LITZ (LEITZ)? WIRE.....WHAT IS IT?

I've read about Litz wire used in coils....what is it and how does it vary from the standard coil wire?....I would appreciate answers in technical and laymans terms.
Does anyone have photo(s) of a cutaway section of a coil ?
Also, how does a coil deteriorate with age if it's only wire inside (unless it's steel wire that rusts)!
Finally, is it possible for manufacturers to use gold or silver wire because of their superior conductivity characteristics....please don't reply to this question based on economics (if we pay over $6,000 for a detector, what's another $1,000 or so for a top quality coil ?).

I await replies with bated breath..............

Without getting complicated; The original Leitz Wire from way way back in the days of valve radios was a fine multi stranded wire that was used to wind (in a braided fashion) "IF" Coupling Transformers to reduce the effects of induced electromagnetic interference between IF, (Intermediate Frequency Transformers in radio TX and RX units).

It is expensive to manufacture compared to single stranded wire and it servs the same purpose in metal detector coils. (Helps keeps outside electromagnetic interference to a minimum

I believe Litz wire has a larger surface area compared to other types of wire. This may or may not be the result of being composed of multiple strands. The larger surface area apparently allows for better results (on a detector coil) in terms of emission.

Some interesting links.

Wikipedia

MWS wire

Material resistance comparisons

All good links there.
I had forgotten about the Skin Effect aspect, which is a bit sad on my part (gettin old I guess) because it is the most important feature of Leitz Wire.

While litz wire has been used in Minelab, and other coils there is no evidence to prove it is superior to other types of wire, especially the modern low oxygen content copper wire available for some years now.

To illustrate this point: Minelab have always used Litz wire but when the Coiltek coils came on the market they were considered far superior to anything Minelab could produce and Coiltek have never used Litz wire. Coiltek continue to produce coils that are still considered by many to be the best on the market, as does Minelab.

Nugget Finder, as far as I have been informed, have always used Litz wire and promoted Litz wire content as the reason they are superior. But while they are considered by many to be the best on the market, and there is no denying they are good, there is no evidence to show Litz wire makes them superior.

I'm not trying to start a verbal stoush on the pros and cons of different coils (although I know of at least on person who will become upset by this post and I expect a rabid response) but to simply illustrate that I have never found coils containing Litz wire to be superior by simply containing this wire.

Cheers, Jim

granite2 wrote:While litz wire has been used in Minelab, and other coils there is no evidence to prove it is superior to other types of wire, especially the modern low oxygen content copper wire available for some years now.

To illustrate this point: Minelab have always used Litz wire but when the Coiltek coils came on the market they were considered far superior to anything Minelab could produce and Coiltek have never used Litz wire. Coiltek continue to produce coils that are still considered by many to be the best on the market, as does Minelab.

Nugget Finder, as far as I have been informed, have always used Litz wire and promoted Litz wire content as the reason they are superior. But while they are considered by many to be the best on the market, and there is no denying they are good, there is no evidence to show Litz wire makes them superior.

I'm not trying to start a verbal stoush on the pros and cons of different coils (although I know of at least on person who will become upset by this post and I expect a rabid response) but to simply illustrate that I have never found coils containing Litz wire to be superior by simply containing this wire.

Cheers, Jim

Jim, I think you should try a GPX-5000 using Fine Gold timings in variable ground before you say too much more. Those coils were considered superior in the past for only one reason, they had a larger range of sizes and shapes to choose from. The DD coils of yesteryear were fine in their day but I would always take a Litz wound mono over another variant any day. I was once sent two 18" DD coils one black and one other and asked to test them in the field, the other one came up trumps which surprised me because in the past I felt the Litz wound ones were sharper and clearer in response until I twigged to the fact that the housings had been switched.

I would not consider my reply to you to be upset or rabid, assuming it is me your referring to?

Jim sometimes it's best to let sleeping dogs lie, there is a very good reason why there is a letter from the CEO of Minelab in each and every GPX-5000 sold.

