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1% capacitors source UK

I

Ian Bell

Jan 1, 1970
0
I am looking for a source of small quantities of 1% tolerance capacitors in
the UK. Values needed are 1.2nF, 22nF and 68nF. Farnell do them but they
have a minimum £20 order.

Ian
 
I

Ian Bell

Jan 1, 1970
0
martin.shoebridge said:
rapid electronics?

Nope, tried them and RS and Maplin. Few have any 1% caps and fewer have the
values I want. Only Farnell has the lot so far but they add up to £5 worth
and their minimum order is £20.

Ian
 
E

Eeyore

Jan 1, 1970
0
Ian said:
Nope, tried them and RS and Maplin. Few have any 1% caps and fewer have the
values I want. Only Farnell has the lot so far but they add up to £5 worth
and their minimum order is £20.

Can't justify anything else to pad the order out ?

Graham
 
I

Ian Bell

Jan 1, 1970
0
Eeyore said:
Can't justify anything else to pad the order out ?

Graham

That is my current best option but thought I'd ask here first just in case.

Ian
 
R

Ross Herbert

Jan 1, 1970
0
That is my current best option but thought I'd ask here first just in case.

Ian


If you have a cap meter take it down to a place which stocks 5% caps
and go through them and select the 1% items. Of course, this will only
work if they will let you loose on their stock - self service parts
retailers do.
 
E

Eeyore

Jan 1, 1970
0
Ross said:
If you have a cap meter take it down to a place which stocks 5% caps
and go through them and select the 1% items. Of course, this will only
work if they will let you loose on their stock - self service parts
retailers do.

I have had to do something similar in the past as it happens.

If you need 10 x 1% parts buy maybe 50 x 5% parts and you'll probably get what
you're looking for.

Graham
 
T

Tim Auton

Jan 1, 1970
0
Eeyore said:
Ross Herbert wrote: [1% caps]
If you have a cap meter take it down to a place which stocks 5% caps
and go through them and select the 1% items. Of course, this will only
work if they will let you loose on their stock - self service parts
retailers do.

I have had to do something similar in the past as it happens.

If you need 10 x 1% parts buy maybe 50 x 5% parts and you'll probably get what
you're looking for.

It's not all about initial accuracy. 5% parts generally have poorer
temperature coefficients and long-term stability than those with tighter
tolerances.


Tim
 
E

Eeyore

Jan 1, 1970
0
Tim said:
Eeyore said:
Ross Herbert wrote: [1% caps]
If you have a cap meter take it down to a place which stocks 5% caps
and go through them and select the 1% items. Of course, this will only
work if they will let you loose on their stock - self service parts
retailers do.

I have had to do something similar in the past as it happens.

If you need 10 x 1% parts buy maybe 50 x 5% parts and you'll probably get what
you're looking for.

It's not all about initial accuracy. 5% parts generally have poorer
temperature coefficients and long-term stability than those with tighter
tolerances.

Rubbish.

Where do you think the 1% parts come from ?

Graham
 
T

Tim Auton

Jan 1, 1970
0
Eeyore said:
Tim said:
Eeyore said:
Ross Herbert wrote: [1% caps]
If you have a cap meter take it down to a place which stocks 5% caps
and go through them and select the 1% items. Of course, this will
only work if they will let you loose on their stock - self service
parts retailers do.

I have had to do something similar in the past as it happens.

If you need 10 x 1% parts buy maybe 50 x 5% parts and you'll probably
get what you're looking for.

It's not all about initial accuracy. 5% parts generally have poorer
temperature coefficients and long-term stability than those with tighter
tolerances.

Rubbish.

Where do you think the 1% parts come from ?

Sometimes different materials, sometimes a different process, sometimes
they are the same thing as lower tolerance parts but sorted/graded. Only
in the latter case would sorting 5% parts get you the equivalent of what
is sold as a 1% part. For example, you can buy 5% ceramic caps with X7R
dielectric. I probably wouldn't want X7R for my '1%' capacitors, what
with its 15% change in capacitance over temperature and 1% per decade
ageing.

You can buy 5% cermaic caps with C0G dielectric though. Sorting them
might be worthwhile, if stability and matched values is what you're
after. If you want within 1% of the nominal value you'd best hope all
those ones haven't already been sorted out by the manufacturer.


