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Guest
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 Posted:
Thu Oct 06, 2005 6:22 pm Post subject:
Where to get 1watt 1% resistors. |
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Where to get 1watt 1% metal film resistors?
Nobody seems to stock them. Newark, Mouser ect want 500pc min order for the
Vishay/Dale.
Any ideas??
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Phil Allison
Guest
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| Posted:
Thu Oct 06, 2005 6:26 pm Post subject:
Re: Where to get 1watt 1% resistors. |
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<r.laury@comcast.net>
| Quote: |
Where to get 1watt 1% metal film resistors?
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** Use two 0.5, 0.6 or 0.75 watt 1% MF types in series.
............. Phil |
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beeah
Guest
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| Posted:
Thu Oct 06, 2005 6:45 pm Post subject:
Re: Where to get 1watt 1% resistors. |
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I just bought a single Dale RN65 from Mouser less than a month ago...
According to Vishay/Dale, the RN65 is rated at 1/2W. However, this is
the milspec rating; the commercial rating is actually 1W. Similarly,
the RN60 is actually what we consider a 1/2W resistor but for the
milspec rating it is a 1/4W resistor. According to their own spec
sheets, the RN series are the same resistors as the CMF series - just
with different markings and ratings.
See:
http://www.vishay.com/docs/31018/cmfind.pdf
http://www.vishay.com/docs/31027/cmfmil.pdf
j
<r.la...@comcast.net> wrote:
| Quote: | Where to get 1watt 1% metal film resistors?
Nobody seems to stock them. Newark, Mouser ect want 500pc min order for the
Vishay/Dale.
Any ideas?? |
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Iain M Churches
Guest
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| Posted:
Thu Oct 06, 2005 8:54 pm Post subject:
Re: Where to get 1watt 1% resistors. |
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<r.laury@comcast.net> wrote in message
news:Ao2dnSlXTYWxuNjeRVn-qw@comcast.com...
| Quote: | Where to get 1watt 1% metal film resistors?
Nobody seems to stock them. Newark, Mouser ect want 500pc min order for
the Vishay/Dale.
Any ideas??
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| Quote: |
Antique Electronic Supply |
http://www.tubesandmore.com/
Iain |
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Dope mcSmoke
Guest
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| Posted:
Fri Oct 07, 2005 2:39 am Post subject:
Re: Where to get 1watt 1% resistors. |
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Phil Allison wrote:
| Quote: | r.laury@comcast.net
Where to get 1watt 1% metal film resistors?
** Use two 0.5, 0.6 or 0.75 watt 1% MF types in series.
............ Phil
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That'd be like a 1W 2% resistor |
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Phil Allison
Guest
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| Posted:
Fri Oct 07, 2005 4:43 am Post subject:
Re: Where to get 1watt 1% resistors. |
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"Dope mcSmoke"
| Quote: | Phil Allison wrote:
** Use two 0.5, 0.6 or 0.75 watt 1% MF types in series.
That'd be like a 1W 2% resistor
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** WRONG !!!
Even if *both* resistors were 1% high, the series value is also 1% high.
Using resistors in series or parallel IMPROVES the % accuracy of the final
value.
......... Phil |
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Phil Allison
Guest
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| Posted:
Fri Oct 07, 2005 4:43 am Post subject:
Re: Where to get 1watt 1% resistors. |
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"Ian Iveson"
** A colossal, MASTURBATING, TOP POSTING , context REMOVING, fucking
pommy IDIOT !!!!
** Only seems that way to someone with GROSS autism.
** Go get rooted - you grossly autistic prick.
** WRONG.
It will be within tolerance for all non faulty resistors.
** No it does not.
The % tolerance of a resistor is the MAX amount that any sample will differ
from the nominal value INCLUDING the effects of a normal service life.
......... Phil |
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Ian Iveson
Guest
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| Posted:
Fri Oct 07, 2005 4:43 am Post subject:
Re: Where to get 1watt 1% resistors. |
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Phil wrote [below...seems a bit angry again...]
Perhaps a simple illustration will help you, Phil.
