SV: Re: [Fwd: Re: Op Amp pinouts was Re: [sdiy] more LM3900 stuff]

[harrybissell]

I did an instrument for a major automotive customer.

They wanted to upgrade from a 12 bit A/D to a 16 bit A/D...

I told them "impossible"

They said, "oh no, we can just plug in this new card..."

except that they probably had two bits buried in the noise
floor of all the sensors already.

I told them if they were willing to pay me, I could put the
card in and give them SIX BITS of noise instead of two...
but that if they wanted six bite more SIGNAL they would have to do
a ground-up re-design :^P

sad, but true

H^) harry

Grant Richter wrote:
> 
> Your in the range of thermoelectric voltages produce by differing
> metals.
> I think they call it the "Seebeck effect".
> 
> Probably a chapter on it in the DVM manual.
> Must be some amazing common mode rejection to get rid of RF hash.
> 
> When I see figures like 0.00008% THD, I know it came from marketing
> and not engineering.
> 
> I mean what is the X bar distribution on THD for practical
> manufacturing?
> Can the process be controlled? Do they test for the THD spec?
> 
> Silly numbers stuff.
> 
> On Jan 21, 2006, at 6:28 PM, karl dalen wrote:
> 
> > Oh! Impressive!
> > ""8 1/2 digits with 10 nV DC resolution""!
> >
> > This is not any "off the shelf dual slope" ADC,ing thing!
> >
> > 10nV!! Slightest oxidation on a component
> > leg would ruin that i suppose! There must be
> > an entire manual of just cleansing legs before
> > measurements!
> >
> > KD
> >
> > --- Ian Fritz <ijfritz at earthlink.net> skrev:
> >
> >> At 12:01 PM 1/21/06, Ian Fritz wrote:
> >>> At 11:36 PM 1/20/06, Grant Richter wrote:
> >>>
> >>>>> Have you looked at the OPA134?  Distortion = .00008%
> >>>>
> >>>> How do you even measure that? A 24 bit sine wave is 0.001% THD
> >>>
> >>> I believe a 24 bit sine is better than that.  But, whatever, you
> >>> can get a
> >>> DVM with enough precision:
> >>
> >> <http://www.home.agilent.com/cgi-bin/pub/agilent/Product/
> >> cp_Product.jsp?
> >> LANGUAGE_CODE=eng&COUNTRY_CODE=US&NAV_ID=-11250.536881781.00&cmpid=96
> >> 200>
> >>
> >>>
> >>
> >> Crap, that link has a timeout.  Just go to agilent.com and look up
> >> the
> >> 3458A DVM.
> >>
> >>