Tim
 
R

Ross Herbert

Jan 1, 1970
0
Eeyore said:
Tim said:
Ross Herbert wrote:
[1% caps]
If you have a cap meter take it down to a place which stocks 5% caps
and go through them and select the 1% items. Of course, this will
only work if they will let you loose on their stock - self service
parts retailers do.

I have had to do something similar in the past as it happens.

If you need 10 x 1% parts buy maybe 50 x 5% parts and you'll probably
get what you're looking for.

It's not all about initial accuracy. 5% parts generally have poorer
temperature coefficients and long-term stability than those with tighter
tolerances.

Rubbish.

Where do you think the 1% parts come from ?

Sometimes different materials, sometimes a different process, sometimes
they are the same thing as lower tolerance parts but sorted/graded. Only
in the latter case would sorting 5% parts get you the equivalent of what
is sold as a 1% part. For example, you can buy 5% ceramic caps with X7R
dielectric. I probably wouldn't want X7R for my '1%' capacitors, what
with its 15% change in capacitance over temperature and 1% per decade
ageing.

You can buy 5% cermaic caps with C0G dielectric though. Sorting them
might be worthwhile, if stability and matched values is what you're
after. If you want within 1% of the nominal value you'd best hope all
those ones haven't already been sorted out by the manufacturer.


Tim


You are wrong on this Tim. As Eeyore says, "where do you think the 1%
items come from?"

The manufacturer doesn't go around changing his process on any
particular type of capacitor so that he specifically produces 1%, 2%
or any other value. It is a fact that production variations produce
the whole range of tolerances from rejects to perfect value in any
particular batch. Now after sorting the 1% values do you imagine that
all the rest are going to be rejects? It is possible to dredge 1%
items from the 5% range without any other characteristics being
affected.
 
E

Eeyore

Jan 1, 1970
0
Ross said:
Eeyore said:
Tim Auton wrote:
Ross Herbert wrote:
[1% caps]
If you have a cap meter take it down to a place which stocks 5% caps
and go through them and select the 1% items. Of course, this will
only work if they will let you loose on their stock - self service
parts retailers do.

I have had to do something similar in the past as it happens.

If you need 10 x 1% parts buy maybe 50 x 5% parts and you'll probably
get what you're looking for.

It's not all about initial accuracy. 5% parts generally have poorer
temperature coefficients and long-term stability than those with tighter
tolerances.

Rubbish.

Where do you think the 1% parts come from ?

Sometimes different materials, sometimes a different process, sometimes
they are the same thing as lower tolerance parts but sorted/graded. Only
in the latter case would sorting 5% parts get you the equivalent of what
is sold as a 1% part. For example, you can buy 5% ceramic caps with X7R
dielectric. I probably wouldn't want X7R for my '1%' capacitors, what
with its 15% change in capacitance over temperature and 1% per decade
ageing.

You can buy 5% cermaic caps with C0G dielectric though. Sorting them
might be worthwhile, if stability and matched values is what you're
after. If you want within 1% of the nominal value you'd best hope all
those ones haven't already been sorted out by the manufacturer.


Tim

You are wrong on this Tim. As Eeyore says, "where do you think the 1%
items come from?"

The manufacturer doesn't go around changing his process on any
particular type of capacitor so that he specifically produces 1%, 2%
or any other value. It is a fact that production variations produce
the whole range of tolerances from rejects to perfect value in any
particular batch. Now after sorting the 1% values do you imagine that
all the rest are going to be rejects? It is possible to dredge 1%
items from the 5% range without any other characteristics being
affected.

I do know of a couple of capacitor lines where all the production is say 1 or 2 %
but these are quite rare.

Graham
 
T

Tim Auton

Jan 1, 1970
0
Ross Herbert said:
You are wrong on this Tim.

Wrong on what? Be specific.
As Eeyore says, "where do you think the 1%
items come from?"

Did you read my post? I just explained that. You have to ask yourself
"where do the 5% items come from?". Merely specifying '5%' isn't enough,
as (for example) 5% ceramic capacitors might come from the line
producing 1%-5% items of one type (eg C0G), or they might come from the
line producing 5%-20% items of another type (eg X7R). You need to
specify the right type too. The difference is likely to be significant
in any application where you'd want a 1% item in the first place.


