How does a metal detector work?

A metal detector works like this. You put some batteries into the control box and turn it on. Then you wave the coil over the ground from left to right and when you hear a beep then you dig!. For the actual scientific method

First let’s look at a metal detector.

Metal Detector Parts

Almost all metal detectors consist of the parts shown in this picture. The control box and the search coil. The control box is exactly that, a box that houses or holds all of the controls. These controls will vary greatly on the model of metal detector. The search coil is the part of the metal detector that you move over the surface to be searched. Now let’s get down to the guts and how they work.

All metal detectors work in the same way, they transmit, receive and some discriminate. No there are not racist metal detectors but models that offer discrimination can zero out the trash and save you time and effort by ignoring the junk. You won’t be digging every little piece of metal but discriminating with a metal detector can also cause you to loose precious metals such as gold or platinum. So it is up to you to find the correct balance with your machine and they are all different! It is your job to decide whether to use discrimination or not and your choice will also depend on the area that you plan on hunting. For instance there are underwater metal detectors that have no discrimination at all. The Tesoro Sand Shark is one of these models and I own one and I must say it is amazing, but you might be asking yourself, why would you want a machine that offers no discrimination. The Tesoro Sand Shark is made for metal detecting at the beach, mostly in the water. There is very little trash or garbage metals at the beach so discrimination might not be needed. The sand shark also is a Pulse Induction or PI metal detector. These metal detectors are known for their ability to find metal at amazing depths and salt water does not affect them like it does other metal detectors. What do I mean by that? Salt water can have lots of minerals which will make some metal detectors give false signals and you don’t need to be confused on where to dig. If you plan on metal detecting in a trashy area like a playground then discrimination is a must!

Electricity is sent through the search coil creating an electromagnetic field. The direction of the electricity is reversed thousands of times per second. When the electricity moves in one direction, a magnetic field is created whose polarity is pointed outward or towards the ground.  When the polarity is reversed it sends a signal back to the control box. If there is metal underneath the search coil, the electrical current will travel through it creating it’s own magnetic field which will work opposite of the transmitting signal and force it’s way back to the detector. There is a second coil inside of the search coil and it’s job is to receive the current  created by the electromagnetic field of the object in the ground and send this signal to the control box which will alert you usually with a sound. Ah ha, bingo we now have a target to dig!

As always comments are welcomed!