General > General Technical Chat
i won't buy chinise parts from aliexpress or ebay
chickenHeadKnob:
--- Quote from: SilverSolder on September 02, 2020, 08:58:12 pm ---
Agree 100%. But using a cheap transistor in a non-critical hobby circuit in your basement... hardly reckless, and possibly a learning opportunity? :D
--- End quote ---
Wraper is correct even for the case of the young student tinkering in his basement. Not because of safety or any professional type risk but rather it is highly demotivational to have your project fail for mysterious reasons when you are just starting out. They will think did I goof up? is my circuit bad ?, etcetera . Leading some students to give up early in frustration. Experienced people have far better awareness and debugging skills so they detect the bad part quickly and move on,
In my teenage years I wanted to learn all I could about computers, both the programming side and hardware. This was during the 1970's so no internets, no online datasheets, no digikey/mouser/ebay, and no arduino. My options consisted of going to the engineering library of one university 80kms away round trip to get photocopies out of the few data books they had and buying parts from radio shack from the limited selection they had. There was also one hobby electronics magazine Electronics Today International edition that I followed, and I went to a second university 40 kms away to steal mainframe time ;D
No one I knew had my perseverance or auto-didactic drive to learn electronics and computing so by the time I reached the University level it was easy for me to obtain teaching assistant jobs in digital electronic lab classes. These consisted of helping the 'tards students make basic circuits from 74 series parts and some pre-built modules. They would be stymied by the simplest of problems. Bent pin under chip because of ham-fisted insertion into breadboard, crap wiring, reversed power or no power connected. They also couldn't discern when the problem was simple connection error or if the chip was bad because the previous retard had destroyed it. Things which would hardly have slowed me down when I was a teen by myself would cause them to give up right away.
The situation with analog components is even worse as a bad but functioning part can depart from the expected datasheet in very subtle ways.
SilverSolder:
--- Quote from: chickenHeadKnob on September 03, 2020, 08:02:21 am ---
--- Quote from: SilverSolder on September 02, 2020, 08:58:12 pm ---
Agree 100%. But using a cheap transistor in a non-critical hobby circuit in your basement... hardly reckless, and possibly a learning opportunity? :D
--- End quote ---
Wraper is correct even for the case of the young student tinkering in his basement. Not because of safety or any professional type risk but rather it is highly demotivational to have your project fail for mysterious reasons when you are just starting out. They will think did I goof up? is my circuit bad ?, etcetera . Leading some students to give up early in frustration. Experienced people have far better awareness and debugging skills so they detect the bad part quickly and move on,
In my teenage years I wanted to learn all I could about computers, both the programming side and hardware. This was during the 1970's so no internets, no online datasheets, no digikey/mouser/ebay, and no arduino. My options consisted of going to the engineering library of one university 80kms away round trip to get photocopies out of the few data books they had and buying parts from radio shack from the limited selection they had. There was also one hobby electronics magazine Electronics Today International edition that I followed, and I went to a second university 40 kms away to steal mainframe time ;D
No one I knew had my perseverance or auto-didactic drive to learn electronics and computing so by the time I reached the University level it was easy for me to obtain teaching assistant jobs in digital electronic lab classes. These consisted of helping the 'tards students make basic circuits from 74 series parts and some pre-built modules. They would be stymied by the simplest of problems. Bent pin under chip because of ham-fisted insertion into breadboard, crap wiring, reversed power or no power connected. They also couldn't discern when the problem was simple connection error or if the chip was bad because the previous retard had destroyed it. Things which would hardly have slowed me down when I was a teen by myself would cause them to give up right away.
The situation with analog components is even worse as a bad but functioning part can depart from the expected datasheet in very subtle ways.
--- End quote ---
OK, that's a fair point. I would also add that most of the time, components are cheap enough that we can buy new, high quality stuff and should not be tempted into the dark side.
But that still leaves the situation where an experienced person buys cheap parts that he/she is familiar with, in the full knowledge that these are not prime parts... in return for paying a lot less for them.
