3. Main structure of the Metal Detector

5. Components of the CMD Coils Sectional view Top view Transformer action Oscillators Conditions for oscillations Amplifiers

6. Cross Sectional View of the coil Top view

7. Top view of the coil

8. Transformer action

10. Conditions for sustained oscillations For oscillations to sustained the following two conditions must be satisfied, 1. The loop gain |Aβ| = 1 2. The loop phase shift must be equal to 2nπ or ∟ Aβ = 2nπ where n = 1,2,3,…….

11. Amplifiers An Amplifier is made of: 1) A Gain "Block" (ideally possessing infinite gain) 2) Feedback 3) A Network that sets the amount of feedback (e.g., resistors) Also an amplifier should be capable of amplifying very small or weak Signal at its input

12. System Overview TRANSMITT OSCILLTTATOR SEARCH COIL RECEIVE AMPLIFIER STAGE BUZZER

13. Data Flow Diagram START ENTER THE CAPSULES INTO THE TRAY CAPSULES CONTAIN METAL Yes No

14. Data flow Diagram START ENTER THE CAPSULES INTO THE TRAY CAPSULES CONTAIN METAL STOP THE COIL DETECTS THE CONTAMINATED CAPSULE THE CIRCUIT GIVES THE SIGNAL TO THE BUZZER

15. Data Flow Diagram START ENTER THE CAPSULES INTO THE TRAY CAPSULES CONTAIN METAL CAPSULES COME OUT STOP