JP

When I first heard of Leitz Wire being used in metal detector coils my initial thought was, "What The Blazes Use Will That be'? Hf Skin Effect will be of no relevants, however because this wire will reduce the strength of HF induced Eddy currents (flows on the outer surfaces of a conductor) caused by lightning, and some radio TX's and maybe harmonics from other detectors, then it is possible that a metal detector coil made from Leitz Wire may reduce electrical interference affects and therefore the coils may run quieter in certain areas and atmospheric conditions.

Hi JP, no it wasn’t you who I thought would come back with a rabid reply. You do get a bit enthusiastic but not usually rabid.

As far as the Coiltek coils only being popular because they had many more coils than Minelab to choose from is not quite on the mark.

When Minelab, a company I have always supported and continue to do so brought out the SD2100 they had at least 3 coils. The 18” garbage bin lid mono, the 11” DD and the 11” mono.

Coiltek hit the market with the their round 18” DD that blew everyone away. This was somewhere between the 2100 and 2200 arriving on the market. It was wildly popular for one reason – it found gold – lots of gold and at better depths than before. It was quieter, crisper and very easy to understand. Coiltek couldn’t hope to keep up with demand and had to move to much larger premises.

Then they came out with the round 14” DD and that was even more popular. Being lighter and easier to use than the 18” it appealed to a wider range of people, especially the older folk who had trouble with the weight of the 18” until later when the Easy Swing came out.

When the Minelab SD2200 came out, if my memory serves me correctly, both they and Coiltek had only 3 coils in their range. The 3rd Coiltek was a round 14” mono that went on to win the hearts and minds of many people, especially on the GPXtreme.

This meant that by the time the SD 2200 was getting into its second year both Coiltek and Minelab were pretty well neck and neck on both number and shapes of coils available. It was soon after that when Coiltek doubled the number of shapes and sizes of its coils but Coiltek had long had a fantastic name for the quality, durability and ability of its coils. These days the 3 main manufactures are pretty well neck and neck when it comes to all of the above.

So if it wasn’t the larger number of sizes and shapes of Coiltek verses Minelab that gave Coiltek the advantage it must have been the amount of gold their first 3 coils found.

Now I am sure if you want to research the subject you will find I may be a little out with my times, but close enough.

By the way, I have not used a DD coil in the last 3 years and even before that I was using them as much as possible when the ground allowed it.

As for the 5000, I look forward to trying one next year when we buy 2 before heading west again. Not having had the chance to yet see the letter enclosed I await with interest you posting one on this forum for all those unfortunates like myself who haven’t yet been blessed by the wisdom of the CEO of Minelab.

I have been detecting since 1979, cutting my teeth on the Garrett Deepseeker before buying one of the first the first Minelab detectors in about 1985. Since that Minelab machine I have been 100% Minelab owning and using every model (except the 5000) they brought on the market. If it weren’t for Minelab neither Coiltek nor Nugget Finder would exist and the argument as to whether or not litz wire is better than any other wire would not matter.

It is still my opinion that there is no conclusive proof that litz wire is any better than other wires used in coil manufacture. If this clashes with your personal opinion then so be it but until someone can scientifically demonstrate that litz is better we can agree to disagree.

Cheers, Jim

I'm hearing of quite a few people with Double-D Coiltek coils doing marvelously well over in WA right now. They're using them on the GPX-5000 and a few 4500's.

Jim, I suggest you take a peek at the letter included with each and every GPX-5000.

For your interest I had prototype 18" DD coils made by John Kah in prototype housings for the second style 18" Monoloop Minelab (Kevlar two piece housing) released at the end of the SD2100 production run and included with the SD2200, so in reality it was my requests to John Kah that got the process going for the demand of more DD coil options. This was back when Coiltek were still making coils for Minelab in the very same factory they are in today which was brand new at the time. I had permission from Minelab to get John Kah to make me coils, with all discoveries to remain Minelab IP but with payment to be worked out between John and myself, accordingly he made me a number of 18" DD's which I did really well with once we sorted out issues with flex etc.

Initially however the big coil demand really took off when I had some hand made Aquacell coils made for me under license in mid 1996 (22 inch Mono and DD), this came about when the associate I was working with at the time got his hands on one and was then seen working in WA with it which then created huge demand ending up in a batch of coils being made for Bob Garbutt at Prospectors Patch in Perth, shortly after (1997 I think) Minelab decided to take coil manufacturing in house leaving John Kah with a large shed and nothing to manufacture eventually leading to the Coiltek we know today.

