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Carbon coils?


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Hi,

I've been away from this hobby for a while but recently picked up a used GPX 5K and so I'm back in the game I hope. I am looking for a coil to complement the 11" mono and 11" DD commander coils that came with the detector. In doing so I came across a company in Australia that hand makes coils using Litz wire and carbon rods. They look pretty cool and light weight. The company or person calls his business Carbon Coils. I searched the internet for comparisons of his coils to other similar coils but almost no info to be found. It appears these coils have been around a few years but very little said about them on-line neither good nor bad. Anybody use one or know of anyone who has?

Thanks,

Terry.

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Appreciate you responding Garimpo. Hope you are still finding lots of gold down south. I have looked at the Nugget Finders and newest coiltek's and they look great and there is no lack of info about either online. It is true that the newer coilteks and probably the nugget finders as well use Litz wire. Personally I'm not real sure what the advantage of Litz wire is but maybe someone will chirp in and educate me but it seems like the thing to use now-a days in a coil.

There's really not a lot to a detector coil. The coil its's self is just basically a wire bundle and is the plastic, epoxy etc around it that makes up most of the weight.

What I'm getting at is I think one could be made a lot lighter like the one's the company called Carbon coils is making. Hard to find out anything about them though as either nobody is buying them or nobody's admitting they have. I may contact them and see if you would provide more info. However, it's always best to hear it from a source not affiliated with the company to get a unbiased opinion.

post-788-0-90052200-1457391418_thumb.jpg

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I feel a bit odd replying to my own thread so I'll just call this an update so it don't look like I'm talking to myself. :nutty: I emailed Chris at Carbon Coils in Australia. Apparently he is experiencing quality issues with his Litz wire so isn't presently selling any coils. Also I did an internet search of Litz wire to find out why it might be better. Here is a link to the site I felt had a pretty thorough description of the wire. http://www.litz-wire.com/applications.php. Seems it's stranded wire woven in a special way that reduces skin effect and proximity effect. Looks like litz wire can be engineered to have minimal AC loss at your specific frequency.

I guess it means it better wire. :idunno:

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  • 1 month later...

Hi Terry.

 

Those Carbon Coils aren't much chop, especially the mid to large size/huge size.

I tried a small one moons ago, just around the eleven inch, maybe under, on two different machines and it falsed very badly.

The larger one I owned myself, it was way over thirty inches and consistently falsed very badly.

Once the coils reach that size and above  (actually twenty four inch and above) they splay both transmit and receive signals hell west and crooked and are pretty much useless in all applications.

 

The smaller one on the right hand side of the pic would have been the size I had, and it was bad enough.

Wouldn't mind betting both the depth and sensitivity on the all in that range, especially the largest, would be horrible.

 

Never liked the produced or hand made drag coils or harnessed coils either, same uselessness about them.

Pity the theory of larger coils doesn't pan out.

IMG_1557.jpg

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As for Litz Wire across any of the many different company coil ranges, I really do not think there is any advantage (excuse the pun) over Litz and the wire used in the range before.

 

I'm sure, theoretically anyway, that there would be engineers specs that say differently though.

Edited by argyle
dodgy spelling
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This is the advantage of 'Litz' as I understand it...

High powered PI detectors (Minelab) put a lot of current through the coil on each pulse.  In order to move the current and not fry anything, the coil has to have a low resistance.  You get a low resistance by using larger wire.  Problem with larger wire is, at some point, as the wire diameter increases, the coil will be able to 'see itself' and not function properly.  There are other drawbacks to larger wire, but I'll leave it at that.  Litz wire is made up of dozens if not usually hundreds of strands of individually insulated very small diameter wire.  The hundreds of strands, together, act as a larger gauge wire and provide for a coil with lower resistance.  Since the gauge of the individual wires is so small, the coil is invisible to itself while still giving the benefit of low resistance.  Small wire also makes for lower 'skin effect', and the individually insulated wire reduces the capacitance of the coil which helps to make the coil 'faster'.

Luke

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Thanks Luke and Argyle.

Too bad the coils didn't work out.  Looked like a good idea of having a large and light coil.  Maybe building a large efficient coil is more complicated than I assumed? 

Back more than 5 years ago I made a  several coils (7" and 13X18") including a 1 Meter coil and maybe got the incorrect impression that a PI mono coil was simple to build as the one's I built all seemed to work fine.  I say fine, but I really didn't check them out thoroughly but they did work for sure.  The only one I even remember doing a simple test on was the 3 meter coil.  I had a very large steel Nut I had found somewhere that probably weighted 6 ounces or so.  I just wanted to see how deep it could detect a fairly large metal object.  If could detect it at around 6 feet (air Test).  So I was pleased with that.  I had to get on a fiberglass ladder to fully test it.   I think I was just thrilled that it worked at all.  

Attached is the one meter build.  1. First made the loop, 2. then wrapped with shielding, 3 the wrapped with a spiral wrap 4. encased in PVC.  Had to split the PVC.  Looks simple but a few other time consuming steps there so it took a while to build.  It came out as 28X44".    

 

   

28X44 coil1.JPG

close upshielded.JPG

close spiral1.JPG

completeind1.JPG

1Mcoilalmostdone1.JPG

Edited by Roughwater51
Add some additional info
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Hey have you ever tried making say a fat elliptical around the 18"x 16" mark Terry?

Or a round coil of any size? In any of the types, Mono, DD, folded ect.

Then either make your own mold out whatever compound, or have a small local plastics firm make it up for you?

(I do not have the nous or even the slightest understanding of the tech side of things at all, not a clue. I only know how to use them, so not a touch of knowhow in my head)

 

I only ask because I've aways been very interested when guys start to nut out the correct way of building their own coils, and in the end a few actually go into production, then onto a run of an initial stock line ...

 

Some that did produce coils many years ago, and they were actually fine coils, never went on with it after the second or so Run.

 

Then others like Barrie Johnson kept persisting and producing, then his son Rohan kept at it right up the current range of Nuggetfinder Evo's.

 

You have the nous, and with retirement around the bend, could be an enjoyable hobby in between detecting trips. Maybe $$ for the future even.

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