Tim
 
I

Ian Bell

Jan 1, 1970
0
Ross said:
On Wed, 30 Aug 2006 03:52:33 +0100, Eeyore


Yes, I am fairly sure that's true for the axial polystyrene types.
Some manufacturers will even produce to +/- 1pF.
http://www.lcrcapacitors.co.uk/fsc.htm

My research confirms this too. All the 1% types I have found are unique - in
other words there are no 5% types that are also available as 1% and vice
versa. So if 1% types are selected, what happens to all the rejects???

ian
 
E

Eeyore

Jan 1, 1970
0
Ian said:
My research confirms this too. All the 1% types I have found are unique - in
other words there are no 5% types that are also available as 1% and vice
versa.

There are planty of lines available as 20, 10 and 5 % though.
So if 1% types are selected, what happens to all the rejects???

They go back in the bin as 5% or whatever. The demand for 1% is so low as to
make it inconsequential.

Graham
 
D

Dave Platt

Jan 1, 1970
0
My research confirms this too. All the 1% types I have found are unique - in
other words there are no 5% types that are also available as 1% and vice
versa. So if 1% types are selected, what happens to all the rejects???

Based on what I've heard, it's likely that those parts which don't hit
one of the special-selection points (e.g. the 1% values) simply get
dropped into the next-less-precise binning category.

I've been told that if you buy a sufficiently-large number of (e.g.)
5% resistors from a reliable vendor, and measure them accurately,
you'll find that they do fall within the 5% accuracy window, but that
you're likely to notice a significant "dip" in the number of parts
which fall within 1% of the marked value. The probability
distribution ends up with two peaks - one above the rated value and
one below. The parts coming through the line which measured out
accurately were selected out and sold as 1% parts; the remainder were
sold as 5% parts.

[I haven't actually tried this experiment myself... consider it
folklore of uncertain heritage.]

By a rough analogy, if you buy "2N3055" power transistors from several
different vendors, you may end up with transistors which all meet the
(very loose) 2N3055 part specs, but which may exceed the specs by very
different amounts in different respects. The "2N3055" parts may very
well be manufactured from dice which were intended for different part
numbers, failed to test out well enough to meet those specs, and were
simply binned as 2N3055s rather than being thrown away.
 
E

Eeyore

Jan 1, 1970
0
Dave said:
My research confirms this too. All the 1% types I have found are unique - in
other words there are no 5% types that are also available as 1% and vice
versa. So if 1% types are selected, what happens to all the rejects???

Based on what I've heard, it's likely that those parts which don't hit
one of the special-selection points (e.g. the 1% values) simply get
dropped into the next-less-precise binning category.

I've been told that if you buy a sufficiently-large number of (e.g.)
5% resistors from a reliable vendor, and measure them accurately,
you'll find that they do fall within the 5% accuracy window, but that
you're likely to notice a significant "dip" in the number of parts
which fall within 1% of the marked value. The probability
distribution ends up with two peaks - one above the rated value and
one below. The parts coming through the line which measured out
accurately were selected out and sold as 1% parts; the remainder were
sold as 5% parts.

[I haven't actually tried this experiment myself... consider it
folklore of uncertain heritage.]

By a rough analogy, if you buy "2N3055" power transistors from several
different vendors, you may end up with transistors which all meet the
(very loose) 2N3055 part specs, but which may exceed the specs by very
different amounts in different respects. The "2N3055" parts may very
well be manufactured from dice which were intended for different part
numbers, failed to test out well enough to meet those specs, and were
simply binned as 2N3055s rather than being thrown away.

This does happen. Back in 1980 ! I had some trouble with RCA's version of
Motorola's MJ410. Some batches of RCA410s would oscillate in an audio amplifier. I
took the lids off and found 3 dice in use. All were indeed drop-outs from other
lines that passed the MJ410 spec it turned out.

RCA Europe were obliged to 'fess up' and from them one we simply ordered the ones
that worked OK ( the 3 different types had a specific 'hard code' stamped on the
header ).

Graham
 
H

Homer J Simpson

Jan 1, 1970
0
This does happen. Back in 1980 ! I had some trouble with RCA's version of
Motorola's MJ410. Some batches of RCA410s would oscillate in an audio
amplifier. I
took the lids off and found 3 dice in use. All were indeed drop-outs from
other
lines that passed the MJ410 spec it turned out.

I recall a tube stereo receiver amplifier which was OK when new, but when
the tubes ran in it would oscillate at supersonic frequencies and burn out
the undersized output transformers. I put half shields around the base of
the output tubes which stopped the oscillation.
 
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