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1% capacitors source UK

Discussion in 'Electronic Components' started by Ian Bell, Aug 28, 2006.

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  1. Ian Bell

    Ian Bell Guest

    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
     
  2. rapid electronics?
     
  3. Dear Ian,

    We are ready to supply you once you are interested to our company.

    Our contact is as following :

    Thanks !

    --
    Patrick Cheung
    townt.com
    Address : 1805, Wu Sang House, 655 Nathan Road, Mongkok, Kowloon, Hong Kong
    Tel : +852-25055838
    Fax : +852-25058121
    E-mail :
    Web-site : http://www.townt.com/towne/ or http://www.towntarget.com.hk
     
  4. Ian Bell

    Ian Bell Guest

    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
     
  5. Eeyore

    Eeyore Guest

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

    Graham
     
  6. Ian Bell

    Ian Bell Guest

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

    Ian
     
  7. Ross Herbert

    Ross Herbert Guest


    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.
     
  8. Eeyore

    Eeyore Guest

    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
     
  9. Tim Auton

    Tim Auton Guest

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


    Tim
     
  10. Eeyore

    Eeyore Guest

    Rubbish.

    Where do you think the 1% parts come from ?

    Graham
     
  11. Tim Auton

    Tim Auton Guest

    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
     
  12. Ross Herbert

    Ross Herbert Guest


    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.
     
  13. Eeyore

    Eeyore Guest

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

    Graham
     
  14. Ross Herbert

    Ross Herbert Guest

    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
     
  15. Tim Auton

    Tim Auton Guest

    Wrong on what? Be specific.
    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
     
  16. Ian Bell

    Ian Bell Guest

    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
     
  17. Eeyore

    Eeyore Guest

    There are planty of lines available as 20, 10 and 5 % though.
    They go back in the bin as 5% or whatever. The demand for 1% is so low as to
    make it inconsequential.

    Graham
     
  18. Dave Platt

    Dave Platt Guest

    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.
     
  19. Eeyore

    Eeyore Guest

    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
     
  20. 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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