1% capacitors source UK

rapid electronics?

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 : snipped-for-privacy@towntarget.com.hk Web-site :

or

"Ian Bell" ???????:44f2d421.0@entanet...

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

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

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

[1% caps]

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

Tim

what

Rubbish.

Where do you think the 1% parts come from ?

Graham

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

%

Yes, I am fairly sure that's true for the axial polystyrene types. Some manufacturers will even produce to +/- 1pF.

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

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

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.

--
Dave Platt                                    AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
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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

"Eeyore" wrote in message news: snipped-for-privacy@REMOVETHIS.hotmail.com...

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.

Any idea what the burn-in was doing ?

Graham

Some 1% parts are individually laser trimmed on automated machinery.

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

in

Perhaps you could explain what for. The values you mention are obviously standard values, and you're probably calculating the value of other L's or R's based on these. Why can't you trim the L's or R's? It's a whole lot easier to remove turns from a toroid, or turn a trimpot, than to try to buy or adjust capacitors (although it's been done, with a grinding wheel).

Alternatively it might be easier to design your circuit for values say

7% higher than those standard values, then sneak up on those values by paralleling capacitors.