文章介绍电磁式膜厚计的电路设计。该计有一接触式恒压探头,电路部分有贮存数据和打印显示功能。在探头的初级线圈上加上交流电压后,产生感应电压。当探头靠近铁磁材料时,由于磁通变化而使次级线圈的感应电压改变,从而测出膜厚。文章简介了振荡电路,桥式电路、相位检波、低通滤波、电平移动、灵敏度调整、A/D转换器等电路并给出主程序流程和实测结果。 The article introduces the circuit design of electromagnetic film thickness gauge. The meter has a contact constant pressure probe, the circuit part has stored data and print display. After the primary coil of the probe is ac voltage added, an induced voltage is generated. When the probe is close to the ferromagnetic material, the induced voltage of the secondary coil is changed due to the change of the magnetic flux, and the film thickness is measured. The article introduces the circuits of oscillating circuit, bridge circuit, phase detector, low pass filter, level shift, sensitivity adjustment, A / D converter circuit and gives the main program flow and the measured results.