Simplex VDI question

[Sandog]

My grandson found this beer can, face up at about 2 feet depth. Okay, I understand it's a big target, but his machine kept reading 92-96 on the display. Isn't that awfully high for a beer can? Got to give him and the Simplex credit. The machine was ringing out loud and clear, and that number kept driving him on in spite of the depth he had to dig. We double checked and there was no other signal at all after removing the can.

 

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[Slowtaknow]

Target size matters

 

[gunsil]

Metal detectors do not tell you what kind of metal one has. Metal detectors measure electrical conductivity and guess what the metal is for a coin sized object. Anything with a high conductivity reads high numbers on VDI so a larger chunk of iron or aluminum can easily read the same as a silver coin because they are high conductors. The best way to avoid digging such targets is to lift your coil six inches above the soil and see if the signal is just as loud and solid. If it is, the chances are it is a large target and not a coin or jewelry. Of course then you might pass up that jar full of silver quarters. The only true discrimination is when the target is in your hand and he who makes the most holes finds the most good stuff.

 

[Sandog]

Metal detectors do not tell you what kind of metal one has. Metal detectors measure electrical conductivity and guess what the metal is for a coin sized object. Anything with a high conductivity reads high numbers on VDI so a larger chunk of iron or aluminum can easily read the same as a silver coin because they are high conductors. The best way to avoid digging such targets is to lift your coil six inches above the soil and see if the signal is just as loud and solid. If it is, the chances are it is a large target and not a coin or jewelry. Of course then you might pass up that jar full of silver quarters. The only true discrimination is when the target is in your hand and he who makes the most holes finds the most good stuff.

Thanks for that explanation. And while I understand the principal of a detector actually measuring conductivity, hence the wide gap between gold and silver objects of similar size, I am not sure I understand how size of an object affects it's conductivity. Or is it just a matter of the size of the reflected signal in those cases?