CN102333255A - Simple and reliable frequency modulation wireless microphone - Google Patents
Simple and reliable frequency modulation wireless microphone Download PDFInfo
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- CN102333255A CN102333255A CN201110280289A CN201110280289A CN102333255A CN 102333255 A CN102333255 A CN 102333255A CN 201110280289 A CN201110280289 A CN 201110280289A CN 201110280289 A CN201110280289 A CN 201110280289A CN 102333255 A CN102333255 A CN 102333255A
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Abstract
The invention relates to a simple and reliable frequency modulation wireless microphone. The frequency modulation wireless microphone consists of a DC (direct current) power supply, a power filtering circuit, an audio signal input circuit and a high-frequency oscillation and transmission circuit. The frequency modulation wireless microphone is characterized in that the high-frequency oscillation and transmission circuit comprises a biasing circuit of an NPN (negative-positive-negative) type transistor VT1 and an audio signal input circuit. In the invention, a single NPN type transistor and a single battery are adopted, and the frequency of a high-frequency oscillator is changed by changing the junction capacitance change between b and c of the NPN type transistor in the high-frequency oscillation circuit so as to modulate the oscillation frequency into frequency modulation wave. As the circuit uses only one NPN type transistor, the frequency of the oscillation circuit is relatively stable; therefore the simple and reliable frequency modulation wireless microphone is suitable for the television wireless earphones and the like of which the signal transmission has relatively high requirement on the fidelity.
Description
Technical field
The invention belongs to electronics and communication technique field, relate to a kind of simplest and dependable frequency modulation wireless microphone.
Background technology
The present invention adopts single NPN transistor, single battery, and the junction capacitance between transistor b-c changes the frequency that changes high-frequency generator in the high-frequency oscillating circuits through changing, 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 tv wireless earphone is had relatively high expectations, or is used for field such as classroom instruction.Evidence: the present invention uses several common discrete components, has realized that frequency modulation wireless microphone circuit structure is simple, the stable difficult purposes such as easy, with low cost and little power consumption of running frequently, make of frequency of oscillation.
Below specify the correlation technique content that this simplest and dependable frequency modulation wireless microphone relates in manufacturing process.
Summary of the invention
Goal of the invention and beneficial effect: the present invention adopts single NPN transistor, single battery; The junction capacitance between the NPN transistor b-c changes the frequency that changes high-frequency generator in the high-frequency oscillating circuits through changing, 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.Evidence: the present invention only uses several common discrete components, has realized that frequency modulation wireless microphone circuit structure is simple, frequency of oscillation stablely is difficult for running frequently, with low cost and little power consumption, make easily.
Technical characterictic: simplest and dependable frequency modulation wireless microphone; Be made up of battery DC, electric source filter circuit, audio signal input circuit, the higher-order of oscillation and radiating circuit, it is characterized in that: the higher-order of oscillation and radiating circuit comprise biasing circuit and the audio signal input circuit of NPN transistor VT1.
Annexation in the composition of other circuit and the circuit between the element
The characteristic of the biasing circuit of NPN transistor VT1 and audio signal input circuit is: 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 metal shell end S of Electret condenser microphone MIC links to each other with circuit ground GND.
The higher-order of oscillation and radiating circuit: the base stage of NPN transistor VT1 is with connecing an end of capacitor C 1 and the end of higher-order of oscillation coil L; The other end of the other end of capacitor C 1 and higher-order of oscillation coil L 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 characteristic of battery DC and electric source filter circuit is: an end of capacitor C 2 and the positive pole of electrochemical capacitor C3 connect the end of mains switch K; The positive pole of another termination battery DC of mains switch K; The negative pole connection circuit ground GND of the other end of capacitor C 2 and electrochemical capacitor C3, the negative pole connection circuit ground GND of battery DC.
The circuit working principle: simplest and dependable frequency modulation wireless microphone 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 L 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 (FM wave band) is reduced into sound through loud speaker, realizes the radio transmission of sound.
Description of drawings
Accompanying drawing 1 is the embodiment circuit working schematic diagram that the present invention provides a simplest and dependable frequency modulation wireless microphone; For reducing the interference of electromagnetic signal, require to use the Electret condenser microphone of two ends output type to Electret condenser microphone MIC.
Embodiment
According to the circuit working schematic diagram and the description of drawings of the wireless microphone of simplest and dependable 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
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, to improve the anti-interference of circuit.
