Counterfeits will always use some existing product, and typically repackage or remark it. It costs a lot of money to tool up for a new chip. There is no money to be made unless you can sell large quantities, or charge premium prices.
A reputable manufacturer might buy the tooling for a discontinued device and resume manufacturing and distributing it. I would not consider that a counterfeit.
Some counterfeits are reportedly pretty good and many will actually work in some circuits. Counterfeit power transistors are all too common.
When I see some stuff on Ebay that is so awesome and so cheap (like an assembled amplifier board that costs less that the parts if you bought them from Digikey) then I can't help but assume that it's just too good to be true. If I had any confidence that they were assembled from genuine parts, I probably would have bought a couple things.
A reputable manufacturer might buy the tooling for a discontinued device and resume manufacturing and distributing it. I would not consider that a counterfeit.
Some counterfeits are reportedly pretty good and many will actually work in some circuits. Counterfeit power transistors are all too common.
When I see some stuff on Ebay that is so awesome and so cheap (like an assembled amplifier board that costs less that the parts if you bought them from Digikey) then I can't help but assume that it's just too good to be true. If I had any confidence that they were assembled from genuine parts, I probably would have bought a couple things.
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Counterfeit parts are junk in my book. They can undermine the reputation of the authentic product if the user does not understand that they are using a questionable part. They can impact the bottom line of the manufacturer of the authentic part reducing their ability to R&D new and better products.
Counterfeit parts may work initially, however the cheap parts I have tested and compared to authentic pieces fail to meet the specs of the authentic part. For example, Some fake TDA2050s I bought off of ebay delivered a few watts less output power than the authentic ones did at the same supply voltage. Some fake TDA2040 ICs I bought had no short circuit protection. After time the smaller die size of the counterfeit part is going to cause failure if pushed to the normal operating range of the authentic part.
I've tested a lot of LEDs too, and those are the worst. Many fade in brightness with low hours. Some power LEDs had some of the die inside not lighting right out of the package and efficiency is relatively low.
A shame people are suckered by the low price.
To make a long story short, I agree with you. And I am not surprised at your firsthand accounts of counterfeits.
My point is that some counterfeits will work in some circuits that don't require the full specification. I would never recommend a counterfeit part and would never knowingly buy them.
My point is that some counterfeits will work in some circuits that don't require the full specification. I would never recommend a counterfeit part and would never knowingly buy them.
I've opened an LM1875 which was giving me a DC offset of 20V 
Now i'm not saying this one is a counterfeit, however my pcb/circuit was good, so could also be just bad luck.
What do you guys think? Unfortunately i was not able to keep the die intact. @johnr66 how did you manage to get that off so clean?
The die size is 2.7mm by 3.7mm
Now i'm not saying this one is a counterfeit, however my pcb/circuit was good, so could also be just bad luck.
What do you guys think? Unfortunately i was not able to keep the die intact. @johnr66 how did you manage to get that off so clean?
The die size is 2.7mm by 3.7mm
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I have a very bad experience with LEDs.
A LED company in China sent me LEDs with 20mA die instead of 100mA. And i used them in the end product which needed 100 mA LEDs. My customer asked for a return/replace a month after i sent the finished products because of very high failure rate. I returned his money, and he never bought from me again.
Chinese manufacturer told me the price they gave me was only good for 20mA LEDs. They refused replacement/return. But the price was what they gave me for 100 mA LED in the proforma invoice they sent me before.
So, i learned never trusting in a no-name Chinese company with lower prices until i got correct product which is a gamble.
For LED, i, since then, bought from known firms like Cree, Osram, Nichia..
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I've opened an LM1875 which was giving me a DC offset of 20V
Now i'm not saying this one is a counterfeit, however my pcb/circuit was good, so could also be just bad luck.
What do you guys think? Unfortunately i was not able to keep the die intact. @johnr66 how did you manage to get that off so clean?
The die size is 2.7mm by 3.7mm
If you bought your PCB as a kit, where did you get it? I would think a larger die is from an authentic part.
I was driving a power transformer with mine. With no load, it sees pure reactance which drives the transistors beyond the supply rails and shorts them out. The bond wires vaporize and the expanding gas cracks the epoxy. I was able to peel it off.
I have seen videos on YouTube on how to decap ICs cleanly. I think they use fuming nitric acid and a hot plate.
That is a shame to lose business and have a hurt reputation due to deceptive Chinese suppliers. I have a light meter test bench setup where I'd test the LEDs and some would start to fade in a couple days!
