Thanks Finds for the XS info...

[Nicksterdemus]

After a few days of snooping I found a sight w/plenty of info on the old XS Sovereign w/DTI II meter. Manage to read the last 5 pages so far. I guess it's a golden oldie that still produces. Is the old solid white 8" coinsearch coil a DD? I've played around in the yard after refreshing my memory through this and other sites. This site appears to have quite a bit of info on the old gal and it makes for some nice reading. Thinking somewhere down the road of picking up a larger coil. Excelerator, Sunray and the WOT all have fans. Can be a tad confusing. Likewise I can see where a small coil would come in handy. No mineralization where I'm @ and it makes sense that a concentric coil would get a little deeper just as a DD would have better coverage and pinpoint the target easier. Thanks to all the participants. Feel free to share any wisdom on this older unit. I'm all ears...

 

[Ron from Michigan]

Nick,welcome to the forum.I tried a 8 inch concentric coil a couple seasons ago,the tones and ID doesn't lock as well it didn't have the depth of the stock coil.If I was only going to have one coil for a Sovereign I would flip a coin for the 10 Tornado or 8 inch Coinsearch.Deep targets the S12 to separate targets in trash a 5 inch coil.The old Sovereign is still a great and among the top units.

 

[Neil]

Rons mentioned some good coils, those I would look at also. Another you might look at it is the 10X12 SEF coil, Kellyco sells them.
The DD coils get real deep, I wouldnt think of putting a concentric on any of my minelabs. You can isolate targets better with the DD coil also.

HH
Neil

 

[Nicksterdemus]

So, I'm out in the yard practicing and picking up AL foil rolled in a ball, AL pie plates pieces and such from the last 40 years.I throw down a quarter and start to ease the old coinsearch over the two bits. As soon as I have an edge of the coil over my target I get a hit. The strongest signal is when the coil is centered, like a bulls-eye, over the target. Is that normal? With the coin laying on top of the ground I'm only 4" from the side to the middle of the coil, yet I keep getting this image of the DD coil working only out of a center slice of the coil. The way I see the DD coil illustrated it appears that I would have as strong a hit when in the center slice of the coil from the front to the back. I hope I'm making sense in my description. I'm trying to get a feel for the unit. I know it's sensitive because I've run it in all metal and found tiny pieces. Small enough that it was hard to see so I'd grab a handful of dirt and wave it in front of the coil. Had a solid 170 hit in disc and it ended up being a 3/8" Al rivet. Practicing the wiggle as well. My trowel is a mini-shovel. A shade over 2' long the rounded spade is 8"deep and 6" wide. So far my pinpointing ability has been contained within a square w/six inch sides. It is my yard, but I can see how one of those little pinpointers could come in handy. So much for my rambling. Feel free throw any advice/words o' wit my way...

 

[Bling]

i like the S12 the best of all,just remember the 8" white coin serch coil is not water proof.its a great land coil,maby the best,just not water proof. and these pic's might help you understand the diff.

 

[Art (NWOH)]

Your coil is working right.
The more shallow, or the larger the object is, the sooner the coil will start to see it. The hottest place on the coil is the strip right down the center.
Don't be confused by diagrams of what the coil's detection field are supposed to look like....they are bunk. The coil's transmit field resembles a large doughnut that extends a considerable distance above, below, and around the coil. This induces currents and resulting magnetic fields in metal objects at considerable distances. When the recieve part of the coil starts to pick up these fields strongly enough that the detector can see them, you will get a response....even though the center of the coil is not close to being right over the object.

To get a better idea about what the magnetic field looks like, google magnets , inductors, magnetic fields. Find pictures of what magnetic flux lines look like that are created by magnets and coils carrying current.

HH

 

[Nicksterdemus]

I always envisioned that DD illustration that you posted of being a slot, down the middle of the coil from the front to the back.
Because it looks like a slice of a rectangle it gives the appearance, to me, of being just as good detecting at the front or back as the middle "bulls-eye" of the coil.
As well I thought I wouldn't receive a signal from the left or right side of the coil. I thought those sides were only there to hold the rounded part of the D windings that supported this knife-edge/2-3" slot of detection running down the middle from front to back along the straight sides of the D windings.

As I understand now, if a target is shallow you get a good signal anywhere on the coinsearch coil. The deeper the target the more you will notice a signal towards the center slot that rounds out shallower to the sides.
I still have a hard time understanding why I'm receiving the strongest signal in the bulls-eye area of the coil. It seems a concentric coil would naturally be stronger in the direct center, but as stated I was thinking the DD would be just as strong anywhere along the center/rectangular slot. ..

After reading this again I think I understand. The DD is stronger in this middle slot and the strength fades/slopes to the front & back as well as the left & right sides, yet in differing proportions. The field of the coil tapers slowly and gently from the front to the back because of the two straight, parallel windings. As a result the taper is more abrupt and harsher moving 90 degrees, left or right side of the same parallel windings.

