Tx and Rx coil inductance ratio

[ifrenide]

Hello.
If your opinion is wrong, each time you attempt to support it, for sure you will make another mistake.You can know if you're wrong or far from the truth by looking at you examples "exceptions, unpractical,not popular".

-WM6 my brother. you show as a picture"not real picture" of unpractical device, so each time I want to test a place, I have to move the big coils and the 2 units.there is other technical problem.how to make them working together in armonic way,I mean you play around microseconds.how we make a separate receiving unite, get the signal of a target just a moment when the transmit signal is off ????? in a one unit yes "easy".finnaly this is a PI metal detector.different from VFL system.
Nexus
my brother.your coil is an exeption and you said : "that was made only for few customers" you know why , because it is unpractical and sometimes you can find some people like testing and trying some stange stuff "the world's biggest VLF coil" we love unusual things. you said :" like Carl mentioned the increase of sensitivity is not only to targets, but to ground as well" I respect him, of course he's the lion here . but I want tell something mybe I'm wrong. If if we get a high sensitivity for both ground and target, we stand and watching them? no,we will solve this problem by using electronics" make a good ground balance system".
in theory making a big VLF coil is a true fact .un practical if we take in consideration sweep speed of coil and human force to match this speed, and there is a problem when we want to take this coil with as "it's too big ".we need a truck to make metal detecting so! .Without talking about effeciency. it's like you bay a bus instead, of car. and you bay it for personnel use . you can use it but, look around you .only cars is used for personnel purposes.

[Nandor]

Thank you for sharing this information about you coils!

[Nexus]

WoW ! It is really huge coil . But not 4 meter of diameter of course or even 1 meter .

The Nexus 41"CC is 104 cm in diameter.
There is an older model that was made only for few customers with a figure of 8 or dual 1 meter coil (185cm x 100 cm) - Nexus Exselsior.
Now the 41"CC will be manufactured for Minelab GPX.

For anyone who would be interested.
Nexus coils are all made with equal ration TX to RX number of turns, equal inductance ect. I found it a waste of time to do coils with different ratios as just like Carl mentioned the increase of sensitivity is not only to targets, but to ground as well.
The best "transformer" connection between TX and RX is a full resonance and of course the best possible sensitivity to derive from any coil. A fully tuned in resonance coil will replace about 20 times of the input gain, meaning the input stage will need 20 times less gain compared to the use of a RX coil not tuned at all.
I hope this helps.

[WM6]

WoW ! It is really huge coil . But not 4 meter of diameter of course or even 1 meter .

What about so called "Ground Loop" coils:




Applied to PI for now.

[ifrenide]

WoW ! It is really huge coil . But not 4 meter of diameter of course or even 1 meter .

[Qiaozhi]

I don't think so Mr Davor . I never seen a VLF coil bigger than this one [ATTACH]46723[/ATTACH].

In that case, try these ->

https://www.nexusdetectors.com/aftermarketsearchcoils.html

[ifrenide]

I don't think so Mr Davor . I never seen a VLF coil bigger than this one .

[Davor]

Oh, but we can. And we do.

[ifrenide]

Hello,I forget ,bobines shape and size.we can't make a vlf coil with 4 meter of diameter, or a coil with unregular shape. good bye

[ifrenide]

Hello, actually I want to mention something important. every on talks about transformer,witch has two bibines . here if we want anderstand this subjectwe have to bring all elecments wich is the window of any vlf metal detector.elements are:
1-(TX bobinel inductance ,frequency and amplitude ,wire gauge)
2-(RX bobine inductance, frequency and amlitude to be amplified,wire gauge)
3-( op amp gain and its characterestics)
4-RX tuning capacitor.can we make for example RX bobine with 456 mh and a 470 pf to match the frequency desired?we will take care about RX tuning capacitor characterestics to avoid amplification quality problems.
5-one more thing is this transformer you talking about, has (four) 4 bobines if we consider target and ground as bobines too .So this transformer is complicated ,since there is two dynamic bobines witch is ground and target, and two other static bobines in terms of inductance. so we have to introduce all these elements in how we choose characterestics of TX and RX bobines, to get the best result.
we can't take only one element and we say: this is the rule of thumb to make a good coil (transformer).
all these elements affect our coil including temperature,and elecromagnetic noise in metal detector's environment and we can consider it also as a micro bobine.
so we have a transformer with 5 bobines interacting with each other and affect RX signal witch is our litle boy ti take care about, and make it a strong man wich tell as the truth about what is under the ground .
best regards

[Nandor]

So the goal to reach the best sensitivity is to find a frequency other than Tx were the link is strong, at it can have a pretty high phase shift ralitive to Tx signal right?

[kt315]

first pic in the article

[Qiaozhi]

Translation?

Wasn't originally written in English as above?

The original Kostin article is written in Russian, and Altra supplied a translation in English.
Carl meant that a lot of the technical meaning has become lost during the translation from Russian to English.

[WM6]

Good article, but a lot gets lost in translation.

Translation?

Wasn't originally written in English as above?

[Nandor]

What about the Quality factor of the Rx coil, should I make Rx coils with ticker wire than 0.25mm to reduce resistance? That Explorer coil with only 470uH must have low resistance so I think the Q factor must be high.
I was thinking about a DD coil for my Minelab oscillator TGS, with Tx 1mH 0.45mm and Rx 1mH with 0.30mm wire.