Simple Wireless Karaoke Singing Microphone

The microphone is an indispensable, if the cable microphone is changed to a wireless microphone, the microphone introduced is more calm, and the microphone introduced is handled by hand, or it is put down, it will not happen, and the cost is low. Simple and easy. Working Principle: The working principle of this microphone is basically the same as common wireless microphone circuit, but the connection and sound quality effect have improved. The circuit is described with reference to the drawings, V1 and L1, C2, C3, etc. constitute an FM high-frequency oscillation circuit, adjusting L1, and C2 values ​​can change the operating frequency. C3 is a feedback capacitor for maintaining oscillations. The microphone signal is not input from the triode base as in the past, but is connected to the emitter in the emitter, and when the microphone self-integrated current changes with the sound size, the working current of V1 will change, and the V1 section capacitor CBe varies. The CBE is connected in parallel with the LC circuit in series, and therefore, the frequency modulation is implemented. This approach to the MIC completely avoids distortion of the audio signal through the coupling capacitor. 1882. Therefore, the frequency response range of this microphone is wide, the sound quality is pure, and the operation is stable, even if the hand-torched antenna does not affect the LC oscillation frequency. Component selection: oscillating tube V1 selects FT>1000MHz, ICM ≥ 100mA, high-frequency tube having a large beta value, such as C3355, C3358, BFR96, and the like. The ICM of 9018 is only 50mA, but can be used according to actual choice; MIC selection 600Ω dynamic microphone, currently high-grade cable microphone is more; L1 inner diameter is 5mm, with φ0.5mm enameled wire empty core around 5T; launch antenna The finished antenna can be used directly, and it can also be self-made: the coil portion has an inner diameter of 1 cm, the hollow core is from 15T and the straight portion is 7cm, which is heated on the heat shrink, and can also be used for a soft wire of about 10 cm. replace. Installation and debugging: After the component is installed, after the check is correct, turn on the power supply, and use a pocket-free radio to make a receiver. It is worth noting that the VCD with radio frequency output is severely interfered with the reception effect, so the power switch must be installed to the RF modulator, and the program is played using the AV terminal. Adjust the FM receiver and the L1 turns, so that the C2 is changed if necessary. The audio signal output from the radio is delivered to the VCD or megaphone for power amplification. The emission distance is a big relationship with the sensitivity of the radio, but generally ≥10 meters.

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