Making your own Litz wire

[sido]

Hi Everyone,

First of all, I am no expert in this field and only experimented with the concept to see what can be achieved at home for the average person/experimenter. The aim for me was to achieve a low R and fast coil for early sampling.

So, I am posting this in response to a previous thread from the one GTblocker started and want to keep this topic above in line with the practical side of things in actually making the wire itself only. In saying this and no disrespect to you Gtblocker, I started this thread so as to make people searching this topic on this forum easier, since no other posted material can be found in previous thread's on here relating to the actual making of something similar to Litz wire.

Ever wanted to make your own Litz compatable wire at home that seems to get similar results, if not better than off the shelf products already selling in the consumer market??...Well read on.

(I say if not better because i was supprised at the initial results and the potential there to be equal or better in your custom made wire and coil application).

Well you can make your own with some patience, time and techniques similar to what i have observed in a first attempt in doing so.

After all, by me posting what i have observed will allow others to experiment and post their own techniques and observations for others to see and try out for themselves.

You can make your own and the benefits of doing so, may even help in making the ideal coil suited to your application. You have the benefit of winding the wire with as many strands you like. In my case i wound the wire in a 38 strand configuration because i did not know what i was doing

I will break up the posting as they can become lengthy.

Below is what i used as the wire. It is from Microwave oven fan motors which i removed the metal frame supporting the motor itself and used the copper wire as you see in the picture below. I used 2 of them in my experiment to get 38 strand wire with a combined length of 33 feet or there abouts.

I will measure the wire size when i get my digital vernier working again once a fresh new battery is fitted.

So far i achieved a 38 strand, 6 inch coil, 160uh, 0.2-0.3 ohms coil.
Pretty good in my books.

Cheers Sid

[sido]

The next step i had to consider was how to support each individual insulated strand of copper wire.

So here was born the idea of supporting the wire on the fence boundary line at home. The longer the fence the more longer the wire that can be made.......but.......I have not experimented with it yet and may complicate things when it comes time to twist the wire in a bundle at such larger lengths....Who knows, some of you might know if already done. Only when its been experimented with, we will know, but i think it should be ok if you have someone else helping you out somewhere down the line.

Using 4 hooks spaced out approximately every 9 feet as in the picture below.

Start at one end and tie the knot hehe

IMPORTANT: Please note that the wire is very fragile and can break. This is where most people may fail if the wire is mis-treated eg, applying to much pressure, over stretching it's breaking point and not taking your time, in other words go slow and not rush the wire build.

It is time consuming. For me, it took me all up around 10 hours spaced out over 2 days. It took longer though for me because it was more difficult to unwind the copper wire off the rectangular wire spool i used (Microwave oven fan motor) than to place it on the hooks.

HINT/TIP: If you do break a wire, remove it to the nearest previous end, tie it there.
Then re-tie the spool wire there also and continue.

Cheers Sid

[sido]

The next step,

Once you have placed the amount of strands that your happy with (in my case it was 38 strands)
It is time to begin winding the wire into one complete solid wire.

The first thing you have to do though is glue each ends as shown in the pictures below.

Allow enough time for the glue to dry........You are almost there.......... so kick back now and have a beer and marvell at your creation that is being created before your eyes.

In saying this, one beer only as you could still stuff things up at this point

Cheers Sid

[sido]

Once glue is dry, its time to wind the wire up by using a drill. Much easier to use a cordless drill than a power drill and set the revolutions at low speed.

Clamp one end of the wire on the drill chuck as shown in the pictures below.

I used clockwise winding, i think.

Begin to wind the wire at slow intervals and keep checking that it is winding ok.

HINT/TIP: VERY IMPORTANT......There is a point where you have to stop or else the wire bundle will begin to twist in itself, so once you feel that the wire bundle is rigid (which you could do by observing that it is all neatly twisted).......DONT go any further or you will stuff it all up and it will be all a waist of time for you.
If it does happen though, rewind anti-clockwise and hope that it unwinds itself and has not broken any strands.

Note: when you wind the wire with the drill, the total length will become shorter by about a foot or so due to the winding.

Cheers Sid

[sido]

Now its time to remove the wire from the drill chuck and wind it back on to a spool.

See Pictures below.

Now you have some coil building wire that was created by yourself which could be a benefit in your application. please post your results for all to see.

Would like to see others experiments and other techniques if you may have and i will be experimenting further when time permits with more strands, less strands, wire sizes and all, then post results here.

NOTE: Talking about Microwave ovens......dont forget to keep aside the large Capacitor and large diode in them as the Mylar material can be extracted and possibly be used as shielding material for your coils. I have pulled one apart and when time permits will use it as shielding materal and start a new thread all about it.

I hope this was helpfull

Cheers Sid

P.S: Litz wire is for all experimenters in coil building for metal detectors and not just for the one minded bandit have it all Corp out there, Enjoy

[multieagle]

Thanks for this. Very interesting experiment.

[Midas]

Hi Sido,

Possibly not what you want to hear having spent 10 hours on it but.. I think technically speaking what you've created still isn't Litz wire. You needed to split the wire into several bundles and twist them together separately first. By twisting the whole lot together straight up some of the strands likely stay on the outside of the conductor for the full length while some stay in the middle, when they should alternate.

