Self-made tapered radios, dedicated active speakers ----- Active Speaker

Homemade Rapid-raising Source Speakers Author: Mai Yongqiang I have a virtue multi-band radio, often listen to short-wave stations to learn foreign languages. However, the United States is inadequate: First, the speaker caliber in the machine is small, the distortion is large; the second is to listen to the short wave, the noise is large, and the external general active speaker play is particularly obvious. One day suddenly wants, why not make a source of noise with noise reduction function. Considering that the radio is mono-output, it is only necessary to make a mono journal box. Also because the broadcast is dominated by voice, there is no need for excessive pursuit. I designed the icon circuit. The left portion of the figure is a noise reduction circuit that is the core of LML894, which can effectively reduce the noise and to 10 dB per channel. Where W1 is a 1kΩ adjustable resistor. The right half is the power amplification portion, W2 is a volume potentiometer, which is selected to be a BTL, circuit, which has a simple circuit, and a large advantage of power. When debugging, adjust the volume potentiometer to the appropriate position, enter the radio signal and adjust W1, make the noise reduction effect obvious, distortion is smaller. When playing broadcasting broadcasts, especially short waves, usually have a lot of high-frequency noise, and people are more prominent, and the effect is very satisfied.

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