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本文介绍的两用话筒采用了优质集成电路,使该话筒能高保真地传送声音,它具有工作性能稳定,有效距离远,制作、调试都很容易。电路工作原理:如图1所示,M将拾取的声信号转变成电信号,经运放NE5534及外围元件组成前置放大器放大后,信号由⑥脚输出,经C3耦合加在电位器W两端,再经中间抽头、开关K、C5耦合到三极管T的基极,使基极电位变化,从而使基极到集电极之间的结电容器随音频电压的变化而变化,实现了对高频振荡信号的调制,调制后的射频信号经天线发射出去。
This article describes the dual-use microphones using high-quality integrated circuits, so that the microphone can be transmitted with high fidelity, it has a stable performance, effective distance, production, commissioning is very easy. Circuit works: Shown in Figure 1, M will pick up the acoustic signal into electrical signals, the op amp NE5534 and the external components of the preamplifier to enlarge, the signal output by the ⑥ feet, coupled by the C3 potentiometer W two End, and then the middle tap, the switch K, C5 coupled to the base of the transistor T, so that the base potential changes, so that the base to collector junction capacitor with the audio voltage changes, to achieve high-frequency Oscillation signal modulation, the modulated RF signal emitted by the antenna.