CN102231633A

CN102231633A - Wireless frequency modulation transmitter manufactured by using varactor diode

Info

Publication number: CN102231633A
Application number: CN2011100699188A
Authority: CN
Inventors: 刘昭利
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-03-23
Filing date: 2011-03-23
Publication date: 2011-11-02

Abstract

The invention belongs to the field of electronic technologies and wireless communication technologies and discloses a wireless frequency modulation transmitter manufactured by using a varactor diode. The wireless transmitter consists of a direct-current (DC) power supply, an audio pickup and audio amplification circuit, a low-pass filter circuit and an oscillation and high-frequency amplification circuit. The wireless transmitter is characterized that the emitter of a silicon transistor BG1 in the audio amplification circuit is connected with an alternating-current negative feedback loop, and a frequency modulation circuit comprises a varactor diode and a bias circuit. The invention overcomes the defects of easily produced parasitic amplitude modulation, lots of harmonic components and the like caused by a frequency modulation mode of a wireless frequency modulation microphone through the change of the capacitance between a base and an emitter of a transistor. The invention ensures that the capacity of the varactor diode is changed along the change of audio signals and then the audio signals are loaded into an oscillation circuit so as to realize the frequency modulation. The transmitter needs no external antenna so as to bring great convenience for the use of users.

Description

Frequency modulation wireless launcher with the capister making

Technical field

The invention belongs to electronic technology and wireless communication technology field, is the frequency modulation wireless launcher of making of capister about a kind of.

Background technology

The operation principle of most frequency modulation wireless microphones is by changing electric capacity realization frequency modulation between transistorized base stage and the emitter on the market, when the sound voltage signal is added to transistorized base stage, electric capacity can change synchronously along with sound voltage signal size between transistorized base stage and the emitter, transistorized tranmitting frequency is changed, and then realize modulation frequency.

Core parts of the present invention are capisters, and audio signal makes the capacity of capister change along with the variation of audio voltage, then audio signal are loaded in the oscillating circuit, thereby have realized frequency modulation.This reflector need not external antenna, greatly facilitates user's use.

Below describe this frequency modulation wireless launcher of making of capister in detail and make related relevant technologies measure.

Summary of the invention

Goal of the invention and beneficial effect: the frequency modulation work that the objective of the invention is to overcome most frequency modulation wireless microphones is to realize frequency modulation by changing between transistorized base stage and the emitter electric capacity, this mode of frequency regulation exists easy generation parasitic amplitude modulation phenomenon, and defective such as harmonic components is many.The present invention utilizes capister, and the capacity of capister is changed along with the variation of audio signal, then audio signal is loaded in the oscillating circuit, thereby realizes frequency modulation.This reflector need not external antenna, greatly facilitates user's use.This frequency-modulated transmitter also has simple, the characteristics such as cost is low, dependable performance of making.

Technical scheme: with the frequency modulation wireless launcher of capister making, pick up and audio amplifier circuit, low-pass filter circuit and vibration and high-frequency amplifier circuit are formed by DC power supply DC, audio frequency, it is characterized in that: the emitter of silicon transistor BG1 is connected to the interchange negative feedback loop in audio amplifier circuit, and FM circuit is capister and biasing circuit.

Connection features in the composition of each several part circuit and the circuit between the components and parts

Audio frequency picks up and audio amplifier circuit: the base stage of silicon transistor BG1 links to each other with the negative pole of electrochemical capacitor C1, an end of resistance R 1, the positive pole of electrochemical capacitor C1 connects the output of capacitor microphone MIC, the shell connection circuit ground GND of capacitor microphone MIC, the anodal VCC of the other end connection circuit of resistance R 1, the collector electrode of silicon transistor BG1 connects the positive pole of electrochemical capacitor C2 and an end of resistance R 2, the anodal VCC of the other end connection circuit of resistance R 2, the emitter of silicon transistor BG1 connects the interchange negative feedback loop.

Exchange negative feedback loop: the emitter of silicon transistor BG1 links to each other with the positive pole of electrochemical capacitor C3, the end of potentiometer RP, and the other end of the negative pole of electrochemical capacitor C3 and potentiometer RP and the lever arm of potentiometer RP are with connection circuit ground GND.

Low-pass filter circuit: the negative pole of electrochemical capacitor C2 links to each other with an end of capacitor C 4, an end of resistance R 3 and the end of inductance coil L1, the other end of the other end of capacitor C 4 and resistance R 3 is with the anodal VCC of connection circuit, the negative pole of another termination capister D1 of inductance coil L1.

