Re: Help: How to wind a toroidal output transformer for push-pullapplications?

[Patrick Turner]

Steve Kendall wrote:

> I am planning to DIY output transformers for my future push pull power
> amplifier. After a few days search on the net, I can only find one
> place to sell EI laminations and another one to sell toroidal core in
> small quantity. Since the company selling EI laminations only offers
> EI-112 and the price is high, so I decide to stick to toroidal core.
>
> My first question is: can I use a toroidal core made by grain oriented
> silicon steel to make a good PP output transformer?
>
> My second question is: if yes to Q1, then how to wind the toroidal
> core to keep the leak inductance and shunt capacitance minimum?
>
> If slight mismatch between output tubes makes the toroidal core
> saturate fast so that it can't be used in PP applicaiton, then can I
> at least use toroidal output transformer in a parafeed application?
>
> Thanks!

Before we might waste time advising you through your R&D process,
how do you propose to place neat and tightly wound turns onto the core?
Most people use a special machine, so have you got one,
if not, then how would you wind it?

Patrick Turner.

[Shiva]

"Patrick Turner" > wrote in message
...
>
>
> Steve Kendall wrote:
>
> > I am planning to DIY output transformers for my future push pull power
> > amplifier. After a few days search on the net, I can only find one
> > place to sell EI laminations and another one to sell toroidal core in
> > small quantity. Since the company selling EI laminations only offers
> > EI-112 and the price is high, so I decide to stick to toroidal core.
> >
> > My first question is: can I use a toroidal core made by grain oriented
> > silicon steel to make a good PP output transformer?
> >
> > My second question is: if yes to Q1, then how to wind the toroidal
> > core to keep the leak inductance and shunt capacitance minimum?
> >
> > If slight mismatch between output tubes makes the toroidal core
> > saturate fast so that it can't be used in PP applicaiton, then can I
> > at least use toroidal output transformer in a parafeed application?
> >
> > Thanks!
>
> Before we might waste time advising you through your R&D process,
> how do you propose to place neat and tightly wound turns onto the core?
> Most people use a special machine, so have you got one,
> if not, then how would you wind it?
>
> Patrick Turner.
>
With a shuttle? Sorry. Anyhow, doughnuts are wound by hand all the time,
it's pretty tedious but straight-forward. Mind you, I've only *un* wound
them myself (to change the ratio), but it seems really doable, especially if
you're laying multiple sections...

[Patrick Turner]

Shiva wrote:

> "Patrick Turner" > wrote in message
> ...
> >
> >
> > Steve Kendall wrote:
> >
> > > I am planning to DIY output transformers for my future push pull power
> > > amplifier. After a few days search on the net, I can only find one
> > > place to sell EI laminations and another one to sell toroidal core in
> > > small quantity. Since the company selling EI laminations only offers
> > > EI-112 and the price is high, so I decide to stick to toroidal core.
> > >
> > > My first question is: can I use a toroidal core made by grain oriented
> > > silicon steel to make a good PP output transformer?
> > >
> > > My second question is: if yes to Q1, then how to wind the toroidal
> > > core to keep the leak inductance and shunt capacitance minimum?
> > >
> > > If slight mismatch between output tubes makes the toroidal core
> > > saturate fast so that it can't be used in PP applicaiton, then can I
> > > at least use toroidal output transformer in a parafeed application?
> > >
> > > Thanks!
> >
> > Before we might waste time advising you through your R&D process,
> > how do you propose to place neat and tightly wound turns onto the core?
> > Most people use a special machine, so have you got one,
> > if not, then how would you wind it?
> >
> > Patrick Turner.
> >
> With a shuttle? Sorry. Anyhow, doughnuts are wound by hand all the time,
> it's pretty tedious but straight-forward. Mind you, I've only *un* wound
> them myself (to change the ratio), but it seems really doable, especially if
> you're laying multiple sections...

