How to check if an operational amplifier is fake

[@AllElectronicsChannel]

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[@RomeWithTheHEMIs]

Just found this absolute gem of a channel. Love your content! So educational.

[@AllElectronicsChannel]

Welcome!

[@gammaleader96]

Wow, that is a pretty powerful analog scope. Beautiful machine and interesting usage.

[@y_x2]

Fun to see. Where is the formula that take care of the slew rate of the oscilloscope?

[@AllElectronicsChannel]

😂😂😂

[@andymouse]

Why are you laughing at this guy ? The formula is SR = ∆V / ∆T you need to explain this. Also the whole video's about fake parts and you didn't show the difference ! how close are the fake ones ? could they work fine in some applications and you wouldn't know ? You basically showed off the scope now do it with a cheaper more 'run of the mill' scope and explain that ! that is the way to learn. I am very disappointed in this video as your work is usually better than this.@@AllElectronicsChannel

[@andymouse]

See my comment below please.

[@ernestb.2377]

Slew-rate check is indeed an fast way to check. Good tip. But I am interested to hear which specifications are most likely to be expected to be violated, from the experience, as I have not dealt yet with this fake parts. Where, who and how do they make these components? Quite curious. It is not something you can make in your garage. You need advanced technology and yet you produce crap. Steange. 🤔

[@jvkew]

Just a note: Check out the patents assigned to Hekimian Laboratories in Maryland for circuit tricks with discretes. Dr Hekimian, a a Fellow of the IEEE for Circuit Design who deserved it. I learned more from him than any other wizard I worked for. Saddly, much of what we did was/is not public.

[@AllElectronicsChannel]

I will check!

[@like_cabezon3810]

very interesting video, as allways

[@oliverlangrall2014]

Is there any other way to check fakes without a scope? I'm not an engineer, just a hobbyist who likes to build guitar pedals. Maybe fake opamps don't really influence how distortion pedals work or sound as much as other applications where slew rate or other specific aspects of the opamp need to be accurate, or maybe I'm totally wrong! However, if they do affect the sound of the pedals I build I would like to be able to check somehow. I have a multimeter and a breadboard and a large variety of parts. I'm pretty sure this pack of 20 JRC4558 from amazon are fake because I have a few real ones from Texas Instruments and they don't sound quite the same and were not packaged as nice and static resistant as the T.I. ones. It doesn't mean I won't use fakes because they still make a usable sound (in building pedals all sounds are useable!) but for consistency I would appreciate actually knowing. Thanks!

[@AllElectronicsChannel]

Hey man, let's think about it.. 1) You can try to measure the current at the supply, to see if it matches the originals. 2) You can try to measure the input bias current, using a voltage follower configuration, and a resistor to ground. The voltage over the resistor will be bias current * R. 3) You can try to measure the voltage offset. 4) You can try to measure the rail-to-rail maximum excursion of the output. 5) ... I think that making a comparison table, with some original ones as reference, you will be fake to distinguish which ones are fake, by the deviation from the standard..

[@oliverlangrall2014]

@ thanks that’s really helpful! Seems kind of obvious now that you said to compare them haha

[@AllElectronicsChannel]

Let me know the results! hehe

[@oliverlangrall2014]

@@AllElectronicsChannel I tested a couple before work and they seem to be legit, they're jrc4558 opamps so maybe it's just my own perception bias that made me think they were fake since they were cheap from amazon and the printing on them with no company logo like the texas instruments ones I have that are laser printed.

[@cjay2]

Just spend the money and buy them new from Digikey or Mouser, in your region.

[@rodrigoluisschropfer6159]

bah, que top, vimos sobre isso nesse semestre da faculdade.

[@ernestb.2377]

What is so special about an analog scope? You can do the same measurement with a digital one, right? Don't get me wrong, I have a few analog scopes just for the sake of fun and nostalgia foremost, and for the cases I need to check something simple and fast.

[@AllElectronicsChannel]

You are right.

[@NeTurizm]

Привет! Спасибо)