Dirt fishing

 

More often than I can count, I get a little visitor come up to me and ask me questions about what I'm doing.  It will be in a park area, or on a beach somewhere in the middle of what I call "Dirt Fishing". The headphones are on and I am swinging a strange looking stick from side to side.  A curiosity for any young child to see.  And at that point I get the most innocent questions. 

 

"Hey mister, what are you doing?" and, "What are you looking for?"

 

Photo: Contributed

I often give them a simple explanation that seems to satisfy their curiosity and then they run back to their friends or parents.

 

This got me thinking, how many adults see me metal detecting but are too embarrassed to come up and ask me what I am looking for?  Or even what metal detecting is really all about.  There is something lost with the innocence of simple questions, so I have decided to write a simple answer to the question not asked.

 

"What is metal detecting all about?"

 

When the subject of metal detecting comes up, it's not hard to picture some older guy on the beach waving an MD across the sand and picking up lost change.  But this would be like describing fishing as putting a line in the water and waiting for fish.

 

Just like fishing, it's not as simple as that.

 

To put this as simply as possible, metal detectors use the science of induction to locate metal underground.  There are three different types of metal detection technology that we will be talking  about.  They are Pulse Induction, or PI,  VLF, or very low frequency, and BFO, or beat frequency oscillator.

 

VLF, as well with the other two, create a magnetic field from the coil at the end of the metal detector.  Do you remember using a magnet and metal filings in science class?  It was used to help you see what the invisible magnetic field looked like.  That is pretty much what the electronic magnetic field looks like from the coil.  Nice curved lines that bubble out from the magnet.  Now when a piece of metal comes in contact with that nice magnetic bubble, it disrupts the field and becomes energized by the field.  The VLF creates this field very fast and then listens to any possible disturbance.  Once a disturbance is detected, it alerts the user of the MD with some sort of tone or signal.  Ta-da - your gold diamond ring is found!  It is simply inducing a charge in the ground and listening for an echo from metal that might be there.  The one big selling point of this type of detector is that you can discriminate the echo and tell if the metal object detected is either ferrous or nonferrous.  Why is this important?  All precious metal is nonferrous.  This nice feature allows you to skip over the junk and only dig up what could be a gold ring.

 

Next time we will get into more detail about the other two types and what detector is best for what job.  Just like cars, they are all not created the same.