Hand Coil Wave-Winder

[Retired]

Hi,

Excellent David and very interesting; well done.

The correct winding wire is indeed very expensive and paying for a bobbin of this wire would bring tears to eyes. In 2009 I fully restored an AVO wave winder but never used it in anger because not only is the wire so expensive it is difficult to obtain unlike ordinary enameled winding wire which I used to have a lot of.

I received many requests to wind assorted wave coils and had to turn every one down in fact I was asked if I could bulk wind and money didn't seem to be a problem?

Such projects are fascinating though David and I'm sure you enjoyed making your wave winder and trying it out; thanks for sharing your story.

Kind regards, Col.

[Yorkie]

That's a splendid job young David. I've got other Repanco Coils if you want to practice.
ebay Item 121353070909 looks promising. They don't say so but I expect you could buy it in longer lengths. It works out at about 60p/m I think.
I'm sitting very firmly on my hands for fear of starting something I won't be able to finish in the current climate.

Alan

Thanks for the offer of the loan of the other coils Alan - that's kind of you so I'll bear it in mind!

As to the Litz wire on e-bay, that was well spotted Alan, and on the face of things, I guess 60p a Metre doesn't sound too bad if only a small quantity is needed for the purpose that it's offered. But for example, the test coils I've wound with 25 Metres would have cost £15.60 so it would be prohibitively expensive. The retail division of 'Wires&Co, (which used to be known as the Scientific Wire Co) doesn't show Litz, (I tried to avoid saying 'it doesn't list Litz in its listings'!), but their trade catalogue lists Litz in various gauges. For example, a 100 gram reel of 36 strands of .04 mm (as offered on the e-bay site) costs £25.20 inc VAT and consists of 225 Metres of wire, so that works out at 11p a Metre - less than a fifth of the e-bay price. For anyone who is into this big style, a 500g reel is 1,125 Metres and costs £80.64 inc VAT which is only 7p a Metre:

http://wires.co.uk/acatalog/litzwire.html

I can only speculate on what sophisticated and intricate manufacturing processes are involved in producing this wire, and when we consider the factory gate price, and the mark-up along the way to the end user, maybe it's not so expensive after all? Strewth, how do they even draw wire so fine through a die without it fracturing? They even make 342 Strands of 0.05mm Silk Covered Stranded Copper Litz Wire, which Wires&Co sell. Jeepers - it's a good job it's solderable - imagine scraping the enamel off 342 strands to terminate it!

Many thanks to Andy, Nick and Alan for the helpful info on the gearing of the Morris winder. What a nice little machine to own. Come on guys - get weaving!

[pwdrive]

Those coils look first rate David, I know where to go now for IF transformer rewinds...

Lawrence.

[Yorkie]

Those coils look first rate David, I know where to go now for IF transformer rewinds...

Lawrence.

Me too Lawrence - Ed Dinning or Mike Barker!!

Inductors have a mind of their own and often produce peculiar results.

In the Denco DRR2 coil for example, the tapped MW coil shows 30uH and 70uH when each part of the coil is separately measured, so we might reasonably expect the total inductance to be 100uH. Not a bit of it - the total is actually 170uH, the reason being that when coils are closely coupled - as is the case in this example - mutual inductance arises which affects the total inductance. If a single layer tapped coil is wound, on say a 1" diameter coil former, the total inductance will be the same as, or close to, the sum of the two parts of the coil.

I've attached the Repanco data sheet on the DRR2 coil, annotated with my findings back in Nov 2012.

I think this is one aspect of electronics where it pays to be afflicted with OCD so one can intensely focus on the task in hand to the exclusion of everything else until the mission is accomplished. I'm afraid I'm just not programmed that way - I tend to dabble in lots of things, but not properly get involved in anything - more to the ADHD end of the spectrum! Maybe that's why my eyes glaze over when I try, but repeatedly fail, to raise my game when it comes to CAD. No excuse of course - more by way of explanation. 15 minutes with a CAD programme is positively soporific - I'm nodding off and dribbling all over the keyboard.

[AlanBeckett]

David,

I've long regarded that Circuit Sheet and indeed 'my' DRR2 as not as I remember them, nor does it match the others I have. It was meant for a Valve Circuit with Reaction. DRX1 was the Crystal Set Coil.

The Tags should be Colour Coded and the Former should be translucent. I also seem to remember that originally the Former was fully moulded, including the Tags. With the aid of my amateur 11 year old soldering I kept melting the Former around the Tags
DRR2 was the first Coil I ever bought and used it to build my first so-called Set.

   

The Valve was a DF92 I think. It was built in an OXO tin obtained by my Mum from the Co-op.

I've also got the DRM3 and the SH4 Kits.

