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'[PIC] ethernet transformer'
2010\02\18@112009 by Dario Greggio

face picon face
A quick one:
Is it safe to invert the so-called TX and RX windings of an Ethernet
10Mb transformer, due to PCB constraints?

It seems it's ok but...

TIA :)

--

Ciao, Dario
--
Cyberdyne

2010\02\18@122620 by Wouter van Ooijen

face picon face
Dario Greggio wrote:
> A quick one:
> Is it safe to invert the so-called TX and RX windings of an Ethernet
> 10Mb transformer, due to PCB constraints?
>
> It seems it's ok but...

invert what? Tx<->RX, primary<->secundary, the two connections of one coil?

--

Wouter van Ooijen

-- -------------------------------------------
Van Ooijen Technische Informatica: http://www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: http://www.voti.nl/hvu

2010\02\18@125527 by Dario Greggio

face picon face
Wouter van Ooijen ha scritto:
> Dario Greggio wrote:
>> A quick one:
>> Is it safe to invert the so-called TX and RX windings of an Ethernet
>> 10Mb transformer, due to PCB constraints?
>>
>> It seems it's ok but...
>
> invert what? Tx<->RX, primary<->secundary, the two connections of one coil?


sorry :) thought I had been clear: TX <-> RX; keep primary and secondary
at place, and so the polarities.

thx

2010\02\18@131234 by Wouter van Ooijen

face picon face
> sorry :) thought I had been clear: TX <-> RX; keep primary and secondary
> at place, and so the polarities.

I guess that might work, but I can imagine a manufacturer using a
physically smaller core for the receiver transformer. I would ask the
manufacturer before doing this in quantities.

To save space: maybe use a jack with built-in transformers?

--

Wouter van Ooijen

-- -------------------------------------------
Van Ooijen Technische Informatica: http://www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: http://www.voti.nl/hvu

2010\02\18@132148 by Dario Greggio

face picon face
Wouter van Ooijen ha scritto:
>> sorry :) thought I had been clear: TX <-> RX; keep primary and secondary
>> at place, and so the polarities.
>
> I guess that might work, but I can imagine a manufacturer using a
> physically smaller core for the receiver transformer. I would ask the
> manufacturer before doing this in quantities.

I see, yeah, makes sense indeed...
I can try asking them: it is a TS6121C, though I am not sure who
actually is the manufacturer...


> To save space: maybe use a jack with built-in transformers?

More than that, it's a housing/casing issue: we'd need a 90° or rather
180° connector, and no complete magnetics is available like that; so
we're designing the PCB with either a RJ connector or a molex strip to
move some few cm apart to a panel connector.

thank you Wouter



--

Ciao, Dario
--
Cyberdyne

2010\02\18@134115 by Wouter van Ooijen

face picon face
> More than that, it's a housing/casing issue: we'd need a 90° or rather
> 180° connector, and no complete magnetics is available like that; so
> we're designing the PCB with either a RJ connector or a molex strip to
> move some few cm apart to a panel connector.

Another option might be a jack-with-coils on small PCB, at a right angle
to your main PCB.

--

Wouter van Ooijen

-- -------------------------------------------
Van Ooijen Technische Informatica: http://www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: http://www.voti.nl/hvu

2010\02\18@140316 by Dario Greggio

face picon face
Wouter van Ooijen ha scritto:
>> More than that, it's a housing/casing issue: we'd need a 90° or rather
>> 180° connector, and no complete magnetics is available like that; so
>> we're designing the PCB with either a RJ connector or a molex strip to
>> move some few cm apart to a panel connector.
>
> Another option might be a jack-with-coils on small PCB, at a right angle
> to your main PCB.


Hmm, indeed this was not taken into account! I have to say that there
might be some room in between, i.e. the border of the pcb is not
straight close to the case, but we'll consider it!

thanks again!

