Author Topic: Price Difference between Digikey and Aliexpress  (Read 15831 times)

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Online janoc

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Re: Price Difference between Digikey and Aliexpress
« Reply #25 on: May 31, 2017, 08:58:37 am »
Even if the AliExpress chips were genuine, you can't really compare it like this. Don't forget the US costs of labor, electricity, shipping by UPS, customer service, warranty, etc. that you pay in the Digikey price. That stuff isn't for free and shows up in the price of the product.

The AliExpress vendor could well be a small mom&pop store operating from a shack somewhere in Shenzen with minimal expenses, shipping by the cheapest and slowest postal service. And good luck getting customer service or warranty claim from them - most I had to deal with were genuinely  trying to help and to fix any problems but it is far from the same level of service as Digikey (or another major vendor). By buying from a large distributor you are literally also paying for having someone available on the phone that you can scream at should they screw up. That is important for business clients (who are the majority of their customers).

Also LM2596 are fairly old parts, running at low frequencies, thus requiring massive inductors. I would probably look for a newer part for a new design.
« Last Edit: May 31, 2017, 09:03:13 am by janoc »
 
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Offline Kean

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Re: Price Difference between Digikey and Aliexpress
« Reply #26 on: May 31, 2017, 02:38:09 pm »
Very good chance they are fake LM2596 - operationally similar, but poor quality.  I have some boards from ebay & AliExpress using this chip (very common on ebay, I think these were the ones with a voltage display).  They worked fine for a few days before basically failing in the worst possible way, putting the 24V input straight out onto the 5V rail.  They were running nowhere near their full rating, or getting particularly warm.
 

Offline krho

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Re: Price Difference between Digikey and Aliexpress
« Reply #27 on: June 01, 2017, 04:57:51 am »
Yelling at someone from digikey/mouser doesn't help you when the fuck up and order the chip which has a lead time of 14 weeks in the wrong package. (Yes, we provided the correct one.) And then you have to wait another 14weeks to get the chips. And you fail to launch the product at the right time because of that.
 

Offline dmills

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Re: Price Difference between Digikey and Aliexpress
« Reply #28 on: June 01, 2017, 10:34:24 am »
That sort of fuck up on a preprod run is what the grey market is for.

Note that there are grey market vendors and grey market vendors, use someone respectable (Usually means paying MORE then list) and you have an excellent chance the parts are genuine, you are paying for the lack of a 14 week leadtime.

My personal hate on is for distributors who have their own house numbered products (Farnell Multicomp, looking at you), especially when some prat designs in something like a Multicomp SD card socket that then goes on 20 weeks leadtime, because you are NOT going to find that part anywhere else. 

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Online janoc

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Re: Price Difference between Digikey and Aliexpress
« Reply #29 on: June 01, 2017, 01:53:47 pm »
Very good chance they are fake LM2596 - operationally similar, but poor quality.  I have some boards from ebay & AliExpress using this chip (very common on ebay, I think these were the ones with a voltage display).  They worked fine for a few days before basically failing in the worst possible way, putting the 24V input straight out onto the 5V rail.  They were running nowhere near their full rating, or getting particularly warm.

 :o Yikes!

I have two or three such modules too, only without displays. I have planned to use them with some microcontroller to get some "brains" for my Roomba long time ago. I guess I better build that dummy load that I am putting off for months and test them first.

However, it is very common that the Ali/eBay ads will advertise these as 3-5A modules (the maximum current from the datasheet) - except that module has often no or very inadequate heatsinking and then people wonder ... That likely haven't been your case but it is another very common issue with these devices.
 

Offline Kjelt

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Re: Price Difference between Digikey and Aliexpress
« Reply #30 on: June 01, 2017, 04:21:41 pm »
Add a fuse and crowbar circuit @6V to the output and you can sleep again  ;)
 

Offline ebclr

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Re: Price Difference between Digikey and Aliexpress
« Reply #31 on: June 01, 2017, 04:40:59 pm »
Finally a decent point of view

"Even if the AliExpress chips were genuine, you can't really compare it like this. Don't forget the US costs of labor, electricity, shipping by UPS, customer service, warranty, etc. that you pay in the Digikey price. That stuff isn't for free and shows up in the price of the product."

