Basic Theory of How a Metal Detector Works
Tuesday, 01 January 2008

If you have ever wondered how a metal detector works, and how can they tell the difference between good and bad targets. Here is a simple explanation of how they work.

 

Most people know that a metal detector uses magnetism to the coil to detect objects in the ground.

 

Magnetism is an invisible field produced by electicity passed through a conductor coil. When a metal object is passed through the invisible magnetic field it affects the magnetic field intesity, either increasing or decreasing the magnetic field.

 

This affect is called reluctance and acceptance. This is how the detector identifies the target,

 

It's as simple as understanding that some metals are Ferrous (Iron Containing) and some are non-ferrous (Non Iron conatining). An example of non-ferrous metals are Gold, Silver, Brass, Copper, Platinum, Etc...

 

To put this concept into understandable terms:

When ferrous metal (Iron Containing) is passed through a magnetic field the field accepts the object and assists the field by conducting and amplifying the field. This is called "ACCEPTANCE".

 

When non-ferrous metal (Non-Iron Containing) is passed through a magnetic field, the field will reject the object, the field will resist the non-ferrous metal by NOT conducting the field. This is called "RELUCTANCE".

 

This is how metal detectors descrimination actually works, by measuring the ACCEPTANCE or RELUCTANCE of the magnetic field.

 

So when you are out nugget detecting and you pass your detectors coil over a gold nugget, the detector measures the reluctance of the field, basically measuring a decrease in the field, thus producing a sound in the speaker from the difference in the field from a predefined reference or threashold.

 
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