Inside the Metal Detector

[ZuMi77]

Dear Carl-NC,

How can I get the last edition of Inside the Metal Detector? I mean PDF copy.

[Carl-NC]

The second edition is available as an ebook on Amazon. The third edition will be print only.

[kosacid]

i have the second addition just wondering what's in the first and third ? basicly what are they based on

[Qiaozhi]

i have the second addition just wondering what's in the first and third ? basicly what are they based on

See page xiii and xiv in ITMD2. There's a long explanation of what changed between ITMD1 and ITMD2.

Carl can explain what's in ITMD3 ...

[Carl-NC]

Here is where it is at:



Everything is finished and even indexed, except for a little bit of Ch24. That requires taking a lot of data which I have done now 3 times and did not like the results, so I am now taking it a fourth time. It is target responses over frequency which is harder to do than it sounds. The cover of the book is also ready:

[dbanner]

Very interesting Carl. I can't wait for the book to be out. What is this data you mentioned above?
I read an excerpt from George Payne in which he describes target vs freq. response.

Payne: ""The x and r target signals are frequency dependent and obey very predictable characteristics when the operating frequency changes. We know that the x component decreases as the operating frequency decreases. Above a certain frequency the x component reaches a maximum. The r component acts differently. It is maximum at one particular frequency and decreases if you go up or down in frequency. We call the special frequency at which the r signal is maximum, the target’s “-3db” frequency. It also turns out that at the -3db frequency the x signal is one-half of its maximum value. This special frequency is unique to each target and is different for different target.

The higher the conductivity of the target the higher will be the targets -3db frequency. Conversely, the lower the conductivity the lower the -3db frequency. The -3db frequency of the high conductivity target will also make the r signal peak at a high frequency, normally well above the operating frequency of the VLF detector. This will make the high conductivity target have lower sensitivity on the VLF detector because the r signal amplitude drops if we are significantly below the -3db frequency. Simply put, maximum sensitivity on a VLF detector would be if we position the operating frequency directly at the target’s -3db frequency. For example, a dime and penny have a -3db frequency of about 2.7KHz. This is where their r signal peaks and would be the best frequency for picking them up using a VLF detector. However, a silver dollar has a -3db frequency of 800Hz. Nickels, on the other hand, have a -3db frequency, where its r peaks, at about 17KHz. Targets like thin rings and fine gold are higher still. Clearly there is no one frequency that is best for all these targets. The best you can do is have an operating frequency that is a compromise."---END


So real time multi-freq is attempting to get the best of all worlds?
Why not release this data when ready as a supplemental to the book that someone can download online from the forum website. The supplement could be updated as new analyses are done.
Seems like an awful ton of work Carl, please make the book as expensive as possible

[dbanner]

BTW I like the Book cover.

[Pete61]

BTW I like the Book cover.

Thought it was well done too.
I now see why Carl wanted to contact the original poster of that image.

Price is only 11 Salt.
I wonder what size the salt must be?
Ive got a range of Himalayan rock salt in the kitchen.

[Carl-NC]

I read an excerpt from George Payne in which he describes target vs freq. response.

What he says is true for well-behaved eddy targets. Here is what US coins look like:



But iron, soil, and salt don't behave like this. I'm currently taking data on 41 different targets.

Carl, please make the book as expensive as possible

With over 2x the pages of 2ed, plus increased publishing fess, it will unfortunately be a little expensive. Don't know yet how much.

[ivconic]

Oh, I see the book is already available in some markets!?
I didn't expect such a high price though!?

[Qiaozhi]

That's obviously a SCAM!
Carl hasn't published the book yet, and it's not going to be made available as a Kindle ebook.

[Orbit]

That's obviously a SCAM!
Carl hasn't published the book yet, and it's not going to be made available as a Kindle ebook.

Let Karl check that the book has not appeared on AliExpress

[Qiaozhi]

Perhaps it's the Monte Python edition.
https://www.youtube.com/watch?v=G6D1YI-41ao

[Orbit]

Perhaps it's the Monte Python edition.
https://www.youtube.com/watch?v=G6D1YI-41ao

[ivconic]

Perhaps it's the Monte Python edition.
https://www.youtube.com/watch?v=G6D1YI-41ao

Your Hungarian is extremely fluent, well done!