CN202931294U - High sensitivity FM transmitter - Google Patents
High sensitivity FM transmitter Download PDFInfo
- Publication number
- CN202931294U CN202931294U CN 201220523020 CN201220523020U CN202931294U CN 202931294 U CN202931294 U CN 202931294U CN 201220523020 CN201220523020 CN 201220523020 CN 201220523020 U CN201220523020 U CN 201220523020U CN 202931294 U CN202931294 U CN 202931294U
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- resistance
- triode
- electric capacity
- resistor
- microphone
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Abstract
The utility model discloses a high sensitivity FM transmitter, which comprises a cell, a microphone, an antenna, a first triode, a second triode, an inductance, a first capacitance to a sixth capacitance, and a first resistor to an eighth resistor. According to the utility model, an audio frequency part employs the high sensitivity capacitive microphone and a built-in field effect transistor, the low level sound in a speech spectra scope can be clearly picked, voice voltage generated on a seventh resistor is coupled to a base electrode of the second triode of the audio frequency amplifier transistor through the sixth capacitance by the microphone; and the direct current bias of the first triode for transistor oscillation is provided by the first resistor and a second resistor, thereby the high sensitivity FM transmitter is characterized in that the modulation degree is deep, no amplitude modulation(PAM) is generated, the distortion is less, the signal emission distance is far, and the work is stable when in use.
Description
Technical field
The utility model relates to a kind of FM transmitter, relates in particular to a kind of highly sensitive FM transmitter.
Background technology
The small-power modulated transmitting device circuit that existing audio devices adopts, great majority adopt integrated circuit to consist of, adopt special-purpose voicefrequency circuit, therefore can cause modulation degree more shallow, produce that amplitude modulation(PAM) is excessive, distortion is large, transmitting range is short, the phenomenon of job insecurity.
Summary of the invention
The purpose of this utility model provides a kind of highly sensitive FM transmitter with regard to being in order to address the above problem.
The utility model is achieved through the following technical solutions above-mentioned purpose:
the utility model comprises 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 be connected the first end of the 3rd electric capacity and connect, the negative pole of described battery is simultaneously 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 be connected the second end of the 3rd electric capacity and connect, the second end of described the 8th resistance simultaneously with the first end of described the 5th resistance be connected the first end of the 7th resistance and be connected, the second end of described the 7th resistance simultaneously with the second end of described microphone be connected the first end of the 6th electric capacity and be connected, the second end of described the 6th electric capacity simultaneously with the first end of described the 6th resistance be connected the base stage of the second triode and be connected, 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 be connected the first end of the 5th electric capacity and connect, 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 be connected the base stage of the first triode and connect, the emitter of described the first triode simultaneously with the second end of described the 3rd resistance be connected the first end of the second electric capacity and be connected, 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 be connected the second end of inductance and connect, 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.
The beneficial effects of the utility model are:
The utility model audio-frequency unit has adopted a high sensitivity capacitive microphone and built effect transistor, and will clearly pick up low level sound in the voice spectrum scope, in use modulation degree does not produce deeply, that amplitude modulation(PAM), distortion are little, distance, working stability are sent in the signal emission.
Description of drawings
Fig. 1 is circuit structure schematic diagram of the present utility model.
Embodiment
The utility model is described in further detail below in conjunction with accompanying drawing:
as shown in Figure 1: the utility model comprises battery B, microphone ML, antenna ANT, the first triode Q1, the second triode Q2, inductance L, the first capacitor C 1 to the 6th capacitor C 6, the first resistance R 1 to the 8th resistance R 8, the anodal while of battery B and the first end of the first resistance R 1, the first end of the 8th resistance R 8, the first end of the 4th capacitor C 4, the first end of the first end of inductance L and the 3rd capacitor C 3 connects, 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 second end of the first end of the 3rd resistance R 3 and the 3rd capacitor C 3 connects, the second end of the 8th resistance R 8 is connected with the first end of the 5th resistance R 5 and the first end of the 7th resistance R 7 simultaneously, the second end of the 7th resistance R 7 is connected with the second end of microphone ML and the first end of the 6th capacitor C 6 simultaneously, the second end of the 6th capacitor C 6 simultaneously with the first end of the 6th resistance R 6 be connected the base stage of triode Q2 and be connected, the second end while of the 6th resistance R 6 and the second end of the 5th resistance R 5, the first end of the collector electrode of the second triode Q2 and the 5th capacitor C 5 connects, 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 be connected the base stage of triode Q1 and connect, the emitter of the first triode Q1 simultaneously with the second end of the 3rd resistance R 3 be connected the first end of capacitor C 2 and be connected, 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 is connected the second end and is connected with inductance L, 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 Figure 1: the first triode Q1 consists of a more stable RF oscillator, and its frequency is determined by coil inductance L and the 4th capacitor C 4.Determine the operating frequency of expectation by adjusting the 4th capacitor C 4, 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 keep oscillating condition.The first resistance R 1 and the second resistance R 2 provide correct work needed emitter junction bias voltage, all radiofrequency signals that the first capacitor C 1 will be added to base stage switch to ground, the 3rd capacitor C 3 provides radio frequency path for the accumulator of inductance L and the 4th capacitor C 4 formations, and blocking-up simultaneously is added to the supply voltage of the collector electrode of the first triode Q1.As shown in Figure 1: audio-frequency unit a high sensitivity capacitive microphone ML and built effect transistor, and will clearly pick up the interior low level sound of voice spectrum scope.The voice voltage that microphone ML produces on 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 Dc bias of oscillistor the first triode Q1 is provided by the first resistance R 1 and the 2nd R2.Now, a signal voltage that produces on 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 carries out FM and AM modulation by the dc point of a small amount of mobile base stage part to oscillating circuit.The 8th 8 pairs of resistance R oscillator and voicefrequency circuit uncoupling prevents feedback and other undesired effects.
Claims (3)
1. highly sensitive FM transmitter, 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 be connected the first end of the 3rd electric capacity and connect, 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 be connected the second end of the 3rd electric capacity and connect, the second end of described the 8th resistance simultaneously with the first end of described the 5th resistance be connected the first end of the 7th resistance and be connected, the second end of described the 7th resistance simultaneously with the second end of described microphone be connected the first end of the 6th electric capacity and be connected, the second end of described the 6th electric capacity simultaneously with the first end of described the 6th resistance be connected the base stage of the second triode and be connected, 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 be connected the first end of the 5th electric capacity and connect, 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 be connected the base stage of the first triode and connect, the emitter of described the first triode simultaneously with the second end of described the 3rd resistance be connected the first end of the second electric capacity and be connected, 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 be connected the second end of inductance and connect, the tap of described inductance is connected with described antenna.
2. the highly sensitive FM transmitter shown according to claim 1, it is characterized in that: described the 4th electric capacity is variable capacitance.
3. the highly sensitive FM transmitter shown according to 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 |
|---|---|---|---|
| CN 201220523020 CN202931294U (en) | 2012-10-14 | 2012-10-14 | High sensitivity FM transmitter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220523020 CN202931294U (en) | 2012-10-14 | 2012-10-14 | High sensitivity FM transmitter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN202931294U true CN202931294U (en) | 2013-05-08 |
Family
ID=48221203
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 201220523020 Expired - Fee Related CN202931294U (en) | 2012-10-14 | 2012-10-14 | High sensitivity FM transmitter |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN202931294U (en) |
Cited By (1)
| 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 |
-
2012
- 2012-10-14 CN CN 201220523020 patent/CN202931294U/en not_active Expired - Fee Related
Cited By (1)
| 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 |
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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: 20130508 Termination date: 20131014 |