Take an example 100R 1% resistor. Let's say the probability of it
being only 99R is P.
Take another from the same batch. The probability of it also being
99R is also P
The chance of them *both* being 99R is Psquared. Since P is always
less than one, Psquared is always smaller than P.
There is no other combination of values that adds up to 198R, so the
chance of the two in series being 1% is smaller than either on its
own.
OTOH, there are many possible combinations of values, the one larger
and the other smaller than the nominal value, or vice versa, that
could add up to the nominal value, making it more likely that two in
series would be near the nominal value.
In other words, even if the probability distribution of values in
the batch is flat with vertical limits at 1%, as you suggest, the
distribution of two in series will be an inverted U shape. With many
resistors in series, it will approach a normal distribution I think.
I have been trying to find out whether resistors are sampled, or if
each one is measured. The above works for either but, if they are
sampled then the compound resistor will have a better tolerance than
the single value.
So, does "1%" mean every one, or is there a confidence limit,
perhaps 99.9%within 1%?
Anyone know whether the nominal value is the mean, mode, median, or
none of those? Anyone know what the distribution is around the
nominal value?
I'm sure it's not actually flat. They aren't made by chance.
cheers, Ian
"Phil Allison" <philallison@tpg.com.au> wrote in message
news:3qm5evFfian5U1@individual.net...
| Quote: |
"Ian Iveson"
** A colossal, context REMOVING, fucking pommy IDIOT !!!!
** WRONG !!!
Even if *both* resistors were 1% high, the series value is also
1% high.
Using resistors in series or parallel IMPROVES the % accuracy
of the final value.
Phil, those two statements appear contradictory, because your use
of "%" changes from the first to the second.
** Only seems that way to someone with autism.
Or you are wrong...
** Go get rooted - you autistic prick.
What improves is the *chance* that a resulting value will be
within tolerance.
** WRONG.
It will be within tolerance for all non faulty resistors.
Since quoted tolerance assumes a particular distribution of
values around the quoted value,
** No it does not.
The % tolerance of a resistor is the MAX amount that any sample
will differ from the nominal value INCLUDING the effects of a
normal service life.
........ Phil
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Phil Allison
Guest
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| Posted:
Fri Oct 07, 2005 4:43 am Post subject:
Re: Where to get 1watt 1% resistors. |
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"Ian Iveson"
** A colossal, context REMOVING, fucking pommy IDIOT !!!!
| Quote: |
** WRONG !!!
Even if *both* resistors were 1% high, the series value is also 1% high.
Using resistors in series or parallel IMPROVES the % accuracy of the
final value.
Phil, those two statements appear contradictory, because your use of "%"
changes from the first to the second.
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** Only seems that way to someone with autism.
| Quote: | Or you are wrong...
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** Go get rooted - you autistic prick.
| Quote: | What improves is the *chance* that a resulting value will be within
tolerance.
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** WRONG.
It will be within tolerance for all non faulty resistors.
| Quote: | Since quoted tolerance assumes a particular distribution of values around
the quoted value,
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** No it does not.
The % tolerance of a resistor is the MAX amount that any sample will differ
from the nominal value INCLUDING the effects of a normal service life.
......... Phil |
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Ian Iveson
Guest
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| Posted:
Fri Oct 07, 2005 4:43 am Post subject:
Re: Where to get 1watt 1% resistors. |
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"Phil Allison" wrote
| Quote: | That'd be like a 1W 2% resistor
** WRONG !!!
Even if *both* resistors were 1% high, the series value is also
1% high.
Using resistors in series or parallel IMPROVES the % accuracy of
the final value.
|
Phil, those two statements appear contradictory, because your use of
"%" changes from the first to the second. Or you are wrong...
What improves is the *chance* that a resulting value will be within
tolerance. Since quoted tolerance assumes a particular distribution
of values around the quoted value, improving that chance is the same
thing as narrowing the tolerance.
cheers, Ian |
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flipper
Guest
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| Posted:
Fri Oct 07, 2005 4:43 am Post subject:
Re: Where to get 1watt 1% resistors. |
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On Fri, 07 Oct 2005 02:21:16 GMT, "Ian Iveson"
<IanIveson.home@blueyonder.co.uk> wrote:
| Quote: | "Phil Allison" wrote
That'd be like a 1W 2% resistor
** WRONG !!!
Even if *both* resistors were 1% high, the series value is also
1% high.