From the wiki on Litz:
Furthermore, the strands cannot occupy the same radial position in the bundle: the electromagnetic effects that cause the skin effect would still disrupt conduction. The bundle is constructed so the individual strands are on the outside of the bundle (and provides low resistance) for a time, but also reside in the interior of the bundle (where the EM field changes are the strongest and the resistance is higher). If each strand provides about the same average resistance, then each strand will contribute equally to the conduction of the entire cable. The weaving or twisting pattern of litz wire is designed so individual strands will reside for short intervals on the outside of cable and for short intervals on the inside of the cable. This allows the interior of the litz wire to contribute to the cable's conductivity.


The benefit for a MD of true Litz over what you've created may well be very small though so I wouldn't stress, it would be interesting to see.

Midas

[golfnut]

Old school fine Litz is often woven or like a hair plaits.

But some of the thicker modern litz appears spun like sids.


The main thing is having multiple strands in parallel which are isolated from each other - connected only at the ends and Sid should have that. Watch out for twisting them up real tight though as the recycled enamel can fracture and get shorted turns. You dont want too much spiral wrap or it will have more L and R per unit length.

Good effort sido.

S

[Midas]

Old school fine Litz is often woven or like a hair plaits.

But some of the thicker modern litz appears spun like sids.


The main thing is having multiple strands in parallel which are isolated from each other - connected only at the ends and Sid should have that. Watch out for twisting them up real tight though as the recycled enamel can fracture and get shorted turns. You dont want too much spiral wrap or it will have more L and R per unit length.

Good effort sido.

S

I think if you look closer you'll find its made up of multiple 'twists of twists'. Quite apart from its litz properties there is practical reasons too. Which is why rope is made much the same, it distributes the tensile loads better amongst the strands and stop it from untwisting. The outer wires in Sids coil will have to break before the center wires take any real load. As I said though it won't necessarily matter that much, but if you were starting from scratch its not much harder to do and would make it true litz.

[Tepco]

Now its time to remove the wire from the drill chuck and wind it back on to a spool.

See Pictures below.

Now you have some coil building wire that was created by yourself which could be a benefit in your application. please post your results for all to see.

Would like to see others experiments and other techniques if you may have and i will be experimenting further when time permits with more strands, less strands, wire sizes and all, then post results here.

NOTE: Talking about Microwave ovens......dont forget to keep aside the large Capacitor and large diode in them as the Mylar material can be extracted and possibly be used as shielding material for your coils. I have pulled one apart and when time permits will use it as shielding materal and start a new thread all about it.

I hope this was helpfull

Cheers Sid

P.S: Litz wire is for all experimenters in coil building for metal detectors and not just for the one minded bandit have it all Corp out there, Enjoy

What diameter wire is used? Looks like lot of metal. Try to find very thin wire for this, less than 0.1mm, something like 0.05mm or even 0.032mm (old automotive ignition coil is good source of it). Recently I tried two identical coils, one made of solid conductor, another is 24strand 0.2mm litz wire, from old CRT deflection coil, no advantage at all. Solid wire coil performed almost better, 0.2mm diameter is too large to reduce eddy current formation, just too much metal in searchcoil.

[golfnut]

Im sure there will be a small advantage in using the correct litz in a Pi -- otherwise in boutique aussie machines they may not bother.

[sido]

What diameter wire is used? Looks like lot of metal. Try to find very thin wire for this, less than 0.1mm, something like 0.05mm or even 0.032mm (old automotive ignition coil is good source of it). Recently I tried two identical coils, one made of solid conductor, another is 24strand 0.2mm litz wire, from old CRT deflection coil, no advantage at all. Solid wire coil performed almost better, 0.2mm diameter is too large to reduce eddy current formation, just too much metal in searchcoil.

Thanks all for the feedback. Its experimental for now and seems to have a low R which was my initial aim.

I am sure some individual wires are twisted in/out of the whole length, so no individual wire is constantly twisted on the outside perimeter of the bundle or inside for that matter.

The size of the wire looks around the 0.1-0.2mm mark, but can only confirm when i use the digital vernier for accurate measuement.

Tepco, working with 0.05mm or even a more demanding 0.032mm as you suggest is beyond our practical capabilities.
Thanks for the tip in obtaining similar size wire from car ignition coil

Besides i will shield this coil and compare to a similar solid copper wire for comparison in a working PI.

Any others have attempted to make a similar wire configuration. Please post your results.

Cheers Sid

[Tepco]

Real thing is to get proper RF litz wire, multistrand it say, 5 times to reduce resistance, but over 100m of it is needed for one coil. Without some machinery, probably impossible to be made from 0.032mm wire in DIY version, RF litz can be even 0.016mm each wire. Only thing important is diameter if individual wires (as small as possible), not so important if it is true Litz configuration, twisted or run in parallel. 0.2mm is too much. Then some advantage over solid conductor can be seen.

[Midas]

Hmm its sounding harder and harder. The other thing that hasn't even been mentioned is how you would insulate it. Home-made teflon coating doesn't sound too practical and using a crappy dielectric could remove any benefit over solid.