15" Deus Coil.

[golfnut]

I think the opportunity we missed was not doing the inside like the Deus, plus your good coils.



If you wrap it in paper strip, then with pvc insulating tape over top, try on wet grass again. Maybe ok? Then could lac heavy coat.?


The effectiveness of the sheilding requirement is probably linked in with coil size..

Big coils have more capacitive effects to guard against over the ground and would maybe benefit from your best ever solution.
Unfortunately your biggest coil has the least screening.. S

[Henrikras]

Thanks Steve... But I was allready out at own testbed (grass field) this evening and do a sussecfull test with some standard spray paint over the graphite lay, just like you said, I need to isolate the graphite, else will touch give signals. Or something like that.
Ist working now !!!!! Look at this http://www.youtube.com/watch?v=aasYYHByMmA&sns=em
To me it seems that the shielding can Be done outside and inside... and in combination like XP did.
okay the coil hasn't been out on a field a full day search, so there is still some Maybee's !
But so fare its looking good.
Next test is sensitivity... I made a test before the shielding, with the Stock coil Bigfoot vs this 15" coil, that same test with different object will Be done again... The will Be Interesting. Maybee Skippy is right that the lose will Be about 20% will so high resistance I did with the graphite.
See you.. Thanks everybody.
Henrik.

[Qiaozhi]

Yes Qiaozhi - this is an exsperiment. At my 7" coil I first made some Sheilding inside, but had to paint much outside allso. That coil ended perfect (in my newbie World) - same was done with my little eliptical coil... Out and inside. I let the drain wire come out by a small 1mm hole and back inside again.

If you have a coil cover, you could try putting the shield inside the cover. Then you will avoid any contact of the shield with the ground.

[golfnut]

"To me it seems that the shielding can Be done outside and inside... and in combination like XP did."

I think you proved that well.

[Henrikras]

If you have a coil cover, you could try putting the shield inside the cover. Then you will avoid any contact of the shield with the ground.

No Coil cover ! If those cover a made to this 15" Shell, I will ordre some next time I need some of this big Shells.

Gulfnut... It could Be the case that I dont need so much graphite... Properly a isolated lay had done the job earlyer... !!!!
If the lost is to Big, I can easy removed all shielding, be carefull to safe the drainwires, and try another version with a thin lay and then the isolater.

Do you agree that an airtest in lab testing the sens., would Be an okay way to know the lost !!! Or shall it Be done outside with ground / soil to make it reel.?

henrik.

[golfnut]

Do you agree that an airtest in lab testing the sens., would Be an okay way to know the lost !!! Or shall it Be done outside with ground / soil to make it reel.?


I would have to take a guess,, my guess would be air test is ok.

[Henrikras]

I just made a test... Indoor in my workshop, 15" coil vs the 11"/13" Stock coil. The 15" is so little like 1cm more sensitive to give me a ID. That is like the same (to little different) at that was at 11 khz. At 17 khz they gave the same results, those two coils.
Before the shielding I had close to 1" advantage with 15" coil.
Next step is to go out a do some swinging, that would give me some more answers.
Its seems that Skippy was right about the lost, painting to much Sheilding material like I did with the graphite powder mixture.
The tone from the 15" coil wasn't sharpe and solid when the test coin came out at max. distance from the coil, the reason could Be a indoor problem, with to much interference in the room!!
Thats why I'm not saticefired with this indoor test, to many Maybee's - but any how I made a video. (Uploading now)
Wait for a outdoor test at a field some hours... Things are just going a little slow at the moment, got many projects running.
See you.
Henrik.

[golfnut]

No drama. S

[Henrikras]

No.. - and here is the test. - http://www.youtube.com/watch?v=i3sIUCdvTV8&sns=em
A lot of rain here, so some delay with a further test.
Have a nice weekend.
Henrik.

[Henrikras]

Hi
Soon I will receive some new Shells from Donald Bowers to continue my small coil work, but I'm still working at the 15" coil to the Deus...
I found out that with drain wire like the picture 1, the shielding dont need so thick lay of graphite...
with that design of drain wires ist much easyer to spray a graphite lay and get control over the Sheilding resistance.
This 15" coil first try didn't had much advantage as it should in this big size, properly beacuse of many reason, but one reason was that my Sheilding was to thick... (Low resistance was measured).
Now I change some few thinks, still the same coils inside and I hope to get a little more advantage in depth...
I need this Big coil to those fields with Very few finds and no iron.
In the same time I had work with a 13" Vista Gold coil, and that seem to be a succes.. The largest Stock coil to this model is 10.5" round coil, so a 13" coil working perfect gives me some more depth... I had been out and do some search with this 13" coil and its working good.
picture 2 is the 13" VG coil - prototype / outside shielding and lak with drainwires turned around the coil.
Airtest 15" Deus one silver coin 11 khz 10.0" and the Deus Stock coil 9.25"
Airtest 13" Vista gold low conducted coin 11,0" and the Stock coil 9.5" (11" with a strong clear signal isn't bad)
Im still learning a lot making my coils. Maybee one day it will end with a ultimate made coil...
Ps. I found a good mixture with acetone, lak and powder. This mixture can I now spray at my coils and make a smooth nice lay, and its drying up. Its even a little solid allso. My drainwire is a silver coated 0.05 mm wire from a B&O link cable..Very thin and strong.
Henrik

[golfnut]

spiral wrapped on the outside, nice. Obviously not continuous. S

[Henrikras]

No no... Not continuous From the soldering point 3 wires, one right, one left and one in the middle.
The distance from each wires in the spiral is Very similar all the way around. The first try I made, I had a upper wire and a down wire.. With that try the sides of the Shell needed more graphite. This spiral its fare more easy to make the perfect lay, not less and not to much. But still learning..
Henrik.

[golfnut]

you may benefit from 2only. soldered at same point. But with one spiral sitting between the other.. Both could go almost right around and in oppsite directions,, like DNA

There it is, the DNA sheild

(none of them should touch each other)

[Henrikras]

Thanks.. New good ideas again.

[Skippy]

Has the spiral-wrapped arrangement been tried in the real world? My feeling is that too much wire (ie. more than is strictly neccessary) may give electrical interference pickup, just a hunch. I guess it depends how well 'shorted-out' each loop of wire is. If you had a high surface resistivity graphite coating, the wire would behave more like what it is - a long length of wire.
I'm now thinking about the post of mine in the "Deus small-coil" thread, about using very-low resistivity carbon paint (50 Ohms / square?) as an alternative to the drain wire.