It is similar to buying a used car, or a "cheap brand" car, in my view. If you are buying an old junker that has been repaired by dozens of people, with banana skins in the gearbox and differential to keep them quiet, you do not have the same expectations that you do when buying a brand new car - and you don't expect to pay new car prices, in return for that. You can also choose a cheaper brand of car. You might have different expectations from a BMW compared to a Perouda, for example. Does that make the Perouda buyer, or the used car buyer, a reckless person? It all depends what their expectations or requirements are!
Why wouldn't the same principle apply with electronic components?
wraper:
--- Quote from: SilverSolder on September 03, 2020, 01:27:48 pm ---OK, that's a fair point. I would also add that most of the time, components are cheap enough that we can buy new, high quality stuff and should not be tempted into the dark side.
But that still leaves the situation where an experienced person buys cheap parts that he/she is familiar with, in the full knowledge that these are not prime parts... in return for paying a lot less for them.
It is similar to buying a used car, or a "cheap brand" car, in my view. If you are buying an old junker that has been repaired by dozens of people, with banana skins in the gearbox and differential to keep them quiet, you do not have the same expectations that you do when buying a brand new car - and you don't expect to pay new car prices, in return for that. You can also choose a cheaper brand of car. You might have different expectations from a BMW compared to a Perouda, for example. Does that make the Perouda buyer, or the used car buyer, a reckless person? It all depends what their expectations or requirements are!
Why wouldn't the same principle apply with electronic components?
--- End quote ---
Experienced person saves money by buying parts of lesser known Chinese brands. Buying on aliexpress/ebay is a valid option only for some sorts of parts, say you want to buy a Richetek PWM controller to repair a graphics card. Hard to obtain otherwise and chance of counterfeiting is very low. Otherwise it's like searching in a pit full of crap in hope of finding gold. You may find it, but in the process you will be covered in shit from top to bottom.
SilverSolder:
--- Quote from: wraper on September 03, 2020, 01:58:12 pm ---
--- Quote from: SilverSolder on September 03, 2020, 01:27:48 pm ---OK, that's a fair point. I would also add that most of the time, components are cheap enough that we can buy new, high quality stuff and should not be tempted into the dark side.
But that still leaves the situation where an experienced person buys cheap parts that he/she is familiar with, in the full knowledge that these are not prime parts... in return for paying a lot less for them.
It is similar to buying a used car, or a "cheap brand" car, in my view. If you are buying an old junker that has been repaired by dozens of people, with banana skins in the gearbox and differential to keep them quiet, you do not have the same expectations that you do when buying a brand new car - and you don't expect to pay new car prices, in return for that. You can also choose a cheaper brand of car. You might have different expectations from a BMW compared to a Perouda, for example. Does that make the Perouda buyer, or the used car buyer, a reckless person? It all depends what their expectations or requirements are!
Why wouldn't the same principle apply with electronic components?
--- End quote ---
Experienced person saves money by buying parts of lesser known Chinese brands. Buying on aliexpress/ebay is a valid option only for some sorts of parts, say you want to buy a Richetek PWM controller to repair a graphics card. Hard to obtain otherwise and chance of counterfeiting is very low. Otherwise it's like searching in a pit full of crap in hope of finding gold. You may find it, but in the process you will be covered in shit from top to bottom.
--- End quote ---
I guess another thing we are not mentioning is that you have to be experienced not just with electronics per se, but also with buying stuff via the various Internet shopping sites in general.
After years of experience buying smelly stuff, you develop a "sixth sense" as a buyer and then the percentage of crap you end up with drops to quite acceptable levels.
wraper:
--- Quote from: blueskull on September 03, 2020, 02:08:29 pm ---I'd like to hear about in what kind of cases you get fake parts from Ali assuming you paid a reasonable amount of money and not dreaming of electronic parts growing on trees in China.
--- End quote ---
I received relabeled nvidia GPUs, one part number sold as another. Same silicon physically but config is not. Got one Toshiba stepper driver relabeled as another. Found out by measuring pins, if I didn't do so, I would have explosion and probably burnt traces in my device. Got relabeled UV EPROMs, 25V part relabeled as 12.5V. Got mix of attiny24 and 24A blacktopped and relabeled as 24A with a fresh date code, terminals soldered like shit. Those were not insanely cheap. For components which could be obtained from normal distributors it was the same or a little bit lower price than you would expect from Mouser or similar at qty of 100-1000.
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