Portable Metal Detector Based on Beat Frequency Oscillator Principle

Abstract

This research focuses on the implementation of the portable metal detector based on beat
frequency oscillator principle. The proposed circuit comprises of two oscillators, the differencing
frequency detector, and the amplifier circuit used to driving the speaker. The first oscillator circuit
employs one coil to function as a search coil. The second oscillator circuit is used as a frequency
reference generator for the system. The obvious advantage of the proposed detector is ease of
hardware implementation. The design method makes use of the commercially available electronics
component in our country. In addition, the proposed detector is also sensitive for coins and small
keys in a pocket.

Keywords: Metal detector, beat frequency oscillator, eddy current