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三端单片AM波段收音机集成电路ZN414于70年代研制成功,其国产型号是D501、D7642、NT484等,它们均采用塑封,其外型如图1所示。图2是内部电路。图3是用414构成的收音机电路。R_1是输入偏流电阻。R_2是AGC电阻,其阻值范围是0.1～1.5kΩ,改变R_2可改变AGC范围及输出功率。C_1是高频旁路电容,它可滤除天线LC回路高频信号。C_2为滤波电容。C_2是隔直流电容。B为收听耳机。LC
Three-terminal single-chip AM band radio IC ZN414 successfully developed in the 1970s, its domestic models are D501, D7642, NT484, etc., which are plastic, its appearance shown in Figure 1. Figure 2 shows the internal circuit. Figure 3 is a radio circuit 414. R_1 is the input bias current. R_2 is AGC resistance, its resistance range is 0.1 ~ 1.5kΩ, change R_2 can change AGC range and output power. C_1 is a high frequency bypass capacitor that filters high frequency signals from the antenna LC loop. C_2 is the filter capacitor. C_2 is a DC blocking capacitor. B to listen to headphones. LC