Using resistors in series or parallel IMPROVES the % accuracy of
the final value.
Phil, those two statements appear contradictory, because your use of
"%" changes from the first to the second. Or you are wrong...
|
The part that's incorrect is thinking it improves the % accuracy, as
the first, and correct, statement shows. If they're 1% tolerance they
can be 1% off. That's what it means. And 2 of them together can be 1%
off as well. The tolerance is 1%.
| Quote: |
What improves is the *chance* that a resulting value will be within
tolerance.
|
The "chance" of the pair being within tolerance is 100%. Well, if the
individuals are within tolerance, as specified, that is.
| Quote: | Since quoted tolerance assumes a particular distribution
of values around the quoted value, improving that chance is the same
thing as narrowing the tolerance.
|
Neither of those is correct. The tolerance number assumes nothing;
they'll simply be within 1% and if they're all 1% off it's just as
valid as if only one of them is off 1% off.. It is you who are
apparently assuming a particular distribution.
Second, 'chance' has nothing to do with the tolerance unless you are
'hoping' to get something other than what's specified. But, in any
case, the tolerance is neither 'improved' nor lessened. You can still
end up with 1% off and that's all a 1% tolerance says: you can't
*depend* on them being any closer than 1% and it doesn't tell you 'how
much' you can or can't depend on it. And it 'might be' anywhere
in-between. The *only* thing known is they'll be within 1%
Which gets back to the distribution and the dangers of assuming one.
What you are probably thinking of is the classic bell curve
distribution and assuming that distribution applies but it may very
well not depending on how they're made and selected. For example, take
a resistor line that includes .1%, .5%, and 1% tolerance ranges. It is
not uncommon for those to be selected from the same manufacturing
process so the .1% resistors are culled out first, then the .5%, and
then the remaining are 1%. Which means the .1% resistors may very well
have a classic bell curve distribution but the .5% values will have a
..1% 'hole' around the .1% value and the 1% resistors will have a .5%
'hole' (might be multiple holes too). So your 'chances' of finding a
right spot on 1% resistor might be virtually 0, unless there's not
enough demand for .1% and .5% values so that some of the 'better' ones
get the lower tolerance rating anyway to fill the larger demand in
that market. Which means you can't even 'depend' on the dern 'hole'
being there.
Assuming distributions when none is specified can lead to
disappointing surprises.
Now, if you were hand selecting a tighter tolerance from a lower
tolerance batch then pairing them might improve your yield because
there might be more 'good' combinations of offsetting pairs than
solely single values, if the unknown distribution allowed it. But,
then, you can't necessarily count on that. (the manufacturer can
because he knows the distribution)
Lastly, to cover the subsequent message, tolerance is the initial
tolerance, at 25C, as delivered to your doorstep and before you begin
torturing the thing. Everything else, solder, lead stress, temperature
coefficient, long term drift, surge, voltage stress, temperature
cycling, etc. are in addition to the initial tolerance.
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Phil Allison
Guest
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| Posted:
Fri Oct 07, 2005 4:43 am Post subject:
Re: Where to get 1watt 1% resistors. |
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"Ian Iveson"
** A colossal, context REMOVING, fucking pommy IDIOT !!!!
** Only seems that way to someone with autism.
** Go get rooted - you autistic prick.
** WRONG.
It will be within tolerance for all non faulty resistors.
** No it does not.
The % tolerance of a resistor is the MAX amount that any sample will differ
from the nominal value INCLUDING the effects of a normal service life.
......... Phil |
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Ian Iveson
Guest
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| Posted:
Fri Oct 07, 2005 4:43 am Post subject:
Re: Where to get 1watt 1% resistors. |
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Oops! Over the edge he goes...
