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<DIV><FONT face=Arial size=2>Yeah, Tom, we're kinda back to why Lindberg didn't
choose the twin Bellanca... I think he said "twice as many things to go
wrong", or at least that's my clouded recollection of the movie
version...</FONT></DIV>
<DIV> </DIV>
<DIV>Bob Pastorello<BR>NSRCA 199 AMA 46373<BR><A
href="mailto:rcaerobob@cox.net">rcaerobob@cox.net</A><BR><A
href="http://www.rcaerobats.net">www.rcaerobats.net</A></DIV>
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style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=nsrca@shinymetalass.com href="mailto:nsrca@shinymetalass.com">Tom
Simes</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=discussion@nsrca.org
href="mailto:discussion@nsrca.org">discussion@nsrca.org</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Monday, January 24, 2005 4:28
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: any merit in running dual
battery packs ?</DIV>
<DIV><BR></DIV>On Mon, 24 Jan 2005 14:45:32 -0500<BR>"Dean Pappas" <<A
href="mailto:d.pappas@kodeos.com">d.pappas@kodeos.com</A>>
wrote:<BR><BR>> LEDs have large voltage drops. Something more interesting
would have<BR>> to be done. You have to figure out what is most likely to
fail. My<BR>> high-falutin' analysis, done ages ago, showed that switches
and<BR>> connectors are the worst culprits. I use one battery withtwin
leads,<BR>> and cvarry the twin leads all the way to the RX. Of course, I
don't<BR>> buy the cheapie batteries. Hello SR! Dean<BR><BR>So I can see
that your method likely reduces the probability of failure,<BR>but as far as I
can see you still have no indication that a failure has<BR>occurred in the
primary system until a failure occurs in the secondary<BR>system as well -
although when the notification occurs it's a doozy!<BR><BR>Checking Digikey it
looks like even the high efficiency LEDs are<BR>still in the neighborhood of 2
V forward drop and the drop is fairly<BR>consistent across their operating
current range (darn physics!). <BR><BR>It looks like one might be able
to use something in the TI TPS61010 thru<BR>TPS61016 family to drive the LED
(although obviously at the cost of<BR>increased input current). Or what
about using a dropping resistor and<BR>tapping the current flow downstream of
the regulator with the lowest<BR>voltage setting? Should I crawl back in
my hole with this? I'm just<BR>thinking that some kind of visual failure
indicator would really be<BR>a beneficial addition to a two pack
design.<BR><BR>Of course that wouldn't show you that the backup pack had a
failure<BR>while the primary pack was still operating... Although you
could have<BR>an LED on both regulators and as long as the expected one was
on...<BR>Vague memories of statistics class, MTBF calculations and the effect
of<BR>adding components to a system are starting to crop up about
now...<BR><BR>Nevermind, straight back to my hole it is - now where did I put
that<BR>tinfoil
hat?<BR><BR><BR>Tom<BR><BR>_____________________________________________________________________<BR><BR>
| ,
|
Tom Simes<BR>---------(@)---------
AMA 230068<BR>
--|--
NSRCA 3830<BR>
'
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