18-06-2015, 02:58 PM
report on metal detector of 557 from vegakit
Metal Detector Project
This circuit is most useful for security checking. Metal Detector available in the market are quite expensive.
This metal detector can be used to detect slightly big size metallic objects. It used a sensing coil. This coil should be kept near metallic objects for detection. Input of Circuit is a week colpitt’s R.F. range Oscillator. Sensing coil forms parts of tuned oscillator.
When coil is brought near a metallic object magnetic energy is observed and Oscillator fails to work. Then final transistor conducts and buzzer is activated. Use a 9 volts battery. After connecting battery, adjust the 4.7k preset till circuit just stop sounding.
PARTS LIST:-
RESISTORS
R1,R4 – 56K
R2 – 3K3
R3 – 22K
R5 – 2K7
R6 – 2K2
R7,R9 – 680E
R8 – 15K
P1 – 5K 3386 Trim
CAPACITORS
C1,C6 – .1PF (104) 100 KPF
C2 – 1KPF (102).001PF
C3 – 220PF
C4 – 270PF/100V
C5 – 12KPF/ 100V (.012/25V)
C7 – 100/25V
TRANSISTORS
Q1,2,3,4 – BC 547 PH
DIODE
D1,2,3,4 – IN 4148
MISCELLANEOUS
LED1 – 5MM Red LED
COIL1 – Metal Detector Coil
Buzzer – VK 27 CT (S)
Supply – 9v Snapper
PCB – VK 557 PCB