Four wireless microphone circuits (attached brush circuit board)

"1 wireless microphone This wireless microphone, the circuit is simple, easily obtained, clear voice, very stable frequency. Its main feature is the small size, the machine can be installed in a marker. Small and exquisite appearance, attractive. Be Schematic: Be FIG board: Select element:.. 1. MIC high quality electret microphone; 2 enameled wire wound inductor L2 with φ0.35mm 6 turns on the pen core φ3mm, were derived from; 3 Ll φ0.51mm enameled in the same manner with the winding 8 turns, after taking a television womb core periphery screwed therein. In order to reduce the volume of the magnetic core can be pinched off from the middle, only half;. 4 Vl, V2 using ultra-high frequency low power transistors, C9018, β≥80. If the selected UHF low noise tube BFR96S the better; in order to reduce the space occupied by the element, all the optional miniature high frequency capacitance ceramic capacitors; 5. resistance in all 1 / 16W miniature metal film resistors; values ​​for all elements except C4 , C8 outside, a small discrepancy will not affect its performance; with a power supply battery 7; power switch with a manual selection of a long-handled television micro switch. Microphone shell with a large marker. As shown below: Be Be Machine by the modulation frequency and an oscillation amplification of two parts. Vl and peripheral elements by a three-point capacitance oscillator. MIC microphone sound signal into a corresponding electrical signal, coupled via Cl to the base electrode of Vl, Vl so bc junction capacitance signal changes with the change, so that the oscillation frequency is changed, to achieve frequency modulation. C6 is input to the FM signal V2 from the Group A consisting of buffer amplifier stage multiplier, to obtain high power radio frequency signal is twice the fundamental frequency, and then transmits to the space via antenna TX. This depends on the operating frequency of the circuit L1, C3 tuning circuit composed. Be Be 2. The wireless microphone attached to the circuit board of FIG. Be I. Production notes 1, this paragraph wireless microphone circuit design is reasonable, attractive appearance Fang, sound transmission distance, the state long life, cost-effective, low power consumption, adapt to ordinary FM FM radio, read this material carefully before assembly. 2, the oscillation coil L production: straight shank diameter of 5 mm drill towel take off after about four turns with a diameter of 0.5 mm enameled wire flat Serve. 3, L the adjustment of the oscillation coil: on the radio (FM section disposed) and the microphone switch K (at turn ON) and handset, the microphone speech while receiving station while adjusting knob (or frequency selection keys) pass until the radio Until the own voice, if (i.e., a 88 l 08MHz) still have not received their voice is carefully struck across the band oscillator coil L. Simply pull or reduce the distance between lines during each turn toggle periphery, the entire side should be carefully. If the coil is still no slack adjuster should continue to work unless the above-described L Kuai whole after welding to increase a turn down or turn a decrease (due to the influence of electronic components parameters), the re-weld. 4, prior to the present set of circuits made ready to install, use the multimeter at the mass of each filter element. If the conditions for measurement of each ceramic capacitor capacitance meter at capacity, so foolproof, i.e., a loaded successfully. This kit with very careful screening element, and in particular to ensure the quality of virtual, false error weld during welding. Under normal circumstances can be successful. Be Second, the list of components Be Third, the circuit schematics Be Fourth, the printed circuit 3. Make a remote wireless microphone attached to the circuit board of FIG. Be Be Be Above video signal transmission for demonstration, far greater than the actual distance from the video, local prevail. Foreword Wireless microphone want to have good results, use a good power, antenna, means, in the best condition and debugging circuits. Some models site wireless microphone (the component package) will have greater distances and higher performance, complete with some practical value. If you need more longer distances (greater than 500 meters) and higher performance, first to the radio management application, we recommend that you design yourself or others or entrust site design. Enhanced wireless microphone, FM radio work, good sound quality, you can listen to ordinary radio. The microphone voice signal into electrical signals, first retransmission by a modulation stage audio voltage amplifier, which can pick up a faint voice farther and more. Modulated high frequency signal and then by an oscillating tuned antenna transmission power amplification before transmission, and transmit farther reduce the effects of hand touch the antenna oscillating stage to reduce the