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Anyone know a commercial source for HV, HF transformer windings?

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dude_500

Sat Mar 09 2013, 06:12PM

Registered Member #2288 Joined: Wed Aug 12 2009, 10:42PM
Location: Cambridge, MA
Posts: 179

Glassman makes their own magnetics in their New Jersey facility. Primaries are hand wound and cores are hand assembled to get a calibrated leakage beyond what tolerances pre-manufactured transformers can be supplied at. I'm 99% sure they said they do pie winding in house.

klugesmith

Sun Mar 10 2013, 05:36AM

Registered Member #2099 Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716

Hazmatt_(The Underdog) wrote ...

Found a site with the video of your layout there.
The coil it winds is remarkably well done.

Funny, that's the same youtube video as the one linked in my previous post! But your primary link is a gold mine of information about well-ventilated inductors -- thank you!
I am disappointed that youtube lets people embed links in a "click to play" format which obscures the attribution, in this case KC9KEP who built the winder and produced the video.

Today I visited my local electronics flea market (swap meet) for the beginning of its 2013 season. One of the regular sellers happened to have an old (prewar) catalog open to a page showing a universal coil winder. We got to talking, and he said he owns two specimens. Said they're more robust than the Gingery DIY version, with cast iron frames etc. And that he might sell one but not both. I'm not interested myself, but could follow up next month if Carl or anyone else here in interested.
-Rich

Ash Small

Sun Mar 10 2013, 09:50AM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

I missed the EDIT in your earlier post too, Rich. (I generally only use the 'edit' function when no no further posts have been made, as I generally don't re-read the whole thread each time I read new posts.)

Did the universal coil winder in the catalog look like the one pictured below?

1362909044 3414 FT151510 Coil Winding Machine

It appears to have a slider mechanism for traversing the feed, but as I said in my earlier post, I can't make out the full mechanism.

I read, I think in the Gingery book, that the maximum angle, if you want to maintain tension, is ~72 degrees. The coils Carl wants have the wire traversing the width of the coil in one turn (360 degrees), it also looks like Carl's coil follows the 'average diameter equals three times the width' general rule.

I've not found a cheap machine locally yet, so I'm planning on building a 'beefed up' version of the Gingery machine to try winding some secondaries for my own project. Tha cam and friction drive wheels are such a simple idea.

Wastrel

Sun Mar 10 2013, 01:31PM

Registered Member #4095 Joined: Thu Sept 15 2011, 03:19PM
Location: England.
Posts: 122

Description of the $300 machine says it does layer winding, it doesn't say anywhere it does universal winding.

Ash Small

Sun Mar 10 2013, 03:35PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

Wastrel wrote ...

Description of the $300 machine says it does layer winding, it doesn't say anywhere it does universal winding.

Yep, I think you're right. There is what looks like a sliding mechanism than the wire feed is mounted to, and there is an adjustment on the side for different wire guage (see other pictures on the Ebay ad), there is also what looks like it may be a friction wheel behind the gears, but I think this is all just part of a mechanism that moves the wire feed accross each layer. I may be mistaken, though.

EDIT: I've googled 'Morris Universal Coil Winding Machine' and the Gingery machine is a pretty close copy of it.

Steve Conner

Mon Mar 11 2013, 10:45AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

I first saw this style of coil in the IF transformers of an old tube radio. The Radiotron Designer's Handbook ("RDH4") refers to it as a "universal winding". I call it a basketweave winding. To me, a pie winding is any winding shaped like a Scotch pie. :)

The main idea behind the basketweave winding is to reduce self-capacitance and losses from proximity effect. It does this effectively because hardly any of the wires lie directly alongside each other, they mostly cross at an angle.

I'm sure there are advantages in self-supportingness and holes for oil impregnation, that make it great for high voltage power electronic service, but those are incidental.

dude_500

Mon Mar 11 2013, 02:35PM

Registered Member #2288 Joined: Wed Aug 12 2009, 10:42PM
Location: Cambridge, MA
Posts: 179

Ash Small wrote ...

I read, I think in the Gingery book, that the maximum angle, if you want to maintain tension, is ~72 degrees. The coils Carl wants have the wire traversing the width of the coil in one turn (360 degrees), it also looks like Carl's coil follows the 'average diameter equals three times the width' general rule.

I think I'm going to try making one of these winding machines. By 72 degrees, do you mean the gear ratio between the bobbin spinning and the wire slider completing a cycle should be 5 or greater? I was thinking of making it just over 1. Would that describe the 360 degree option?

Ash Small

Mon Mar 11 2013, 03:01PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

dude_500 wrote ...

I think I'm going to try making one of these winding machines. By 72 degrees, do you mean the gear ratio between the bobbin spinning and the wire slider completing a cycle should be 5 or greater? I was thinking of making it just over 1. Would that describe the 360 degree option?

I read the 72 degree bit as meaning the angle between the wire and the edge of the bobbin, ie, looking at the first turn on the bobbin, you'd see 'N' or'l\l'.

Just over 1 is correct, the actual amount 'over 1' would depend on the wire diameter, I presume (at least that's how I read it). The 'friction wheel' design means this is infinitely adjustable.

I'm planning on building one too, but a more 'beefed up' version. I've just been looking at Plummer blocks and linear bearings on Ebay, they are much cheaper than I expected (from some sellers anyway).

Maybe we should start a new thread on 'Universal Coil Winding Machine construction'?

EDIT: I'm also doing some calculations regarding heart shaped cams (the shape needs to be different for different diameters and offsets)

Steve Conner

Mon Mar 11 2013, 05:30PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

This guy does a great CNC coil winding machine.

It's aimed at guitar pickup makers, but I bet it could do universal windings.

It's expensive, but there's nothing stopping you making your own, driven by something like the Mach3 software. Instead of filing out heart-shaped cams, you would write G-code.

Ash Small

Mon Mar 11 2013, 08:15PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

Steve Conner wrote ...

This guy does a great CNC coil winding machine.

Thanks for posting that link, Steve. I did suggest using a stepper motor earlier in the thread, but using two does make a lot of sense. I'm currently planning on building one that can be hand operated or driven by a small electric motor, but I will probably design it so that it could be converted to stepper motor drive at a later date.

As far as heart shaped cams are concerned, with a large diameter cam and a small offset (The secondaries I need for my current project will be a maximum of 5mm wide), they are not really needed (eg an 80mm diameter circular cam for a 5mm wide coil is only ever ~0.1mm out, which is negligible when the minimum circumferance is over 200mm, at least as far as my preliminary calculations suggest). This would obviously be much more of a problem when winding a small diameter, wider coil using using a cam ~38mm in diameter, as used in the Gingery machine.

I've not yet finished plotting the results, so it may be a bigger problem than I suspect from just interpreting the figures.

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