torroidal transformer vendor

[John Larkin]

Hi,

Can anybody recommend a good source for a custom torroidal power
transformer? It will be roughly 50 VA; we need prototypes fast, and
maybe 100 per year after that.

There are about 200 suppliers listed in the EEM for torroids, and I
guess we'll spam lots of them with our spec, but I just wondered if
anybody has a vendor they especially like.

Thanks,

John

 

[Harry Dellamano]

Hi,

Can anybody recommend a good source for a custom torroidal power
transformer? It will be roughly 50 VA; we need prototypes fast, and
maybe 100 per year after that.

There are about 200 suppliers listed in the EEM for torroids, and I
guess we'll spam lots of them with our spec, but I just wondered if
anybody has a vendor they especially like.

Thanks,

John

Hey John,
Rayco Electronics, lightning free prototypes, great production prices,
works for me.
http://www.raycoelectronics.com/index.html
Regards,
Harry

 

[John Larkin]

Hey John,
Rayco Electronics, lightning free prototypes, great production prices,
works for me.
http://www.raycoelectronics.com/index.html
Regards,
Harry

Thanks! We'll zap them our spec.

John

 

[Spehro Pefhany]

Hi,

Can anybody recommend a good source for a custom torroidal power
transformer? It will be roughly 50 VA; we need prototypes fast, and
maybe 100 per year after that.

There are about 200 suppliers listed in the EEM for torroids, and I
guess we'll spam lots of them with our spec, but I just wondered if
anybody has a vendor they especially like.

Thanks,

John

I've used their standard products in that range:
http://www.plitron.com/

You know this, but toroidal power xfmrs can have a nasty turn-on
current surge.


Best regards,
Spehro Pefhany

 

[John Larkin]

I've used their standard products in that range:
http://www.plitron.com/

You know this, but toroidal power xfmrs can have a nasty turn-on
current surge.

Thanks; we'll try them. And yeah, we had to go to TT superslow fuzes
for this one. We also used the inrush limiter thingies, the ones that
look like black disc caps. Primary resistance runs about 5 ohms per
120 winding, 2.5 or so in parallel, so it's not all that bad, 50 amps
without the thermistor gadgets. But our existing transformer vendor
mucked the design and they saturate at 50 Hz, so we're blowing fuzes
in Europe. These are megabuck systems and our customer is not happy.

John

 

[Joerg]

Hello John,

I had lots of good experience with Ulveco. There have been mergers et
cetera and I believe in the US it might now be:

http://www.amveco.com/

Regards, Joerg

 

[John Larkin]

Hello John,

I had lots of good experience with Ulveco. There have been mergers et
cetera and I believe in the US it might now be:

http://www.amveco.com/

Regards, Joerg

Thanks. We'll add them to the bid list.

I hate magnetics.

John

 

[Joerg]

Hello John,

I hate magnetics.

Power transformers can be kind of boring. But I love ferrite stuff. You
can do cool things with those.

Regards, Joerg

 

[John Larkin]

Hello John,


Power transformers can be kind of boring. But I love ferrite stuff. You
can do cool things with those.

I do like transmission-line transformers wound with micro-coax. We
just did a small 1:1 that puts a 60 volt pulse into 50 ohms with
rise/fall around 2 ns. That's fun.

John

 

[Paul Mathews]

Hi,

Can anybody recommend a good source for a custom torroidal power
transformer? It will be roughly 50 VA; we need prototypes fast, and
maybe 100 per year after that.

There are about 200 suppliers listed in the EEM for torroids, and I
guess we'll spam lots of them with our spec, but I just wondered if
anybody has a vendor they especially like.

Thanks,

John

You'll get farther with your searching if you spell it 'toroid', with
one R.

If you're serious about wanting production pricing, I suggest you
contact Bridgeport/Alphacore/Tortran (all the same company, really)

http://www.tortran.com/

Piece prices from them are often much lower than the competition.
Quality is good.

If you're concerned about turn-on surges, look for an article about new
toroid transformers designed to limit power-on surge:

http://www.powerelectronics.com

Paul Mathews

 

[John Larkin]

You'll get farther with your searching if you spell it 'toroid', with
one R.

No problem photocopying the page out of the EEM and giving it to
purchasing. It must have 200 vendors.

If you're serious about wanting production pricing, I suggest you
contact Bridgeport/Alphacore/Tortran (all the same company, really)

http://www.tortran.com/

Piece prices from them are often much lower than the competition.
Quality is good.

Thanks.

If you're concerned about turn-on surges, look for an article about new
toroid transformers designed to limit power-on surge:

http://www.powerelectronics.com

As I told Speff, we have NTC surge limiters and TT fuzes, so that
seems to be under control.

John

 

[legg]

without the thermistor gadgets. But our existing transformer vendor
mucked the design and they saturate at 50 Hz, so we're blowing fuzes
in Europe. These are megabuck systems and our customer is not happy.

Your own spotty behind was covered by the mention of 50Hz, somewhere
in the spec?

Don't you test these things?

RL

 

[Pooh Bear]

Hi,

Can anybody recommend a good source for a custom torroidal power
transformer? It will be roughly 50 VA; we need prototypes fast, and
maybe 100 per year after that.

There are about 200 suppliers listed in the EEM for torroids, and I
guess we'll spam lots of them with our spec, but I just wondered if
anybody has a vendor they especially like.

