Let's Invent Another Metal Detecting Coil

[Aziz]

Hi all,

yeah, let's do it!
Anyone with a super-duper idea, which is well worth to be investigated?
Or did we invent all coils already?

I'm looking forward to the countless ideas you're bringing here..

Cheers,
Aziz

[6666]

Pi or Vlf ?

[Aziz]

Pi or Vlf ?

Both and whatever you prefer.

[Tepco]

Search for “vector inversion generator” or “Pitchugin generator” and you may get some nice crazy ideas for PI.
PS. What software screenshot is on your avatar, it is Field Precision?

[Aziz]

Search for “vector inversion generator” or “Pitchugin generator” and you may get some nice crazy ideas for PI.
PS. What software screenshot is on your avatar, it is Field Precision?

That's an interesting application for the (low frequency) GPR transmitter. But not an appropriate application for us.

Re: Avatar screen shot
It's just the magnetic field strength of two torus coils (has nothing to do with metal detector coils). I haven't changed it, well, I'll keep it so you can recognize my posts easier.
I've finally found the big picture now. See below.


Cheers,
Aziz

[Tepco]

Not meant to be used in it's original form and for original purpose, just “vector inversion” principle, to speed up normal coils.

[satdaveuk]

Hi
Maybe we should be not thinking coil as a pick up anymore, lets forget coil and think of something else a totaly new concept.
Far as the down lead between pickup and recevier/ transmitter, I nominate using fiber optic, it does away with all common problems such as intercapacitance, emf etc.
I use this stuff alot now within the satellite industrie, and the days of having to work out cable losses within a housing complex are a thing of the past because fiber optic technically has know limits.
What we need is engineers on here to start thinking away from the designes we know and come up with something totaly different.
Regards

[golfnut]

I fancy the idea of having a 3 phase Tx coil so it can be electrically rotated. This would give true non motion performance. The electronic drive could be an ESC for electric models.

[Aziz]

Well, I tend to challenge the EMI noise induction reduction with highly magnetic non-conducting shielding material on top of the coil arrangement (half-space magnetic field shielding). Yep, no one would bring such a hot magnetic material (relative) close to the coil. Just a non-conducting magnetic shielding plate (several mm thickness) at 1 cm -2 cm above the coil would reduce the EMI noise induction. I did try the proof of the concept and it works.

(Hey patent-trolls: Hurry up!, run to the patent office. )

Cheers,
Aziz

[Tepco]

“Passive dumping”, using very conductive nonmetallic and nonmagnetic material on coil surface can be interesting to investigate too.

[Overtheedge]

How about modeling a half toroid used for an off-resonance probe? By half toroid, I mean a large toroid cut into two U sections.

eric

[Aziz]

How about modeling a half toroid used for an off-resonance probe? By half toroid, I mean a large toroid cut into two U sections.

eric

Eric, a nice general question: Why it hasn't been used before? (Occam's Razor)
No, it doesn't make sense to me. Off-resonance detection method is quite slow too (requires slow coil motion).

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Ok, I'll give you more food on the half-space magnetic field shielding:
Imagine we have a large TX coil and a separate small RX coil. You would need much less magnetic susceptible material for the RX coil to shield it against EMI noise. This is going to be a worthy application.

Aziz

[Davor]

I'm about to try a makeover of my stealth setup to accommodate a kind of 2box arrangement. I came to conclusion that the only effective way of fighting non-linear effects in soil due to magnetic relaxation of small domains is by ... equalising the field depth-wise, and that's precisely what a 2box arrangement does. It is applied tangent-wise. When you think about it, our detectors are capable of finding small objects at 10 inches or more, but we also bang them with shallow target responses all the time. And noise too. A 2box arrangement is almost orthogonal in free air, and balance is increasingly ruined with depth. That's a +. Also a Tx coil is not in close proximity to the soil surface, hence no liftoff effects either.

Aziz, could you be so kind and see to the 2box arrangement with your fabulous software? I'd be very happy to see some kind of equalising effect depth-wise that would ruin the 6th power law, and the ways to enhance it. Reducing the required dynamic range would be a great bonus.
-------------------edit
It does not have to be perfectly balanced for PI application.

[Aziz]

A simple sketch is saying all. Exaggerated, the RX coil can be smaller. The TX coil can be much larger.
The magnetic field shielding is round of course.

Aziz

[Aziz]

Hi Davor,

2box is well known. There is nothing to investigate or improve.
Aziz