For calibration you need to measure an amplified value, even if the
amplification is 1. You can't do that by grounding the signal. That just
sets the zero null point.
John Loffink
The Microtonal Synthesis Web Site
http://www.microtonal-synthesis.comThe Wavemakers Synthesizer Web Site
http://www.wavemakers-synth.com > -----Original Message-----
> From: ComputerVoltageSources@yahoogroups.com
> [mailto:ComputerVoltageSources@yahoogroups.com] On Behalf Of Larry T.
> Sent: Saturday, March 25, 2006 8:03 PM
> To: ComputerVoltageSources@yahoogroups.com
> Subject: [ComputerVoltageSources] Re: resistor matching, was RE:
> Calibrated Inputs
>
> Thinking about it, I believe this would also account for varrainces in
> the ADC's thenselves would'nt it?
>
> Larry T.
>
> --- In ComputerVoltageSources@yahoogroups.com, "Larry T." <larry@...>
> wrote:
> >
> > HI All
> >
> > Given that I'm not an EE or even a decent hobby designer, why is this
> > calibration such a problem? Why not use trim pots and the Analog
> > inputs themselves as follows:
> >
> > First: Ground the input to be calibrated. (This should ALWAYS be a
> > constant of 0 right?)
> >
> > Second: Run a small program on the modules CPU to continously return
> > the value of the converters input via the serial port to a 'telnet'
> > session on a PC or Mac, followed by a Carriage Return and a Line Feed.
> > (This will give you a continous dump of the converters value down the
> > screen.)
> >
> > Third: Adjust the timpot until you get 0.00... as the returned value,
> > and it stays that way for a minute or two.
> >
> > Would'nt this handle it with NO tools of any kind except those we
> > already need to use the module anyway?
> >
> > Larry T.
> >