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Search coil 'dynamics.'

April 18, 2017 09:38AM avatar
This could be the topic heading of a very interesting discussion, but it could end up going around in circles depending upon the people who get involved in the discussion, their biased, and often unconfirmed viewpoints, as well as the more technical 'engineer; type examples of coil shape differences.

Personally, as I frequently mention, I like to keep things 'simple.' Yes, many (most ? thinking ) of my Forum post replies can get lengthy, but that is often because I might use different examples or explain some things a little differently so readers might understand what I am trying to get across.

In the end, all the discussion we have about things we read, or have heard others say, or have picked up in different manufacturers ads and comments, is really all about a hobby. Just a pastime we enjoy to get out and explore and try to find things of interest and hopefully learn as we go about the task of having 'FUN.'

To enjoy this great outdoor sport he most I like to maintain an arsenal of working detectors and search coils that will serve my needs and provide me with the comfort to enjoy as mush search time as possible, and while being comfortable I also want to not have to tinker around with a detector a lot, preferring to keep it 'Simple.'

There is a point of things being too simple for some challenging hunt environments so I also want my detectors for different tasks to be very 'Functional' so I can feel confident I am getting the most performance from a particular detector and coil in use, and that will all lead to enjoying very adequate 'Performance.' To blend 'Simplicity' and 'Functionality' to archive desired 'Performance,' it helps to have a 'basic' understanding of search coil design (that being the internal Tx and RX windings combined with the physical size and shape of the coil) and to have a good understanding of the effects ferrous and non-ferrous metals might have on the generated EMF.

Then, one you have a working understanding of how coils are designed, sized and shaped and the type of site challenges you might face, the next step is to select the best coil you personally feel confident with and mount it on a detector make and models that also complies with the 'Simple,' 'Functional' and 'Performance' demands each of us should have.

Thanks Monte, coil and machine are both on there way to Prescott.
Good news and please, let us know what the issue was that caused your frustrations. Tesoro is generally quick at getting service work done and the equipment returned, so you should have it before too long to be able to enjoy the 2017 'detecting season.' Hopefully you have another detector or two to keep you active while the Outlaw and coil(s) are being checked out and taken care of.

Do Widescan coils typically preform differently than, say SEF coils?
Q: What is a 'wide-scan' coil design? Wide-Scan, for many newcomers to this sport, is just another name used to describe a Double-D search coil. Tesoro uses that definition a lot and a few other manufactures have used Wide-scan in the past as well. Some other names are used, such as Teknetics reference to their roughly 7X11 coil they names BiAxial. Just another way to describe a Double-D coil.

So, what is a 'Double-D' coil? .... and I remind you, I like to keep things 'Simple.' It is basically a search coil that is designed in such a way that the internal Transmit (Tx) windings and Receive (Rx) wire windings are positioned is some sort of fashion that the two are over-lapping in some fashion. While we use the term 'Double-D' it really doesn't always represent two wire windings forming a 'D' and reverse 'D' appearance.

DD coils have been in use since 1971 in hobby-based detectors starting with Compass Electronics and their Yukon series of TR metal/mineral locators (another old-use term that got changed to metal detectors). Popular back then were mainly BFO's but the trend was shifting to more of the TR type circuitry designs, and there were many different coil names used that were 'descriptive' even if technically incorrect. One example was the 'triplet' coils offered by White's.

One of two engineers who left White's back then, Don Dykstra, had an idea to change the coil design and improve performance. Another, Henry Gorgas, also had ideas to make things better. The old 'If it ain't broke and is selling, don't fix it' attitude seemed to be the attitude there at the time, so Don and henry left White's and joined Ron Mack in starting Compass Electronics. They mane BFO's in the Klondike series but what set them apart for the rest of the manufacturers at the time, was they used Don's idea for the wide-scan/double-d coil design and the two of them brought us the Yukon series of straight TR detectors.

Those popular-size 6" and 8" Double-D coils were in a round coil configuration. DD coils have been made in a wide range of physical shapes such as a more elliptical design, a somewhat more ovalish appearance, the elongated squarish design like the Tesoro CleanSweep, and we can include coils that are more of the Double-O shape, but they, to include the SEF model design, are still just a form of a Double-D coil. All of these misshaped coil concepts have one thing in common. They employ the over-lapping Tx and Rx wire winding layout internally.

