[sdiy] LM741 substitute

[JH.]

Nothing is flawless.
Every opamp has its flaws, and not neccessarily the same flaws as another 
type.
Before you substitute an opamp type in a circuit, make sure that the design, 
that obviously was made to live with the flaws of the chosen opamp type, 
will also work with the flaws of the opamp of your choice.

The TL071 is no drop-in replacement for a 741. Far from it, actually.

The EMS circuit Magnus referred to goes one step further than working around 
flaws:
It makes a clever use of the opamp's internal circuit, shutting down part of 
it. Granted, that's not using the opamp concept - it's transistor level 
design, using some of the transistors readily integrated in a cheap, 
available chip.

JH.

----- Original Message ----- 
From: "David G. Dixon" <dixon at interchange.ubc.ca>
To: "'Magnus Danielson'" <magnus at rubidium.dyndns.org>; "'Samppa Tolvanen'" 
<samppa.tolvanen at gmail.com>
Cc: "'sdiy diy'" <synth-diy at dropmix.xs4all.nl>
Sent: Friday, July 10, 2009 8:21 PM
Subject: RE: [sdiy] LM741 substitute


> Also, some rare curcuits do depend on the internal layout of a
> particular op-amp. Jürgen Haible reported on one such design in the
> Synthi-A project he did. It's deep into the archives, but google should
> help you.

I can't see any excuse for such a design.  Doesn't that just defeat the
whole point of opamps?


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