Chronic Philharmonic wrote:

"Eeyore" wrote
tony sayer wrote:

And a scope to see what its getting up to in the MHz region;!...

Too true. Circuits that may be stable with junk op-amps may respond
differently when given the chance.

Random thoughts... Could it be that the original designers were aware of the
device's limitations, and took care to stay within those parameters? If they
used them in low-gain, low-voltage applications, with minimal gain
downstream, I can see how they could comfortably stay within the product
design specifications. And the intrinsic stability might have been a bonus.

You'd have to be a truly **** designer to need a 4558 to keep your circuits
stable ! Hever mind their noise contribution.


I wonder what made them choose that part in the first place.

Because they had 100,000 in stock ?


Could it be cost? Or stability problems that went away by subbing a part
without the
need to rev the PCB?

In which case they're incompetent.

Graham