can anyone tell me how can i connect this circuit to arduino
I want a metal detector that will simply light a led on when detecting a metal
(I don't want the buzzer )
thank you all
You don't need an arduino for that.
Just replace the buzzer with an LED and a resistor.
I didn't understand how it will work
because when I looked on the output of the circuit with an oscilloscope
the output amplitude doesn't change only the frequancy does
You could have an Arduino determine when the frequency changes and light an LED, but it might be easier to build a different type metal detector.
Ok then an arduino can help.
Since a LED doesn't react to frequency the way a buzzer or speaker does. You will need a way to detect the frequency . Fortunately there is a library for that: frequency counter library
At the bottom of that page ( just below the download link) is a link to a thread on this forum where you can get help using that library.
You could have the arduino adjust the brightness of the LED to indicate the frequency, but it might be better to have a row of LED's like a bar graph to display the frequency.