REAL semiconductors on eBay

tomchr

Member
Paid Member
2009-02-11 12:58 am
Calgary
www.neurochrome.com
Why buy off eBay when Digikey, Mouser, Newark, Farnell, RS, Jameco, and dozens of other distributors can provide parts directly from the manufacturer, often for a lower cost than what you pay on ePay? I've never understood the rationale there.

An example. I needed a resistor kit for prototyping. Those will set you back about $70-80 from the distributors, so the much lower eBay pricing was attractive. I did my research, found a seller with a good rating who seemed to offer a good product. The resistors were advertised as ±1 % tolerance. Received the resistors. They were indeed marked as ±1 % tolerance, but they measure ±5 % tolerance, if not worse, on my calibrated bench top multimeter. On top of that, the enamel used for the markings is of such poor quality that it rubs off. They're fine for prototyping, but not useful for anything that might reach a customer. I would never use them for an actual build. Lesson learned. I should have bought from the distributor.

Tom
 

pcan

Member
Paid Member
2015-12-31 4:57 pm
The seller makes the difference, I guess. I bought several bargain resistor and film capacitors assortment kits (such as 500Pcs 50 Value 1W Metal Film Resistor @ 10 USD including shipping) from a China-based web site with good reputation. They turned out to be ALL rejects, of course, but all but one proved to be totally usable for prototyping and repair purposes. Many were old stock; the glue on the paper ribbon package at both sides of the axial component was degraded. The components are unfit for mechanical assembly and a bit messy due to tacky glue anywere, but electrical specifications are fine. Other assortment kits looked as they were made by assorted leftovers from pick-and-place reels (maybe too short to be mounted again on the machine for a production run). Other have bent pins, easy to reshape. Some capacitor values were out of specs but most of them checked OK. I never buy expensive semiconductors from this source because they may well be fake, and also electrolytic capacitors because testing them troughly is time consuming and is not worth the effort.
 
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*One place I found online that Specializes in Audio-Grade Components for Speakers:
Erseaudio.com
They sell allot of Polyester & Polypropylene Capacitors, as well as electrolytics.
I have found that they're Polyester & Polypropylene Capacitors are of high quality.
They're electrolytic capacitors are hit & miss, though...
Which is why I use Polyester & Polypropylene on the Crossovers for the Tweeter's & Midrange, sometimes the Woofers. But oftentimes you can't find a 120µf (Or Higher) Polypropylene Cap in the budget. Woofer Capacitors tend to last longer in most speakers, and you usually can't tell the difference when a Woofer Cap is up to 15% out-of-spec.
Also, the way Capacitors wear-out, they usually Gain Capacity, and that brings the low-pass filter up higher, as apposed to loosing sound. When a Midrange or Tweeter Capacitor gains Capacity, you loose the bottom-limit of the sound frequency. A.K.A., 'Rolloff'. And that doesn't sound good.
 

silverprout

Member
2008-04-03 4:19 pm
All the resistors and capacitors that i've bought on ebay are in the tolerances.

I've tested some NPO SMD in boiling water too see if they were rebadged X7R... no derivation at all, not fake.

You should care at the ebay seller reputation !
 
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I have purchased of Ebay for a matter of convenience. My biggest complaint about Mouser or Digikey, or any of the large suppliers, is the lag time of part order vs part arrival.

Also, Ebay sellers, typically provide faster response, when the seller is competing with another seller and feedback actually matters. I also look for the location of the sellers, because I would pay a few dollars extra, to have it here quicker.

The people who repair for a living, tend to want quick turn around. The person who is perhaps building a project, may have different needs.
 
Hit rate: 50-50

I generally avoid buying semiconductors on ebay from Chinese/Hong Kong sites, but with more and more through-hole parts being discontinued, sometimes I have to. Recently I needed to buy some Motorola MC1350 RF amplifier ICs for a project. I bought four from a Chinese site and four from a seller in Oregon. The ones from Oregon looked like genuine NOS. Two of the Chinese ones looked new and two looked like they had been removed from a PC board. They all worked, though. Since this is a unique IC, it would be essentially impossible to substitute another type for it.

A few years ago, a friend was repairing a ham transceiver that needed some special transistors that have high, symmetrical B-E breakdown voltages. These transistors are often used for muting in stereo amplifiers. Worried about fakes, I ordered from two different Chinese sites on ebay. When I received them, I checked them on a curve tracer, and the batch from one dealer had the usual 6V VBE breakdown voltage, thus were re-marked generic NPN transistors. The other batch were indeed the correct type. So the hit rate was 50-50.

- John Atwood
 

tomchr

Member
Paid Member
2009-02-11 12:58 am
Calgary
www.neurochrome.com
My biggest complaint about Mouser or Digikey, or any of the large suppliers, is the lag time of part order vs part arrival.

What lag time is that? My Mouser and Digikey orders arrive overnight as long as I make the cutoff time. Order by early afternoon and get parts the next morning. Free shipping for orders over $100. UPS international shipping. You really can't beat that unless you expect a Digikey/Mouser employee to jump in a car and hand-carry the parts to you.

Even within the US, you can get speedy delivery. You just have to pay the shipping charges. Or go with USPS Priority Mail - same as what the eBay vendors use.

Tom
 

gabe75

Banned
2014-05-20 1:40 am
"You really can't beat that unless you expect a Digikey/Mouser employee to jump in a car and hand-carry the parts to you.

Even within the US, you can get speedy delivery. You just have to pay the shipping charges. Or go with USPS Priority Mail - same as what the eBay vendors use."

+1 for Tom, mouser and digikey are great indeed.
Guys , don't say that eBay sells only junk! It's a market, you have to look around , chose and buy. Don't jump on the first seller , and don't look it up by the lowest price!

I use to sell on eBay , I had audio amplifier chips , power transistors and capacitors.
My items were 100% authentic , and I had 0 complains , many of the diyaudio guys are using my components.
I stopped selling on eBay because eBay sucks . Period . Seller has no rights , buyer can say whatever....
 

tomchr

Member
Paid Member
2009-02-11 12:58 am
Calgary
www.neurochrome.com
Guys , don't say that eBay sells only junk! It's a market, you have to look around , chose and buy. Don't jump on the first seller , and don't look it up by the lowest price!

It's a market with a very high percentage of fake products in certain areas, electronic components being one of these areas. Unless you are buying a product that isn't easy to copy or you're buying from a reputable seller, why buy there at all?

I use to sell on eBay , I had audio amplifier chips , power transistors and capacitors.
My items were 100% authentic , and I had 0 complains , many of the diyaudio guys are using my components.
I stopped selling on eBay because eBay sucks . Period . Seller has no rights , buyer can say whatever....

I've sold a bit on eBay as well and consider myself to be an honest person. So, yes, there are honest people on eBay. I do agree on the eBay policies, though. If a buyer gets buyer's remorse or otherwise feel like returning the item they bought (even if there is a NO RETURNS policy), all they have to do is to file an "Item Not As Described" claim with eBay and they get their money back. No questions asked, no documentation needed from the buyer.

Tom
 
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