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许多万用表交流电压档的最低量程是10伏,如果用它测量半导体收音机的输出电压,则表针摆动幅度太小,不易观察。现将万用表改制成简易“毫伏表”,用它测量半导体收音机的输出电压,观察比较方便。下面就来介绍这种毫伏表。电路如图1所示:a b两点接在收音机的喇叭上,这里的二极管最好选用2AP9或2AP10,电解电容器的容量选10μ——30μ,额定工作电压不限,万用表选用直流电压2.5V、3V等挡,如果电表只有0.5V档,串联上一只三倍或四倍于电表该档内阻的电阻也很适用。
Many multimeter AC voltage range of the minimum voltage is 10 volts, if it is used to measure the output voltage of the semiconductor radio, then the amplitude of the watch swing is too small, not easy to observe. Meter is now converted into a simple “millivolt table”, use it to measure the semiconductor radio output voltage, more convenient to observe. Here’s to introduce this millivolt meter. Circuit shown in Figure 1: ab two points connected to the radio speaker, where the best choice of diode 2AP9 or 2AP10, electrolytic capacitor capacity selection 10μ - 30μ, the rated operating voltage is not limited to multimeter selection of DC voltage 2.5V, 3V and other stalls, if the meter only 0.5V file, a triple or quadruple the meter resistance of the resistance of the file is also very applicable.