Chinese resistors on eBay - opinions?

Hey guys,

Just wondering what peoples opinion is of the boxes of metal film resistors for incredibly dirt cheap prices.  I seem to be able to get between 1500 and 2500 for $15.00 including shipping.  This is way below 1 cent.

I did purchase a box of these resistors.  They came quickly.  Seem to work well but I don't really know about resistors failing outside of using them out of spec.

So what are peoples thoughts (before I order another box!)

CC

If you can't measure or hear a difference you probably shouldn't worry about it.

JR

Try measuring it to see if it's within the 1% tolerance.

You know, you can buy 1000pc boxes of 1% metal film resistors for $12 each at Mouser.

I bought a kit of those resistors from china, like 50 of each value or something.
I think they are 5% carbon, as opposed to 1% metal film, as advertised.
They measure more than 1% off the nominal, and change value when heated, more than metal film supposed to...
Cheap though!
:

Modern resistors are MILES better than the stuff most "vintage" designers could dream of.

Probable problems:

* Carbon-film mis-sold as "metal film". That's a rip-off, but not a problem: modern carbon film is WAY better than old carbon-composition, and in some ways better than wire-wound.

* Low Wattage. Everything is battery or wall-wart now, 1/4 watt is now standard unless it is 1/8 watt. Now, at least half the places I used to fling 1/2W parts could be fine with 1/16W or even 1/100W (what is the dissipation in a grid resistor?). But there are some places where you need real dissipation. 12AU7 plate resistors, 50L6 cathode resistor, bootstraps on a 40W Fisher stereo.

"Wattage" -may- also affect noise in some systems. bcarso said he traced excess hiss to some very small SMD resistors.

> see if it's within the 1% tolerance.

I suspect that is not a problem. It may be possible to buy rejects, but when there is a steady supply of specific values, it is probably regular production, same as they sell to Sony, Honda, Asus, Apple.

In the old-old days, they mixed rough proportions of clay and coal-dust, got a wide range of values, and bin-sorted. The rationalized number sequence is about being sure there is a bin for every possible random value. And I'm sure there is a machine to put the stripes on now.

But carbon-film is a potentially precise process. In small batches, 99% of parts may be 1% value. When pushing large batches for lowest price, 2%-off seems to be common, so I bet very few are 5% out.

And really: there are very few places in an audio system which need better than 5%. Gain-matching between left and right is about the only place I would aim tighter. OK, differential amplifiers with high CMRR. If something "depends" on 1% or the gig is ruined, the design should be re-considered.

I would look at the paint. Maybe there is a cheap way to do it perfect. And rough paint may have zero effect on function or life. And I have seen some very fine products which routinely had cosmetic blemishes. But pinholes, skips, bubbles, etc, would make me dubious.

Thanks for your thoughts.  They list the specs.  Now is there a nice easy way to blow one up if it is lower than 1/4 watt?  My multi meter is reasonably accurate - they seem to be good within 1% assuming my MM is within spec.  I don't have a way (that I know of) to test the resistance when it's hot - to see if of changes.

Sounds like PRR may be of the opinion to go for it again.

BTW the paint looks ok.
CC

Buying from Chinese suppliers on e-bay is a hit or miss. I once purchased power regulator ICs. They were all junk. So few hunded pounds went down the drain. On the other hand I bought 5000 pieces of 16,000mcd blue LEDs from a Hongkong supplier, who purchased them from China and they were abosultely spot on saving me hundreds of pounds. By the way on the LEDs, between my bro and I our record is soldering around 16,000 nodes in one and a half day for making clusters.

Ive bought several of these Packs and they aren"t bad ... I believe they are metal film but they definately aren"t 1% parts closer to 2-5% , the leads are a bit thinner than standard Metal films but overall they aren"t bad ... I believe the company on e-bay I bought mine from was called "Sure Electronics" .....

Cheers

There are even larger packs from Hong Kong - anyone know if they are the same thing?

I've ordered a set so will let you know when they arrive !

MM

the resistors from mouser are made in china / taiwan too.
if they measure close to the stated resistance, I'd imagine they're as good as any other metal films.

kato said:

the resistors from mouser are made in china / taiwan too.
if they measure close to the stated resistance, I'd imagine they're as good as any other metal films.

Click to expand...

My thoughts also !

MM

MartyMart said:

kato said:

the resistors from mouser are made in china / taiwan too.
if they measure close to the stated resistance, I'd imagine they're as good as any other metal films.

Click to expand...

My thoughts also !

MM

Click to expand...

Ditto!

My question would be:

Did they make your hands glow after you touched them?

I purchased a pack from a Hong Kong supplier.  I had doubts so I always measure them before soldering.  This has improved my build skills and I realised that I should measure and check everything as I go.  I am yet to find any more than 1-2% out, but I have found some incorrectly marked, or so I thought.  I find it difficult to tell brown from red sometimes as do many men.

Seedysea said:

I find it difficult to tell brown from red sometimes as do many men.

Click to expand...

Easy tiger !!!    ;D

MM

MartyMart said:

Seedysea said:

I find it difficult to tell brown from red sometimes as do many men.

Click to expand...

Easy tiger !!!    ;D

MM

Click to expand...

I don't know what you mean. I've never had a problem with this!

Oooops.

I must have meant:



and:

My resistor pack arrived this morning :

So, after several measurements I would say they are more like 5% tolerance or worse, which is OK.
EG- 6k8's measure from 6k58 to 6k65 ( from sample of about 15 of them ) I didn't find one that was
actually 6k8 at all.

The leads are very thin, I have used similar ones before with no issue but if you bend the lead 4-5 times
they will break off !
..... so don't do that

MM.

I remember reading test results and comments on Electro-music.com of chinese resistors bought from ebay.
At least one person had received resistors that were supposed to be 1% but were actually closer to 5%... And some of the resistors did actually change their resistance permanently after heating which is even worse than regular carbon types! 
It might be useful to measure how the resistance recovers after heating as well, just for certainty.

As I said in another thread, "if it's too good to be true..."
For general experimentation, personal DIY projects these will do. For breadboarding, it will be a pain.


BTW, 10 resistors picked randomly from my pile of 10K 1% Mouser resistors

(in Kohms)
9.966
9.981
9.972
9.974
9.965
9.962
9.971
9.951
9.967
9.944

All less than 1%