At the time John did not want to be held to an agreement about using Litz wire so started experimenting with other wire types and discovered the wire you have described. Sorry to tell you this Jim but I can tell the difference between a Litz wound coil and the other variant and as such I have never used the other options in the Mono configurations. I have however in the past successfully used their DD coils due to their not being any other choice, but as I mentioned in my previous post once Minelab released the GP extreme and started making an 18" DD of their own I could easily tell the difference between the two.

Times have changed and manufacturers need to be willing to change to keep pace, in the case of the GPX 5000 there are now 3 timings that have very specific requirements which with the initial two were reasonably forgiving in most cases, but in the case of the new Fine Gold timings the criteria is even more specific to the point were coils now have to meet those requirements if they want to avoid problems. If Bruce Candy tells me there is a very good scientific reason for using Litz wire especially when it concurs with my own experiences then that is more than enough scientific proof for me. This does not detract from the incredible amount of gold found with Coiltek coils over the years but at some stage people need to start to at least give credit to the electronics that was driving them!!

I started detecting in 1987 with a Minelab GT-16000, I went professional with the XT 17000 in June 1993, since then I've pretty much done nothing else but detect for a living or at least in recent years due to family commitments maintained a large proportion of my yearly income from detecting gold. In 1979 I was still in primary school occasionally digging gold out of the bitumen (roads were made out of old mullock) around Gympie. I found my first piece of detected gold in 1988 in the gully below the Sunburst Chance mine on the Jessops range on the North Palmer (now since mined by alluvial miners).

JP

Ther is one awful fact about Littz or Leitz wire, It is multi stranded and has a very large surface area compared to single stranded Copper wire, and that makes it heavier, try lugging a 15" by 12" Minelab coil around all day on the stick on your detector and you will see what I mean. Believe me, as far as I am concerned its the most profitable coil I have ever used but it is so so bloody heavy

Have you tried using a hip stick??

Happy hunting

JW

I have been making mono coils for the Minelab detectors since 1996 and used only litz wire. The problem was that in order to get the right Q ( 4.5 @ 1000hz for SD2000) I had to make my own litz wire. Still do. Those first coils were heavy as I was using a fibre glass construction. Once I worked out how to use the minimum amount of fibre glass to make a robust coil, the coils fabricated became much lighter. Could lug around a 14 inch mono all day without too much trouble. Spent about 2 years trying different shielding methods from graphite tape to mylar aluminium tape and many other variations.. Finally discovered a way to get effective shielding without the corresponding problem of inducing eddy currents in the shield. With this type of shielding the effect does not degrade as per the graphite shielding used on some manufacturers coils.

Further winding techniques and construction of the litz wire reduced interwinding capacitance in the coil. This is a prelude to making fast coils. Carefull construction of the coil without the need for epoxy to fix the coil eliminated the problem of false detection when the coil hit a rock.

Now I have a way of making coils lighter using some new products made available. Continually improving my coils. The coils are robust and light and can design to any Q. ie the sensitivity of the coil. There is no great magic in making mono coils but it does take skill and some fabrication tricks to make good coils. Using litz wire, would use no other and it is easy to make. Just takes time.

Stefan

You make your own litz wire!!!???

granite2 wrote:You make your own litz wire!!!???

Yes sure do. The litz I make for a 14 inch coil would have 57 strands of enameled copper wire in the bundle.

Stefan

Billsymo wrote:Ther is one awful fact about Littz or Leitz wire, It is multi stranded and has a very large surface area compared to single stranded Copper wire, and that makes it heavier, try lugging a 15" by 12" Minelab coil around all day on the stick on your detector and you will see what I mean. Believe me, as far as I am concerned its the most profitable coil I have ever used but it is so so bloody heavy

I just brought myself a 15x12dd coil, I have only done a few hours detecting with it so far and I didnt notice bugger all difference in weight compared to my 11'' dd, I know physically there would be a big difference in weight but I didnt notice it straight away, but my holes have got alot bigger.

koeh wrote:

Billsymo wrote:Ther is one awful fact about Littz or Leitz wire, It is multi stranded and has a very large surface area compared to single stranded Copper wire, and that makes it heavier, try lugging a 15" by 12" Minelab coil around all day on the stick on your detector and you will see what I mean. Believe me, as far as I am concerned its the most profitable coil I have ever used but it is so so bloody heavy

I just brought myself a 15x12dd coil, I have only done a few hours detecting with it so far and I didnt notice bugger all difference in weight compared to my 11'' dd, I know physically there would be a big difference in weight but I didnt notice it straight away, but my holes have got alot bigger.

