Vanquish 440: Correlation Between ID Values, Notch Segments, And Audio Tones

[mcjtom]

After a brief encounter with a Mental Detector, I came to my senses and got Vanquish 440.  Trying to learn what it does, I think I figured out what the actual correlation between the target ID values, notch segments display, and the audio tones is.  Perhaps it could be useful to others:

The target ID scale on this detector is non-linear, with the middle range between 0 and 20 stretched and both ends compressed.

The break points between tones, except for one case of Low-Med in Jewelry Mode, do not correspond to break-points between notch segments.

The yellow values, below the target identification guide graphics, represent the standard response (+/-1) for modern (Rama IX/X, 2008+) Thai Baht coins, when the target signal is strong.

 

 

[mcjtom]

I also did some testing on the 'stable' standard targets - the new Thai coins (still looking for the older ones) and ranked the common metals conductivity relative to Copper, to at least arrange this aspect in my mind when guessing the targets.

 

[PimentoUK]

A few notes regarding the metal conductivities:
The 60% IACS figure for Al is for pure, or near-pure aluminium. Everyday kitchen foil is near-pure, as are the thicker foil types that are used for food containers, pie trays etc. They have the distinguishing characterisitc of being very soft. All aluminium alloys that are created for strength, such as beer/drinks cans, and their ring-pulls/tabs, have noticeably lower conductivity, a typical figure is 37% IACS.
Likewise, pure gold is rarely found used in jewellery, it's too soft. Alloying it with copper/silver and sometimes nickel to change the hardness/colour/carat significantly lowers the conductivity. Figures in the 5 - 20% IACS range are typical. For example, 0.900 fine gold, as used in older USA coins, has conductivity of 15% IACS.
Cupro-nickel is widely used for coins, and 5% IACS is a typical figure. Your 1986 1 Baht coin will likely read low down, about 10 on the Vanquish ID scale.
Here's a decent table of conductivity for many metals/alloys:
http://eddy-current.com/conductivity-of-metals-sorted-by-resistivity/

 

You will soon have plenty more older coins, it's not usually hard to find coins over 100 years old. You have a good machine, it will soon reward you with some great finds. Don't forget to show us, especially the silver ones.

[mcjtom]

Cheers for that!  I've updated the conductivity table above a little - it's all approximate, but there is a trend.

[PimentoUK]

Your 'conductivity table' does have a rather glaring error : you have included ferromagnetic materials among the 'non-ferrous'; namely iron, steel, nickel. These will all read as "Iron" to a detector, as their phase shift will be 'negative' , relative to the non-ferrous scale.
Hence why the nickel-plated steel Thai coin reads with a -ve number. The detector sees it as an iron-plated iron item.

It's worth accumulating a random selection of foreign coins, for 'scientific testing' purposes. Ask around your friends , see if they will donate / sell you their leftover holiday change for face value. USA money is often used as a reference, that's one coinage worth looking for.

For interest, pure nickel is unlikely to be found in the ground, though Canada did make their 5 cent coin from it for many years.

[mcjtom]

Cheers again!

[mcjtom]

Would I be correct to think that a digital detector, no matter what the internal processing, produce, first, some target ID number, which is later binned with other numbers to produce an appropriate notch flashing and sound tone?

i.e. if a detector, like Vanquish 440, has 12 discrimination segments, but a range of 50 IDs, is it still reporting the target IDs at the resolution of 1/50 of the full ID scale?  Segments and tones just lump the ID ranges together?

[Chase Goldman]

First of all, you can’t necessarily lump all “digital detectors’” behavior together based on the Vanquish 440 implementation.  But in the specific case of 440, you get a target ID and the detector bins the applicable TIDs into one of 5 fixed tone groups for audio tone ID target identification to the operator or if it falls into a segment notch bin, the applicable IDs are silenced/suppressed.  Other higher end models such as Equinox can provide individual TID tones and notches or (two-tone ferrous/non-ferrous configurations) as well as the ability to adjust the bin breakpoints.  HTH.

[PimentoUK]

"Segments and tones just lump the ID ranges together? "

Broadly speaking, yes, that's what happens.
However .... the audio and the visual ID's do not HAVE to correlate. Audio performance needs to be fairly 'immediate' , whereas a visual identifier can be slower. Advantage can be taken of this difference to produce visual data that is more 'averaged', to produce more repeatable/consistent/less jumpy information.

I've no idea what ML do on their Eqx/Vanquish models, but as an example from First Texas Products:
The Teknetics T2 machine used exactly the same processing for audio ID and visual ID. It's design was later developed into the improved 'park-hunting variant', the Fisher F75. This used different processing for the two outputs, and their publicity material drew attention to this improved target ID ability. As a user of the F75, I have seen the odd 'discrepancy' that this produces. We have a lot of coke ( part-burnt coal ) in our UK farmland, and it often reads in the very-low non-ferrous range, but can be in the 'large iron' zone, or up as high as some coins. Sometimes a lump will consistently give 'Iron' audio, but low non-ferrous ID's on the screen.