I was just robbing an old dead PC Power supply of some bits, and I saw
this inside, and wondered what it was for?

It looks like a transformer, but it only has two wires connected to it,
one of them looks to be connected to one leg of a bridge rectifier, the
other, not so sure at the moment...

I haven't seen one inside a PSU before - it was screwed to the inside of
the PSU case, separate from the main board.


http://www.tobybell.co.uk/images/psu2.jpg


--
Toby...
Remove pants to reply

On Tue, 24 Jan 2012 23:36:02 +0000, Toby
wrote:

http://www.tobybell.co.uk/images/psu2.jpg

A choke.

On 24/01/2012 23:47, wrote:
On Tue, 24 Jan 2012 23:36:02 +0000,
wrote:

http://www.tobybell.co.uk/images/psu2.jpg

A choke.

Ah, okay, but this one is pretty big
280grams 5x4.5x3.5cm

Normally they just have these in them from what I have seen before
http://media.digikey.com/Photos/Wurt...tos/744154.jpg


--
Toby...
Remove pants to reply

On Tue, 24 Jan 2012 23:59:55 +0000, Toby wrote:

On 24/01/2012 23:47, wrote:
On Tue, 24 Jan 2012 23:36:02 +0000,
wrote:

http://www.tobybell.co.uk/images/psu2.jpg

A choke.

Ah, okay, but this one is pretty big
280grams 5x4.5x3.5cm

Normally they just have these in them from what I have seen before
http://media.digikey.com/Photos/Wurt...tos/744154.jpg

High frequency choke, low frequency choke. Different parts of the PSU.



--
Use the BIG mirror service in the UK:
http://www.mirrorservice.org

*lightning protection* - a w_tom conductor

On Jan 24, 11:36*pm, Toby wrote:
I was just robbing an old dead PC Power supply of some bits, and I saw
this inside, and wondered what it was for?

It looks like a transformer, but it only has two wires connected to it,
one of them looks to be connected to one leg of a bridge rectifier, the
other, not so sure at the moment...

I haven't seen one inside a PSU before - it was screwed to the inside of
the PSU case, separate from the main board.

http://www.tobybell.co.uk/images/psu2.jpg

--
Toby...
Remove pants to reply

It is an inductor/choke. Its mooths the ripple out of the rectified
DC. It goes in series with the output. Capacitors go in parallel for
the same job.. You often have both.

On Wed, 25 Jan 2012 00:08:53 -0800, harry wrote:

On Jan 24, 11:36Â*pm, Toby wrote:
I was just robbing an old dead PC Power supply of some bits, and I saw
this inside, and wondered what it was for?

It looks like a transformer, but it only has two wires connected to it,
one of them looks to be connected to one leg of a bridge rectifier, the
other, not so sure at the moment...

I haven't seen one inside a PSU before - it was screwed to the inside
of the PSU case, separate from the main board.

http://www.tobybell.co.uk/images/psu2.jpg

--
Toby...
Remove pants to reply

It is an inductor/choke. Its mooths the ripple out of the rectified DC.
It goes in series with the output. Capacitors go in parallel for the
same job.. You often have both.

I suspect this was an SMPS, and it was in series with the input (some
rough smoothing on the rectified DC before it went to be chopped up
again).


--
Use the BIG mirror service in the UK:
http://www.mirrorservice.org

*lightning protection* - a w_tom conductor

Cannot see it of course but there are significant attempts in at least some
to suppress the crap switch mode supplies give out.
This might be part of that.
Brian

--
Brian Gaff -
Note:- In order to reduce spam, any email without 'Brian Gaff'
in the display name may be lost.
Blind user, so no pictures please!
"Toby" wrote in message
...

I was just robbing an old dead PC Power supply of some bits, and I saw
this inside, and wondered what it was for?

It looks like a transformer, but it only has two wires connected to it,
one of them looks to be connected to one leg of a bridge rectifier, the
other, not so sure at the moment...

I haven't seen one inside a PSU before - it was screwed to the inside of
the PSU case, separate from the main board.


http://www.tobybell.co.uk/images/psu2.jpg


--
Toby...
Remove pants to reply

On 25/01/2012 09:18, Brian Gaff wrote:
Cannot see it of course but there are significant attempts in at least some
to suppress the crap switch mode supplies give out.
This might be part of that.
Brian

Most likely that is what the choke is for, more modern designs tend to
have active PFC allowing the choke to be smaller and thus cheaper.

Of course some "ultra budget" PSUs still don't have any chokes or PFC
correction but hopefully there are not too many of these around these
days...

In message , Toby
writes
On 24/01/2012 23:47, wrote:
On Tue, 24 Jan 2012 23:36:02 +0000,
wrote:

http://www.tobybell.co.uk/images/psu2.jpg

A choke.

Ah, okay, but this one is pretty big

In which case, it's a pretty BIG choke.