I tested some .5 watt LEDs (150ma) at only 100ma and they were nearly completely dark after only one week (168 hrs) of testing.
Here in the US, Cree LEDs are easy and cheap to obtain and I have tested them to be very dependable over time. I have little white SMD 20ma LEDs running on my bench for 3 years continuous at 30ma and they have not faded!
The Chinese fraudsters usually ship a product that seems good at first (unless tested to reveal the faults) but it fails later on. Same with all the crap audio kits.
i used "waterprof" 5m with 5050 led strip from ebay, china, ultra low cost. which worked for almost full month non stop then got dark.
next time i ordered from same seller and removed waterproof part and amazingly this 5 meters has been working for almost half year with same brightness. in my opinion not chinease sellers fault ,how can you expect rubber to dissipate heat?it got brown and firm from heat.
lt1083 for 1buck piece i bought later knowing its impossible to be original, out of 10 pieces 4 are working so there is possibility sellers got their hands on bad yield which again is not sellers error or he knows what he bought and puts low price for same reason.
next time i ordered from same seller and removed waterproof part and amazingly this 5 meters has been working for almost half year with same brightness. in my opinion not chinease sellers fault ,how can you expect rubber to dissipate heat?it got brown and firm from heat.
lt1083 for 1buck piece i bought later knowing its impossible to be original, out of 10 pieces 4 are working so there is possibility sellers got their hands on bad yield which again is not sellers error or he knows what he bought and puts low price for same reason.
I live nearby Parts Express and visit their catalog showroom often. On the wall above where they have all the speaker drivers hanging are color changing LED strips demos running. After visiting again a couple months later, I noticed the blue LED's in the strips lighting uneven and nearly faded out. I believe these are "Sure Electronics" products. That and those amplifier kits they make are junk. I bought some Sure Electronics power LEDs off eBay and most of them were defective right out of the pack. I got a partial refund.
I have a few counterfeit 2030a's lying around. Cracked one open to confirm, yep, the die is about 1/3 the size. I have thought about playing around with these, I have about 8 to burn up. Thought about putting in some btl setup after a preamp for a sub. I need about 250W - I know it might die, but the speaker was bought from a thrift store. So this is a learning project. Ideas?
If the mystery chips are capable of running on the proposed voltage. . .
Hybrid Audio Amplifier Circuit
An externally hosted image should be here but it was not working when we last tested it.
And, instead of BD249/50, use MJ15003/4 http://www.onsemi.com/pub_link/Collateral/MJ15003-D.PDF
Bad yield in chip manufacturing ? All the legit manufacturers utilize 6 Sigma to maximize yield to the point of 1 failure per 1 million parts- however an incorrect sample size to find the true process yield is a sticky point with many companies professing ISO certification and 6 Sigma requirements may have passed certification during a review, but do not continue those high standards all the time.
Sent from my XT1055 using Tapatalk
Nice. Thanks for the suggestion!! Any idea if this will tolerate pbtl? I actually could use a bit more power...
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It is already bridged.
It is not especially problematic to parallel BJT output devices.
So, I think that the answer was yes.
However, please do consider that post#55 (plus the output device swap in the footnote) has enough power to burn most speakers. Please don't exchange peak power specs for steady power specs. That post was also contingent on your "driver" op amp tolerating sufficient voltage to do the job.
At this point I'd like to know the application, its room/venue, the range/distance to listeners, and the specs of the speaker.
It is not especially problematic to parallel BJT output devices.
So, I think that the answer was yes.
However, please do consider that post#55 (plus the output device swap in the footnote) has enough power to burn most speakers. Please don't exchange peak power specs for steady power specs. That post was also contingent on your "driver" op amp tolerating sufficient voltage to do the job.
At this point I'd like to know the application, its room/venue, the range/distance to listeners, and the specs of the speaker.
The driver I'm talking about is for a subwoofer. It's nominal RMS rating is between 300 to 400w. (depending on the model) and the unit had the particular problem of burning out every digital plate amp in about a year. I suspect that while the speaker was nominal 4 ohms I think their ratings were not accurate... so I'm thinking a load isn't going to do well if I match it to the nominal rating.
And then of course this is after a set up proper filters - this unit it did all of that digitally.
It was a $10 thrift store buy. What can I say.
And then of course this is after a set up proper filters - this unit it did all of that digitally.
It was a $10 thrift store buy. What can I say.
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