It's obvious that Digikey labor, cost is an order of magnitude higher than any China company, Also in USA a company need to expand a huge money on attorneys due to how people love to sue others there, and this is why China components are cheaper.

The fools like to point as is fake, but this isn't what really what happens, is very easy to find real and original component cheaper in China. Of course, the ones extra cheap( I mean less than average in a China) have a probability of having sort kind of problems, China component volume is 2 orders of magnitude higher than any other country, and is quite easy to find high-quality components on sale for less than high volume factories price for an immense  sea of reasons other than being fake.
 

Offline edavid

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Re: Price Difference between Digikey and Aliexpress
« Reply #32 on: June 01, 2017, 05:23:31 pm »
The "LM2596" parts that you commonly find on AliExpress are remarked Chinese ICs that are similar to the LM2576.
They are probably perfectly good parts, if you had the real datasheet.

If you want to buy from AliExpress, I suggest sticking with Chinese parts such as XL4015 - you have a much better chance of getting what you expect.

 

Offline ebclr

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Re: Price Difference between Digikey and Aliexpress
« Reply #33 on: June 01, 2017, 06:15:42 pm »
Do you have any statistically valid evidence of your claim?
 

Online janoc

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Re: Price Difference between Digikey and Aliexpress
« Reply #34 on: June 01, 2017, 07:10:31 pm »
Add a fuse and crowbar circuit @6V to the output and you can sleep again  ;)

Or just ditch the junkers.
 

Offline Habropoda

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Re: Price Difference between Digikey and Aliexpress
« Reply #35 on: June 01, 2017, 07:30:03 pm »
The "LM2596" parts that you commonly find on AliExpress are remarked Chinese ICs that are similar to the LM2576.
They are probably perfectly good parts, if you had the real datasheet.

If you want to buy from AliExpress, I suggest sticking with Chinese parts such as XL4015 - you have a much better chance of getting what you expect.

The LM2596 modules I have purchased in the last couple of years run at about half of the 150khz they are supposed to run at and have poor ripple, so they are remarked chips for sure.  Modules I purchased years ago run at 150k and have the expected ripple.

Many products seem to have gotten worse over time.  Recently I got some 18ga wire, marked as such, that was half that.  I also got some of those so called Dupont ribbon cables but I could pick them up with a magnet.

I'm buying more stuff from Digikey these days.
 

Offline Kjelt

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Re: Price Difference between Digikey and Aliexpress
« Reply #36 on: June 01, 2017, 08:40:37 pm »
I must say I used quite a bit of those fake modules but at limited current like 750mA or so.
 

Online wraper

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Re: Price Difference between Digikey and Aliexpress
« Reply #37 on: June 01, 2017, 10:38:08 pm »
My personal hate on is for distributors who have their own house numbered products (Farnell Multicomp, looking at you), especially when some prat designs in something like a Multicomp SD card socket that then goes on 20 weeks leadtime, because you are NOT going to find that part anywhere else.
The only thing you need is figuring out original part number which is quiet easy in most cases.
 

Offline Kean

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Re: Price Difference between Digikey and Aliexpress
« Reply #38 on: June 02, 2017, 10:21:39 am »
Very good chance they are fake LM2596 - operationally similar, but poor quality.  I have some boards from ebay & AliExpress using this chip (very common on ebay, I think these were the ones with a voltage display).  They worked fine for a few days before basically failing in the worst possible way, putting the 24V input straight out onto the 5V rail.  They were running nowhere near their full rating, or getting particularly warm.

 :o Yikes!

I have two or three such modules too, only without displays. I have planned to use them with some microcontroller to get some "brains" for my Roomba long time ago. I guess I better build that dummy load that I am putting off for months and test them first.

However, it is very common that the Ali/eBay ads will advertise these as 3-5A modules (the maximum current from the datasheet) - except that module has often no or very inadequate heatsinking and then people wonder ... That likely haven't been your case but it is another very common issue with these devices.

I was running them at less than 1A - powering a Raspberry Pi and some custom sensors and controls, all from a DIN rail PSU.

