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Black Sand Beach Hunters


midalake

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This has been a two-year project of testing and I am ready to provide the results. I have a love/hate relationship with the Equinox, everyone who follows me knows that. The Nox is a great west sand machine but add moving wave wash and black sand and the Nox falls on its face. I know there will be lots of questions so I will be short here. My Goal: Was to make the Nox a better machine in the wave wash by increasing sensitivity, reduce falsing, and get better depth.  

After much testing and comparison, I have accomplished those goals without reducing performance in other hunting conditions. Also, recovery once you open a hole is better, there is less chance in burying the target.  

I have done a two-step process where coatings are applied to the coil. In the version where you see the white coil, this is a one step process of applying Marine Epoxy. Note where it starts and end with the original coil.  The second process and most important is the application of TWO coats of acrylic paint containing graphite powder. [approx 1 teaspoon per two ounces] thick enough to where you can still paint it on.  Which is applied to the same location as the white epoxy. 

The results are a night and day difference in moving wave wash and black sand. Questions? 

 

 

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OK, I'll start. 

1) Do you execute the same treatment on the bottom side of the coil housing?

2) I noticed immediately that between the epoxy step and the paint step you removed to 3 O'clock and 9 O'clock structural members.  Reason for that?

3) This is for saltwater detecting, right?  Is this helpful for freshwater detecting?  (You already said it doesn't hurt any other detecting application.)

4) Any ideas about whats going on (physics-wise) that leads to this performance improvement?  (I have an idea, but I'm not a water detectorists of either kind.  Those of you who are probably have a pretty good idea of what is going on, from experience.)

I wonder if this is going to be helpful with the Manticore (or even Eqx 900) or if Minelab might have gotten something similar incorporated in those new models.  XP Deus 2??

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1 hour ago, GB_Amateur said:

1) Do you execute the same treatment on the bottom side of the coil housing?

No. I do not hunt with a coil cover. I do have a protective coating of marine epoxy on the bottom of my coil. But this coating has zero effect on coil performance. 
 

 

1 hour ago, GB_Amateur said:

2) I noticed immediately that between the epoxy step and the paint step you removed to 3 O'clock and 9 O'clock structural members.  Reason for that?

No particular reason, except if I screwed up it would be less to remove.😂  After testing it worked so well, I decided not to continue the graphite further.

1 hour ago, GB_Amateur said:

3) This is for saltwater detecting, right?  Is this helpful for freshwater detecting?  (You already said it doesn't hurt any other detecting application.)

Yes,  I hunt Salt Water.  Is does not hurt effect of wet or dry sand hunting.  I have not put the coil in fresh water or land. No effect on air tests or buried targets from stock coil from what I can see either.
 

1 hour ago, GB_Amateur said:

4) Any ideas about whats going on (physics-wise) that leads to this performance improvement?  (I have an idea, but I'm not a water detectorists of either kind. 

Nope! I have an idea too. It works and it is not even close. Night and day! 
 

1 hour ago, GB_Amateur said:

I wonder if this is going to be helpful with the Manticore (or even Eqx 900) or if Minelab might have gotten something similar incorporated in those new models.  XP Deus 2??

Nox 900, I would say yes. I will have a Manticore here at the end of February and will be able to see how the stock coil is affected by the wave wash and black sand.
I have not done this to the Deus 2 coil. My D2[on this beach] does not have the harsh reaction as compared to the Equinox. In fact my D2 is used only for water contact. 

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The graphite infused paint blocks EMI. Similar treatments are used in electronic enclosures to block outside EMI and block EMI emission from the internal electronics.

In this application it should cut down on interference from salt water wave wash over the top of the coil's graphite painted surfaces by restricting the coil's electromagnetic field radiated on the top of the coil and possibly focusing it more downward, which may or may not increase the downward depth of the overall radiated field. I'm sure some of the electrical engineers are going to chime in here.

Of couse the center of the coil where the transmit and receive wires cross is the most sensitive area and you might want to graphite paint that area for maximum effect.

So while it seems like an effective remedy for salt water wave wash, I can't help but wonder why coil manufacturers have not put EMI shielding in the top of all coil housings. 

