maybe i can add that in my understanding the constantly raising (6 dB/oct) high uneven harmonics of my fake 5532 (see distorsion graphs) are a clear sign of a rudimentary class b output.
Feedback will partially compensate for crossover distorsion, but as feedback reduces due to bandwidth limit the distorsion rises.
Ugly 358 class detected
Many red flags.
Somebody must be making them by the Millions.
Less than a Month ago somebody was offering here in Argentina bulk quantities of house brand Op Amps for literally peanuts.
Claimed original use (and sounds reasonable to me) was in home appliances, think washing/bread/coffee machines and such.
All run on microprocessors but some analog signal processing is needed (sensors, etc.), LM358 fills the bill nicely so there's a huge market there.
Many red flags.
Somebody must be making them by the Millions.
Less than a Month ago somebody was offering here in Argentina bulk quantities of house brand Op Amps for literally peanuts.
Claimed original use (and sounds reasonable to me) was in home appliances, think washing/bread/coffee machines and such.
All run on microprocessors but some analog signal processing is needed (sensors, etc.), LM358 fills the bill nicely so there's a huge market there.
In my case it's not a 358 - i think it's "even worse". My fake opamp can actually sink a lot of current. And it does invert phase at low output voltages.
I hope every low-noise bipolar opamp does - otherwise switch-on and switch-off transients in the circuit can cause zener-breakdown of the inputs' base-emitter junctions and ruin the noise performance.
Note that this is also why you can't just use an opamp as a comparator - you have to check the datasheet for the max differential input voltage. Anyway an opamp is never a very good comparator...
Sometimes you don’t need that good of a comparator and if you happen to have a tube of LM358’s or TL072’s on hand and need a comparator they work fine. Fan speed control, DC protect, power good…. Also why some of those “crummy” op amps are still popular - they work for damn near anything that doesnt need especially high fidelity.
The classic situation is having a quad opamp package and a circuit that calls for 3 opamp stages and 1 comparator (for the clipping LED). Yet another reason not to roll opamps without first understanding the circuit requirements.
On fakes I suppose now the 5534/5532 end-of-life is upon us I expect to see container-loads of fakes for these parts appearing. Ho hum.
Remember no analog parts bought from a random ebay source are real these days, to within experimental error!
On fakes I suppose now the 5534/5532 end-of-life is upon us I expect to see container-loads of fakes for these parts appearing. Ho hum.
Remember no analog parts bought from a random ebay source are real these days, to within experimental error!