Re: Standard non-inverting opamp with a cap across + and - terminals...... Why?

On Apr 16, 3:48 pm, John Larkin
<jjlar...@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
On Thu, 16 Apr 2009 01:56:01 -0700 (PDT), bill.slo...@xxxxxxxx wrote:
On Apr 15, 3:42 pm, MooseFET <kensm...@xxxxxxxxx> wrote:
On Apr 15, 5:54 am, bill.slo...@xxxxxxxx wrote:

On Apr 15, 3:22 am, MooseFET <kensm...@xxxxxxxxx> wrote:

On Apr 14, 2:57 pm, bill.slo...@xxxxxxxx wrote:

On Apr 14, 2:45 am, MooseFET <kensm...@xxxxxxxxx> wrote:

<snip>

Since I've never denied that the bias currents are affected, this is
asking me if I've stopped beating my wife. Since it doesn't seem to be
an effect that is worth worrying about, I couldn't care less about it.

 Before you claim to educate others, I suggest you study up
a bit.

You might think about taking your own advice.

I did and carefully.  Now it is your turn.  Do you now admit that the
bias current changes?

Carefully, but not intelligently. You've fixated on an irrelelvant
detail.

Idiot. There are lots of situations where microvolts of offset, or nA
of input bias current shift, would trash a signal. How can you glibly
declare an effect "irrelelvant" and not "worth worrying about", "don't
have a signficant effect?"

Because the bias current changes produce smaller offsets than the
nonlinearity of the large signal voltage transfer. You are making a
fuss about a mouse and ignoring the elephant.

You can if you never design real electronics.

Probably true, but irrelevant, since I've designed a lot of real
electronics, some of it precision stuff where "small" offsets
presented big problems.

I'm currently working on a rather large and expensive analytical
instrument, and just got the schematics of the existing stuff. It's
ghastly, throwing away at least 20 dB of s/n ratio, on a gadget where
extensive signal averaging - using many squirts of rare samples, on a
megabuck machine - is the norm. 20 dB == 100x signal averaging.

The electronics was designed by physical chemists. Why are scientists,
with a few rare exceptions, such notoriously bad circuit designers?

It's not their primary job. Back when I read Review of Scientific
Instruments regularly I'd send them a comment every year of so,
pointing out that one of their articles included electronic nonsense.
A few of them ended up getting published. They show up on
scholar.google if you search on "A. W. Sloman".

Back when I was getting my Ph.D. in Physical Chemistry, I ended up
having to design some circuits to monitor the chemical reaction that I
was studying. They weren't very good, but they worked. Since then I've
had more practice.

--
Bill Sloman, Nijmegen
.

Relevant Pages

  • Re: Tool for drawing electrical circuits
    ... Ohmigawd that first site is hawg heaven for "retired" electronics ... designers on a budget. ... >> transistors digital blocks such as triggers, ...
    (Fedora)
  • Re: Does Bill Gates Have a Hot Wife
    ... You know the expression "You are what you eat" ...It might be ... designers sometimes suffer from... ... Sometimes it's not just an electronics problem.... ... please see the DVD post..If I recall correctly, ...
    (sci.electronics.design)
  • Re: Please clarify European resistor value notation for me
    ... Listen up, Clyde: I design electronics. ... But I've never met any good circuit designers who were any of those ... designers either, but that's not enough statistics to prove anything. ... But I am sure those good English E designers must exist. ...
    (sci.electronics.design)
  • Re: Are there any great electronic watches
    ... Well it is obvious that when quartz watches are designed that the entire ... The way it should have been done was for the electronics guys to build ... designers to use to make a watch. ...
    (alt.horology)
  • Re: Ada.Directories problems, a summary
    ... Ivan Levashew a écrit: ... and I'd like to deal with these abstractions and not with ... what particular cases OS designers gave me instead. ... bias. ...
    (comp.lang.ada)