Circuit Diagram of Twin-Coil Metal Detector Composed of 555

Published:2011/9/7 0:47:00 Author:Vicky | Keyword: Twin-Coil Metal Detector | From:SeekIC

Picture (a) is a twin-coil metal detector. It iscomposed ofprobing head, emitter, receptor, timer, and audio transmitter etc. As shown in picture (B), emitter in made of multivibrator (IC1,R1,R2,C2) and monostable timer (IC2,R4,C4). The timer IC2 is triggered by the pulse sent by multivibraror IC1. The vibrator’s frequency is f=1.44/(R1+2R2)C2. Picture (C) is receiving circuit which is mainly made of difference amplifier and detection amplifier. Picture (d) is timer circuit. It iscomposed oftwo monostable time-delay circuit which are composed of IC3,R10,C7 and IC4,R12,C9 respectively. The IC4 is controlled by the output of IC3. The delay time of IC3 is td=l.1R12C9 while IC4 is td2=1.1R10C7. Picture (e) is audio generator. The multivibrator which is composed of 555(IC9), BG4, R26, R27,C17 is its core part. When there is no metal-actuated signal, BG4 is stopped by the signal sent out by pin ⑥ of IC6, the multivibrator and the correspondent speak do not work.



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