This study discusses the design and realization of a spiral flat coil-based vibration sensor combined with a phase detector IC CD4046 circuit and Fast Fourier Transform (FFT) analysis. The sensor was made on an FR4 PCB substrate with a configuration of 20 turns, a distance between turns of 0.254 mm, and a diameter of 25.4 mm. Its working principle is based on changes in inductance due to the in…