[ale] Raspberry πdeas

Tue Oct 30 10:52:08 EDT 2012

On Fri, 2012-10-26 at 17:23 -0400, Michael H. Warfield wrote:
> On Fri, 2012-10-26 at 13:56 -0400, Michael Trausch wrote:
> > Gonna present the line analyzer? :-D 

> I honestly do not know.  I do know that I have two Raspberry π's on the
> way (shipping in about 2 weeks), 3 200 Amp current transformers plus 2
> 30 Amp pickups and just ordered 1 Alamode to go with one of the
> Raspberry π's (so I can mount more shields).  I'm looking at sensor /
> capture boards now.

Just talked with a gal from Newark (aka Element 14) who was thanking me
for my order.  She asked me if I was going to use one and give one away
as a gift.  "Oh, no, I may order several more.  I've got several
projects I'm developing for them."  She said she's sending me a discount
coupon for accessories in their catalog (not applicable to the Pi
itself).  Hmmm...  "Does that apply to components?" (I use to my all
sorts of stuff from Newark for decades.) "Anything in our catalog.
Share it with your family and friends too."  Then I told her about our
group and this little idea of a presentation next year.  I think she was
impressed.

IAC...  For the power line analyzer...  I may go the line isolation
transformer route for voltage.  I can get some 6VA 115/230 VAC isolation
transformers with 10KV isolation for under 15 a piece.  They won't have
near the high frequency characteristics I want but I think I'm going to
try to use the alamode board I have on order and the 8 channel ADC on
that in leu of a stack of USB audio interfaces.

The Ariundo alamod board can be pushed to a 1MHz clock into DAC which
(at 10 bits) has a theoretical limit of 100K samples per second total.
If I'm only sampling two channels, that gives me 50K samples per
channel, limiting me to 25KHz.  More channels, lower high frequency
limit.  The clock can be pushed above 1MHz but the characteristics of
the 10bit DAC at the heart of the ADC is "unprofiled".  Could be fun to
play with that with my WaveTek waveform generator to see just how well
it can keep up.  Two channels, voltage only, should keep up very nicely.
Four channels, voltage and current may be marginal.

Still, this would prove the concept with a minimum of external
components, minimal cost, and minimal bread-boarding.  Maybe the
simplest way to go but I'm still considering the audio interfaces for
sampling as well.  Those will give me 44K samples per second for 22KHz
max that does not degrade as you add more channels because you're adding
more interfaces and running the sampling in parallel.

Some of my inductive couplers (30A) have arrived as have the cases.
Waiting on the 200A couplers for the mains, the RPs, and the alamode
board.

I've also got an Ariundo shield on the way with an 8 channel relay
board.  Me thinks, irrigation controller.  Yeah...

Regards,
Mike

> Regards,
> Mike

> > On Oct 26, 2012 1:20 PM, "Michael H. Warfield" <mhw at wittsend.com>
> > wrote:
> >         Oh, hell...  I am so there.
> >         
> >         On Fri, 2012-10-26 at 11:56 -0500, Doug Hall wrote:
> >         > Let's each come up with a cool way to use the Raspberry Pi
> >         device,
> >         > then plan a meeting at some time in the future (maybe next
> >         June, or
> >         > so) to show our implementations off. The ideas don't have to
> >         be
> >         > original - just cool or interesting in some way. It could be
> >         a
> >         > competition, but it doesn't have to be. That would give us a
> >         deadline
> >         > (which certainly helps me get stuff done), and would make
> >         for one hell
> >         > of a meeting. Who's in?
> >         > _______________________________________________
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> >         
> >         --
> >         Michael H. Warfield (AI4NB) | (770) 985-6132 |
> >          mhw at WittsEnd.com
> >            /\/\|=mhw=|\/\/          | (678) 463-0932 |
> >          http://www.wittsend.com/mhw/
> >            NIC whois: MHW9          | An optimist believes we live in
> >         the best of all
> >          PGP Key: 0x674627FF        | possible worlds.  A pessimist is
> >         sure of it!
> >         
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-- 
Michael H. Warfield (AI4NB) | (770) 985-6132 |  mhw at WittsEnd.com
   /\/\|=mhw=|\/\/          | (678) 463-0932 |  http://www.wittsend.com/mhw/
   NIC whois: MHW9          | An optimist believes we live in the best of all
 PGP Key: 0x674627FF        | possible worlds.  A pessimist is sure of it!
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