Metal Detecting Forum

Welcome! Log In Register
Coins on edge. Concentric or Double-D coils ??
Posted by: Rick73
Date: November 15, 2018 09:09AM
I mainly search fields after harvest that are plowed before winter. These fields are old picnic grounds. The coins lay at every angle possible. From experience what coils work best for coins at angles or on edge. The detectors I have now are all DD coiled detectors.

Re: Coins on edge. Concentric or Double-D coils ??
Posted by: Mkus
Date: November 15, 2018 11:26AM
I think your good with the DD all I use in fields no problems

Re: Coins on edge. Concentric or Double-D coils ??
Posted by: still looking 52
Date: November 15, 2018 03:15PM
I use a DD coil on my f5 and it does just fine on coins on there edge. What I've learned over the last couple years is that angle the coil passes over the target is critical for receiving a good signal, you can get a good signal from East to West and absolutely nothing from North to South and sometimes you can only get a signal in a 20 degree window on your deeper targets.

Re: Coins on edge. Concentric or Double-D coils ??
Posted by: Tom_in_CA
Date: November 15, 2018 05:05PM
....The coins lay at every angle possible. From experience what coils work best for coins at angles or on edge. ....

Good question. I've never thought of that, in relation to "coins on edge" question. Coins on edge, of course, give a smaller surface area to be "seen". So their signal isn't as good, and you're more likely to need to hit them @ the sweep angles "just right". So this is a good question.

Seems to me to be no difference on DD vs concentric. But that's just based on anecdotal feelings. No hard proof. Consider that the "blade" (swath) of detection window on a DD is NOT "knife-blade" thin. Isn't it like an inch across ? So that it theoretically shouldn't make a difference ? Because all coins are less than an inch across. Thus each coil "sees" exactly the same thing (same disadvantage to each) regardless of the North-to-south swing vs the east to west swing. JMHO

Flat, Canted and On-Edge coins and use of Concentric or Double-D coils.
Posted by: Monte
Date: November 16, 2018 05:15AM
We know that coins laying "flat-to-the-coil" or just very mildly canted are going to be the easiest to find, regardless of the search coil and detector used. Coins that are "very canted to on-edge" are going to be the most difficult for any search coil type or detector. Things to consider:

#1.. If you are searching a plowed field that has good potential for old coin loss, and that is something I used to do quite often, you have to factor in the likelihood of there also being a good chance for the site to have masking metal trash, especially iron debris. When I hunt plowed fields near an old barn or former dwelling or other structure, or where that type of building might have once stood, then I know there is a greater chance of nails and other ferrous debris that can cause good-target masking and that makes the already more difficult-to-find coins even tougher to find.

When I hunted strawberry fields and similar hand-harvested sites that were structure-free, but all of us, like the harvesters from decades past, were paid with change after we weighed our wooden crate and went back to bending, stooping and kneeling our way through the fields, coins were lost. Back in the latter '60s and into the late '70s I had the opportunity to hunt many such fields where I lived and, while there were some occasional nails or junk, the plowed fields were 'ripe' :wink: for coin harvesting.

Back then there wasn't much talk about Concentric or Co-Planer or so-called Triplet coils compared with Double-D designs, and most Double-D's back then were on Compass TR's and some Garrett TR and TR-Disc. models. We were also hunting with BFO's, TR's and TR-Disc. models until some VLF/TR-Disc. models started into their life cycle so it was long before there was any 'digital' detector design or visual Target ID. The main attention to technique for success was learning if the plowed field was relatively free of iron debris or very littered with iron debris. Then it was all a matter of listening to the audio response and using a proper search coil sweep and overlapping combined with gridding an area to work from a few directions before moving on.

#2.. We need to remember that even in a trash-free environment, the difficult-positioned targets are simply going to be that ... difficult to find. We are not going to always sweep across an on-edge coin lengthwise to the coin's edge or crosswise to the coin's edge, and the target can be approached from any angle and that can create differing effects on the generated ElectroMagneticField. Because of this, we need to do OUR PART to achieve success by:

• Listening to as much audio signal as possible which can sometimes be in favor of a Threshold-based search mode.

• Use the least amount of Discrimination as possible.

• Use the most efficient sweep speed for the particular detector and search coil type used.

• Overlap each and every sweep as much as possible regardless of the search coil used.

• Mark or visually grid an area to work well before moving on by using a search approach from at least two and better still three directions.

Then, the other factor to consider is the DETCTOR & COIL PART used and how each of those components can handle more difficultly oriented coins because:

• Not all search coils handle conditions the same.

• Not all metal detectors handle challenges the same.

• Some detector circuitry designs tend to work better with a Concentric type coil while other detector models might be designed to favor a Double-D type coil., and a few models do well with either type.

Your very good question also points out a very good reason to justify owning at least two or more detectors and coils in order to have a choice of a better detector and/or search coil to handle different detecting challenges. You never mentioned what detector make or model was being used and that can make a difference in performance on severely canted or on-edge coins. We also need to be attentive to the search coil's size and shape as well as design type because sometimes a wider or larger-size coil might not perform on par with a smaller diameter or an elliptically-shaped coil, and again it depends upon the detector's circuitry design as well.

