biasing circuit, high-frequency oscillating circuits and radiating circuit, and its characteristic comprises:

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 negative 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 positive pole of electrochemical capacitor C1 connects the base stage of NPN type triode VT1;

The triode biasing circuit is made up of NPN type triode VT1, resistance R 2 and capacitor C 2, and the base stage of NPN type triode VT1 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;

High-frequency oscillating circuits and radiating circuit are made up of NPN type triode VT1, higher-order of oscillation coil L1, oscillating capacitance C5, capacitor C 3, negative feedback capacitor C 4, negative feedback resistor R3, coupling capacitance C6 and transmitting antenna AT; The collector electrode of NPN type triode VT1 links to each other with the end of the end of higher-order of oscillation coil L1, oscillating capacitance C5, an end of negative feedback capacitor C 4 and the end of coupling capacitance C6; The anodal VCC of the other end of higher-order of oscillation coil L1 and the other end connection circuit of oscillating capacitance C5; Antenna AT is penetrated in the other end sending and receiving of coupling capacitance C6; The emitter of NPN type triode VT1 links to each other with the end of the other end of negative feedback capacitor C 4, negative feedback resistor R3 and an end of capacitor C 3; The anodal VCC of the other end connection circuit of capacitor C 3, the other end of negative feedback resistor R3 links to each other with circuit ground GND.

2. single tube frequency modulation wireless microphone according to claim 1 is characterized in that: the positive pole of 1.5V battery links to each other with circuit anode VCC, and the negative pole of 1.5V battery links to each other with circuit ground GND.