[sdiy] low input bias current opamps

[Ben Bradley]

On Tue, Aug 14, 2018 at 11:43 PM, David G Dixon <dixon at mail.ubc.ca> wrote:
> Hey Team,
>
> I'm looking for opamps with the following properties:
>

> 4) High power range (+/-18V, say)

So, does this mean an absolute maximum rating of +/-18V and running
off the 'standard' +/-15V, or will the device be OPERATING at +/- 18V?

I hope that's not an insulting question, but I've seen this exact
thing before (obstinate forum poster, perhaps not for the faint of
heart):
https://groupdiy.com/index.php?topic=63399.0

> 7) Not LF444 (cuz they all seem to be defective)

Looking at the datasheet,
http://www.ti.com/lit/ds/symlink/lf444.pdf
there's an LF444A that has absolute maximum rating of +/-22V and
operating voltage of +/-20V. Digikey shows the LF444A at $2.69 vs.
$1.89 for the LF444. That's a significant increase, but you're already
paying a good bit for the original.

Presuming (as I recall you said later) that  you've successfully used
the LF444 in this circuit before, you may have just got a bad batch.
Regardless, since the LF444A is tested (or at least rated) for a
higher voltage, I'd think it would be worth using to make the circuit
more reliable.