"Phil Allison" <philallison@tpg.com.au> wrote in message
news:3qm9p7Ff8l3eU1@individual.net...
| Quote: |
"Ian Iveson"
** A colossal, context REMOVING, fucking pommy IDIOT !!!!
** Only seems that way to someone with autism.
** Go get rooted - you autistic prick.
** WRONG.
It will be within tolerance for all non faulty resistors.
** No it does not.
The % tolerance of a resistor is the MAX amount that any sample
will differ
from the nominal value INCLUDING the effects of a normal service
life.
........ Phil
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Phil Allison
Guest
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| Posted:
Fri Oct 07, 2005 10:26 am Post subject:
Re: Where to get 1watt 1% resistors. |
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"flipper"
| Quote: |
The "chance" of the pair being within tolerance is 100%. Well, if the
individuals are within tolerance, as specified, that is.
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** Correct.
| Quote: | The tolerance number assumes nothing;
they'll simply be within 1% ...
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** WRONG.
New Metal Film resistors are and need to be well within the 1% error maximum
to allow for aging.
| Quote: | You can still
end up with 1% off and that's all a 1% tolerance says:
|
** Nope - the chances of being even 0.5 % are low with new stock.
| Quote: | For example, take
a resistor line that includes .1%, .5%, and 1% tolerance ranges.
It is not uncommon for those to be selected from the same manufacturing
process so the .1% resistors are culled out first, then the .5%, and
then the remaining are 1%.
|
** Completely false.
Metal film resistors of 0.1 % tolerance are made in a different way to
guarantee stability over life of 0.05%.
| Quote: | Lastly, to cover the subsequent message, tolerance is the initial
tolerance, at 25C, as delivered to your doorstep and before you begin
torturing the thing. Everything else, solder, lead stress, temperature
coefficient, long term drift, surge, voltage stress, temperature
cycling, etc. are in addition to the initial tolerance.
|
** That is NOT my experience over 40 years of dealing with the critters.
The topic is tubular METAL FILM resistors that have been spiralled to a
value.
Forget any WW or composition types.
.......... Phil |
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Ian Iveson
Guest
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| Posted:
Fri Oct 07, 2005 11:16 am Post subject:
Re: Where to get 1watt 1% resistors. |
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"flipper" <flipper@fish.net> wrote [below and...]
See the next post I made to Phil. You have made false assumptions
about what I assumed.
Whatever the distribution of single values, multiplying the number
of resistors will make it more bell-shaped than it was.
If 1% tolerance means that all the resistors are individually
measured to be within 1%, then my statement that a compound resistor
has a better chance of being within tolerance would be incorrect.
But my main point, that compound resistors will be more tightly
clustered around a nominal value and sparse at the edges, is true.
Furthermore, I have said that resistors aren't manufactured by
chance. That is, they don't make random values and then sort them.
They actually target a particular nominal value for each batch. We
should expect some kind of bell-like distribution, therefore.
Looking at a few pages on the net, for example:
http://www.circuitree.com/CDA/ArticleInformation/coverstory/BNPCoverStoryItem/0,2135,108386,00.html
http://www.mcm.dupont.com/MCM/en_US/PDF/embpass_tech5.pdf
you can see that this is true.
The question to which I can't find an answer is, do they chop off
the tails of the distribution? The only way that could be done would
be by measuring every resistor.
Looks like they do.
If Phil is right when he says that normal service life is included,
then they absolutely definitely *cannot* chop off the tails of the
distribution.
In any case, my main point about *chance* is correct: a compound
resistor will probably be closer to its nominal value than the
individual resistors it is made of.
More points below in context:
| Quote: | "Phil Allison" wrote
That'd be like a 1W 2% resistor
** WRONG !!!
Even if *both* resistors were 1% high, the series value is also
1% high.
Using resistors in series or parallel IMPROVES the % accuracy
of
the final value.
Phil, those two statements appear contradictory, because your use
of
"%" changes from the first to the second. Or you are wrong...
The part that's incorrect is thinking it improves the % accuracy,
as
the first, and correct, statement shows. If they're 1% tolerance
they
can be 1% off. That's what it means. And 2 of them together can be
1%
off as well. The tolerance is 1%.
