Actually, I'm convinced that figuring out the optimum refresh rate for a
given screen size and resolution is a black art, too complex for us mere
mortals.  If it looks good to you, the rate must be OK.

As far as lightbulbs go, they are not really affected by flicker because
the hot filaments have a very long persistence.  Fluorescent lights,
however, do pulsate in time with the AC frequency.  This is why those
strobe rings on  LP turntables don't work with incandescent light.  You
need fluorescent or neon illumination to set the turntable speed with this
method.

CIAO - Martin R. Green
elimar@bigfoot.com

----------
From:   Eric van Es[SMTP:vanes@ILINK.NIS.ZA]
Sent:   Wednesday, September 17, 1997 3:45 PM
To:     PICLIST@mitvma.mit.edu
Subject:        Re: Multiplexing Seven Segment Displays

Martin R. Green wrote:

> 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.
>

Do you need higher refresh rates, because the monitor has a large area
to refresh?The 7seg would be very small...

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

After all the lightsbulbs in SA all run off 220V 50Hz. Only sometimes
you detect a flicker - usually when there's a power dip. I suppose it's
because the filament does not dissipate its rated power and
illuminescence....

Cheers!

--
Eric van Es               | Cape Town, South Africa
mailto:vanes@ilink.nis.za | http://www.nis.za/~vanes
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