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.