15" Deus Coil.

[Henrikras]

Yes Skippy... Both my newest Big coils works fine with a spiral drainwire.
Remember the wire is Very thin. I not sure what problem it should give, only If the wire in the lay is lose...
I will post some proof to you. A drainwire will help a lot to get a even surface / resistance graphite lay. With out drain wires the lay will be thick and difficult to make same thickness everywhere, in corners and at the side. This spiral is a good idea.. Here is a test with the 13" Vista coil this evening. http://www.youtube.com/watch?v=SnmLMC5YNec&sns=em http://www.youtube.com/watch?v=SnmLMC5YNec&sns=em

Picture 1 is the Vista Stock coil with spiral made drainwires... Thickness 0.15 mm cobber.
picture 2 is a macro FOTO of the thin wires 0.05/0.06 mm I using.
Henrik.

ps. Made this video in a test day.. http://www.youtube.com/watch?v=SnmLMC5YNec&sns=em

[Henrikras]

So fare so good ... My 15" Deus coil got a new shielding this evening. Maybee you saw the coil clean, ready to get painted..( Picture.) My mixture with acetone, powder and lak was sprayed in a medium lay, then I used a Big brush to make a smooth surface and removed lose dust, before I finish with the protection lak.
Back to the workshop and do the same airtest, same way I did some days ago, where I vs the Big Stock coil. Result was like hoped, I got a little more sens. and depht.. The measured resistance at the graphite was 3-350 ohm (measured before the finish lak) Very close to my goal... The earlyer made Sheilding which I removed went down to 100 ohm even a little lower at some places, and that was properly why there wasn't much advantage in this Big coil... Now the result was better.
My way to test this, is the maximum distance where the ID is stable, and I got now 1.5" inch more with my Home made 15" coil.
In the same time I was working with the Sheilding, I removed some weight... The coil is at 690 gram now and I only need some more lak and protection. Not bad If it ends arround 720-730 grams. The Big Stock coil is allso +700gr
Next step is to go out and do some detecting.. Thats the only way to find out, how good the coil is.
By the way... Did you see my lower stem improvement to XP Deus.. If you had a Deus in your hand with the Big Stock coil, you would know that its shakes... Picture 2. Two Carbon tubes 9.10 mm fits perfect in lower stem...
Henrik.

[golfnut]

I would guess that if the resitivity of the carbon layer got really low, we would benefit from having a break in it - i..e not continuous. S

[golfnut]

my main machine has graphite golf shaft.

It was a little whippy and I solved it with sime kevlar cotton - - used by Fishermen for tying flies.

I put multiple long spiral threads and linear threads, lots and lots anchored with super glue at each end - under tesion.

Spray acrylic laquer over the top - stiffenend it up a treat for almost no weight gain . S

[Henrikras]

Those Carbon tubes are from my Archery Compound bow.. I had to Press them with force to get them down in the stem..
2 x 9.10 mm was perfect. Another solution could be made, but this was easy and fast. Weight + 15-18 gram, both tubes.

[golfnut]

yes very nice solution, stiff srong light and not seen by detector...

[Skippy]

Ever since Henrik started making low surface resistivity coatings, I have been wondering what detail changes would allow low resistance, without having negative consequences on detection.
If you take a thin copper wire, you can make an incomplete loop with it, close to the searchcoil, and it is invisible. Closing the loop makes it very visible. If the same thing applies to the graphite shield, then having a gap (or high-resistance region) might still give good shielding, with less problems to the detector.
What I have not tried is seeing if a loop of wire going perpendicular to the wire loop, around it, is detectable. If it is, then maybe a small gap going 'all the way round' might help. Then there's the question of 'what about where the loops are crossed?', in the centre-rib.

[Henrikras]

It looks like I dont got the knowledge in what I'm doing... Just trying something and If it dosn't work, just try something else until it works.. .. 3 words - stubborn, persistent and a little lucky. In two or three years from now, I would properly think "oh God" to some of this coil work I just made.
Ps. Pictures / the coil is drying up after lak, tape and protection... Ups. 745 gram. The bottom lay took 30 gram extra.
Side picture to see this rubber tape I'm using to seal plugs at my satellit dish work..
Bottom picture.. The drainwire is Secured behind this resin bottom lay.
Henrik.

[golfnut]

looks nice, probably get lighter as the solvent evaporates.. S

[Henrikras]

Yeah - one day at Stone field and its uselees but Very lightweight.
Its Absolutly not a design there will hold for ever... I know that.

[Henrikras]

Skippy I think this theory could be right;
If the signal is strong and the object is close to the coil, you wouldn't feel or notice a Heavy thick low resistance shielding, but when you are working with weak deep signals, the thick Heavy shielding lay would give you unclear signals trying to get through...(signals like Breaking up and still some clearness - different from iron signals, Breaking up in another way.)
I just realize that (again), my shielding is still TO thick..... Airtest in lab weak signals nice clear, but when I do the test out at my field
(just done it) with some deep targets, the weak signals is unclear. Difficult to explain but I can easy hear the different, Stock coil vs the 15" coil. I think the next try will be with the graphite spray cans (graphite 33), starting with a high resistance 1-2 Kohm, I never tryed this with the Big coil..
So all my nice lak and finish "Good bye", the sanding machine with Heavy corn 40 is Warming up.
Henrik..
Ps. Is know there is a chance that this project never succesed.

[golfnut]

If the stock coil is smaller than your 15" then this is maybe the main factor for the difference.

I estimate that the target scale links to the area under the coil.

Big coils dont generate large responses from small targets..

[Henrikras]

Thanks Gulfnut.... Maybee it not so bad after all. I will do a test with a deep hoard.

[Henrikras]

I have to admit that this 15" project didn't end like I hoped. All kind off test is made and it isn't better than this largest Stock coil.
The project gave me some more coil building exsperience and now the coil is hanging at the Wall in the workshop.
Thanks for all the help you gave me.
Building a coil with high sens. to find deep targets is Very difficult, everything shall be 110% perfect and I don't got enough experience / knogled and tools to do this. Maybee in the feature I will try Once more, but now I realize that my limit is found.
Henrik.

[golfnut]

Im sure you gave it a good go, I cant think why its not so sensitive.

If it was an IDX I would say tune the Rx coil a little closer to the Tx to boost the Rx performance a little - but alas I dont know the architecure of the xp