Capister and biasing circuit: the positive pole of capister D1 links to each other with an end of capacitor C 5, an end of resistance R 4 and an end of resistance R 5, the other end of the other end of capacitor C 5 and resistance R 4 is with the anodal VCC of circuit, the other end connection circuit ground GND of resistance R 5.

Vibration and high-frequency amplifier circuit: an end of the base stage of silicon transistor BG2 and capacitor C 6, one end of resistance R 6 and an end of resistance R 7 link to each other, the other end of the other end of capacitor C 6 and resistance R 6 is with the anodal VCC of connection circuit, the other end connection circuit ground GND of resistance R 7, one end of the collector electrode of silicon transistor BG2 and capacitor C 8, the end of oscillator coil L2, one end of capacitor C 7 links to each other with an end of capacitor C 9, the other end of capacitor C 8, the anodal VCC of the other end connection circuit of oscillator coil L2, the negative pole of another termination capister D1 of capacitor C 7, the emitter of silicon transistor BG2 links to each other the other end connection circuit ground GND of resistance R 8 with the other end of capacitor C 9 and an end of resistance R 8.

The circuit working principle: this frequency modulation wireless launcher is made up of low-frequency amplifier circuit, low-pass filter circuit, capister and biasing circuit, vibration and high-frequency amplifier circuit.After the audio signal that capacitor microphone MIC produces is amplified by silicon transistor BG1, deliver to capister D1, its capacity is changed along with the variation of audio signal, and then the oscillating circuit of forming by silicon transistor BG2 carries out frequency modulation, frequency-modulatd radiofrequency signal by oscillator coil L2 to aerial radiation.This oscillating circuit has been eliminated and has been adopted transistorized junction capacitance frequency modulation to be easy to generate the parasitic amplitude modulation phenomenon, and defective such as harmonic components is few.

Description of drawings

Accompanying drawing is to the invention provides an embodiment circuit working schematic diagram with the frequency modulation wireless launcher of capister making.Require the shell connection circuit ground GND of electret capacitor microphone MIC.

Embodiment

Implement according to the circuit working schematic diagram of the frequency modulation wireless launcher of making of capister shown in the accompanying drawing and the components and parts specification requirement of description of drawings and the following stated, can realize the present invention.

The selection of components and parts and technical parameter thereof

BG1 is a silicon transistor, and model 2SC9014 requires β 〉=200; BG2 is a silicon transistor, requires models such as 2SC9018, characteristic frequency requirement 〉=350MHz.

D1 is a capister; Resistance 510 Ω of potentiometer RP.

Resistance all uses RTX-1/8W type metalfilmresistor, the resistance 470K Ω of resistance R 1, resistance 800 Ω of resistance R 2, the resistance 100K Ω of resistance R 3, the resistance 22K Ω of resistance R 4, the resistance 56K Ω of resistance R 5, the resistance 12K Ω of resistance R 6, the resistance 4.7K Ω of resistance R 7, resistance 330 Ω of resistance R 8.

C1～C3 is a CD11-25V type electrochemical capacitor, and capacity is respectively 22 μ F, 2.2 μ F, 220 μ F.

C4, C5 are the ordinary porcelain chip capacitor, and capacity is 0.01 μ F; C6 is a ceramic disc capacitor, and capacity is 1500PF, and C7, C8, C9 are the high-quality ceramic disc capacitor, and capacity is 5.1PF.

MIC is a microphone, selects the electret capacitor microphone of two lead-out terminals for use, the shell connection circuit ground GND of capacitor microphone MIC.

The making of element

When making the circuit of this device, require circuit board to use high-frequency loss circlet epoxy resins plate.

Inductance coil L1 puts down around 100 circles greater than the fixed carbon resister higher slice of 120K Ω in 1/4W, resistance with the enamelled wire of ￠ 0.25～0.3mm, and two joints are welded in the two ends of 100K Ω resistance.

Oscillator coil L2 puts down around 5 circles on ￠ 8mm pole with the enamelled wire of ￠ 1mm, and it is hollow that tread flaking becomes.

The adjustment of circuit

The circuit of the frequency modulation wireless launcher that making is made of capister, as long as the electronic devices and components performance of selecting for use is intact, and the components and parts annexation in the accompanying drawing is welded to specifications, after the physical connection line of circuit and welding quality process scrutiny were errorless, circuit only need simply be debugged and get final product operate as normal.

