Coil questions, I don't think have been asked..

[neo]

First of all shapes and sizes for Surf pi mono...
Is a circle or oval really the best shape? has anyone tried square and triangle to get a longer thinner emf? (If they did and it failed i expect the depth was bad?)

Second Shielding..
I noticed a lot of people covering the coil with tinfoil and saying this improves depth anyone have any idea if this is true and why it improves depth?
and speaking of depth in a video I saw where they were building garret security detectors they added a piece of iron and said this increases the field strength could that not be used in some way for ground MB?
And depth again, If we shielded only the top half of the coil with tinfoil would this improve depth? would previously upward emf be forced down? or would it only work if all the coil was covered?

Third gauge...
Is there an optimum gauge wire to use? i think most people recommend between 22-28 awg, Is more turns not better?
DD coil has anyone experimented with different gauge rx and tx coils? tx thicker and rx thinner? its one thing I would really like to try.


Fourth resistance..
How does the resistance issue work with the coil? is it a case of winding until you have max tolerance resistance? is more turns with less resistance better?

Wire layout
Is standard way of winding best or just cheaper to do? i have seen flat wound coils but never managed to see any kind of test same with "basket"

I am waiting for all my parts to arrive but would really appreciate answers if anyone has any I plan on experimenting with coils a lot and have the time and funds to do it.
Myself and a friend love to experiment and have been messing with perpetual motion and overunity machines for years even have one being looked at by Defra (though this was simply green energy not OU).
and as soon as we have enough funds for the next OU project I'll be doing that too. Funny how im in the Pathology line of work and nothing technical but you make sacrifices for the ones you love.

Anyway please feel free to answer as best you can any of these questions I'd really appreciate it.

[bernte_one]

if you start first testing with surf pi you will see that every theory nothing cares about your practical results in real field
what i found out. at some concepts metal shield is very bad at other it can improove Performance - i suppose it dependes on the working frequency

[neo]

I think I understand that, Theory is just theory? but yes test results are what is needed, I was hoping some people may have tested a few of the above or even have results handy.

[Koala]

I have tried square oval and circle

No point in square tried for fun has no advantage. Circle gave best depth good pinpointing and all in all best all round. Oval gave about the same depth as a circle of the narrow width but with greater coverage could be useful to poke the point around rocks. Have to admit I was slightly disappointed with the oval detection depth still fell of quite quickly from the center.

All in all I stuck with circle.

Very hard to test properly as you have to change the delay and damping resistor for best results and some of you results are subject to slight errors.

[neo]

Yeah I thought that would be the case, any results for triangle? ever tried an iron core to see if depth is affected?

[Koala]

Yeah I thought that would be the case, any results for triangle? ever tried an iron core to see if depth is affected?

Nope never tried any core. Did try quite a few rectangles after reading a thread on here. None better than a circle.

Once you have your detector up and running its easy to try as many shapes as you like but you will need to change the damping resistor and delay for best results


As for the rest of your questions its always best to try and stick to the original design parameters but there is quite a bit of leeway


Once you get so big with the wire diameter going bigger just adds weight

Shielding tinfoil is probably a bit thick. There are several threads on here.

[sinclairuser]

i built a dd style coil where the coils were triangles instead of the d shape, this was for use on a pi, i wondered if it was any easier to achieve a null, it did seem to null quite quickly, but its standard dd config coil counterpart had better depth, also the shape of the coil wastes space in a standard housing.
don bowers who makes coil shells for sale did some triangular shells, maybe a mono for pi would be ok, the point may make detecting between rocks easier.

[SVEN1]

I had Don make up some triangle shells to my specs for my PI, pictured on his website. They were a good novelty item but the round coils had much better performance.

[neo]

Nice to see another yorkshire guy on here, So many shapes have been tried and tested what about shielding in particular shielding just the top of the coil i'l really interested in seeing how that performs I doubt it will give a stronger downward field but who knows maybe it will be more sensitive?

Thanks for all the replys I'm really looking forward to all the parts arriving I just hope i'm up for when hey arrive just another reason to not like working nights.

[sinclairuser]

I had Don make up some triangle shells to my specs for my PI, pictured on his website. They were a good novelty item but the round coils had much better performance.

hi sven, i wondered if triangular coils may work for split setups like the garrett gt1 2500 hoard setup, or indeed two box detectors, if nothing else they would pack into travel cases more easily, and they look cool.
i found the point of the triangle to be quite sensitive, if the coils were orientated so the receive coil was pointing down, it may add tighter pinpointing on a split hoard setup.
@ neo only shielding the upper part with graphite has been tried here before, but i cannot remember the thread, a good place to look is TOOLS AND TECHNIQUES, and of course COILS, as for yorkshire there are loads of users on here.

[SVEN1]

I got the idea of building a triangle coil from a post post on a forum about a guys friend who made a detector and used the triangle coil. A much larger size that he used to help prospect and hunt in-between rocks and crevices.

VLF machines

Built my coil in a much smaller size something like a 5x7" for my PI. The tip was nice for pinpointing within a hole after digging a plug. Comparing my 5 and 7" round mono coils to it, I concluded the 5 and 7" round coils had much better overall performance.
These are the shells I had Don make for me, the round is the 7".



Garrett had been making a small triangle coil for their Industrial Valve Locator Metal Detector that look like Garrett ADS Master Hunters.