Concentric coil for TGSL.

[multieagle]

Same thing outdoors. The two unshielded coils display no action with positive/neg wires hanging free. Once the neg/pos wires are connected, the coils become very lively, with a magnetic field detected about five inches from surfaces. The other shielded coil shows low level activity until the pos/neg/shield ground wires are connected and then I get the high level magnetic aura detectable by the pro-pointer. With all three coils the whole inner coil is active over the perimeter established by the coil dimensions. I assume this is natural. I did not expect there to be a detectable field until a DC power/current was applied. Just a learning curve, I guess.

Thanks for the replies.

[golfnut]

Hi multi eagle - in order to help we need to know more.


What machine is this coil on - PI? IB VLF?

What is the coil construction? Mono? Saying "I constructed a 9" coil with doubled (-+ wires)," conveys little


Are there 1,2,3 coils.

Were you trying to make a concentric - like in the thread?


20 unknowns leaves us, not knowing..

S



I

[multieagle]

Looking back, I see that I sort of hijacked this thread. Chalk it up to being a novice at this detecting forum thingy, and my habit of scattered thinking. I apologize to dfbowers for screwing up the drift of things. Will start a new thread dealing with my particular questions, PI coil peculiarities through the eyes of a novice.

[golfnut]

No worries, I do this all of the time - I too am scatterbrained -

S

[ashefr10]

hi Don , my coil double D house is sensitive to wet grass, I however correctly armoured this one which do you do propose to me? thanks

[dfbowers]

Hello Nico.
I prefer this grounding configuration.
Don..

[ashefr10]

Ok Don Thanks ,
So the second cabblage is best for the wet grass. it does not need to connect Tx end and Rx end shielding. So the screen is just connected to the aluminum around the coils

Hello Nico.
I prefer this grounding configuration.
Don..

[golfnut]

Many commercial coils do this ML and Nel do on at least some of their models.

Nel have two coaxes. The coaxes are kept apart in the Head and the cable - the braids are grounded in the box end only.



s

[ashefr10]

ok , thanks , are what what value of capacitor is known puts you one between the 2 gnd?

Many commercial coils do this ML and Nel do on at least some of their models.

Nel have two coaxes. The coaxes are kept apart in the Head and the cable - the braids are grounded in the box end only.

[ATTACH]27933[/ATTACH]

s

[golfnut]

On a popular beginner machine from US in yellow plastic - they use a 2.2uF

Im not saying you need a cap.


But some brands have one. Try without and with there may be not difference. S

[saber]

Thanks Don

Can i use this coil for quasar AVR? Please help me.

[BKY1337]

Do you guys think this pattern is usable for a good pinpoint and widescan coil?

[Koala]

Do you guys think this pattern is usable for a good pinpoint and widescan coil?

[ATTACH]39583[/ATTACH]

Usable yes

Best for pinpointing no

Coins at an angle will pinpoint somewhere around the top and bottom of the inner Rx ellipse which is further from the centre than a circle.


Separation is half the coil width so you will be able to detect nearer to large iron.




Not tried any different shapes on a VLF but did try square, oblong, triangle and so on with my PI. Circle was the best for both pinpointing and depth. Elliptical preforms the same as a circle of is smallest width but with greater coverage top and bottom.


Always wondered how the fisher concentric coil with a circle Tx and elliptical Rx fit in

[BKY1337]

Ok, i want to make a concentric one because i have no pinpointer and its very hard to pinpoint things with my DD coil.
But i dont like to change the coils. I have thought that it is like something between. Maybe its better to build a pinpointer.
But i definately will build a concentric one because it looks like its very light without the resin. My DD has about 600g.

I think you can sweep the coil again 90 degrees turned to pinpoint things, this doesnt work with my DD coil , maybe because of the big magnetic field
of the D coils. Maybe its smaller with this elliptic concentric coil but i dont know.

[homefire]

DB ! What is the smallest Round housing you make ? 6" . I'll be using some of these Idea's for a 6" Concentric for my GMT I think.