# checking for fake OPA2134?



## lcipher3 (Sep 16, 2020)

I think _ChuckDBones_ posted awhile back that he had spotted some fake OPA2134 by measuring current - is this the geneal method to check for fakes?


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## Cybercow (Sep 20, 2020)

Testing for current draw merely determines the current draw of the device. Using a DC input in the manner demonstrated in the schematic will not tell anyone if it is a genuine OPA2134 - only that it's an opamp if the Vref measures exactly 1/2 Vcc. And the Texas Instruments OPA2134 has a quiescent current draw of 4 to 5 mA - according to the datasheet.

The OPA2134 is a very clean opamp and I would test the AC signal output instead of just the DC aspect. Connect the power per the spec sheet and connect the output to the negative input terminal, then put an AC signal on the plus input terminal. You should see an exact copy of the input on the output terminal. Some cheap opamps will have a DC offset, so the resultant AC output will not precisely match the input.


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## Chuck D. Bones (Sep 21, 2020)

Measuring current draw is a quick & dirty way to tell if someone has relabeled a TL072.  

I also posted pix of a real and a fake.  I suppose that the counterfeiters could do a better job with the labeling, but the guys who made that particular fake did a pretty sloppy job of it.

DC offset voltage won't tell you if an opamp is OPA2134 or not because lot of opamps have tight offset voltage specs.  

One of the things that distinguishes the OPA2134 is the very low crossover distortion.  Not easy to measure and you won't see it looking at a scope trace.  You need a distortion analyzer or a spectrum analyzer.

The easiest way to know you have the real deal is to buy it from an authorized distributor.


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## mywmyw (Sep 21, 2020)

you should post a close up pic, sometimes the fakes are obvious by their construction. i got a few from ebay that were very obviously unlike the bonafides i got from digikey.


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## lcipher3 (Sep 21, 2020)

Chuck D. Bones said:


> Measuring current draw is a quick & dirty way to tell if someone has relabeled a TL072.



That was my thoughts - TL072 would be the most likely one to use as a "fake" and the ~ 8 mA (2x4mA in a dip8) would be a "rough" check.  
I actually remembered I had a stash I bought 10 years ago from Digikey so I'm pretty sure they're good ones.


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## Chuck D. Bones (Sep 22, 2020)

DigiKey doesn't sell fakes.  If you got them from DigiKey, they're good.  eBay sellers... ya never know.  Some eBay sellers have no idea what they're selling, others deliberately sell counterfeit parts.  It's possible to buy good electronic components on eBay, I've done it, but it's a gamble.  Like the saying goes: "If the price is too good to be true..."


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