Toroid International.

http://www.toroid.co.uk/

The MD owns the company and is highly knowledgable and most helpful.
Their prices are good too as they manufacture in asia.


Graham

 

[John Larkin]

Your own spotty behind was covered by the mention of 50Hz, somewhere
in the spec?

Sure. At 10% overvoltage.

Don't you test these things?

The guy who spec'd and tested the trannies no longer works for me; one
day he walked into my office, said "it's time to move on" and left.
Interestingly, he used to work for Signal Transformer. I guess he
didn't test it for saturation. All you really need to do is
overvoltage it at 60 Hz, find the knee, and multiply by 5/6.

Our customer (it's an OEM product) took our gadget to a major test lab
for the full CE suite, including specific transformer tests. Their
test report *justifies* why it was not necessary to actually test at
50 Hz. There's lots of blame to go around.

John

 

[Pooh Bear]

Thanks; we'll try them. And yeah, we had to go to TT superslow fuzes
for this one. We also used the inrush limiter thingies, the ones that
look like black disc caps. Primary resistance runs about 5 ohms per
120 winding, 2.5 or so in parallel, so it's not all that bad, 50 amps
without the thermistor gadgets. But our existing transformer vendor
mucked the design and they saturate at 50 Hz, so we're blowing fuzes
in Europe. These are megabuck systems and our customer is not happy.

You didn't put 50Hz on the spec ?

Sounds like a transformer supplier who doesn't understand that there's a
whole world out there.

Oh - and if you're selling in Europe don't forget to use IEC spec fuses
not UL. The blowing characteristics are very different too.

I've *never* had to use a TT fuse. Ts normally work just fine for me and
I regularly use toroids.

Fuse only needs to blow when ( typically ) you short out any one of the
secondary side reservoir caps btw.


Graham

 

[John Larkin]

You didn't put 50Hz on the spec ?

Of course we did.

Sounds like a transformer supplier who doesn't understand that there's a
whole world out there.

Oh - and if you're selling in Europe don't forget to use IEC spec fuses
not UL. The blowing characteristics are very different too.

We're using TT fuses.

I've *never* had to use a TT fuse. Ts normally work just fine for me and
I regularly use toroids.

Fuse only needs to blow when ( typically ) you short out any one of the
secondary side reservoir caps btw.

The CE test involves loading the transformer secondary to just below
the fuse blow point and then waiting to see how hot the transformer
gets; that is a lot nastier than a clean short. And this box has no
fans. So we have to use the smallest possible fuse rating, or we pay
for it in transformer iron. So between the powerup surges (core+caps)
and the fact that this is a pulsed power amp, things get interesting.

I think what happened was that the original transformer design was OK
but a bit too big. Somebody at the transformer company (another
somebody "no longer here") scrunched the design program and wound up
with a transformer that was smaller but had no saturation margin.


John

 

[Tony Williams]

I think what happened was that the original transformer design
was OK but a bit too big. Somebody at the transformer company
(another somebody "no longer here") scrunched the design program
and wound up with a transformer that was smaller but had no
saturation margin.

There used to be a UK contributor to sed (Mark
Daniels) who owns his own transformer company.
I bought some custom transformers from him a
couple of years ago. They were ok.

Jem Electronics,
173a High Street,
Clay Cross,
Chesterfield,
S45 9DZ,
0870 787 1708.

<[email protected]>

BTW: What's the rough spec?
Size?
PCB-mount or flying leads?
Secondary Volts/Amps?

Note that Soddes Law says that urgently trying to
get a new transformer designed and wound, by an
unknown supplier, in a different country, could bite
you in the bum.

 

[John Woodgate]

I read in sci.electronics.design that John Larkin <jjSNIPlarkin@highTHIS
landPLEASEtechnology.XXX> wrote (in <mu6j01ds31dgvsq8mfa0br3eft55946dbl@
4ax.com>) about 'torroidal transformer vendor', on Tue, 8 Feb 2005:

The CE test involves loading the transformer secondary to just below the
fuse blow point and then waiting to see how hot the transformer gets;

Which standard are you applying? It sounds to me that you may not be
applying the correct one.

 

[John Woodgate]

I read in sci.electronics.design that Paul Mathews
..googlegroups.com>) about 'torroidal transformer vendor', on Tue, 8 Feb
2005:

If you're concerned about turn-on surges, look for an article about new
toroid transformers designed to limit power-on surge:

http://www.powerelectronics.com

Do you have the title of the article? I couldn't find it on the site.

 

[Pooh Bear]

Of course we did.


We're using TT fuses.


The CE test involves loading the transformer secondary to just below
the fuse blow point and then waiting to see how hot the transformer
gets; that is a lot nastier than a clean short.

This sounds very wrong. IEC regs simply apply component failure simulations
to test such stuff.

And this box has no
fans. So we have to use the smallest possible fuse rating, or we pay
for it in transformer iron. So between the powerup surges (core+caps)
and the fact that this is a pulsed power amp, things get interesting.

I think what happened was that the original transformer design was OK
but a bit too big. Somebody at the transformer company (another
somebody "no longer here") scrunched the design program and wound up
with a transformer that was smaller but had no saturation margin.

I think someone's misadvising you re: the CE safety test btw.

I have considerable experience of both safety and EMC CE approvals.

Is it a US lab that thinks you have to test that way ?


Graham