harmonics. This circuit is installed in accordance with the frequency in about 83MHz, simply turn coil L from the poke point, so that the oscillation frequency of 88MHz-108MHz can work, can be used with any FM radio receives the frequency signal, and restore the sound signal from the high frequency signal. Also with an external audio jack and a variable resistance adjusting an amount of attenuation of the input audio signal. Performance parameters: Frequency range: 80MHz-103MHz (a circuit diagram according to the parameters, adjust only the coil turns away) Operating voltage: 1.5V -9V transmit radius: more than 100 m test conditions: voltage 4.5V, ordinary radio receiver, a wireless microphone is 50cm long antenna the thin wire test sites: high residential buildings Wireless transmitter development potential: The following is a partial function or use of the wireless microphone can be achieved. For the purpose of this site to learn techniques of everyone, so do not consider the practical value of the product and other factors. 1, wireless microphone: user singing, can be free to rotate 360 ​​degrees and moves, the wire will not stumble or when performing speech, Che Houtui. 2, radio: teacher be broadcast live lectures, many students can receive radio lectures called, greatly increased the number of lectures. 3, selling wireless devices: when to sell goods on the street, selling wireless microphone with a certain novelty, will receive more than ordinary microphone good advertising effect. 4, radio listener: a better concealment and security, can listen to the radio with a headset in the distance, do not worry about embarrassing scene meet. 5, wireless alarm devices hold: unattended certain distance. For example, can monitor the sound floor door of the second floor, it acts as a burglar alarm. 6, wireless electronic doorbell: since radio propagation sound, and therefore may be radio propagation doorbell sound, may also be converted into pairing radios. 7, wireless electronic musical instruments: the harmonica, erhu, guitar and other instruments sound receiving radio broadcast or use an amplifier to expand, can better enjoy the music. 8, the electronic hearing aid: by adjusting the volume of the radio or microphone, then amplifies the sound with the headphones can effectively improve the elderly hearing. 9, small voice lights: the output of the power amplifier connected to a speaker change corresponding wattage 6V, 12V automotive bulb, adjust the volume place. 10, reading memory booster: hearing aids and similar to the microphone at yourself, listen to your own voice reading to exclude outside interference, from the focus effect. 11, small radio stations: suitable for schools, factories and other units have organized various programs on their own, can play music, news, notices, etc., by listening to the radio. 12, television sound transponders: Listen can not influence others sleep with headphones while watching TV, but by the headphone cord length control. This device can be used without this restriction. Referring to FIG circuit working principle MIC nature first audio signal into an audio electrical signals, C2 is coupled to the base of Q modulated, when a voice signal, the transistor junction capacitance will change the oscillation frequency is changed → complete frequency modulation, FM i.e. . C8 then coupled via a high frequency tuning amplifier for amplifying the modulated high frequency signal, and then through C12, L3 and TX antennas transmit high frequency electromagnetic waves with a frequency change of the sound signal changes outward. Wherein R1 is a bias resistor microphone MIC, generally selected in the 2K-5.6K. Collector resistor R4. R5 is the base resistance, bias current to Q1. R6 is an emitter resistor, the stabilizing effect of the DC operating point Q1; Q2, R7, R8, C4, C5, L1, C6, C7 frequency oscillating circuit composition, R7 to provide bias Q2 base, C5 and L1 tank, value can be changed to change its transmission frequency, C4 is the feedback capacitor, R8 Q2 DC operating point stabilizing effect, C7 blocking flow of AC capacitors; Q3, R9, R10, L2, C10, C11 composed of a high-frequency power amplifier circuit. R9 power transistor Q3 to base current, C10 and L2 tuning circuit amplification, and tuning the resonant circuit L1 and C5 maximum output power at the same frequency, firing distances. We designed FM radio transmission frequency band can be used with any FM radio receives the frequency signal, and restore the high frequency signal from the sound signal, thereby completing a variety of purposes. PCB board in FIG. Assembly instructions: 1, the resistance of ceramic capacitors do not have positive and negative points, but must pay attention to the resistance and capacitance values ​​no mistake. See the relevant methods of electronic experiment kit Lianyungang electronic network in this article. 