With a bleedin shuttle.
I use a piece of 3/4" plastic conduit, with slots each end,
and its length is one turn long. Pile on the wire, as much as can be
fitted, then spend days trying to be neat and tidy with the wire.
Its ghard to keep track of the turns, and one has to put joins in
along the way.
Insulation is with tape, easy, but slow, but it too has to be just right.
And impregnation must be with a vacuum chamber, because the
varnish or wax just won't run inside with soaking, so I have found,
unless the insulation tape is a mesh tape, and I don't like insulation with
lots of holes in it.
I have done a few power trannies like this, but OPTs need
3 times the turns, and it all is a real PITA.

Its really hard to figure where to put the turns, and have them all lay up
without
crossing over wires, since that's where a short will occur later with a toroid.

I tried to interest a local custom winder to wind me up
some toroidal OPTs, and when I showed him the taps and layers I wanted, he
went pale, and vomited all over me as he collapsed.
And he has the right machines, and has made lotsa mullah from trannies.

I just wind my own E&I trannies.
It does mean I have to buy at least 50Kg of core material at
a time, but the GOSS I get is extremely good low loss material,
and has losses almost identical to good toroidals.
At 0.8 Tesla, the iron U is 17,000.

Plitron make good toroidals. No need to wind one's own if you really want a
toroid.

Patrick Turner.

[Yves Monmagnon]

Hi ! Pat!
"Patrick Turner" > wrote in message
...

> I just wind my own E&I trannies.
> It does mean I have to buy at least 50Kg of core material at
> a time, but the GOSS I get is extremely good low loss material,
> and has losses almost identical to good toroidals.
> At 0.8 Tesla, the iron U is 17,000.

Measured up to 25,000 at this induction value and around 6000 at 1.4T !

Glory day for Lance today !
Yves
>
> Plitron make good toroidals. No need to wind one's own if you really want
a
> toroid.
>
> Patrick Turner.
>
>
>
>

[Gregg]

Behold, Patrick Turner scribbled:

> With a bleedin shuttle.

*choke*

I wound one power-line donut. Next time I get one of those PITA things, it
gets traded for useful junk! ;-)

--
Gregg
*It's probably useful, even if it can't be SPICE'd*

[Patrick Turner]

Yves Monmagnon wrote:

> Hi ! Pat!
> "Patrick Turner" > wrote in message
> ...
>
> > I just wind my own E&I trannies.
> > It does mean I have to buy at least 50Kg of core material at
> > a time, but the GOSS I get is extremely good low loss material,
> > and has losses almost identical to good toroidals.
> > At 0.8 Tesla, the iron U is 17,000.
>
> Measured up to 25,000 at this induction value and around 6000 at 1.4T !
>
> Glory day for Lance today !

I think Lance's fall cost him 30 secs, and he needs that buffer before the time
trial.
But man, what a ride he put in today!

Maybe he wins it next year too!

GOSS can have a high U as you suggest, but 17,000 for E&I
is really good compared to say NOSS, or plain grade iron at 3,500.

1.4T is too high, far better to run at 0.8T, always, and
use a core rated for 2.5 times the actual power needed,
and then make the windings have no more than 2.5 amps/sq.mm.
Then the regulation is OK, and it runs cool, and can take
otherwise disastrous overloads.
Forget bean counter designing, its all BS!

Patrick Turner.

>
> Yves
> >
> > Plitron make good toroidals. No need to wind one's own if you really want
> a
> > toroid.
> >
> > Patrick Turner.
> >
> >
> >
> >

[ShivaNY]