Well there you are. The weight of the copper wire in a 12 inch mono coil is almost the same as in an 18 inch coil. The additional weight is the extra PVC in the housing, epoxy and a few other items. The same applies with DD coils. The older large DD coils were somewhat heavy.

Stefan

Why bother making Litz wire when wire off the shelf will do the same thing? Coiltek coils have never had litz wire and they are as good as any coil out there.

Cheers, Jim

granite2 wrote:Why bother making Litz wire when wire off the shelf will do the same thing? Coiltek coils have never had litz wire and they are as good as any coil out there.

Cheers, Jim

Coiltek coils used ( use) tin plated copper wire. The only problem is that the wire only comes in fixed cross sectional areas. This means that the Q of the coil for different size coils will vary and it is difficult to achieve the Q you want so there is a compromise on sensitivity. For example the Q for a standard SD2000 mono coil is 4.5. I measured a 14 inch coiltek coil and the Q was 3.8. The measuring freq was 1000 Hz.

Making the litz wire allows you to taylor the Q so that for each size coil the Q or sensitivity is the same.. I have made very sensitive coils which would be impossible using the tin plated copper wire cable.

Stefan

All I can say is that I have used all 3 makes, Minelab, Nuggetfinder and Coiltek and have found there is not enough variation in performance between similar sized coils to worry about. As far as I'm concerned it comes down to the ability of the coil to last the distance - and the weight. But one of the major differences is in the ability of the manufacturer to turn out coils without variation in performance. If you have a percentage of coils that perform sub-standard then you have a problem. This is the main problem when bulk manufacturing coils by hand, you get too many variations. Some coils will perform wonderfully well while others from the same manufacturer will be dogs. Thankfully I don't think any manufacturer in Australia still manufactures by hand so the problem is no longer valid.

Just my thoughts from longe experience in the game.

Cheers, Jim

Jim

Dont want to be rude mate but
I think you will find most if not all manufacturers still hand wind the coils loop and assembly
is fully done by hand too.
I worry about the day computer driven robotics might be used to wind coil loops as we all know how much
troubles a computer can have and the amount of glitches that show up from time to time.

I dont think there is anybody better at winding things up,
than my wife winds me up

Hahahaha there we go,,, now ive torn it


Pete in WA

Good one Pete When it comes to winding me up my missus is in the Olympic class.

I have seen how minelab and Coiltek used to wind coils, and I guess still do. The wire was wound onto a motor driven jig using a constant speed geared motor with the operator ensuring the tension on the wire remained the same all through the winding process. That is the critical point, especially where the multi strand litz wire is concerned. Should you attempt to wind the wire onto a jig by simply using your hands to do so you simply cannot ensure the tension is constant throughout the procedure. Using a single strand low oxygen content wire such as Coiltek does/used to, the procedure isn't as critical but still important. As I suggested, I wouldn't think anyone but someone building their own coils for personal use would hand wind a coil these days.

Coil assembly from that point on is, as you said, has always been done by hand. To build a robot to assemble coils would be relatively easy for those who do that stuff but would cost so much you would have to sell many times more coils than all the manufacturers do today.

The main thing is that coil manufacturers continue to build ever better coils for us to find more gold because I for one have no interest whatsoever in the technicalities of building coils. They supply 'em and I just use them to the best of my ability to find the most gold I can and continue to have fun out there looking.

Cheers, Jim

I build coils to get the best performance. I also build coils a hell of a lot cheaper than commercially available coils. I also build coils taylored to my needs. And yes the litz needs some tension on the wire and the coil needs to be carefully wound. I use a former to get the best results.

And finally I like building coils and finding gold with my coils.

Stefan