Metal detector 8

Published:2011/7/29 2:41:00 Author:Ecco | Keyword: Metal detector | From:SeekIC

This example describes a metal detector which uses a PLL (phase locked loop) digital integrated circuit MCl4046, it can emit the alarm signal when detects metal objects, and it can determine detected material which is based on current meter's instructions. The device is suitable for detection of nails in wood, the metal objects in sand, wires in walls and so on. The working principle.The metal detector circuit is composed of dection circuit, PLL phase-locked loop circuit and sound alarm circuit, it is shown in Figure 8-74. Detectioncircuit is composed of the detection coil L, the transistor Vl, resistors Rl-R3, capacitors Cl-C5. PLL phase-locked loop circuit consists of integrated circuit ICl, resistors R4-R8, capacitor C7-Cll. Sound alarm circuitis composed ofthe transistor V2, comparing amplifier integrated circuit IC2, buzzer HA, resistors Rg-R14. Rl-Rl4 use 1/4W carbon film resistors or metal film resistors; Rl5 uses 1/2W metal film resistors. RP uses small potentiometer or variable resistor. Cl, C2, C7-C9, Cl2 and C13 select monolithic capacitors; C3-C6 and ClO use high-frequency ceramic capacitors; C11 uses fine-tuning capacitor (semi variable capacitor). Vl and V2 use S9018 or 2SCl815 NPN silicon transistor. ICl uses MCl4046B PLL PLL CD4046 integrated circuit; IC2 uses PPC393C type operational amplifier integrated circuit.



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