[sdiy] op amp substitutes

[anthony]

Ken Stone wrote:
>>
>>This is in the Analog Shift Register circuit.
>
> In my analog shift register circuit?  Use 3140 instead of the LF356 for 
> best
> effect. I wouldn't waste my time trying a TL0X4.
>

Oh yeah. Yes indeed. The 3140 is another op amp I tried to find a 
replacement for in my pile o' stuff but alas to no avail. I could tell right 
away as I read the 3140's data sheet. They're on my shopping list. I thought 
the TL03X and TL05X might be significant improvements over their 
predecessors as replacements for the 356's.

I knew the C4072's were no good for capacitative loads. .

I thought it might be interesting research to see what op amps might replace 
others in a number of situations. And how this might relate to specs in a 
datasheet and how that ends up translating into real world apps.

Example: I have a huge batch of NJM4558's (JRC) of early 80's vintage (from 
the equipment they were in, the dating is probably fairly accurate depending 
on how long they sat and waited to be put into something) which is 
technically a pretty crappy op amp. Better than a few but not many. But in 
some of the audiophile nut circles (the ones who like op amps) this 
particular make and this particular vintage is choice (I have not tested 
this though. I'll try one against a 5532 some time. the 4072's might be good 
for audio audio.). But for anything other than audio - probably nice for 
filters -  I'd probably only use them where they called for an 358 or a 1458 
or a couple in place of a 324 (but I have a ton of those too - more than 
1458 and 741's combined).

I think there's a lot of the same types of "euphonic shortcomings" in some 
op amps like with tube amps.They're different shotcomings, but to some 
people they sound good But tubes sound cool mostly by virtue of simply being 
tubes. Op amps only in special cases by being quirky or really just a damn 
good op amp. I have tinnitis really bad so I like hiss a lot. (I love pink 
noise. I can't stand noise from a pseudorandom generator though.) As in 
calling for a 741 because it has a slow slew (slow slew slow slew...) rate.
But I digress...

I have fun trying to switch plans around so I can use the crap that I 
already have, but I realise that there's a point of diminishing returns. And 
then I have some things that I think are really really cool, but may not 
actually be as great as I think. Like the Rubycon oil caps that I have. For 
a while I just had them in with my non-polarized electrolytics, but then one 
day I thought 'hey those aren't electrolytics.'  I can't for the life of me 
remember what they were in but there were a lot of them in there.
Digressing again...

But I haven't tried a 386 or a 380 in place of an op amp yet. I'm pretty 
sure that won't work for the buffers in Ken's ASR though. But maybe I'll 
play with it anyway. I have so many IC amps, I'm curious what some of them 
might do in place of an op amp. I'll wager someone has already tried it. 
I'll bet if there's a good reason on paper why they won't work very well in 
most apps real world experience might

And I found a cool use for just a single 3900 (which is all I've got) on 
Ken's site - the Analogic.