Q: What is a Concentric coil design? ... Again, to keep it a Simple explanation, these are search coils that have Tx and Rx windings of different sizes that do NOT overlap. Instead, one winding, usually the smaller-size Rx, is positioned within the center of the larger Tx winding and they are generally in oriented such that the distance from the Tx to Rx is fairly uniform and they forming a concentric shape or pattern. They are most often a round design, but they can also be an elliptical or oval shape, but the windings are separated and not overlapping.

In short, the SEF coils are really just a fashionable shape of a DD or overlapping winding configuration.

You asked: "Do Widescan coils typically preform differently than, say SEF coils?" I will say Yes, and No. You are really asking if some sizes and shapes of a Double-D coil 'type' can perform differently a different size or shape of DD coil, and the answer is Yes, they can. I have several DD and Concentric coils in my detector and accessory arsenal, and I have learned (and am always trying to learn more) about the strengths and weaknesses of each size and type coil I use.

By the way, I do not own a SEF coil because they don't work for me with what I use and where I like to search. I have tried several SEF coils on a few different makes and models and, for the most part, they left me unimpressed over competitive coils from the detector manufacturer they were being used on. I'll go a step farther and say I don't have any after-market search coils in my arsenal for any of my Nokta or Tesoro detectors in my Regular-Use Detector Team because I have factory offered coils mounted that do what I need them to do where I like to use them.

So, Yes, all sorts of DD configured search coils can work well, work fair, or not work acceptably at all, and it gets down to the size and type of targets you are trying to find, and the amount of unwanted junk at the hunt site. Find what works for you. And then don't forget to consider Concentric type coils, too, because some will work better than others, and quite often a Concentric will out-perform a close-to-the-same site DD coil.

Just my thoughts. Do not just go by what you read or other's opinions, especially if they are not that well educated on the benefits or weaknesses of different coils for different site challenges. It is best to get your hands on a coil that interests you and give it an honest workout in-the-field and know for yourself.


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

Stinkwater Wells
Trading Post

Metal Detector Evaluations and Product Reviews
'How-To' help for Coin & Jewelry Hunting, Relic Hunting and Useful Techniques.

My Regular-Use Detector Team are various models from: Makro, Nokta, Tesoro and White's
Pinpointers: Using Nokta and Makro and Uniprobe Pointers.
Headphones: Using Killer B's 'Hornet' and White's Pro Star and Detector Pro's Uniprobe ... All w/'tank style' ear cups.
Recovery Tools: Using White's Ground Hawg Shovel and DigMaster digging tools.
Note: Detectors are listed alphabetically by Brand. Models are chosen as desired based on search site conditions.
Other models on-hand for 'Specialty Use.'
Additional search coils. mounted on spare lower-rods, are on-hand in my Accessory Coil Tote.

*** All working well today to make memories for tomorrow. ***

monte@stinkwaterwells.com .. or .. monte@ahrps.org
(503) 481-8147
Subject Author Views Posted

DD Confusion...

Pablo61 490 April 14, 2017 10:31PM

Some Q & A regarding your Tesoro Outlaw & DD coil issues.

Monte 369 April 16, 2017 02:47AM

Re: Some Q & A regarding your Tesoro Outlaw & DD coil issues.

Pablo61 341 April 16, 2017 07:48AM

Answers to your answers.

Monte 404 April 18, 2017 03:35AM

Re: Answers to your answers.

Pablo61 268 April 18, 2017 06:58AM

Search coil 'dynamics.'

Monte 367 April 18, 2017 09:38AM

Re: Search coil 'dynamics.'

Pablo61 278 April 18, 2017 03:54PM

Re: DD Confusion...

johnedoe 334 April 14, 2017 11:32PM

Re: DD Confusion...

Pablo61 335 April 15, 2017 07:22AM

Re: DD Confusion...

WM6 387 April 17, 2017 05:49AM

Re: DD Confusion...

Pablo61 283 April 17, 2017 01:41PM

Re: DD Confusion...

WM6 359 April 18, 2017 11:27AM

Re: DD Confusion...

Pablo61 310 April 18, 2017 03:34PM

Re: DD Confusion...

WM6 300 April 18, 2017 10:54AM

Re: DD Confusion...

Pablo61 304 April 19, 2017 08:29AM

Re: DD Confusion...

WM6 334 April 19, 2017 01:49PM

Re: DD Confusion...

Pablo61 275 April 20, 2017 05:34AM

Re: DD Confusion...

WM6 355 April 20, 2017 12:15PM

Re: DD Confusion...

Pablo61 319 April 20, 2017 05:08PM

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