Carl-NC: Do VLF signals vary in depth according to target size and mass ?

[ToddB64]

Good Day Carl-NC

Hope I put this subject in the right forum.
I thought your answer to the following question would clear up this issue for everyone, including myself.

Generally speaking, does a VLF metal detector signal vary in depth according to the size and mass of a target, ferrous in this case ?

Thanks !
ToddB64

 

[TechBill]

Open that notification again and click on the your thread title itself.

It should take you directly to your thread and every page have what it called a "breadcrumb" at the near top underneath the forum logo header. It will always show you the forum category and the forum name which you are currently viewing in.

BUT ..... I do think the link itself in the notification need to be more obvious to imply that it a clickable link. I will work on that one ..

Thank you .

 

[ToddB64]

Good Day Carl-NC

Hope I put this subject in the right forum.
I thought your answer to the following question would clear up this issue for everyone, including myself.

Generally speaking, does a VLF metal detector signal vary in depth according to the size and mass of a target, ferrous in this case ?

Thanks !
ToddB64

Hi Carl-NC
This is in reference to my Thread on the Metal Detectors and Treasure Hunting board > Metal Detecting Forum > Titled: Carl-NC: Do VLF signals vary in depth according to target size and mass ? .

Well, I was looking for some information in your book inside the METAL DETECTOR and came across the following sub-title Coil Sensitivity in chapter 15 Loose Ends and after reading it again, since I had read the entire book after receiving it in 2013, I was reminded of the complexities involved and how unfair to you Carl my above question had been, since a reply would probably require a lengthy tutorial on electronics, with some physics thrown in for good measure , most of which would probably have been "over my head" anyway. So, unless you know of a simple answer, just consider my question retracted.

For anyone curious about the content of Coil Sensitivity in chapter 15 Loose Ends it's a short read, so I scanned and attached copies for your review. I hope George and Carl won't mind that I took the liberty of doing that ; perhaps it will encourage studious detectorists to order a copy of the book. I've referred to it often over the years and recommend it highly.

ToddB64

 

[MarkCZ]

A smashed aluminium pop can @ 5" inches will read as a penny/dime @ 1-inch.
And those OLD screw on Ford hub-caps off the large spoke wheels @ 12-inches will read as a quarter @ 6-inches.

 

[ToddB64]

Hi MarkCZ

Thanks for your reply, however, I guess you interpreted the title of my thread-starter post to be the original question which indicated "ferrous" targets, i.e. "Generally speaking, does a VLF metal detector signal vary in depth according to the size and mass of a target, ferrous in this case ?"

When replying to a thread for the first time, it's always best to scroll to the top of the first page and read the full text in the original thread-starter post to get the complete meaning. Quite frequently, if an OP (Original Poster) wants to create a title giving a hint of the post subject, the title will be abbreviated.

Aluminum isn't ferrous of course, so in your scenario although I assume the Old Ford screw-on hub cap contained at least some iron, or maybe it was all iron (ferrous), the test results were not based on comparing "apples-to-apples" metal-wise.

ToddB64

 

[MarkCZ]

Hi MarkCZ

Thanks for your reply, however, I guess you interpreted the title of my thread-starter post to be the original question which indicated "ferrous" targets, i.e. "Generally speaking, does a VLF metal detector signal vary in depth according to the size and mass of a target, ferrous in this case ?"

When replying to a thread for the first time, it's always best to scroll to the top of the first page and read the full text in the original thread-starter post to get the complete meaning. Quite frequently, if an OP (Original Poster) wants to create a title giving a hint of the post subject, the title will be abbreviated.

Aluminum isn't ferrous of course, so in your scenario although I assume the Old Ford screw-on hub cap contained at least some iron, or maybe it was all iron (ferrous), the test results were not based on comparing "apples-to-apples" metal-wise.

ToddB64

Same answer applies with a different metal, ANY metal
Its a bit like all those math questions that only give you XX divided by XXX = xx.x
A small 7/16" washer will be lost at less depth than a 71 model Dodge Dart hood.
A more real example would be an old rusty square shank nail that's a big problem with certain
Tesoro models when you super tune them, and a railroad track spike (and I've dug my fair share of both). If both are rusty than the halo
from both will somewhat increase their size, but the total mass of the railroad spike will extend the detecting
deep of a detector more than the much smaller nail!
I read your title post, and your right "Ferrous" alluded me, but for good reason, it really doesn't change the answer,
Larger MASS will ALWAYS extend a detectors range of deep vs the much smaller average size target!

Good Day.

 

[still looking 52]

Depth will have an effect on your screen readings for sure, for example a dime at 2 inches will read different than at 6 inches, usually the deeper it is the lower the reading.
Another example is a large Target at say a foot deep can read the same as a small Target at 1/2 that depth. The reverse of that is also true, a small Target at 3 inches deep can read like a large Target a lot deeper.
There's a lot more variables than what I've mentioned but this is a simple answer to a complicated question.

 

[Carl-NC]

Todd, there's no simple answer. Unlike non-ferrous metals, ferrous targets can have either a magnetic response, an eddy response, or both. Nails tend to be magnetic, flat bottle caps eddy, and chunky iron both. With eddy targets size matters more than mass, with magnetic targets mass can matter more.

Also keep in mind that depth readings on a metal detector are only valid for coins, and often only certain coins.

 

[Monte]

Off topic for Carl NC. As I recall, you had lost or misplaced that 'Bottle Cap' I gave you. Did you ever find it? If not, I have another one or two that I will get to you. You know, they one you described as a 'fossil.' I do have a lot of fun with those, and it helps start new conversations, especially to the unknowing Simultaneous MF crowd.

I hope to do some more 'Bottle Cap Hunting' the end of May as my supply is down to maybe 5.

Monte

 

[Carl-NC]

I think I know where it is... what was the weird thing that it did?

 

[Monte]

Carl-NC:: I think I know where it is... what was the weird thing that it did?

GPAA Gold Show in Salem. I had 5 Bottle Caps in-hand and at the White's booth you tried them with your pre-production TDI SL, then a display V3i It wasn't the weird thing it did, but what it didn't. I visited the FTP booth and gave them an interesting head-scratcher when Mike Scott was there. I don't know who was manning the Minelab booth, but I've never come across anyone at them that seemed to know much about metal detecting or have good answers for the questions I'd bring up when they had a crowd around. I think Roger was standing outside your booth to my left and he thought it was plastic.

Monte