Simple wireless microphone circuit diagram (seven wireless microphone circuit diagram)

Simple Wireless Microphone Circuit Diagram (1) The radio microphone coil L1 turns is close to the change and the capacitance of the change in capacity is lowered, and the transmit frequency is lowered; the transmit frequency is high, it is necessary to take the opposite measures. The range of capacitance variations in parallel with L1 cannot be too large and too small, otherwise the transmit frequency will be illegible, and there is no high frequency transmit signal (the circuit does not vain). If you want a farther transmission distance, add a better antenna to the radio and wireless microphone, and appropriately raise the power supply voltage of the wireless microphone. The L2 of the simple wireless microphone is short-circuited; adjusting the L2 of the enhanced wireless microphone, L3 can make the distance farthest. The choice of higher sensitivity, and the selective high-end radio can be received more far. Frequency: 88MHz to 108MHz distance range: 20 to 50 m (1V --- 15V) Power supply enhanced schematic: frequency: 88MHz to 108MHz distance range: 100 to 300 m (1V --- 15V) Power supply simple wireless microphone circuit diagram (2) Frequency: 88MHz to 108MHz Distance range: 20 to 30 meters 3V power supply. This circuit (see Figure) adopts a capacitance feedback oscillator with a frequency stable and adjustable. Its feedback signal is in the form of a capacitive partial pressure, and the output signal of the oscillator tube is fed back to the input. Where RE is a DC negative feedback resistor, C3 is a diakor coupling capacitor, and CE is an emitter bypass capacitor. L, C1, C2, C constitute a resonant loop. Since C2 corresponds to between the base and the emitter of the transistor BG, the feedback signal is taken from the feedback circuit of the C1, C2, and the feedback signal is taken from the voltage on C2. The oscillation frequency of the circuit is f = 1 / 2π, where C = C1C2 / C1 + C2. Making Reviews The FM microphone is simple and easy to make, more suitable for beginners. In an open area, the emission distance of this circuit is 20 to 30 meters. Long-term operating frequencies have a large offset. The signal is more harmonic, and the neighboring is generated. When making, the MIC is preferably not taken out with a soft wire, but welcoming it on the board. The inductance L can take a high frequency wax after adjusting the φ0.3mm round rod. When it is judged whether or not the circuit is encapsulated, the following is available. Use a common pointer universal table AC2V block, either the table pen is floating, another table brush contact the antenna, if the pointer is found to swing, the circuit has been oscillated, which can be adjusted. Simple wireless microphone circuit diagram (3) frequency: 70MHz to 120MHz Distance range: 20 to 30 meters 9V power supply simple wireless microphone circuit diagram (4) frequency: 88MHz to 108MHz distance range: 100 to 200 meters 3V power supply simple wireless microphone circuit diagram (5) The BG1 and peripheral components constitute a capacitor three-point oscillator, and the audio voltage generated by the MIC has changed the tubular capacity of the BG1, and in the high frequency, even small capacitance changes can cause a large frequency offset. The FM signal is sent to the line emission after the BG2 is enlarged. BG1, BG2 can be 3dG201, 3DG6, etc., β "80. The capacitance in the circuit uses a small porcelain capacitor. The resistance uses 1 / 8W small resistance, and the L1 uses the ∮ 0.6mm enameled line around 7 laps on the ballpoint pen, taken at 3 turns, and a tire is added to a television medium (also available) Short-wave radio spray magnetic core, but the effect is slightly poor), and the L2 is used in the balloles of the ball with a ∮ 0.35m enamel. The antenna can be used with an 80mm long soft wire, for convenience, a short line of the multi-load core. If the device is assembled in the figure, it is generally not necessary to adjust. Turn on the FM radio, adjust the FM band and the L1 core to disappear to a certain noise. Simple Wireless Microphone Circuit Diagram (6) Working Principle: It can be seen from the circuit diagram, which is divided into two levels, first-level audio amplifiers and one-stage RF oscillator. There is a FET in the actual microphone in the eternal microphone. If you like, the visual is level, and FET amplifies the capacitance of the microphone precursor membrane, which is the sensitive reason for the eradicacy. The audio amplification is carried out by its radiode crystal hub Q1, and the gain is 20 to 50, and the magnified signal is sent to the base of the oscillation level. The oscillation level Q2 is operated from about 88 MHz, which is adjusted by the oscillation coil (a total of 5 laps) and 47PF capacitor, which is also determined in the transistor, 18pf back-to-vehicle capacitor, and a few biasing elements, such as a 470 Ω emitter resistance and 22K base resistance. When the power is turned on, the 1NF base capacitor is gradually charged by 22K resistance, and 18 pf is charged with 470 Ω resistance of oscillating coil, but is more fast, and the 47PF capacitor is also charged (although only two ends of the two ends), the coil generates a magnetic field. . When the base voltage gradually increases, the transistor is turned on and effectively connects the internal resistance and connected to both sides of 18pf. When the 1nf capacitor is charged to the working voltage of the pole, we have a few messy week waves, so we assume that the base voltage continues to rise in the case where the working voltage is discussed, and the 18NF capacitor attempts to prevent the movement of the emitter, to the capacitor When the energy is exhausted and then the incident movement is not blocked, the substance voltage is lowered, the transistor is turned off, and the current of the current coil is also stopped, and the magnetic field is declaced. Magnetic field declaration, generates a voltage in the opposite direction, the collector voltage is reversed from the original 2.9V to more than 3V, and charging in the opposite direction 47PF, this voltage also affects 18PF capacitor charging, and 470Ω emitter resistance The voltage fell to a deeper turnoff of the crystalist. When the 18PF capacitor is charged, the radiation voltage has fallen and falls to a crystalist to start turning on, current flows into the coil, and confronts the declaced magnetic field. The voltage in the coil is reversed, and the collision voltage is lowered. This change is transmitted to the emitter by 18PF capacitance. As a result, the crystalist is removed, and the 18PF capacitor is shorted, and the cycle begins repeating. Therefore, Q2 is formed here An oscillation, generates an AC signal of 88MHz. The zoom in the audio signal is collected into Q2 by 0.1uf capacitor, changing the oscillation frequency, generating the desired FM electromagnetic wave. Simple Wireless Microphone Circuit Diagram (7) This circuit is stable, simple, high success rate, suitable for wireless enthusiasts. The operating voltage of the circuit is 9V, the operating current is 2 ~ 6mA, the element parameters are as shown in the figure, BG1 is 9018, BG2 is C1959 (may also be 9018, but the power is small, if it is D-40 to expand the short distance to 1000 meters ), L1, L2 is 0.5 mm of enamel lines around 4 and 3 laps, and the operating voltage can be increased to 12V, which can increase the distance, but the frequency can be changed, and the entire circuit is preferably powered by battery. The best effect of tone quality and triumph is achieved. When debugging, turn off the work of BG2 first, adjust the frequency you need, and finally open the BG2 circuit adjustment power. This circuit I use BG1: D40, BG2: C1970 effect, voltage 12V, BG1 operating voltage 6V, and distance is 3000 meters (directional experiment). If you want to use D-40, please pay attention to the working voltage of D-40 is 6V. It is best to put this circuit in a iron box and add an attenuation network.

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