Introduction: Metal Detector
This is my metal detector, detect metal using Mosfet and opamps and pair of coil.
component
1) IRLZ44N
2)Opamp LM324
3)Resistor 10k, 1k , 6.2k
4) Bc557 pnp transistor
5)Bc546 npn transistor
6)100mh inductor
7)171uF capacitor
8)22pf capacitor
9)buzzer
10) copper coil of 38 turns.
11)50k pot
Step 1: ZVS Circuit
ZVS circuit .Basically it generates sine wave one the both side of the coil. When the metal comes around the coil the frequency of zvs gets effected . Here you can see three sine waves generated by the Zvs oscillator. We will take the right sided sine wave and will multiply with a Schmitt trigger square wave
Step 2: Schmitt Trigger
Schmitt trigger made by op amp is creating square wave . At the place of 50k resistor we will use a 50k potentiometer to adjust the tuning . We will multiply the square wave with the sine wave of the zvs
Step 3: Multiplying Sine Wave With Square Wave
After multiplying the waves we will cut the useless frequencies by the low pass filter . In that case we will cut down high
frequency which is 1/2 Sine (2 PI t(50.5Khz)) and then we can hear audible sound .
Step 4: Resulting Signal
after filtering you can see the resulting signal is just few HZ .
Step 5: Clean the Signal
with the help of the schmitt comperator the signal gets inverted and cleaned up.
Step 6: High Pass RC Filter
With the High Pass RC filter the inverted signal gets chopped of .So we can hard a sudden click . because one sudden click has multiple harmonics .
Step 7: The Last Inverter
for a sudden click we will use a comparator . the pulse width will remain same regarding the change of the input frequencies.
Step 8: Buzzer
Fed the signal in to the buzzer and enjoy your circuit
Step 9:
https://youtube.com/shorts/SnaiSga-t00?si=SqZ5jsqi09lrI0ma
