CN103532572A - Low-power high-sensitivity FM transmitter - Google Patents
Low-power high-sensitivity FM transmitter Download PDFInfo
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- CN103532572A CN103532572A CN201210223522.9A CN201210223522A CN103532572A CN 103532572 A CN103532572 A CN 103532572A CN 201210223522 A CN201210223522 A CN 201210223522A CN 103532572 A CN103532572 A CN 103532572A
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Abstract
The present invention discloses a low-power high-sensitivity FM transmitter which comprises the following components: a battery, a microphone, an antenna, a first triode, a second triode, an inductor, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor and an eighth resistor. A high-sensitivity capacitive microphone and a built-in field effect transistor are adopted for an audio part of the low-power high-sensitivity FM transmitter. Furthermore low-level sound in the sound spectrum range is clearly picked. The sound voltage which is generated by the microphone on the seventh resistor is coupled with a base electrode of the second triode of an audio amplifier capacitively through the sixth capacitor. DC bias of the first triode of an oscillating transistor is supplied from the first resistor and the second resistor. Therefore, the low-power high-sensitivity FM transmitter has the following advantages: high modulation degree, no amplitude modulation, small distortion, long signal transmission distance and stable operation.
Description
Technical field
The present invention relates to a kind of FM transmitter, relate in particular to the highly sensitive FM transmitter of a kind of low-power.
Background technology
The small-power modulated transmitting device circuit that existing audio devices adopts, great majority adopt integrated circuit to form, do not adopt special-purpose voicefrequency circuit, therefore can cause modulation degree compared with shallow, produce that amplitude modulation(PAM) is excessive, distortion is large, transmitting range is short, the phenomenon of job insecurity.
Summary of the invention
Object of the present invention provides a kind of low-power highly sensitive FM transmitter with regard to being in order to address the above problem.
The present invention is achieved through the following technical solutions above-mentioned purpose:
The present invention includes battery, microphone, antenna, the first triode, the second triode, inductance, the first electric capacity to the six electric capacity, the first resistance to the eight resistance, the anodal while of described battery and the first end of described the first resistance, the first end of described the 8th resistance, the first end of described the 4th electric capacity, the first end of described inductance is connected with the first end of described the 3rd electric capacity, the negative pole while of described battery and the first end of described microphone, the emitter of described the second triode, the first end of described the first electric capacity, the first end of described the second resistance, the first end of described the 3rd resistance is connected with the second end of described the 3rd electric capacity, the second end of described the 8th resistance is connected with the first end of described the 7th resistance with the first end of described the 5th resistance simultaneously, the second end of described the 7th resistance is connected with the first end of described the 6th electric capacity with the second end of described microphone simultaneously, the second end of described the 6th electric capacity is connected with the base stage of described the second triode with the first end of described the 6th resistance simultaneously, the second end while of described the 6th resistance and the second end of described the 5th resistance, the collector electrode of described the second triode is connected with the first end of described the 5th electric capacity, and the second end of described the 5th electric capacity is connected with the first end of described the 4th resistance, the second end while of described the 4th resistance and the second end of described the first electric capacity, the second end of described the second resistance, the second end of described the first resistance is connected with the base stage of described the first triode, the emitter of described the first triode is connected with the first end of described the second electric capacity with the second end of described the 3rd resistance simultaneously, the collector electrode while of described the first triode and the second end of described the 4th electric capacity, the second end of described the second electric capacity and the second end of described inductance are connected, and the tap of described inductance is connected with described antenna.
Particularly, described the 4th electric capacity is variable capacitance; Described the first triode and described the second triode are NPN type triode.
Beneficial effect of the present invention is:
Audio-frequency unit of the present invention has adopted a high sensitivity capacitive microphone and built effect transistor, and by the low level sound clearly picking up within the scope of voice spectrum, in use modulation degree deeply, does not produce that amplitude modulation(PAM), distortion are little, distance, working stability are sent in signal transmitting.
Accompanying drawing explanation
Accompanying drawing is circuit structure schematic diagram of the present invention.