"Patrick Turner" > wrote in message
...
>
>
> Shiva wrote:
>
> > "Patrick Turner" > wrote in message
> > ...
> > >
> > >
> > > Steve Kendall wrote:
> > >
> > > > I am planning to DIY output transformers for my future push pull
power
> > > > amplifier. After a few days search on the net, I can only find one
> > > > place to sell EI laminations and another one to sell toroidal core
in
> > > > small quantity. Since the company selling EI laminations only offers
> > > > EI-112 and the price is high, so I decide to stick to toroidal core.
> > > >
> > > > My first question is: can I use a toroidal core made by grain
oriented
> > > > silicon steel to make a good PP output transformer?
> > > >
> > > > My second question is: if yes to Q1, then how to wind the toroidal
> > > > core to keep the leak inductance and shunt capacitance minimum?
> > > >
> > > > If slight mismatch between output tubes makes the toroidal core
> > > > saturate fast so that it can't be used in PP applicaiton, then can I
> > > > at least use toroidal output transformer in a parafeed application?
> > > >
> > > > Thanks!
> > >
> > > Before we might waste time advising you through your R&D process,
> > > how do you propose to place neat and tightly wound turns onto the
core?
> > > Most people use a special machine, so have you got one,
> > > if not, then how would you wind it?
> > >
> > > Patrick Turner.
> > >
> > With a shuttle? Sorry. Anyhow, doughnuts are wound by hand all the
time,
> > it's pretty tedious but straight-forward. Mind you, I've only *un*
wound
> > them myself (to change the ratio), but it seems really doable,
especially if
> > you're laying multiple sections...
>
> With a bleedin shuttle.
> I use a piece of 3/4" plastic conduit, with slots each end,
> and its length is one turn long. Pile on the wire, as much as can be
> fitted, then spend days trying to be neat and tidy with the wire.
> Its ghard to keep track of the turns, and one has to put joins in
> along the way.
> Insulation is with tape, easy, but slow, but it too has to be just right.
> And impregnation must be with a vacuum chamber, because the
> varnish or wax just won't run inside with soaking, so I have found,
> unless the insulation tape is a mesh tape, and I don't like insulation
with
> lots of holes in it.
> I have done a few power trannies like this, but OPTs need
> 3 times the turns, and it all is a real PITA.
>
> Its really hard to figure where to put the turns, and have them all lay up
> without
> crossing over wires, since that's where a short will occur later with a
toroid.
>
> I tried to interest a local custom winder to wind me up
> some toroidal OPTs, and when I showed him the taps and layers I wanted, he
> went pale, and vomited all over me as he collapsed.
> And he has the right machines, and has made lotsa mullah from trannies.
>

Bwah!!! This reminds me of many run-ins with machine shops, where I would
explain to the guy what i think would be a trivial job for him, and he'd
look at me with that "are you insane or just f8ckin' with me?" look... Soon
the greeting where "Whatthef8ckisit *NOW*?" BTW, i do agree with you on
almost everything you said...
-dim

ust wind my own E&I trannies.
> It does mean I have to buy at least 50Kg of core material at
> a time, but the GOSS I get is extremely good low loss material,
> and has losses almost identical to good toroidals.
> At 0.8 Tesla, the iron U is 17,000.
>
> Plitron make good toroidals. No need to wind one's own if you really want
a
> toroid.
>
> Patrick Turner.
>
>
>
>

[Choky]

"Shiva" > wrote in message
...
> No kiddin'? Where's my________ CD? HMM?
>
methinks that we must outcast our little Tim to RAO;
he deserved that just with your CD

--
Choky
Prodanovic Aleksandar
YU

[Tim Williams]

"Shiva" > wrote in message
...
> No kiddin'? Where's my________ CD? HMM?

That reminds me... <downloading Nero as we speak>

Tim

--
In the immortal words of Ned Flanders: "No foot longs!"
Website @ http://webpages.charter.net/dawill/tmoranwms

[Rich Andrews]

"Choky" > wrote in :

>
> "Shiva" > wrote in message
> ...
>> No kiddin'? Where's my________ CD? HMM?
>>
> methinks that we must outcast our little Tim to RAO;
> he deserved that just with your CD
>
> --
> Choky
> Prodanovic Aleksandar
> YU
>
>
>
>

Not the Gulag! He will never survive!

r


--
"Any sufficiently advanced technology is indistinguishable from
magic."

Arthur C. Clarke (1917 - ), "Technology and the Future"