Electret condenser microphone sensitivity is high more, and the effect of wireless microphone is good more.Electret condenser microphone MIC can select CM-18W type (the higher Electret condenser microphone of sensitivity of φ 10mm * 6.5mm) 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;
L is a higher-order of oscillation coil; K is a mains switch.
The making of circuit and subelement
The making of higher-order of oscillation coil L: flat around 10 circles on the ballpoint pen core of ￠ 3.5mm with the enamelled wire of ￠ 0.5mm, extract the ballpoint pen core then out and form air-core inductance, scrape off behind the coat of paint at inductance coil two ends zinc-plated with pocket knife;
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 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 component pin should stay short as far as possible.Can not make higher-order of oscillation coil L distortion when noting the welding coil.
Inspection printed circuit board (PCB) and welding situation should not have short circuit and empty, dry joint phenomenon earlier, can connect DC power supply then.Measure with the universal instrument shelves of direct voltage between base stage and the emitter of transistor VT1 voltage should＞0.7V, with higher-order of oscillation coil L two terminal shortcircuits once, voltage should have certain variation, this explanation circuit vibrates.
Band switch should place the FM wave band, pulls out the antenna of FM receiver, opens 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 change the width of enamelled wire coil through stretching or compression higher-order of oscillation coil L, 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 9～10m, still can receive clearly till the voice signal.Attention wireless microphone tranmitting frequency in debugging should be avoided 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.Select for use the high-quality alkaline battery about 400mAh of every joint capacity (MAH) to be example, but No. 5 battery running hours of 1 joint were about 40 hours.In actual use, the different times that continue to use of kind because of battery have discrepancy.
Claims (4)
1. simplest and dependable frequency modulation wireless microphone; Be made up of battery DC, electric source filter circuit, audio signal input circuit, the higher-order of oscillation and radiating circuit, it is characterized in that: the higher-order of oscillation and radiating circuit comprise biasing circuit and the audio signal input circuit of NPN transistor VT1.
2. simplest and dependable frequency modulation wireless microphone according to claim 1; It is characterized in that: the base stage of a termination NPN transistor VT1 of the output D of the Electret condenser microphone MIC in the biasing circuit of NPN transistor VT1 and the audio signal input circuit and resistance R 1; The anodal VCC of the other end connection circuit of resistance R 1, the metal shell end S of Electret condenser microphone MIC links to each other with circuit ground GND.
3. simplest and dependable frequency modulation wireless microphone according to claim 1; It is characterized in that: the base stage of the NPN transistor VT1 in the higher-order of oscillation and the radiating circuit is with connecing an end of capacitor C 1 and the end of higher-order of oscillation coil L; The other end of the other end of capacitor C 1 and higher-order of oscillation coil L 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.
4. simplest and dependable frequency modulation wireless microphone according to claim 1; It is characterized in that: an end of the capacitor C 2 in the electric source filter circuit and the positive pole of electrochemical capacitor C3 connect the end of mains switch K; The positive pole of another termination battery DC of mains switch K; The negative pole connection circuit ground GND of the other end of capacitor C 2 and electrochemical capacitor C3, the positive pole of battery DC links to each other with circuit anode VCC, and the negative pole of battery DC links to each other with circuit ground GND.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201110280289A CN102333255A (en) | 2011-09-21 | 2011-09-21 | Simple and reliable frequency modulation wireless microphone |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201110280289A CN102333255A (en) | 2011-09-21 | 2011-09-21 | Simple and reliable frequency modulation wireless microphone |
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| Publication Number | Publication Date |
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| CN102333255A true CN102333255A (en) | 2012-01-25 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201110280289A Pending CN102333255A (en) | 2011-09-21 | 2011-09-21 | Simple and reliable frequency modulation wireless microphone |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104682874A (en) * | 2015-03-18 | 2015-06-03 | 王志 | Micropower frequency modulation repeater without power supply |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN202334879U (en) * | 2011-09-21 | 2012-07-11 | 朱虹 | Simple and reliable frequency modulation wireless microphone |
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2011
- 2011-09-21 CN CN201110280289A patent/CN102333255A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN202334879U (en) * | 2011-09-21 | 2012-07-11 | 朱虹 | Simple and reliable frequency modulation wireless microphone |
Non-Patent Citations (2)
| Title |
|---|
| 张艳丰，孟惠霞: "《音响设备及维修实训》", 31 March 2008 * |
| 门宏: "《图解电子技术速学速用》", 30 June 2010 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104682874A (en) * | 2015-03-18 | 2015-06-03 | 王志 | Micropower frequency modulation repeater without power supply |
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Application publication date: 20120125 |