Embodiment
Below in conjunction with accompanying drawing, the invention will be further described:
As shown in drawings: the present invention includes battery B, microphone ML, antenna ANT, the first triode Q1, the second triode Q2, inductance L, the first capacitor C 1 is to the 6th capacitor C 6, the first resistance R 1 is to the 8th resistance R 8, the first end of simultaneously anodal and the first resistance R 1 of battery B, the first end of the 8th resistance R 8, the first end of the 4th capacitor C 4, the first end of inductance L is connected with the first end of the 3rd capacitor C 3, the negative pole while of battery B and the first end of microphone ML, the emitter of the second triode Q2, the first end of the first capacitor C 1, the first end of the second resistance R 2, the first end of the 3rd resistance R 3 is connected with the second end of the 3rd capacitor C 3, the second end of the 8th resistance R 8 is connected with the first end of the 7th resistance R 7 with the first end of the 5th resistance R 5 simultaneously, the second end of the 7th resistance R 7 is connected with the first end of the 6th capacitor C 6 with the second end of microphone ML simultaneously, the second end of the 6th capacitor C 6 is connected with the base stage of the second triode Q2 with the first end of the 6th resistance R 6 simultaneously, the second end while of the 6th resistance R 6 and the second end of the 5th resistance R 5, the collector electrode of the second triode Q2 is connected with the first end of the 5th capacitor C 5, and the second end of the 5th capacitor C 5 is connected with the first end of the 4th resistance R 4, the second end while of the 4th resistance R 4 and the second end of the first capacitor C 1, the second end of the second resistance R 2, the second end of the first resistance R 1 is connected with the base stage of the first triode Q1, and the emitter of the first triode Q1 is connected with the first end of the second capacitor C 2 with the second end of the 3rd resistance R 3 simultaneously, the collector electrode while of the first triode Q1 and the second end of the 4th capacitor C 4, the second end of the second capacitor C 2 and the second end of inductance L are connected, and the tap of inductance L is connected with antenna ANT, the 4th capacitor C 4 is variable capacitance, the first triode Q1 and the second triode Q2 are NPN type triode.
As shown in drawings: the first triode Q1 forms a more stable RF oscillator, its frequency is determined by coil inductance L and the 4th capacitor C 4.By adjusting the 4th capacitor C 4, determine the operating frequency of expectation, at the FM of standard broadcast band, tuning circuit is designed to the frequency of the highest generation 110MHz.The second capacitor C 2 provides necessary feedback voltage by the 3rd resistance R 3 in the first triode Q1 emitter circuit, to maintain oscillating condition.The first resistance R 1 and the second resistance R 2 provide correct work needed emitter junction bias voltage, the first capacitor C 1 switches to all radiofrequency signals that are added to base stage ground, the 3rd capacitor C 3 provides radio frequency path for the accumulator that inductance L and the 4th capacitor C 4 form, and blocking-up is simultaneously added to the supply voltage of the collector electrode of the first triode Q1.As shown in drawings: audio-frequency unit a high sensitivity capacitive microphone ML and built effect transistor, and by the low level sound clearly picking up within the scope of voice spectrum.The voice voltage that microphone ML produces in the 7th resistance R 7 is coupled to the base stage of audio frequency amplifier transistor the second triode Q2 through the 6th electric capacity capacitor C 6.The direct current (DC) bias of oscillistor the first triode Q1 is provided by the first resistance R 1 and the 2nd R2.Now, the signal voltage producing in the 6th resistance R 6 is coupled to the base stage of the first triode Q1 by nonpolarity the 5th capacitor C 5 through the 4th resistance R 4.The gain of the second triode Q2 is controlled by the ratio of the 7th resistance R 7 and the 6th resistance R 6, and DC point is set to and allows the maximum changing range of collector electrode be the signal after amplifying.Now, the voice signal through amplifying, by the DC point of a small amount of mobile base stage part, carries out FM and AM modulation to oscillating circuit.The 8th 8 pairs of resistance R oscillator and voicefrequency circuit uncoupling, prevents feedback and other undesired effects.
