Design of a Digital Eddy Current Displacement Sensor Based on Seiler Oscillator

To address the issue of short detection distances in small-sized probe heads of existing eddy current displacement sensors, this paper proposed an eddy current displacement sensor based on Seiler oscillator. The proposed sensor features a small probe head, high resolution, and a relatively long detection distance. The sensor consists of a Seiler oscillator, a voltage shaping circuit, and a digital processing section. First, a ferrite material is attached to the back of a 10mm PCB coil; then, a detection circuit is built to convert the change in inductance caused by the eddy current effect into a digital signal input to the MCU, achieving displacement measurement. Finally, through simulation and experimentation, it is demonstrated that the linear measurement range can reach 60% of the coil diameter, with a maximum detection range of up to 75% of the coil diameter.