But if it's working for you more power to you... literally. 😉

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The Cap'n answered my question! 😀

Nice job, glad it's working for you. 👍

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On 2/7/2023 at 11:51 AM, CPT_GhostLight said:

The graphite infused paint blocks EMI. Similar treatments are used in electronic enclosures to block outside EMI and block EMI emission from the internal electronics.

The graphite treatment I put on the Equinox Coil has little effect on EMI.  Sorry to say!
In the mile of beach I have EMI issues. The D2 beats the Equinox with the coating hands down. 

EDIT: It has been a long time since I have compared a stock and treated coil. I did so recently and there is a slight reduction, but not mitigation of EMI. 

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21 hours ago, CPT_GhostLight said:

Of couse the center of the coil where the transmit and receive wires cross is the most sensitive area and you might want to graphite paint that area for maximum effect.

Well, it may be possible to get better results? However, you might find diminishing returns.
In my thinking. I thought where the cord comes into the coil and where the chip is, might be the area needing most protection?

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1 hour ago, midalake said:

Well, it may be possible to get better results? However, you might find diminishing returns.
In my thinking. I thought where the cord comes into the coil and where the chip is, might be the area needing most protection?

That's possible of course, but transmitted EMI will still get in throught the bottom of the coil as well. The improvement you have noticed in performance with your beach's wave wash that carries salt and black sand over the top of the coil may be due to the restricted top flow of the coils transmitted EM field having a reduced interaction with the salt/black sand water on top of the coil. Again, one of the forum's electonics experts could shed more light on this, but your experiment has brought up some interesting points and questions in regards to beach hunting.

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While I don't know about VLF coils the PI coils already have the conductive shielding paint inside them on the surfaces, it's connected via a shield wire to the detector.  I would assume VLF is the same, actually now that I think about it, I cut open a Gold Bug Pro 5" coil some time ago and it had the paint inside it too.

11-spray-the-shield-and-install-the-wire.thumb.jpeg.8a9909e31eacdfe7abec58e0414bf7d6.jpeg

The conductive paint is used a lot for guitars for shielding.

IMG_20190513_092815.jpg.1e351eea88468fdf052a544f6ff89ea7.jpg

I've used it for shielding of metal detectors internals but unless it's connected to the ground it will not provide EMI mitigation.   Read the ingredients of the paint.

It is conductive, you can test with your multimeter once painted on.  You can transmit power through it.

IMG_20190513_165225.jpg.5702f511aecc4a9e4b84c8f3fb363903.jpg

 

You can read about the guitar uses here https://www.artisanluthiers.com/blog/conductive-shielding-guitars/

As far as EMI mitigation goes, from the Guitar website.

The best guitar shielding method is to use either specially designed copper tape or specially designed shielding paint. The commonly overlooked but critical aspect of shielding is correctly grounding the tape or paint. If your shielding is not grounded it is effectively worthless.

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14 minutes ago, phrunt said:

While I don't know about VLF coils the PI coils already have the conductive shielding paint inside them on the surfaces, it's connected via a shield wire to the detector.  I would assume VLF is the same, actually now that I think about it, I cut open a Gold Bug Pro 5" coil some time ago and it had the paint inside it too.

11-spray-the-shield-and-install-the-wire.thumb.jpeg.8a9909e31eacdfe7abec58e0414bf7d6.jpeg

The conductive paint is used a lot for guitars for shielding.

IMG_20190513_092815.jpg.1e351eea88468fdf052a544f6ff89ea7.jpg

I've used it for shielding of metal detectors internals but unless it's connected to the ground it will not provide EMI mitigation.   Read the ingredients of the paint.

It is conductive, you can test with your multimeter once painted on.  You can transmit power through it.

IMG_20190513_165225.jpg.5702f511aecc4a9e4b84c8f3fb363903.jpg

 

You can read about the guitar uses here https://www.artisanluthiers.com/blog/conductive-shielding-guitars/

As far as EMI mitigation goes, from the Guitar website.

The best guitar shielding method is to use either specially designed copper tape or specially designed shielding paint. The commonly overlooked but critical aspect of shielding is correctly grounding the tape or paint. If your shielding is not grounded it is effectively worthless.

That's interesting about the inside of coils being painted, I've never looked inside one.

I always use the copper tape shielding (yes grounded) in my electric guitars because I use use high gain tube amps and it eliminates the hum. 😎🎸 

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