Resistor distribution

Oh, man. All that touching, touching, touching with those henna and curry-tainted hands. I think this kind of place only exists because of historical 40% duties into India and non-tariff barriers such as military procurement... otherwise the East Asians (especially China) would put them out of business promptly. Their duty rate now is "only"

18% or so, according to

Best regards, Spehro Pefhany

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And the distie???

You've got to get them into the store buying basics, before you can flog the high-markup crap.

RL

The disty switches brands. They don't like selling what they can't get, either.

Loss leader.

Z*ntronics.. many, many years ago, before Bill Ford went off and started Tech-Trek.

Best regards, Spehro Pefhany

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That's pretty much it. The grocery store has to sell milk at a very competitive price. So they stick it WAAAY in the back so you have to walk past all kinds of high-margin stuff.

Best regards, Spehro Pefhany

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I remember a prof of mine telling a story about how in the 1960's or

1970's he decided to save a bunch of money on 1% resistors by buying a bunch of 5% (or maybe 10% -- I can't remember) resistors and sorting out the ones that were close to the 1% values.

What he found was a batch of resistors whose distribution was a bell- curve-with-holes. He concluded that the manufacturer had the same bright idea before he did.

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RESISTORS INDIA

ugh

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ttdesign.com- Hide quoted text -

Hi Tim, I?ve heard that story so many times. I wonder if it?s just an urban legend? (Has any one every seen for themselves the fabled ?hole? in the resistor distribution?) Hey I?ve got this old case of carbon comp resistors. From a physics Prof. (RIP)

The 4.7Meg drawer had a bunch in there so I measured those. (4.7 Meg, 1/2 Watt, 10%)

About 30 resistors, values ranged from 4.36 to 4.71 Here?s the data,

No obvious hole at 4.7... but not much data either.

George H.

ight

an

Not an urban legend, but............... The manufacturers used to make the best resistors that they could and then sort them. So you could end up with a hole in a normal distribution. But as the manufacturers got better, they had more 1 % resistors than they had a market for them. So some of the 1 % resistors were sold as 5 % resistors.

The same thing applies to semiconductors where one can buy say low leakage diodes in different grades. The manufacturer makes the best ones it can and then sorts for the higher grades.

Dan

bright

st an

Hmm OK, do you have some personal knowledge? So maybe it was only for a few years that there was a hole in the distribution? (My old resitor box doesn't have any old 5% ers, Maybe there is no hole in the 10% R's?)

Seems if you had a excess of 1% resistors then you should lower the price.

George H.

The same applies to microprocessors, and I'm sure memory. As they get better at producing the parts the yield of the higher speed/lower power parts goes up. Of course the orders are for what they are. The two have to match somehow. One can adjust price and specs to get them in line over the long run but in the short run one goes into battle with the weapons one has.

bell-

bright

just an

Suddenly, i suspect that this was/is a short term stopgap method to ship sufficient quantity of the tighter tolerance units used by various manufacturers as they got their processes under better control.

?-)

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I think the whole story is that CARBON COMPOSITION resistors are made with good temperature coefficient but poor value control. So, there are +/-20% bins in the early factories. Ageing is a problem. Tighter initial-value control is not useful on the oldest production.

Ageing is solved, so manufacturers create +/- 10% bins, and paint a pretty silver ring on the premium product. Then it's

5% bins, with a pretty gold ring. Today, we've also got red rings, +/- 2% bins, but that's for easily-trimmed carbon film resistors, and higher precisions are mainly metal (wire, film, foil) which is easier to mass-produce in controlled fashion.

So, you'd get distribution gaps whenever manufacturer B wanted to compete against manufacturer A's new tighter tolerance parts, without having A's new tighter tolerance plant.

But even if the mean is off, they are still in tolerance, right?

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Good ones are! I think all the 1% resistors that I checked lately were well within 1%. A reel is usually clustered around some mean value that's a bit off.

But lots of people make cheap resistors. I sure somebody does it badly.

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