Metal Detector with Arduino

I have hacked the metal detector to be able to have arduino receive and respond to any metal.

Using a $50 Bounty Hunter metal detector, I am took off the backing, and connect to the input and output on the VU meter. I then run this through a voltage divider, and send the output to the Arduino Analog In.

Being very new (noob) to electrical engineering, one aspect that caught me up is that I must connect the ground of the arduino to the ground of the power source (VU meter on the metal detector.) See the below image for circuitry.



Arduino is doing a great job notifying me of how much metal has passed by. Now to find some gold.