Re: gEDA-user: Re: Looking for a project

[Peter Clifton <pcjc2@xxxxxxxxx>]

On Sat, 2007-03-31 at 17:51 -0400, al davis wrote:
> On Saturday 31 March 2007 17:36, Peter Clifton wrote:
> > > The significant contribution here is to do the whole job,
> > > with PCB layout, assembly procedure, test procedure, and
> > > make the whole package GPL.
> >
> > One word: _Saftey_.
> >
> > We use differential isolating probes in the lab for all sorts
> > of measurements, and for power systems, they must be
> > isolated. I'm not sure what the standards require, but I'd
> > probably design for many kV. (to ground).
> 
> Let's put that in the same category as the wideband one.  There 
> is no reason why someone who just needs it to break ground 
> loops in an audio circuit, or to probe across parts inside, 
> needs all that extra.  A simple op-amp will do.

Ok - I was just making sure the difference was posted on the list.

I'm sure if anyone wants, I could post the schematics and layouts for my
quick hack inst-amp board. It really wants to be powered off say a 12V
keyfob battery, but I used a PSU. For maximum output range, you want to
get close to its 15V maximum rail-rail voltage.

The board is quite small, and comes complete with incorrect footprint
spacing for the de-coupling capacitors (the ones I had to hand anyway).

I've got mine set at 51x gain, but you can set that with two high
accuracy resistors. Its as an exercise to the reader to work out the
component values etc.. though - its all in the data-sheet.

Promise not to laugh though ;) I'm not really into precision analog
stuff. It can't be too far wrong though... it is basically what the
data-sheet prescribed - other than the layout.

Peter





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