2, the microphone board are positive and negative points, and an aluminum electrode is an anode connected to the housing, and the other is a cathode. For ease of installation, please add two welding pins. 3, transistor three pin function is completely different, have to make clear. See recognition of electronic experiment kit Lianyungang electronic network of related electronic information provided. 4, the package member made of copper wire coil, outside of it a layer of insulating varnish. It is a key element, adjusting the winding pitch can change the transmission frequency and distance. L1 turns from near and exchange capacity becomes larger capacitance makes the transmission frequency becomes lower; To transmit frequency becomes higher, it is necessary to take measures contrary. L1 and parallel capacitance variation range not too large or small, or the transmission frequency will be biased to the mark. Even high-frequency transmission signal is not generated (not oscillate). 5, the circuit board containing the component package pins, mounted in the key points, and an electronic test kits can be used in conjunction with a flexible, can be made wider range of electronic experiments. 6, the elements do not install the wrong position, the welding time is preferably controlled at 2-3 seconds and placed in place strive aesthetic element, to repeatedly check, after debugging power use. Packed finished board Hands-on production All Group photo elements: Mount resistor and ceramic capacitors Installation triode Mount Inductor, pay attention to 4.5T and 5.5T, inductance is not the same number of turns. Mounting the electrolytic capacitor, the positive and negative attention. Installation potentiometer, the potentiometer is used to adjust the sound size. Add pins to the microphone. MIC Installation Mounting pin, one end of the antenna, 2 is a power supply terminal, 3 is a signal input terminal. Mounted antenna The basic circuit is installed ~! Commissioning Description: Go first to FM radio (record) sound machine, turn on the power and the volume will be around 100MHz frequency modulation radio-free place. Wireless microphone to the circuit board through the power, a radio aligned, the oscillation coil L1 is adjusted sparsely (distance between the coils) with a screwdriver (non-inductive conditions, please screwdriver, see the website or self), until the outgoing radio screams . In this case the microphone and then slowly moved away from the radio while appropriately adjusting the volume of the radio (or microphone plate), the tuning knob until the clearest sound, and the farthest distance up. In the above-described steps are recommended 88MHz, 98MHz, 108MHz are near to try, so even if there is a large frequency deviation wireless microphone transmitter, the radio can be received. If the radio can not receive it, please check the elements have not installed wrong, there is no damage components, power supply is normal. Selection of higher sensitivity, more selective high-grade radio can receive greater distances Be 4. FM wireless microphone with a voltage regulator circuit Some circuits on the "FM wireless microphone" previously published in the "newsletter", although simple, but there are still many shortcomings. Not from the past, there is noise, and now I introduce a simple, transmission range of up to 200 meters wireless microphone, the general beginners can make success. A circuit principle (see below) The circuit consists of three parts: 1. Audio amplifying portion; 2. High-frequency oscillation portion; 3. Regulators section. Base transistor VT1 signal injection electrode by the microphone MIC, the amplified audio signal is coupled via C2 VT1 to VT2 base frequency oscillating circuit, and then sent via the antenna. The circuit operating frequency is between 85 ~ 104MHz. Second, the selection of components MIC selection of high-sensitivity electret microphone, VT1 is 9013H, β≥125. VT2 is a 2N3866; β≥90, L1, L2, respectively, with tight ∮0.71mm enameled and 4 turns 10 turns on the normal ball pen, C4, C5, C6 using ceramic capacitor, an error ± 5%. Used LM7806 supply three-terminal regulator, a 9V battery, the circuit board can be made. Third, assembly and commissioning Circuit assembly is relatively simple, as long as no damage to the element, a package can be successful. After welding circuit is good, then the antenna through welding, 0.5m antenna radio antenna, debugging at the microphone on the sound source, and then leave the microphone 5 to 6 meters, turn on the FM radio, adjust the tuning knob, if received harmonic is turbid, screwdriver can be used to adjust the spacing oscillation coil L1, the distance L1 is large frequency increases, decreases and vice versa, is not received at this time with the sound harmonics. To increase the transmission power, the length of the transmit antennas may be changed, or the launch tube into 34D50 transistor VT2, R4 resistor 4.7 k [Omega replaced, this time may be further increased emission from about 100 meters. "

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