Claims (3)
1. the highly sensitive FM transmitter of low-power, it is characterized in that: comprise battery, microphone, antenna, the first triode, the second triode, inductance, the first electric capacity to the six electric capacity, the first resistance to the eight resistance, the anodal while of described battery and the first end of described the first resistance, the first end of described the 8th resistance, the first end of described the 4th electric capacity, the first end of described inductance is connected with the first end of described the 3rd electric capacity, the negative pole while of described battery and the first end of described microphone, the emitter of described the second triode, the first end of described the first electric capacity, the first end of described the second resistance, the first end of described the 3rd resistance is connected with the second end of described the 3rd electric capacity, the second end of described the 8th resistance is connected with the first end of described the 7th resistance with the first end of described the 5th resistance simultaneously, the second end of described the 7th resistance is connected with the first end of described the 6th electric capacity with the second end of described microphone simultaneously, the second end of described the 6th electric capacity is connected with the base stage of described the second triode with the first end of described the 6th resistance simultaneously, the second end while of described the 6th resistance and the second end of described the 5th resistance, the collector electrode of described the second triode is connected with the first end of described the 5th electric capacity, the second end of described the 5th electric capacity is connected with the first end of described the 4th resistance, the second end while of described the 4th resistance and the second end of described the first electric capacity, the second end of described the second resistance, the second end of described the first resistance is connected with the base stage of described the first triode, the emitter of described the first triode is connected with the first end of described the second electric capacity with the second end of described the 3rd resistance simultaneously, the collector electrode while of described the first triode and the second end of described the 4th electric capacity, the second end of described the second electric capacity and the second end of described inductance are connected, the tap of described inductance is connected with described antenna.
2. according to the highly sensitive FM transmitter of the low-power shown in claim 1, it is characterized in that: described the 4th electric capacity is variable capacitance.
3. according to the highly sensitive FM transmitter of the low-power shown in claim 1, it is characterized in that: described the first triode and described the second triode are NPN type triode.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210223522.9A CN103532572A (en) | 2012-07-02 | 2012-07-02 | Low-power high-sensitivity FM transmitter |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210223522.9A CN103532572A (en) | 2012-07-02 | 2012-07-02 | Low-power high-sensitivity FM transmitter |
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| Publication Number | Publication Date |
|---|---|
| CN103532572A true CN103532572A (en) | 2014-01-22 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201210223522.9A Pending CN103532572A (en) | 2012-07-02 | 2012-07-02 | Low-power high-sensitivity FM transmitter |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103731164A (en) * | 2012-10-14 | 2014-04-16 | 四川九鼎数码科技有限公司 | Highly-sensitive FM transmitter |
| CN108873722A (en) * | 2018-08-01 | 2018-11-23 | 合肥阅辞科技有限公司 | Wireless intelligent house managing and control system |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN202737853U (en) * | 2012-06-12 | 2013-02-13 | 成都槟果科技有限公司 | FM transmitter with low power and high sensitivity |
| CN202750078U (en) * | 2012-07-02 | 2013-02-20 | 成都默一科技有限公司 | FM transmitter with low power and high sensitivity |
-
2012
- 2012-07-02 CN CN201210223522.9A patent/CN103532572A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN202737853U (en) * | 2012-06-12 | 2013-02-13 | 成都槟果科技有限公司 | FM transmitter with low power and high sensitivity |
| CN202750078U (en) * | 2012-07-02 | 2013-02-20 | 成都默一科技有限公司 | FM transmitter with low power and high sensitivity |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103731164A (en) * | 2012-10-14 | 2014-04-16 | 四川九鼎数码科技有限公司 | Highly-sensitive FM transmitter |
| CN108873722A (en) * | 2018-08-01 | 2018-11-23 | 合肥阅辞科技有限公司 | Wireless intelligent house managing and control system |
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Application publication date: 20140122 |