The moving beam on a CRT introduces new visual problems that are not
present with a simple "all-at-once" display like a MUX'd display or motion
picture.  As you state, 70Hz is borderline for a CRT, especially if your
monitor forces you to use interlaced scanning (my old NEC 3D at 1024x768
required 72Hx interlaced).  Luckily my new Viewsonic 21" gives me 87Hz @
1280x1024.

A 50Hz scan should be sufficient for a LED bar, but there is no reason you
can't go to 100Hz if you want.


CIAO - Martin R. Green
elimar@bigfoot.com

----------
From:   Marc 'Nepomuk' Heuler[SMTP:marc@AARGH.MAYN.DE]
Sent:   Tuesday, September 16, 1997 6:27 PM
To:     PICLIST@mitvma.mit.edu
Subject:        Re: Multiplexing Seven Segment Displays

Hi Martin (Martin R. Green), in <01BCC208.270817E0@ifs-greenm.sybase.com>
on Sep
 15 you wrote:

> All LED's should be
> sequenced in less than 1/30 second to avoid flicker (a few rare people
can
> detect flicker at this high rate so you might want to use 1/40th or
1/50th
> sec. instead).

I can see the 70Hz flicker of my monitor, if it is below the view center
(ie I look slightly above the monitor).  30 Hz is awful, especially if the
display is moving (or I am moving).  It's one of these eye-catchers in
cheap coin solariums.  The display pushes on your sight everytime you come
or leave.