--

Ciao, Dario
--
Cyberdyne

2010\02\18@141219 by Harry H. Arends

flavicon
face
Hi Dario,

If i look at the datasheet it looks that it is manufactured in the
Asia's.
See point 5 there is a diference electrical between TX and RX:

5.DCR (1-3) =0.7 OHM, (6-8)=0.5 OHM, (11-9)=1.1 OHM
(pdf1.alldatasheet.com/datasheet-pdf/view/106159/ETC/TS6121C.ht
ml )

Harry


{Quote hidden}

> -

2010\02\18@141608 by Harry H. Arends

flavicon
face
Found the MF:
Bothhand USA. e-mail: salesspamKILLspambothhandusa.com http://www.bothhandusa.com


{Quote hidden}

> -

2010\02\18@142345 by Harry H. Arends

flavicon
face
Look here:

http://www.datasheetcatalog.org/datasheets2/35/351802_1.pdf

They have serveral versions with diferent configurations.
Maybe that could be helpful.

Harry

{Quote hidden}

> -

2010\02\18@142725 by Dario Greggio

face picon face
Harry H. Arends ha scritto:
> If i look at the datasheet it looks that it is manufactured in the
> Asia's.
> See point 5 there is a diference electrical between TX and RX:
>
> 5.DCR (1-3) =0.7 OHM, (6-8)=0.5 OHM, (11-9)=1.1 OHM
> (<http://pdf1.alldatasheet.com/datasheet-pdf/view/106159/ETC/TS6121C.html> )



Hmmm, you're right: I did check them but somehow I missed it. Maybe
because I was looking for 2 or 4 values :)

> Found the MF:
> Bothhand USA. e-mail: KILLspamsalesKILLspamspambothhandusa.com http://www.bothhandusa.com

and thank you very much for this one as well! how did you find it?


--

Ciao, Dario
--
Cyberdyne

2010\02\18@142944 by Dario Greggio

face picon face
Harry H. Arends ha scritto:
> Look here:
>
> www.datasheetcatalog.org/datasheets2/35/351802_1.pdf
>
> They have serveral versions with diferent configurations.


Hmmm, in this latest one the impedance for RX and TX primary coils seems
to be the same...

strange



--

Ciao, Dario
--
Cyberdyne

2010\02\18@143911 by M. Adam Davis

face picon face
Note that many 100baseT ethernet devices are able to auto-sense the
cable configuration (straight vs crossover) and thus require both TX
and RX coils to be compatible with either function.

However, as others have pointed out you'll have to check with the
manufacturer to see if any particular product is able to do this.

-Adam

On Thu, Feb 18, 2010 at 2:29 PM, Dario Greggio <RemoveMEadpm.toTakeThisOuTspaminwind.it> wrote:
{Quote hidden}

> -

2010\02\18@150025 by Harry H. Arends

flavicon
face
Just Google the typenumber :-)

> -----Oorspronkelijk bericht-----
> Van: spamBeGonepiclist-bouncesspamBeGonespamMIT.EDU [TakeThisOuTpiclist-bouncesEraseMEspamspam_OUTMIT.EDU]
> Namens Dario Greggio
> Verzonden: donderdag 18 februari 2010 20:27
> Aan: Microcontroller discussion list - Public.
> Onderwerp: Re: [PIC] ethernet transformer
>
> Harry H. Arends ha scritto:
> > If i look at the datasheet it looks that it is manufactured in the

> > Asia's.
> > See point 5 there is a diference electrical between TX and RX:
> >
> > 5.DCR (1-3) =0.7 OHM, (6-8)=0.5 OHM, (11-9)=1.1 OHM
> >
>
(<pdf1.alldatasheet.com/datasheet-pdf/view/106159/ETC/TS6121C.h
{Quote hidden}

> -

2010\02\18@155356 by Dario Greggio

face picon face
Harry H. Arends ha scritto:
> Just Google the typenumber :-)


I did, but I mostly found resellers :)

thx!

But now I have that doubt, in that that other datasheet does tell that
the 2 windings are equal...



--

Ciao, Dario
--
Cyberdyne

2010\02\18@161247 by Bob Blick

face
flavicon
face

On Thu, 18 Feb 2010 21:53:48 +0100, "Dario Greggio" said:

> But now I have that doubt, in that that other datasheet does tell that
> the 2 windings are equal...

Hi Dario,

The impedance is the same, because the number of turns of wire is the
same.

They are separate windings wound one on top of the other, and one uses
more wire and that is why the DC resistance is different.

But DC resistance is not really important and should not be the deciding
factor about which winding to use for TX and RX.

