Intelligent vehicle detector, based on the induction doughnut coil detecting principle, detects the information of vehicles traveling on the highways.

基于感应式环形线圈检测原理的智能车辆检测器检测公路上行驶的车辆信息。

To make a seawater antenna, the current probe (an electrical coil roughly the size and shape of a large doughnut) is attached to a radio’s antenna jack.

为制作一根海水天线，电流探针（一种电子线圈，尺寸跟形状大致相当于一个大炸面圈）要连接到一副无线电天线端子上。