What improves is the *chance* that a resulting value will be
within
tolerance.
The "chance" of the pair being within tolerance is 100%. Well, if
the
individuals are within tolerance, as specified, that is.
|
Ok, if they chop off the tails, which it seems they do (but still
not certain...)
| Quote: | Since quoted tolerance assumes a particular distribution
of values around the quoted value, improving that chance is the
same
thing as narrowing the tolerance.
Neither of those is correct. The tolerance number assumes nothing;
they'll simply be within 1% and if they're all 1% off it's just as
valid as if only one of them is off 1% off.. It is you who are
apparently assuming a particular distribution.
|
No, I am only assuming that it has a distribution, which it must
have. Second clause of my statement is wrong only if they chop off
the tails...
| Quote: | Second, 'chance' has nothing to do with the tolerance unless you
are
'hoping' to get something other than what's specified. But, in any
case, the tolerance is neither 'improved' nor lessened. You can
still
end up with 1% off and that's all a 1% tolerance says: you can't
*depend* on them being any closer than 1% and it doesn't tell you
'how
much' you can or can't depend on it. And it 'might be' anywhere
in-between. The *only* thing known is they'll be within 1%
|
No, not the only thing. You know they are more likely to be closer,
and you can calculate exactly by how much. You are getting carried
away with your point now. You were better off keeping it simple.
| Quote: | Which gets back to the distribution and the dangers of assuming
one.
|
There is bound to be a distribution. How could there not be?
| Quote: | What you are probably thinking of is the classic bell curve
distribution and assuming that distribution applies but it may
very
well not depending on how they're made and selected.
|
I did not say that was my assumption, and my point does not require
it. Actually it *is* bell shaped to begin with. The only question
was
whether they chop off the tails...
| Quote: | For example, take
a resistor line that includes .1%, .5%, and 1% tolerance ranges.
It is
not uncommon for those to be selected from the same manufacturing
process so the .1% resistors are culled out first, then the .5%,
and
then the remaining are 1%. Which means the .1% resistors may very
well
have a classic bell curve distribution but the .5% values will
have a
.1% 'hole' around the .1% value and the 1% resistors will have a
.5%
'hole' (might be multiple holes too). So your 'chances' of finding
a
right spot on 1% resistor might be virtually 0, unless there's not
enough demand for .1% and .5% values so that some of the 'better'
ones
get the lower tolerance rating anyway to fill the larger demand in
that market. Which means you can't even 'depend' on the dern
'hole'
being there.
|
This is more useful stuff, if it is true. But here you suggest that
the 1% resistors do *not* have the distribution tails chopped by the
selection process, so you have rather shot yourself in the foot.
Once again, compound resistors, *regardless of the distribution of
their components* will concentrate values around the nominal, and
fewer will be found at the extremes. Also, "holes" near nominal will
be filled in more than those at the extremes.
| Quote: | Assuming distributions when none is specified can lead to
disappointing surprises.
|
You've said that so many times it's stopped making sense.
| Quote: | Now, if you were hand selecting a tighter tolerance from a lower
tolerance batch then pairing them might improve your yield because
there might be more 'good' combinations of offsetting pairs than
solely single values, if the unknown distribution allowed it. But,
then, you can't necessarily count on that. (the manufacturer can
because he knows the distribution)
|
Yes you can count on it. Show me *any* plausible distribution where
it would not be true. Now you are just making things up.
| Quote: | Lastly, to cover the subsequent message, tolerance is the initial
tolerance, at 25C, as delivered to your doorstep and before you
begin
torturing the thing. Everything else, solder, lead stress,
temperature
coefficient, long term drift, surge, voltage stress, temperature
cycling, etc. are in addition to the initial tolerance.
|
What subsequent message? Anyway, if you are correct here
(evidence?), then it does at least mean that it is *possible* they
chop the tails. Altogether you have been quite convincing on that
issue...but where is your evidence?
cheers, Ian
PS More evidence for your chopping...
http://www.keithley.com/data?asset=3871 |
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