Now, to give you a rough reply based upon my current detector arsenal, here is what I like to use for most of the plowed fields I hunt:

a.. If they are plowed but have also been groomed to be relatively flattened out, I will select one of my 13 detectors that has a 5X9½ DD coil or a round-shaped 7" DD or Concentric coil to work the land. If it is a wide-open field with a sparse amount of trash targets, I might swap coils and use a broad-elliptical 7X11 DD, or a round-shaped 9" Concentric, 950 Concentric or even an 11" Double-D coil.

b.. Of my 13 units, consisting of 9 different models, 3 of them (my Tesoro's) do not have a lower Disc. setting to allow me to hear iron nails. All other 10 models do allow a lower Disc. setting and that is what I prefer to use so I can hear most nails and some iron junk.

c.. Of my detector outfit, the 3 Tesoro's and 1 White's model only offer a single-tone design and the other 9 models provide audio Tone ID options. In the more open plowed fields with few masking ferrous targets I prefer to use a 2-Tone audio with all models except my XLT. In the tougher conditions with rough-plowed ground resulting in furrowed conditions I mainly rely on 2-Tone but will opt for a processed 3-Tone audio with some models depending upon other conditions.

d.. If a field is plowed in such a way as to leave furrowed rows or a very rough texture of high ground and low spots, then I might use a search coil as mentioned above with a 2-Tone audio, but I also rework the site (if I don't work all of a smaller area initially) using a detector with a smaller-size search coil, such as a 4.7X5.2 'OOR' shaped DD, a 5" DD, or a 5½, 6" or 6½" Concentric coil to provide better coverage in the furrows and deeper areas and the angled side-slopes of the plowed dirt.

Coil selection (size and type) and detector selection (analog, digital or a digital/analog blend) and how the particular design w/coil selection handles well-angled or on-edge targets combined with sweep speed and coil control and presentation in rough-textured conditions and ground mineralization makes a difference. One of the demonstrations I do in most seminars uses dug up natural dirt from the outdoor locations in a boot box, and a coin laying flat on the ground in plain view and NOT canted or on-edge, to demonstrate the challenges of searching uneven or furrowed dirt. Many detector/coil combinations do not do real well unless a proper and effective search coil presentation is used.

Summarized: Go Prepared. Do not expect to find all desired targets. Realize there will be missed targets for future searches. The right tools and techniques and patience will prevail to achieve the best results possible. In my case, I use both Double-D and Concentric coils depending upon the site and the detector chosen to attach it to.


"Your EYES ... the only 100% accurate form of Discrimination!"

Stinkwater Wells Trading Post
Metal Detector Evaluations and Product Reviews ... or ...
Fisher: 1, Nokta-Makro: 4, Teknetics: 1, Tesoro: 4, White's: 1
Killer B's 'Hornet' and White's 'Pro Star'
Note: Detectors are listed alphabetically by Brand. Models are chosen based on search site conditions.
*** All working well today to make memories for tomorrow. ***

Re: Coins on edge. Concentric or Double-D coils ??
Posted by: Mkus
Date: November 16, 2018 07:35AM
Also it helps to walk around in a circle on your target try all angles usually I go over spots with both of my detectors and finds stuff ones possibly has missed..

Re: Flat, Canted and On-Edge coins and use of Concentric or Double-D coils.
Posted by: Tom_in_CA
Date: November 16, 2018 06:47PM
Monte: As usual, you are an asset to the md'ing community. And anyone who gets your feedback answers, like this one, is fortunate indeed.

Re: Coins on edge. Concentric or Double-D coils ??
Posted by: MarkCZ
Date: November 17, 2018 10:26AM
In my early years of detecting finding edged coins was WAY more common than my more recent years.
Now there could be more than one reason for that, but I'll say this. In the early days I only hunted using concentric coils,
in the more modern times I've leaned WAY more towards using DD coils.
Now, if I can ever get back into the detecting groove I've been thinking about using a concentric more often, not because finding
or not coins on edge, but other reasons like better iron discrimination.

Hunt On!

Avatar, Me and my two brothers from left to right!

WV62 - MarkCZ - Still Looking 52

Re: Flat, Canted and On-Edge coins and use of Concentric or Double-D coils.
Posted by: Rick73
Date: November 17, 2018 11:19AM
Thank you Monte. I use a Deus, CTX 3030 and an Equinox 800. The plowed fields are actually deep ripped at 16” which leaves it looking like bowling balls if that makes sense. It is very hard to walk on making light weight detectors more desirable. The Deus is very light but does not do as well as the Equinox. I have been thinking of a 2.2 pound Vaquero with the concentric coil or the X-Terra 705. I have had several detectors through the last 40 years. Back then they were all concentric.

Sorry, only registered users may post in this forum.

Click here to login