Winding power transformers - a few questions

I've decide to wind my own power transformer for a certain active di box. I have some old scavenged power transformers with weird voltages which aren't really suitable for anything else, so I'll be using the lams and bobbins from those.

I'm looking for advice on where to buy magnet wire, the correct varnish, and that yellow tape.

I won't need a whole lot, and this exercise could end up not working, so I don't want to buy pounds/gallons/miles of the stuff. Just enough to get me started.

Where do y'all get your supplies in the US?

Any othre tips? Thanks.

You can buy everything from Ebay ,Varnish and tape check these stores:
sra-stores
angela5532015

http://www.ebay.com/itm/MG-Chemicals-4228-55ML-Red-Insulating-Varnish-/110903031388?hash=item19d255f65c:g:zuAAAOxy4c5RtrMn

http://www.ebay.com/itm/Insulation-Adhesive-Mylar-tape-High-Temp-for-Transformer-Coil-Wrap-yellow-66M-/221773966464?hash=item33a2c22c80:g:02kAAOSwpDdVVrkD

For Magnet Wire there's a lot of suppliers, search "Manet Wire" on ebay

Tempco will sell you small spools of wire, either off ebait or from their website,

spar varnish or polyurethane will work for processing, bake at 220 for two hours, dip til the small bubbles quit rising, usaally about 5 minutes, then bake overnight

Edcor sells lams and bobbins also,

Ram Sales has not been responsive as of late,

CJ said:

bake at 220 for two hours

Click to expand...

Just a note for European fellow members, the 220 are fahrenheit.

Dont be dumb like me a bake it in 220 celsious, I destroyed a Marinair bobin and coil doing that.
At least I was able to take the lams apart

I would be apprehensive about DIY power transformer fabrication.

Commercial transformers often include thermal fuses inside.

Insulation robustness is important, ungrounded consumer products often require double insulation.

Unless you plan to submit your transformer for agency approval, at least try to learn the requirements they test them too.

I recall one transformer in a product for the euro zone where they required an elevated temperature insulation test that took several weeks.  I didn't want to wait the extra weeks to repeat the test, so specified double insulated wire inside the transformer (primary).

Be careful.

JR

Thanks for the replies, everyone.

I'm trying to avoid ebay, as it's a bit of a hassle for me right now. I'll likely order from Temco because it looks like they have everything I'll need, but those ebay stores will come in handy later.

Although a commercial transformer would be cheaper (and maybe safer?) I'm going through this process so that I can hopefully answer some of my own questions.

JohnRoberts said:

Be careful.

Click to expand...

Yes. The lams I have are a bit larger than I'll need, and I plan on filling up that window area with a reasonable amount of insulation. An excellent suggestion about looking up the agency approval requirements.

I'm estimating that I'll end up winding three or four versions before getting one I'm all-around happy with. But that's part of the fun.