Be very careful when ordering resistors from china !

[Scott Stites]

I'd be very, very surprised if you could find anything but specialty resistors found manufactured in the USA. The point being, just about anything you buy, good or bad, is going to be made in that region of the world these days.

It boils down more to reputable/trustworthy dealers more than anything. I'm with Servo - 1% metal film can be had (here) from Mouser at a price that would befuddle a time traveler from the '70s. If Mouser (or your good dealer of choice) gets scammed, they'll take the heat and you'll not be out your money. Bottom line is, they're very unlikely to get scammed, and, by extension, you won't either.

My advice is to save your exotic purchases for stuff you just can't find anywhere else.

[v-un-v]

Nicely put Scott.

[glacial23]

[Scott Stites]

Probably assembled from parts made in Asia.

[simmeau]

It's interesting because I'd never really given them much thought and just assumed that they were 1% which is quite ridiculous given that they are are around 1/5th the cost of metal films on futurlec. I won't be using them where 1% is specified anymore. But still even if you view them as 5% carbon film, at $13.50 us for 2000 ish (what mine cost), they are still 0.67c each which is pretty hard to beat.(futurlec carbons run at 1c each) And they come in 50 value packs which are quite hard to find. Just out of curiosity, how would they stack up against carbon films made in the 70's?

[cthulu]

When it comes to "china or not..." I think the edges are kind of blurry... Nowadays companys, even smaller ones,
are working really close with eachother over the borders. Some components, no matter what brand are
stamped on them, come from the very same factory. If you get a chinese component in your hand then there was
an american or european company involved. The resistors measuring wrong could very well have just been
put on the wrong shelf by a hyperactive co-worker and come frome the same middle hand.
Some five years ago I was working with circuit board test and repair in a company that made some really hightech
stuff. We shipped to NASA...
During this time we had two incidents in production that came from malfunctioning components/ IC's.
1. A Maxim RS232 chip that was cracked open and found to have errors like scratches or residues from etching
or both, clearly visible in a scope.
2. A Linear chip who wouldn't live up to the spec's.
The impression I got from these two companies was that Maxim was very open about wrong batches and that Linear
wouldn't admit their IC's being, faulty, but the chip was made obsolete. I don't know or think that Maxim and Linear
differs in company ethics but it could have been the nature of the faults that made them act differently. It's easier
to say something is wrong when you can add a picture with a scratch on it because even the catering personel
could see that something wasn't right. I think what I'm trying to say is that when you get to speak to one of those
old engineers that have been around and now work as consultants the picture is getting more complex and rather
often issues that come up are social/cultural rather than technical.

[wmonk]

Tested my 'metal film' resistors from Sure today. Picked 5 different values.
All have iron leads, and the value drops when heated.
I used a 'bain-marie' to heat the resistors. I didn't check it very precisely, but there was clearly a trend: the value drops.

I'll buy metal film resistors for most projects now. What to do with these fake resistors?

[gwaidan]

Hmmm, last lot of "metal film" resistors I got from Futurlec had very thin leads and some of the value bands were very roughly painted, and I was suspicious at the time...

I just tried a highly scientific test with the 1k and 100k resistors I received in that batch (holding them up right under a quartz halogen lamp!)-the resistance of all of the 1k resistors dropped by about 0.67% (which matched a 5% carbon film), but all of the 100k resistors stayed rock-steady, as did "known good" metal film resistors.

Guess the 1K parts will be good for any non-critical uses (ie audio path) but it would be nice to have received what I paid for....

[Ricko]

I think people are jumping to a conclusion when they think that the vendor is unscrupulous if they get some dud product from them. If you get bad product, report it to the vendor before slagging off at them in a public forum: I would have thought that was basic manners. It may be the manufacturers mistake or misdeed, in which case it could propogate to any vendor, not just "Chinese" ones. Futurlec (who operate out of Thailand: I have seen their office) would probably be horrified, for example.

-----------------------

Now to the point. The graph that showed the comparative resistance to temperature plots of several different resistors.

So if we had a metal film and carbon resistor of appropriate values in parallel, we could largely cancel out temperature effects, is that right?

For example, in the plot the Conrad increased .01 of a volt and the carbons decreased by .12 or .16 of a volt. So if we had a 33k metal in parallel with a 500k carbon (i.e. 15 times the value), we would get a 30k resistor with very little drift.

Assuming that is correct, is there any point? (Resistor drift in opposite direction to the transistor drift might be good for example.) Is there much point in reducing resistor drift to lower tolerances than Conrad-style metal film resistors? (Not a rhetorical question, I am really interested in info or thoughts.)

[gwaidan]

I certainly didn't mean to imply that Futurlec were complicit in this-for the record my last order from them had a more serious problem which they rectified promptly, graciously and at their expense, so I don't doubt their commitment to their customers.

What is worth noting is that a well-known supplier outside of China which has been mentioned in this thread as trustworthy has been caught up by this scam, and most likely they're not the only one...

[urbanscallywag]

Thanks for this post. I actually have some of the Sure Electronics resistors and make a point to test ~10 of every value of resistor. I've almost always found them to be within 1%, but I never thought of heating them.

[LetterBeacon]

*bump*

I'm going to buy a whole bunch of CA3080s from eBay, and all the sellers appear to be located in Hong Kong. Does anyone have any experience with buying CA3080s from Hong Kong sellers? Did the CA3080s work well enough?

[Tim Servo]

You might want to check Futurlec. They've been very reliable in my experience, and they show the 3080 in stock at about $2 each.

Tim (loves a good parts source) Servo

[LetterBeacon]

Great, thanks a lot, I didn't realise they delivered to the UK. It only works out £1 more to get 10 delivered and I'd rather pay the extra £1 and buy from a proper company.

[gwaidan]

I bought some 3080s from Hong Kong a year ago and some of them had blue marker pen marks on them, as if they had been tested after being pulled from old equipment. Never again - I'll buy them from Futurlec next time.

[ickystay]

Sure Electronics is now using a graph similar to Sine's to verify that their stock are real metal film. See auction #230367339299. Pity they're not 1%ers..

[Sine]

Sure found a new way alright, They found my graph !

Look at the graph from the ebay auction and at the one I posted at the beginning of this thread, they changed te values an colours ( badly ) and called it their own.

Even my measurement error between 40 and 50 degrees is there, and to show they have no clue what they are talking about they kept the resistor measured with te lowest resolution meter as "their" resistor. A metal film increases a tiny bit in value.

Good job guys !

[blue hell]

[Uncle Krunkus]

Well,
That's just got "integrity" written all over it hey?!?

[Tasmanian Alkaloid]

That's bizzare! I wonder how they found it?

[daverj]

[blue hell]

[daverj]

Please note, I didn't encourage anybody to do anything..

I merely quoted "gubbeper" where he said that he encouraged them to come to this thread

[blue hell]