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本文介绍一例只用12个元件的低压微型无线调频话筒,在1.5V供电时,发射距离约30m左右,6V供电时达到100m以上。电路如图1所示。BG1与C1、C3组成高频振荡电路。驻极体话筒输出的音频信号经C1、C2预加重后送到发射管BG1的基极,在BG1基极与集电极之间产生随音频变化的电压,该电压就会导致BG1 c—e极电容
This article describes a case of only 12 components of low-voltage miniature wireless FM microphone, 1.5V power supply, the launch distance of about 30m, 6V power supply to reach more than 100m. Circuit shown in Figure 1. BG1 and C1, C3 composed of high-frequency oscillator circuit. The audio signal output by the electret microphone is pre-emphasized by C1 and C2 and then sent to the base of the transmitting tube BG1 to generate a voltage that varies with the audio frequency between the base and the collector of BG1. This voltage will cause the BG1 c-e pole capacitance