Actually I just checked, and I was mistaken - the one that never failed was actually the one with the LED V/I display.  The ones without displays were the ones that needed a crowbar, and not of the electronic type  >:D

Anyway, I may have just got a bad/dodgy batch, but I'm extra cautious now with cheap stuff I get from AliExpress or ebay.  I don't care much if an OLED display or I2C sensor breakout I'm using to prototype with fails, but I really don't like valuable stuff going up in smoke.  In this case I was just planning to use them during prototyping on the bench.  I replaced them with my own custom DIN rail DC/DC converter modules, as most of the ones on the market are silly expensive.
 

Offline Psi

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Re: Price Difference between Digikey and Aliexpress
« Reply #39 on: June 02, 2017, 12:06:43 pm »
Usually, if you look at all the aliexpress sellers who are offering the IC you're after and order by price you can see where the price jumps and where they are more likely to be good chips.
Greek letter 'Psi' (not Pounds per Square Inch)
 

Offline zeqing

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Re: Price Difference between Digikey and Aliexpress
« Reply #40 on: August 10, 2017, 03:47:53 am »
As a PCBA producer for more than 5 yeas, i suggestion is :
1. for prototyping,  use the digikey/mouser parts....your time values than the IC, or even you will cry when some fake IC used ;
2. check the IC from aliexpress by yourself before the mass production. as my experence , >95% is OK, at least functional.   

for no-so-big price difference it is because the seller on aliexpress is distributors but not resellers.  the difference can be up to 50%. for even larger price difference, maybe fake IC.
 

Offline jmelson

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Re: Price Difference between Digikey and Aliexpress
« Reply #41 on: August 10, 2017, 04:07:31 am »
Hi,

I'm planning to design a simple buck converter using LM2596. I was estimating the Bill of Material cost using Digikey and Aliexpress and I noticed that there is a huge cost difference between them.

Digikey : https://www.digikey.com/product-detail/en/texas-instruments/LM2596S-ADJ-NOPB/LM2596S-ADJ-NOPB-ND/363705
Cost : $5.41 per IC

Aliexpress : https://goo.gl/4sTsKP    (I have shortened the URL)
Cost : $7 for 50 IC, which roughly comes around $0.14 per IC

I understand that the Aliexpress vendor might be selling counterfeit IC's which are prone to high defective rates. But the cost difference between them is huge. Any Idea on why I should prefer Digikey over Aliexpress? Any Input / Insight will be helpful. TIA

P.S. Cost specified are in USD
Also I'm relatively new to this forum, I'm not sure whether this is the right channel to post my question. Let me know if I need to post it in different channel.
I've had several grey market experiences.  One from a long time ago was a supposedly reputable US distributor, I bought a reel of op-amps.  It took 25 per board.  About 50% of them failed immediately on power up.  Going back over them, I noticed there were 3 different date codes on the same tape.  I called the manufacturer, and they guaranteed that there could never be different date codes on one reel.  So, the parts were apparently salvaged after somebody installed a few thousand backwards and the boards failed testing.

I had blank boards left when some Xilinx CPLDs went end of life, so I ordered them from China.  About 20% of them would not program, or failed in more spectacular ways.  So, I don't know if these were off scrapped wafers, counterfeits, or whatever.  But, I was doing final test on the chips!

So, I avoid buying anything from China unless I am totally up against the wall.  You can read on various newsgroups, etc. about bad experiences with buying parts from China.  Lots of people have gotten total junk, empty packages, completely wrong chip inside, 60 W power transistors with a 1/4 W die inside, so it checks OK on a transistor tester but blows instantly in the intended circuit.  Stuff like that.


Jon
« Last Edit: August 10, 2017, 04:15:14 am by jmelson »
 

Offline DerekG

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Re: Price Difference between Digikey and Aliexpress
« Reply #42 on: August 10, 2017, 06:06:56 am »
So, I avoid buying anything from China unless I am totally up against the wall.

Yes, my sentiments also Jon.

The only time we look at Chinese component purchase is if we can deal directly with the manufacturer in China themselves. This means that we are obviously not buying named brands like Microchip, ST Microelectronics etc.
I also sat between Elvis & Bigfoot on the UFO.
 


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