Device connects the 6V DC power supply, and surveying silicon transistor BG1 emitter should have the voltage of 0.67～0.9V over the ground, otherwise should adjust resistance R 1; Surveying silicon transistor BG2 emitter should have the direct voltage of 1.5～2V over the ground, if should not adjust resistance R 6 in scope; Survey the variable capacitance diode two ends again and answer no-voltage, or the voltage difference at variable capacitance diode two ends if its two ends pressure reduction is bigger than normal, should be adjusted resistance R 3 or resistance R 4 less than 0.28V.

After above-mentioned project adjustment finishes, with the receivable signal of FM receiver to the reflector emission, reflector is away from the distance more than the FM receiver 15m, if can not receive the signal that reflector sends, can adjust oscillator coil L2, stretching oscillator coil L2 fundamental frequency rises, compressional oscillation coil L2 fundamental frequency descends, make the frequency of reflector emission avoid local radio station, can reliable reception be as the criterion again, this reflector need not external antenna.After debugging was good, it is solid that oscillator coil L2 adopts the high-quality high frequency to seal with wax.

In capacitor microphone MIC input audio signal, the careful resistance that exchanges the potentiometer RP in the negative feedback loop of adjusting makes audio signal undistorted being as the criterion when max volume.Audio input end is connected to the audio output of television set, and the acoustical quality that it is clear, stable and the signal of FM radio station are almost as broad as long.

Device in its size suitable plastic of packing into, can't use can after adjusting end to begin a project.Device is when powering with 5V, and transmitting range is about 40m; When using the 6V power supply instead, its transmitting range can reach more than the 100m.

Claims

1. frequency modulation wireless launcher of making of capister, pick up and audio amplifier circuit, low-pass filter circuit and vibration and high-frequency amplifier circuit are formed by DC power supply DC, audio frequency, it is characterized in that: the emitter of silicon transistor BG1 is connected to the interchange negative feedback loop in the audio amplifier circuit, and FM circuit is capister and biasing circuit.

2. the frequency modulation wireless launcher of making of capister according to claim 1, audio frequency picks up and the feature of audio amplifier circuit is: the negative pole of the base stage of silicon transistor BG1 and electrochemical capacitor C1, one end of resistance R 1 links to each other, the positive pole of electrochemical capacitor C1 connects the output of capacitor microphone MIC, the shell connection circuit ground GND of capacitor microphone MIC, the anodal VCC of the other end connection circuit of resistance R 1, the collector electrode of silicon transistor BG1 connects the positive pole of electrochemical capacitor C2 and an end of resistance R 2, the anodal VCC of the other end connection circuit of resistance R 2, the emitter of silicon transistor BG1 connects the interchange negative feedback loop.

3. the frequency modulation wireless launcher of making of capister according to claim 2, the feature that exchanges negative feedback loop is: the emitter of silicon transistor BG1 links to each other with the positive pole of electrochemical capacitor C3, the end of potentiometer RP, and the other end of the negative pole of electrochemical capacitor C3 and potentiometer RP and the lever arm of potentiometer RP are with connection circuit ground GND.

4. the frequency modulation wireless launcher of making of capister according to claim 1, the feature of low-pass filter circuit is: the negative pole of electrochemical capacitor C2 links to each other with an end of capacitor C 4, an end of resistance R 3 and the end of inductance coil L1, the other end of the other end of capacitor C 4 and resistance R 3 is with the anodal VCC of connection circuit, the negative pole of another termination capister D1 of inductance coil L1.

5. the frequency modulation wireless launcher of making of capister according to claim 1, the feature of capister and biasing circuit is: the positive pole of capister D1 links to each other with an end of capacitor C 5, an end of resistance R 4 and an end of resistance R 5, the other end of the other end of capacitor C 5 and resistance R 4 is with the anodal VCC of circuit, the other end connection circuit ground GND of resistance R 5.

6. the frequency modulation wireless launcher of making of capister according to claim 1, the feature of vibration and high-frequency amplifier circuit is: an end of the base stage of silicon transistor BG2 and capacitor C 6, one end of resistance R 6 and an end of resistance R 7 link to each other, the other end of the other end of capacitor C 6 and resistance R 6 is with the anodal VCC of connection circuit, the other end connection circuit ground GND of resistance R 7, one end of the collector electrode of silicon transistor BG2 and capacitor C 8, the end of oscillator coil L2, one end of capacitor C 7 links to each other with an end of capacitor C 9, the other end of capacitor C 8, the anodal VCC of the other end connection circuit of oscillator coil L2, the negative pole of another termination capister D1 of capacitor C 7, the emitter of silicon transistor BG2 links to each other the other end connection circuit ground GND of resistance R 8 with the other end of capacitor C 9 and an end of resistance R 8.