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The signal from a microphone is two weak for a standard line input. This low-noise DC-coupled microphone amplifier provides a solution for anyone who wants to connect a microphone to his or her hi-fi installation. As can be seen from the schematic diagram, a good circuit does not have to be complex. A differential amplifier is built around T1 (MAT-03E), which is a low-noise dual transistor. The combination of T2 and LED D1 forms a constant-current source for the input stage. A low-noise opamp (OP-270E) amplifies the difference signal that appears at the collectors of the dual transistor. The result is an analogue signal at line level.

The bandwidth of the amplifier ranges from 1 Hz to 20 kHz. Within the audio range (20 Hz to 20 kHz), the distortion is less than 0.005 percent. Since only half of the OP-270E is used, the remaining opamp could be used in the output stage of a stereo version. The amplifier can be powered from a stabilized, symmetrical supply with a voltage between ±12 V and ±15 V. Such supply voltages are already present in many amplifier

Wireless FM transmitter circuit Microphone Hi Fi using a model-ready transmitters, this is because the buil-up transmitter module has a transmission capability of a stable and very effective to emit 10 mW RF. so that the target of Hi Fi FM Wireless Microphone transmitter circuit Hi Fi can be realized. The series can be seen from the FM transmitter Microphone Wireless Hi Fi transmitter module is that it stands alone with an additional R7, R8 and C6 to produce high-quality RF frequency.

In the series of FM transmitter Microphone Wireless Hi Fi module requires power consumption of a battery 12 VDC. Transmission antenna is directly connected with the circuit module Wireless FM transmitter Wireless FM Microphone Hi Fi.