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Transformer winding insulation

Hello everyone,

Am I correct in that the winding wire in a transformer is coated with a varnish that acts as an insulator? I've tried to find an answer to this by researching transformer construction, but haven't been able to get anything definitive. If this is so, then I would think that winding ones own x-former would be a tedious undertaking when the slightest knick would possibly render the thing useless. Perhaps that's why not many people wind their own? Or, do they? I'm asking because I am considering constructing some VERY simple x-formers to conduct some VERY simple experiments. No Large Hadron Collider stuff! :>) Thanks for any info you can provide...

Scott

Reply to
sbrehler
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"sbrehler"

** Yep - it is actually an "enamel" coating, sometimes made from polyurethane.
** Just look up "enamel winding wire".
** Nope- enamel coated winding wire is remarkably tough and flexible.
** Cheaper and easier to buy a mass produced transformer on most cases.

But folk often wind their own RF coils and small inductors for loudspeaker x-overs.

..... Phil

Reply to
Phil Allison

You want 'Magnet Wire'

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Reply to
Michael A. Terrell

Classic insulations were Formvar and Heavy Formvar, which are very tough varnishes... so tough they are hard to strip. You can also use nylon or polyurethane insulated magnet wire, which self-strip with a very hot soldering iron but are not as tough. All will wind nicely without much danger of shorting. The Formvar is better for high-temperature use, and HF for high temp and/or high voltage.

I've hand-wound a lot of small transformers, mostly toroids and pot cores, with all sorts of wire as noted, and don't recall any winding shorts. Go for it.

John

Reply to
John Larkin

"sbrehler"

** Yep - it is actually an "enamel" coating, sometimes made from polyurethane.
** Just look up "enamel winding wire".
** Nope - enamel coated winding wire is remarkably tough and flexible.
** Cheaper and easier to buy a mass produced transformer on most cases.

But folk often wind their own RF coils and small inductors for loudspeaker x-overs.

..... Phil

Reply to
Phil Allison

Ah ha! Magnet wire. I get all kinds of hits on that. Once again, thank you both for your help.

Scott

Reply to
sbrehler

Go to powerintegrations.com and download all thie app notes. If you don'y understand after that, you're in the wrong business.

Also look at TEW (triple insulated wire) Google it.

Graaam

Reply to
Eeyore

Thankfully these aren't safety products.

Wht didn't you mention bobbins etc ?

Graham

Reply to
Eeyore

AND an IEC standard.

Graham

Reply to
Eeyore

Are you a MANIAC ?

John, my respect for you has dropped below the floor with such idiotic comments.

Graham

Reply to
Eeyore

Yes, it acts as an insulator but you must ALSO know about MARGINS (these are seperations between primary and secondary essentially).

Forget that, it blows up, and you are in JAIL and your house is repossesed.

Graham

Reply to
Eeyore 

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As if your respect mattered.

JF
Reply to
John Fields

comments.

The fact that the DD doesn't like him raises the respect from anyone with a brain.

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Reply to
Michael A. Terrell

Must be hell to live in a communist nanny state, like yours.

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Reply to
Michael A. Terrell

comments.

He's an audio amateur disco sound guy. No wonder his windings short. Or his shorts are all wound up. Whatever.

John

Reply to
John Larkin

comments.

Austin Powers with a $6 BSR plastic turntable.

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Reply to
Michael A. Terrell

For experiments with low voltage, low current stuff, you can sometimes scrounge the wire from old transformers or from old TV yoke coils.

Ed

Reply to
ehsjr

People do wind their own. If you wind a lot of them you build a winding lathe that spins the bobbins for you and a turns counter that keeps track - and it is a whole lot less tedious.

I suspect people are just too lazy to wind their own - and laminations are a specialty item so you end up salvaging core material from other transformers.

Enamel magnet wire is very resistant to nicks as a rule. Sometimes a kink, pulled tight, will cause it to flake off.

I worked for a PS manufacturer in the 70's. It was SOP on some tight transformers to insulate layers with mylar tape, with an over wrap of heavy paper tape. To get them to fit the laminations sometimes we would hit them with a hammer to get the coils to fit (we protected the surface with a block of nylon then just gave it a whack to make the layers lay down enough to squeeze it in)

Its often easier to wind a big transformer than a small one for line frequencies - big easy to see wire that doesn't break easily, and fewer turns per volt because the iron is large.

I wound an induction coil with thirteen miles of #32 gauge wire in the secondary - four bobbins with paper between layers. Took me a week but I did paint varnish on each layer before laying down another layer. ~40 layers per bobbin. Each layer took about 15 minutes with a motorized winder.

Winding transformers is fun in my opinion.

When the rotor on my motorcycle alternator shorted I wound a new one and saved ~$300

Reply to
default

x-former

own?

He's in the US, so he doesn't need any 'Idiotic European Crap'

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Reply to
Michael A. Terrell

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