--
Ian

In message , Lee
writes
On 25/01/2012 09:18, Brian Gaff wrote:
Cannot see it of course but there are significant attempts in at least some
to suppress the crap switch mode supplies give out.
This might be part of that.
Brian

Most likely that is what the choke is for, more modern designs tend to
have active PFC allowing the choke to be smaller and thus cheaper.

Of course some "ultra budget" PSUs still don't have any chokes or PFC
correction but hopefully there are not too many of these around these
days...

Possibly it would be better to describe it by the more general term
'inductor'. Its function might have nothing to do with suppressing
interference.
--
Ian

On Tue, 24 Jan 2012 23:36:02 +0000, Toby wrote:
It looks like a transformer, but it only has two wires connected to it,
one of them looks to be connected to one leg of a bridge rectifier, the
other, not so sure at the moment...

I haven't seen one inside a PSU before - it was screwed to the inside of
the PSU case, separate from the main board.

http://www.tobybell.co.uk/images/psu2.jpg

CIA bugging device.

On Jan 24, 11:36*pm, Toby wrote:
I was just robbing an old dead PC Power supply of some bits, and I saw
this inside, and wondered what it was for?

It looks like a transformer, but it only has two wires connected to it,
one of them looks to be connected to one leg of a bridge rectifier, the
other, not so sure at the moment...

I haven't seen one inside a PSU before - it was screwed to the inside of
the PSU case, separate from the main board.

http://www.tobybell.co.uk/images/psu2.jpg

Choke/inductor. Such a massive core would not be used primarily to
suppress interference, nor would it be used to smooth output on a
smpsu, nor would it be used to produce an output line since it lacks
isolation, so that leaves PFC as its use.


NT

NT wrote:
Choke/inductor. Such a massive core would not be used primarily to
suppress interference, nor would it be used to smooth output on a
smpsu, nor would it be used to produce an output line since it lacks
isolation, so that leaves PFC as its use.


Power Factor Correction. Just to save everybody having to Google it as I
did.

Another Dave
--
Change nospam to gmx

On 25/01/2012 13:58, Ian Jackson wrote:

Possibly it would be better to describe it by the more general term
'inductor'. Its function might have nothing to do with suppressing
interference.

Ok, it's primary job is to improve the PFC thereby increasing efficiency
and reducing harmonic noise.
Since the reduced noise is a regulatory requirement it can still be
argued that it's part of its primary function....

Lee

In message , Lee
writes
On 25/01/2012 13:58, Ian Jackson wrote:

Possibly it would be better to describe it by the more general term
'inductor'. Its function might have nothing to do with suppressing
interference.

Ok, it's primary job is to improve the PFC thereby increasing
efficiency and reducing harmonic noise.
Since the reduced noise is a regulatory requirement it can still be
argued that it's part of its primary function....

However, I can't help thinking that it's unlikely that an inductor would
be used in a PFC circuit. It's more likely to be an essential part of
the guts of the actual switchmode circuit (although, to me, these beasts
tend to fall in the 'Act of God' category).
--
Ian

Toby presented the following explanation :
On 24/01/2012 23:47, wrote:
On Tue, 24 Jan 2012 23:36:02 +0000,
wrote:

http://www.tobybell.co.uk/images/psu2.jpg

A choke.

Ah, okay, but this one is pretty big
280grams 5x4.5x3.5cm

Its a larger choke.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

Ian Jackson wrote:
In message , Toby
writes
On 24/01/2012 23:47, wrote:
On Tue, 24 Jan 2012 23:36:02 +0000,
wrote:

http://www.tobybell.co.uk/images/psu2.jpg

A choke.

Ah, okay, but this one is pretty big

In which case, it's a pretty BIG choke.


No THESE are pretty big chokes

http://www.energy.siemens.com/co/en/...nt=AC%20Filter

Ian Jackson wrote:
In message , Lee
writes
On 25/01/2012 09:18, Brian Gaff wrote:
Cannot see it of course but there are significant attempts in at
least some
to suppress the crap switch mode supplies give out.
This might be part of that.
Brian

Most likely that is what the choke is for, more modern designs tend to
have active PFC allowing the choke to be smaller and thus cheaper.

Of course some "ultra budget" PSUs still don't have any chokes or PFC
correction but hopefully there are not too many of these around these
days...

Possibly it would be better to describe it by the more general term
'inductor'. Its function might have nothing to do with suppressing
interference.

most probably its output smoothing..

Ian Jackson wrote:
In message , Lee
writes
On 25/01/2012 13:58, Ian Jackson wrote:

Possibly it would be better to describe it by the more general term
'inductor'. Its function might have nothing to do with suppressing
interference.

Ok, it's primary job is to improve the PFC thereby increasing
efficiency and reducing harmonic noise.
Since the reduced noise is a regulatory requirement it can still be
argued that it's part of its primary function....

