CN202340296U - Frequency-modulation (FM) wireless microphone with single battery - Google Patents
Frequency-modulation (FM) wireless microphone with single battery Download PDFInfo
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- CN202340296U CN202340296U CN2011204939218U CN201120493921U CN202340296U CN 202340296 U CN202340296 U CN 202340296U CN 2011204939218 U CN2011204939218 U CN 2011204939218U CN 201120493921 U CN201120493921 U CN 201120493921U CN 202340296 U CN202340296 U CN 202340296U
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Abstract
The utility model relates to a frequency-modulation (FM) wireless microphone with a single battery. The FM wireless microphone is composed of 1.5-V direct-current power supply, a filtering circuit, an audio-frequency signal input and amplification circuit, a high-frequency oscillation and transmission circuit and a transmitting antenna. The FM wireless microphone is only provided with one NPN-type transistor and one battery. The frequency of a high-frequency oscillator is changed by changing junction capacitance between the base electrode and the collector of the NPN-type transistor in the high-frequency oscillation circuit so as to modulate the oscillation frequency into frequency-modulated wave. As only one NPN-type transistor is used in the circuit, the oscillation frequency of the circuit is stable, the FM wireless microphone is suitable for a television wireless headset and the like for signal transmission with higher fidelity. According to the utility model, only eight common discrete components are used, so that the purpose that the FM wireless microphone is simple in circuit structure, stable in oscillation frequency without frequency deviation easily and easy to manufacture and popularize is realized.
Description
Technical field
The utility model belongs to electronics and communication technique field, relates to a kind of frequency modulation wireless microphone of single battery.
Background technology
The typical operation principle of most frequency modulation wireless microphones is to change the modulating frequency that changes high-frequency generator through the junction capacitance between transistor collector and the emitter in the change high-frequency oscillating circuits; Thereby realize that modulation becomes frequency-modulated wave to frequency of oscillation; Amplify through the high frequency selective frequency amplifier circuit, at last by transmitting antenna to space radiation.
The utility model adopts a NPN transistor, a batteries, and the junction capacitance of transistor base and inter-collector changes the frequency that changes high-frequency generator in the high-frequency oscillating circuits through changing, and becomes frequency-modulated wave thereby frequency of oscillation modulated.Because of circuit only uses a NPN transistor, receive involving and disturbing less of circuit front and back level, make the frequency of oscillating circuit more stable, be suitable for the less demanding signal transmission of fidelity such as tv wireless earphone, can be used for fields such as classroom instruction.
Below specify the correlation technique content that the frequency modulation wireless microphone of this single battery relates in manufacturing process.
The utility model content
Goal of the invention and beneficial effect: the utility model adopts a NPN transistor, a batteries; Change the frequency that changes high-frequency generator through the junction capacitance between NPN transistor base stage and the collector electrode in the change high-frequency oscillating circuits, thereby modulation becomes frequency-modulated wave to frequency of oscillation.Because of circuit only uses a NPN transistor, make the circuit oscillation frequency more stable, be well suited for being used for the signal transmission that fidelity such as tv wireless earphone is had relatively high expectations.The utility model only uses 8 common discrete components, has realized that frequency modulation wireless microphone circuit structure is simple, the stable purpose that is difficult for running frequently, makes easily, is easy to popularize of frequency of oscillation.
The circuit working principle: the frequency modulation wireless microphone of single battery changes voice signal into tone currents by Electret condenser microphone MIC; The high-frequency generator of being made up of NPN transistor VT1, higher-order of oscillation coil L1 and capacitor C 1 again forms FM signal and is radiated the space by transmitting antenna TX.In frequency modulation wireless microphone 10m scope, the broadcast receiver reception by frequency modulation(FM) broadcast band is reduced into sound through the radio reception on-board speaker.
Technical scheme: the frequency modulation wireless microphone of single battery, to form by 1.5V DC power supply, filter circuit, audio signal input and amplifying circuit, the higher-order of oscillation and radiating circuit and transmitting antenna, its characteristic comprises:
Audio signal input and amplifying circuit: the base stage of a termination NPN transistor VT1 of the output D of Electret condenser microphone MIC and resistance R 1, the anodal VCC of the other end connection circuit of resistance R 1, the shell end S of Electret condenser microphone MIC links to each other with circuit ground GND;
The higher-order of oscillation and radiating circuit and transmitting antenna: the base stage of NPN transistor VT1 connects an end of capacitor C 1 and the end of higher-order of oscillation coil L1; The other end of the other end of capacitor C 1 and higher-order of oscillation coil L1 links to each other with the collector electrode of NPN transistor VT1, the end of transmitting antenna TX, the emitter connection circuit ground GND of NPN transistor VT1;
Filter circuit: the anodal VCC of the termination circuit of an end of capacitor C 2 and the positive pole of electrochemical capacitor C3 and mains switch SW; Another termination 1.5V dc power anode of mains switch SW; The negative pole connection circuit ground GND of the other end of capacitor C 2 and electrochemical capacitor C3,1.5V dc power cathode connection circuit ground GND.
