PSN-L Email List Message

Subject: Re: Seismic exhibit for kids
From: "Charles R. Patton" charles.r.patton@........
Date: Fri, 18 Aug 2000 00:06:54 -0700

Three orders of magnitude would be hard to see on a standard meter.  A 3
=BD digit DVM would be capable of that display, but you=92re back to the
original problem of it=92s not very visual.  What might be satisfactory i=
to take an A/D chip with 10 bits of resolution or so =96 you=92ll only ne=
8 bits of that, but in order to guarantee no missing codes and so forth
I=92m suggesting a 10 bit one.  The cost is still only a few dollars for
the low frequency sampling you=92ll be using.   I=92d then feed the decod=
A/D output to a string of LED=92s, 255 in this case.  If you get ambitiou=
you could go for 9 bits and 511 LED=92s.  Now a magnitude 1 could be 2
LED=92s on, magnitude 2 would be 20 LED=92s on, and magnitude 3 would be =
LED=92s on.  That would be very visual and could be constructed to fit th=
area you have.  As I sit here, I=92m thinking of that scene in =93Forbidd=
Planet=94 where they=92re in the power control room and the meters are go=
up one by one as the =93ID=94 monster draws on the power to break down th=
vault-like doors =96 but you probably don=92t want to get quite that carr=

Charles R. Patton


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