The receiver coil is tuned to determine when the current that is produced is interrupted. Therefore the coil that induces the magnetic subject plus the separate coil that listens into the disruption in the sector can be considered echolocation by bats. The bat generates a audio (induces a subject by https://angelonzkte.techionblog.com/28662855/metaldetector-blog-things-to-know-before-you-buy