However, I can't help thinking that it's unlikely that an inductor would
be used in a PFC circuit. It's more likely to be an essential part of
the guts of the actual switchmode circuit (although, to me, these beasts
tend to fall in the 'Act of God' category).

well actually that is exactly wrong in an SMPS which is oversupplied
with capacitors as part of its design.

"Ian Jackson" wrote in message
...
In message , Lee
writes
On 25/01/2012 13:58, Ian Jackson wrote:

Possibly it would be better to describe it by the more general term
'inductor'. Its function might have nothing to do with suppressing
interference.

Ok, it's primary job is to improve the PFC thereby increasing efficiency
and reducing harmonic noise.
Since the reduced noise is a regulatory requirement it can still be argued
that it's part of its primary function....

However, I can't help thinking that it's unlikely that an inductor would
be used in a PFC circuit. It's more likely to be an essential part of the
guts of the actual switchmode circuit (although, to me, these beasts tend
to fall in the 'Act of God' category).
--
Ian


The PFC section of switchers that employ that type of front end, does indeed
usually use an inductor, which normally appears to be roughly between the
bridge and the main filter cap. However, I don't believe that this is such
an inductor for two reasons. First, PFC stages run at high frequency, much
like the main supply that follows them, and this requires that the PFC
inductor has a ferrite core. The inductor shown in the photo clearly has
some kind of laminated iron core, which puts it firmly in the low frequency
category. Also, the inductor usually has an ancillary winding on it, which
connects back to the zero crossing detector pin on the controller IC, and
again, it is clear from the photo that no such additional winding is
present. I have also never seen a PFC stage inductor mounted off the board.
Indeed, considering the frequency that they are running at, flying leads to
an off-board inductor, would be asking for EMC problems.

I am also loathe to believe that this is any kind of interference
suppression inductor, as the hash that switchers generate, ranges from
several tens of kHz to the low megs, so again, a ferrite cored inductor is
what is required to block this noise.

Arfa

In article ,
"Arfa Daily" writes:

The PFC section of switchers that employ that type of front end, does indeed
usually use an inductor, which normally appears to be roughly between the
bridge and the main filter cap. However, I don't believe that this is such
an inductor for two reasons. First, PFC stages run at high frequency, much
like the main supply that follows them, and this requires that the PFC
inductor has a ferrite core. The inductor shown in the photo clearly has
some kind of laminated iron core, which puts it firmly in the low frequency
category. Also, the inductor usually has an ancillary winding on it, which
connects back to the zero crossing detector pin on the controller IC, and
again, it is clear from the photo that no such additional winding is
present. I have also never seen a PFC stage inductor mounted off the board.
Indeed, considering the frequency that they are running at, flying leads to
an off-board inductor, would be asking for EMC problems.

If it's connected between the bridge and the storage cap, it will
spread and flatten the current peaks which replenish the storage
capacitors at the mains cycle peaks, and this will improve the
power factor. Off board could be because it's a retrofit on top
of an earlier design without PFC.

It would also provide inrush current limiting, and could correct
the tiny leading phase shift, although I doubt either of these are
its primary purpose.

I am also loathe to believe that this is any kind of interference
suppression inductor, as the hash that switchers generate, ranges from
several tens of kHz to the low megs, so again, a ferrite cored inductor is
what is required to block this noise.

It's not.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

"Andrew Gabriel" wrote in message
...
In article ,
"Arfa Daily" writes:

The PFC section of switchers that employ that type of front end, does
indeed
usually use an inductor, which normally appears to be roughly between the
bridge and the main filter cap. However, I don't believe that this is
such
an inductor for two reasons. First, PFC stages run at high frequency,
much
like the main supply that follows them, and this requires that the PFC
inductor has a ferrite core. The inductor shown in the photo clearly has
some kind of laminated iron core, which puts it firmly in the low
frequency
category. Also, the inductor usually has an ancillary winding on it,
which
connects back to the zero crossing detector pin on the controller IC, and
again, it is clear from the photo that no such additional winding is
present. I have also never seen a PFC stage inductor mounted off the
board.
Indeed, considering the frequency that they are running at, flying leads
to
an off-board inductor, would be asking for EMC problems.

If it's connected between the bridge and the storage cap, it will
spread and flatten the current peaks which replenish the storage
capacitors at the mains cycle peaks, and this will improve the
power factor. Off board could be because it's a retrofit on top
of an earlier design without PFC.

It would also provide inrush current limiting, and could correct
the tiny leading phase shift, although I doubt either of these are
its primary purpose.

I am also loathe to believe that this is any kind of interference
suppression inductor, as the hash that switchers generate, ranges from
several tens of kHz to the low megs, so again, a ferrite cored inductor
is
what is required to block this noise.

It's not.

--
Andrew Gabriel


I think you are right. It probably is an early crude PFC corrector. It's
only in the last few years that designs using chip-based PFC correction,
have become the norm amongst better quality switchers. I guess since the
eco-bollox hysteria took hold ... :-)

Arfa