[sdiy] LM741 substitute

Tom Wiltshire tom at electricdruid.net
Fri Jul 10 22:09:50 CEST 2009


On 10 Jul 2009, at 19:21, David G. Dixon wrote:

>> 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?

I'm inclined to agree. Any design that depends *specifically* on the  
failings of a particular chip isn't a particularly good design in my  
view. If you want limited slew rate, design it in. Chip  
specifications change, and you should try to allow for that if you  
want a design to survive.

The difficulty is the guitar FX, where things that *were* failings of  
the original design have now become the desirable features. Still, I  
know from experience that you can still design a noisy, dirty, hissy  
fuzz pedal with a modern, low-noise op-amp!

T.







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