Cheerful regards,

Bob

--
http://www.fastmail.fm - A no graphics, no pop-ups email service

2010\02\18@185118 by Dario Greggio

face picon face
Bob Blick ha scritto:
> On Thu, 18 Feb 2010 21:53:48 +0100, "Dario Greggio" said:
>
>> But now I have that doubt, in that that other datasheet does tell that
>> the 2 windings are equal...
>
> Hi Dario,
>
> The impedance is the same, because the number of turns of wire is the
> same.
>
> They are separate windings wound one on top of the other, and one uses
> more wire and that is why the DC resistance is different.
>
> But DC resistance is not really important and should not be the deciding
> factor about which winding to use for TX and RX.


thank you Bob. I did not consider exactly the meaning of "DCR" :) , now
I get it. But, still, in one datasheet I can read that DCR (1-3) =0.7
OHM and (6-8)=0.5 OHM,
while in the other (the one you posted), we can see 0.7 Pin 1-3/6-8 &
1.1 Pin 11-9

So... well, I agree in that the inductance is what matters and it should
be the same... but, where can I read it in the datasheet??

thx :)


--

Ciao, Dario
--
Cyberdyne

2010\02\18@192119 by Bob Blick

face
flavicon
face

On Thu, 18 Feb 2010 18:55:20 +0100, "Dario Greggio" <adpm.toEraseMEspam.....inwind.it>
said:
> Wouter van Ooijen ha scritto:
> > Dario Greggio wrote:
> >> A quick one:
> >> Is it safe to invert the so-called TX and RX windings of an Ethernet
> >> 10Mb transformer, due to PCB constraints?
> >>
> >> It seems it's ok but...
> >
> > invert what? Tx<->RX, primary<->secundary, the two connections of one coil?
>
>
> sorry :) thought I had been clear: TX <-> RX; keep primary and secondary
> at place, and so the polarities.
>
> thx
> --

2010\02\18@193259 by Bob Blick

face
flavicon
face
Sorry about the previous email sent without new content. I had a stray
button click event :)

On Fri, 19 Feb 2010 00:51:10 +0100, "Dario Greggio" said:
>
> thank you Bob. I did not consider exactly the meaning of "DCR" :) , now
> I get it. But, still, in one datasheet I can read that DCR (1-3) =0.7
> OHM and (6-8)=0.5 OHM,
> while in the other (the one you posted), we can see 0.7 Pin 1-3/6-8 &
> 1.1 Pin 11-9
>
> So... well, I agree in that the inductance is what matters and it should
> be the same... but, where can I read it in the datasheet??

Hi Dario,

Each manufacturer can decide how they assemble them. It may be that one
of them makes a mirror image for convenience, so one transformer is
rotated and has the lower resistance winding on the primary whereas the
other transformer has the higher resistance winding as the primary, so
the DC resistance will follow their choices. In that one datasheet you
linked to, the primary inductance is listed as 350 uH, I assume for both
TX and RX. The secondary inductance is not listed, I imagine because any
value they got wouldn't be significant since the common-mode coils are
in the package. I'd say the TX and RX designations are arbitrary and you
could safely swap them.

Cheers,

Bob

--
http://www.fastmail.fm - Access all of your messages and folders
                         wherever you are

2010\02\18@202258 by Dario Greggio

face picon face
Bob Blick ha scritto:

> Each manufacturer can decide how they assemble them. It may be that one
> of them makes a mirror image for convenience, so one transformer is
> rotated and has the lower resistance winding on the primary whereas the
> other transformer has the higher resistance winding as the primary, so
> the DC resistance will follow their choices. In that one datasheet you
> linked to, the primary inductance is listed as 350 uH, I assume for both
> TX and RX. The secondary inductance is not listed, I imagine because any
> value they got wouldn't be significant since the common-mode coils are
> in the package. I'd say the TX and RX designations are arbitrary and you
> could safely swap them.


:)
sure they can. I appreciate your "interpretation" :) and it makes sense,
so I guess we can possibly swap them as needed.

In fact, as I said, I was looking for all of the 4 values of impedance ,
but could not find them separately.


thanks again Bob!


--

Ciao, Dario
--
Cyberdyne


'[PIC] ethernet transformer'
2010\03\03@143125 by Dario Greggio
face picon face
Hmmm, back to the TS6121C:
anyone knows if main distributors do sell it? I can't seem to find it
now... that I have the PCB for it :)

thank you again!

--

Ciao, Dario
--
Cyberdyne

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