       

Alan

[Alan Douglas]

Litz is only necessary for its textile covering, though perhaps magnet wire isn't made that way any more, so there's no choice. I've accumulated many spools of cotton, silk, or nylon-covered wire over the years, including one spool that actually came from a radio factory around 1930 and is 10 strands of #38 AWG.

[John M0GLN]

They even make 342 Strands of 0.05mm Silk Covered Stranded Copper Litz Wire, which Wires&Co sell. Jeepers - it's a good job it's solderable - imagine scraping the enamel off 342 strands to terminate it!

You'ld have to do the other end as well.

It's not just modern stuff that's fiddly, I avoid both SMD's and Litz wire.

John

[Radio Fixer]

Very neat winder and coils David: maybe an article ?

Don't try doing the artwork for a complex silk screen dial, with your limited attention span. That is many hours (days) of CAD work to get correct. Particularly if you are like me and want it as perfect as is possible.

Gary

[Yorkie]

Very neat winder and coils David: maybe an article ?

Don't try doing the artwork for a complex silk screen dial, with your limited attention span. That is many hours (days) of CAD work to get correct. Particularly if you are like me and want it as perfect as is possible.

Gary

To take the last point first Gary, there's not a snowball's chance in hell of my elevating my skills on producing artwork for dials to anything like the standard that the likes of you and Robert Darwent attain, which have featured in the Bulletin. Getting the fonts right, the colours, the layout of the dial, the dimensions and so forth. However skilled and competent a person might be at using CAD software, it's evident that there are no short cuts and many hours of effort and refinement are needed in getting from a 'blank sheet of paper' to the finished artwork. The best I can do is to fumble around in Photoshop Elements to tidy up dial scans and PCB artwork, and 'Paint' to do simple sketches. One little circuit drawing program with valves in the library that I've downloaded the free demo of is 'S Plan 7' (which allows you to use the program to draw circuits but not to save or print them), but I don't do enough of that sort of thing to warrant buying the progam.

As to the coil winder, it wouldn't be possible to write it up for the Bulletin as it's made from 24 pages of plans from a copyright book. The book used to be obtainable in the UK from Camden Publications, but not any more it seems. However, it's still available, along with lots of other interesting 'home workshop books' from David Gingery Books in the USA. David Gingery was famed for using ingenuity and inventiveness in making workshop equipment from scrap - the sort of chap I think most of us would warm to. Sadly, he passed away in 2004, but the bookstore still continues.

The coil-winding book is $8.95, shipping is unfortunately double that - $16.75. Total $25.70 = approx. £15.50 at current exchange rates.

http://gingerybookstore.com/CoilWindingMachine.html

I have submitted an article to Carl Glover for his consideration, on the 'sewing machine motor' coil winder I made which has similarities to the one that you made and had published in 2007 in the Bulletin in two parts Gary. (Whether Carl feels that enough time has elapsed or that my winder is sufficiently novel or different to warrant space in the Bulletin is something that Carl will need to consider of course, which I respect).

Other David Gingery books include: Complete Metal Working Shop From Scrap Series - 7 Individual books:

Each book is 5-1/2 x 8-1/2 Perfect Bound (Soft Cover)
ISBN 1-878087-00-2 The Charcoal Foundry
ISBN 1-878087-01-0 The Metal Lathe
ISBN 1-878087-02-9 The Metal Shaper
ISBN 1-878087-03-7 The Milling Machine
ISBN 1-878087-04-5 The Drill Press
ISBN 1-878087-05-3 The Dividing Head & Deluxe Accessories
ISBN 1-878087-06-1 The Sheet Metal Brake

Another book is the 'Gas Fired Crucible Furnace'.

http://gingerybookstore.com/MetalWorking...eries.html

http://gingerybookstore.com/index.html

Hope that's of interest.

[Radio Fixer]

Good Oh! David.

I'm sure he will use your article: he is always short of copy.

As regards the CAD for the dial artwork (HMV 650), it was slow and required a lot of concentration and learning from a thick book. But I was well supported by the CorelDraw forum who are a splendid bunch of guys, from world wide, some even Pro designers, who have all the answers and the response is usually within the day. Often several ways of doing things are suggested and it was good to try them and then make notes of the one or two that I found easiest. Like all long tasks it was a great feeling to be successful and even more so when the silk screener did as perfect a job as I could ask for. His colours were spot on and the dial is much more vibrant than the old ones. I expect colours fade. He didn't get 100% yield but I think with that sort of work, particularly lining up 6pt fonts, its expected. 90% yield was fine by me.

I would have liked to have given him more work but have not had the need to do another dial. Also there are now direct print to glass methods which work out cheaper for small quantity.

Gary