Winding transformers

[StarryNight]

I'm thinking about assembling my first 5E5-A kit but as I'm mostly a pickup winder I thought about winding my own output and power transformers and wondering if anyone here does that kind of thing? It would seem simple enough to do (I already have a coil winder w/counter etc) but I would need some direction to get started. Any advice would be appreciated...

[cminor9]

I haven't heard of anyone else here winding their own transformers. I just replied to tell you that cause I know it can be frustrating to post something and get no replies

I haven't done much with pickup winding (ok, I haven't done anything with pickup winding) but I'd bet it isn't as exact of a science as transformer winding. You'd need to know the winding ratio, Then you'd need to get the iron and the bell ends and so on. Unless you have some serious metal fabrication abilities going on, I'd think it'd just be cheaper to buy new ones or salvage any you can get your hands on. But who knows, you might be able to make it work.

That said, if iron was cheaper, I'd build more amps. If you could find a way to get transformers cheap or make them cheaply, you'd be on easy street.

[StarryNight]

well I appreciate the reply. cobwebs were starting to form on this thread. I've been reading a little more on the subject and you are absolutely right. There are some crazy formulas and the amount of factors involved in getting the right transformer for the right job is frightening. I'm still curious about it and maybe what i'll do is take apart one and make note of the dimensions and turns per layer etc. I'd have to source the insulating material and something called grain oriented silicone steel man if i can pull this off i'll surprise the hell out of myself.

[loudthud]

Winding a power transformer is pretty straight forward. Start with a scrap transformer and take it apart. Try not to scratch the laminations, they are coated with an oxide coating that insulates them. If there is a short in the laminations that makes a shorted turn, the transformer will get too hot and smoke. There will usually be some kind of bobbin, either cardboard or plastic. Save that to wind on but make a wooden 'keeper' to insert in the bobbin while winding so it won't deform and the laminations will still fit after all the winding is done.

Output transformers are more complicated. On well made units the windings are interleaved, broken into small sections so that they couple more efficiently by alternating sec-pri-sec-pri-sec... something like that, usually an odd number. I'm sure there is a book on the subject somewhere.

[Albert Kreuzer]

For starters:
http://www.pmillett.com/Books/Lee_19...d_Circuits.pdf

HTH
Albert

[StarryNight]

that is fantastic! thanks guys. I think a combination of practical trial and error and some book learning will be the best route. Wikipedia has some good general info as well:
Transformer - Wikipedia, the free encyclopedia

It just seems that transfomers are such a key part of amplified sound, at the very least it would be good to understand why on a deeper level.

[tubeswell]

Check out this guys page for tips on winding OTs. (I like the idea of a vacuum pump setup to extract the air)

Thermonic Technology

FWIW Simcha (Delft) also winds transformers and is a member here (simcha) altho hasn't posted very often, but is pretty much into leading edge stuff.

[unparalleled]

I have it from a retired expert in the field that ordinary laminations are often now and were in past years often used for guitar amp OP transformers.
Grain orientated steel was generally used for Hi Fi amps.
You are opening one large can of worms!

[R.G.]

I used to design transformers and power supplies for a living.

It's not hard to do, at least to get something that works. But it is expensive and has a lot of labor content if you are planning to do it in your garage.

However, for the beginner, there are two areas you need to watch.
1. You are betting your life and the lives of everyone who is ever inside the building with you when you use any power transformer that you made. The bet is that you got the isolation of the AC power line and the rest of the circuit right enough for it to be safe and not (a) electrocute anyone or (b) start a fire even if it fails. That is, it has to fail safe if and when it fails, even years in the future. That's a heavy burden on a beginner.
2. Everything matters to the sound of an output transformer. The size of the wires, the placement of every single turn with respect to every other single turn, the spaces between the wires, the chemical composition of the insulation, the materials insulating the layers, whether or not you varnish-impregnate it, the alloy/composition of the laminations, whether the laminations are shorted together, the thickness of the laminations and the physical history of the laminations, whether they are annealed and whether they have ever been struck a blow, like being dropped or hit with a hammer.

It's easy to get a transformer to either transform power or audio. It takes some finesse to get the rest of that right, and the "rest of it" is not necessarily in the same textbooks as the winding design.

I know how to do the designs. For me, it's cheaper to buy the transformer than spend hours I don't have winding them.