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如果您的长辈由于各种原因听力减弱,您不妨试做一个本文介绍的耳聋助听器,也许能解除长辈因耳背带来的苦恼。 该助听器实际上是一个超小型的扩音器。它包括传声器、前置放大器、音频功率放大器和受话器四部分。其电原理图如 附图所示。来 自传声器BM 的微弱信号, 由耦合电容 C2输入到低 噪声管VT 的基极,由 VT组成的电压并联负反馈放大器进行前置放大。放大后的信号又经耦合
If your elder’s hearing weakens for any number of reasons, try a deaf hearing aid described in this article that may relieve elders of distress from the ear. The hearing aid is actually an ultra-small loudspeaker. It includes the microphone, preamplifier, audio power amplifier and receiver four parts. The electrical schematic as shown in the figure. The weak signal from the microphone BM is input to the base of the low-noise tube VT by the coupling capacitor C2, and the voltage composed of VT is parallel-coupled to the negative feedback amplifier for preamplification. The amplified signal is coupled