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在一些偏僻山区打长途电话,由于线路和其它原因,经常会受到杂音干扰,互相听不清对方讲话。本文介绍的电路可解决这一问题,使对方的声音变得清晰响亮,听自动声讯电话时效果尤为明显。另外,还可以用调频收录机在远处听电话声音,音量开大也不会产生回授,并可即时把谈话声音录下,享受个中乐趣。 工作原理 该电路由增音电路和调频无线电发射电路构成。 增音电路由语音滤波与音频放大电路组成。由运放IC1和阻容元件组成一个有源300～3000Hz带通滤波电路,滤除通话语音以外的干扰信号,净化通话背景,提高信噪比。
Making long-distance calls in some remote mountainous areas often suffers from noise interference and can not hear each other’s voices due to routes and other reasons. This article describes the circuit to solve this problem, so that each other’s voice becomes clear and loud, especially when listening to automated voice calls. In addition, you can also use the FM radio to listen to the phone in the distance the sound volume will not produce a large feedback, and immediately recorded the voice of the conversation, enjoy the fun. The working principle of the circuit by the repeater and FM radio transmitter circuit. Pitch circuit consists of voice filtering and audio amplifier circuit. By op amp IC1 and RC components form an active 300 ~ 3000Hz band-pass filter circuit, filter out the interference signal outside the call voice, purify the call background, improve signal to noise ratio.