My apologies for taking so long, using so many words and being redundant in trying to try to explain, to myelf, what I'm sure is understood simply enough by ya'll.
If you ask me for directions you best bring a notebook, pen and plan on staying a while...
========================
Thanks Art, it took me almost an hour to finish up my not so enlightened post. I would've been better off to wait on your response. I have to have a picture in mind so I can make some kind of analytical judgment call while I'm operating the XS. It's slowly sinking in, but I'm thick skulled...

 

[Art (NWOH)]

It is a little early for me and I am notorious for short posts.
The reason the coil is hottest down the center even though the magnetic fields involved are very large is because of this........
The transmit coil and recieve coil overlap down the center. This puts the edge of the recieve coil right into a strong part of the transmit field.....where targets will be hit with some of the strongest transmit signal. So this side of the recieve coil is now in a position to pick up the strongest target response. If the target is strong enough, it can still be picked up at the outside of the recieve coil , but will be weaker because the strongest part of the transmit field is farther away and will not induce as strong of a magnetic field in the target.

If you can google up some drawings of magnetic fields, you will see that a great deal of the transmit field's power is wasted. All of the field above the coil, and all the field below....except for the center stripe area.....is totally worthless. There is no way that I know of to concentrate the magnetic field into only one area or direction with an air core inductor like the coil's transmit loop. We waste a lot of power.

What about interference with other detectors? That's only the distance the detectors can pick each other up. The field extends farther than that.
When you start detecting close to a car, metal trash can, metal siding, or a chain link fence you will see the effects of this large field.

HH

 

[Art (NWOH)]

Your dd coil will do this to some extent too when pinpointing

Concentrics....
Let me use my White's as an example...
In disc mode, the detector actually beeps AFTER the center of the coil has passed over the target. The detector has found the best target response during the sweep, identified it, and responds with a beep that that is not where the target really is. When swinging the coil back and forth over the target, the detector will beep in two distinctly different locations. The weaker the hit, the closer together the beeps will be because the detector picks up the target for a shorter period of time before it determines it's best ID.

Switching to pinpoint or all metal VCO, the target is much wider as the coil sweeps over it. You get a response for as long as the coil sees the target at all, rather than giving a quick beep AFTER the detector has passed the object and has determined it's value at the strongest reading as in disc mode.

HH

 

[Nicksterdemus]

"and all the field below....except for the center stripe area.....is totally worthless"

So, in disc w/shallow target when the left or the right side of the 8" DD coinsearch coil passes over, it signals because of the close proximity to the center stripe/slot?
Thanks again for answering my simpleton questions.

 

[Art (NWOH)]

Yes and no.....
I don't know which side of a coinsearch is transmit and which is recieve, but it don't really matter.
Let's take for example my Minelab coils (BBS800 and T-10). The transmit side is on the left.
Swinging from right to left, the outside of the transmit coil goes over the object first. This is going to produce a lot of signal from the object at that moment.....enough to be picked up by the recieve coil......mostly in the stripe area because it is the closest.
When swinging from left to right, when the outside of the recieve coil passes over an object, it gets picked up because the transmit field is much larger than the physical size of the coil and will induce a field in the object that is strong enough to be picked up at that point.

The closer the object is to the coil windings, the better the signals will be coupled back and forth.

The magnetic field produced by an object does not just go straight up... it radiates in all directions much like the transmit side of the coil does. All that has to happen for it to be detected is for enough signal from it to get to the recieve coil at any point on the recieve coil.

Don't be afraid to ask anything. I understand some of this stuff because I have an electronics background.
I can see that you want an understanding of what is happening, and I will help as much as possible. Some of this stuff is hard to describe to someone who is not familiar with it in the first place.
And I went and put this in the wrong place when I edited it!!!!!!!

At the center of the coil (overlap or stripe) the transmit and recieve coils are in closest proximity, so you get the strongest returns there.


HH

 

[Ron from Michigan]

Nick,in the field the DD coil will pinpoint as well or better than a concentric coil.The double D separates far better than a concentric coil.Minelab would produce a concentric coil of their own if it performed better.If money is tight get yourself an inexpensive handheld pin pointer better than none at all.

 

[Nicksterdemus]

Thanks, that makes sense to me Art. As a matter of fact your explanation was crystal clear as if you were painting a picture. I've noticed that when I'm close to a fence or lay the XS close to a metal tool that it detects well in all directions.
Ron, it makes sense that Minelab designed the XS for what they felt was the superior coil type for their application. A target probe would appear to be worth it's price by being able to move from mini-shovel to my old standby, flat pry bar..

 

[Art (NWOH)]

Wait until you spend 5 minutes trying to find an object in the dirt pile. Or in the side or bottom of the hole.......
ANY probe is better than nothing then!!! It can drive you nuts.

Don't expect to use the pinpointer to pinpoint targets with before you dig.......they vary in depth from about an inch to about 4 inches depending on which one you use. They are a recovery tool that helps you find the object after or during the digging process. Use the coil to pinpoint first.
If you have trouble pinpointing with the detector, let me know. Most give a different explanation than I do, and their explanations sound more like an explanation for a non-motion detector.....which a Sov is not.


HH