I'll bet it was just paper tape and mechanical finger contacts.  The
ASR33 teletypes I once used worked that way.  The fingers were
retracted, the tape advanced, the fingers extended and found holes or
not, cycle repeats faster than you can see.  Centainly fast enough for
scrolling signs.  The tape would last a few hours, by which time the
news would change anyway.  The key is that the fingers never touch the
edges of the holes.  The contacts driven by the fingers could probably
drive the light bulbs directly, no relays or other amplifiers (1/4A @
110V for a 25W bulb).

Sherpa Doug

> -----Original Message-----
> From: Jinx [mailto:joecolquitt@CLEAR.NET.NZ]
> Sent: Friday, March 01, 2002 3:59 PM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: [OT] :Old (ancient) message scrolling
>
>
> > That was a time when paper tape was all the rage
>
> Had the idea that the name "ticker tape" was somehow
> associated with those displays. I believe the properties of
> materials like selenium as a photo-detector, if that's what
> was used, were known at the time, and from there then it
> would be fairly easy to switch valves or relays
>
> The displays show no flicker or strobing (unlikely that they
> are in perfect synch with the camera every time) as they
> aren't scanned or "synthesised", but directly driven in almost
> a bit-mapping way, and that simplicity is appealing, particularly
> as the results are at least equal to what can be accomplished
> today
>
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