[sdiy] input buffer question

[David G. Dixon]

> > Neil, I'm using the diodes in the opposite direction, on the
> > "inside" of the
> > rails.  Hence, assuming diode drops of 0.7V, then my inputs are
> > limited to
> > +/-14.3V.  This is more for spike protection than for phase reversal
> > protection.
> 
> Sorry if I'm being dense, but what do you mean by "inside of the
> rails"..?  Could you draw a diagram and put it on the web somewhere?
> Googledocs or something like that.

No, Neil, I was being dense.  Of course, what I meant was that the inputs
are limited to +/-15.7V.  I was operating on not enough sleep, I guess.

Of course, this won't give any phase reversal protection, at least at the
bottom, but it's only intended to prevent frying the opamp with static
electricity.  It may not even do that, truth be told.  The absolute maximum
ratings for the TL07x inputs are +/-15V.  I think if one really wanted to
prevent phase reversal, one would have to divide the rails to 14.3 on top
and -11.3 on the bottom, and then clamp to those voltages.  Too many
resistors, not enough justification.