Description of drawings
Accompanying drawing 1 is the embodiment circuit working schematic diagram of the utility model frequency modulation wireless microphone that a single battery is provided; For reducing the interference of electromagnetic signal, require to use the Electret condenser microphone of two ends output type, the shell end S connection circuit ground GND of Electret condenser microphone MIC to Electret condenser microphone MIC.
Embodiment
According to the circuit working schematic diagram and the description of drawings of the frequency modulation wireless microphone of single battery shown in the accompanying drawing, 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
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;
Electret condenser microphone sensitivity is high more, and the effect of wireless microphone is good more.Electret condenser microphone MIC can select for use the CM-18W type (the higher Electret condenser microphone of sensitivity of φ 10mm * 6.5mm), its sensitivity is divided into five retainings, representes with color dot respectively, present embodiment is selected the product of white point for use;
VT1 is a NPN transistor, selects power transistor among the NPN type 2SC9018 for use, requires β >=110;
It is 1/8W metalfilmresistor or fixed carbon resister that resistance is selected power for use, and the resistance of resistance R 1 is 1K Ω;
C1 is a ceramic disc capacitor, and capacity is 10PF; C2 is an electric capacity of the dacron, and capacity is 0.01 μ F; C3 is an electrochemical capacitor, and capacity is 220 μ F/10V;
L1 is a higher-order of oscillation coil; SW is a mains switch.
The making of subelement
Higher-order of oscillation coil L1 is with the enamelled wire of ￠ 0.5mm, and is flat around 10 circles on the ballpoint pen core of ￠ 3.5mm, extracts pen core then out and forms air-core inductance, scrapes off behind the coat of paint of inductance coil two ends zinc-plated;
TX is a transmitting antenna, and the telescopic antenna that available 60cm is above also can use 90cm multiply plastics flexible cord as transmitting antenna, and an end is welded on the printed circuit board (PCB), and the other end of transmitting antenna TX is sagging naturally.
Circuit debugging
To require each component pin to stay short as far as possible, and the situation of inspection printed circuit board (PCB) and element welding earlier should not have short circuit and false weldering phenomenon, can not make higher-order of oscillation coil L1 distortion when noting welding.Can connect the 1.5V DC power supply then, with voltage between the base stage of universal instrument shelves of direct voltage measuring N PN transistor npn npn VT1 and the emitter should＞0.7V, with higher-order of oscillation coil L1 two terminal shortcircuits once, voltage should change, and circuit starting of oscillation is described;
Open FM receiver, pull out the antenna of 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 stretch or compress higher-order of oscillation coil L1 gently, change the width of higher-order of oscillation coil L1, careful again tuning modulation broadcast receiver is until receiving voice signal clearly;
Draw back the distance between wireless microphone and the FM receiver, up to distance when reaching 9～10m, still can receive clearly till the voice signal, notice that in debugging wireless microphone tranmitting frequency should avoid the frequency in the broadcasting station in the local fm band;
No. 5 batteries of 1 joint are as power supply, and the operating current of frequency modulation wireless microphone is about 19mA; Selecting the about 400mAh of high-quality alkaline battery capacity for use is example, but 1 saves about 40 hours of No. 5 battery continuous operations.
Claims (1)
1. the frequency modulation wireless microphone of a single battery is made up of 1.5V DC power supply, filter circuit, audio signal input and amplifying circuit, the higher-order of oscillation and radiating circuit and transmitting antenna, and its characteristic comprises:
The base stage of the output D of Electret condenser microphone MIC in audio signal input and the amplifying circuit and a termination NPN transistor VT1 of resistance R 1, the anodal VCC of the other end connection circuit of resistance R 1, the shell end S of Electret condenser microphone MIC links to each other with circuit ground GND;
The base stage of NPN transistor VT1 in the higher-order of oscillation and radiating circuit and the transmitting antenna connects an end of capacitor C 1 and the end of higher-order of oscillation coil L1; The other end of the other end of capacitor C 1 and higher-order of oscillation coil L1 links to each other with the collector electrode of NPN transistor VT1, the end of transmitting antenna TX, the emitter connection circuit ground GND of NPN transistor VT1;
The anodal VCC of the termination circuit of one end of the capacitor C 2 in the filter circuit and the positive pole of electrochemical capacitor C3 and mains switch SW; Another termination 1.5V dc power anode of mains switch SW; The negative pole connection circuit ground GND of the other end of capacitor C 2 and electrochemical capacitor C3,1.5V dc power cathode connection circuit ground GND.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011204939218U CN202340296U (en) | 2011-12-02 | 2011-12-02 | Frequency-modulation (FM) wireless microphone with single battery |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011204939218U CN202340296U (en) | 2011-12-02 | 2011-12-02 | Frequency-modulation (FM) wireless microphone with single battery |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN202340296U true CN202340296U (en) | 2012-07-18 |
Family
ID=46488978
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2011204939218U Expired - Fee Related CN202340296U (en) | 2011-12-02 | 2011-12-02 | Frequency-modulation (FM) wireless microphone with single battery |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN202340296U (en) |
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2011
- 2011-12-02 CN CN2011204939218U patent/CN202340296U/en not_active Expired - Fee Related
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20120718 Termination date: 20121202 |