Re: Electronic Highway Signs

Article: 7667 of alt.hackers
Newsgroups: alt.hackers
From: wiml@netcom.com (William Lewis)
Subject: Re: Electronic Highway Signs
Message-ID: wimlD72H9y.KDE@netcom.com
Organization: The Seattle Group
Date: Sat, 15 Apr 1995 08:08:22 GMT
Approved: You bet your bippy!
Lines: 65
Sender: wiml@netcom4.netcom.com
Status: RO

In article <3m7otl$gpo@jaws.cs.hmc.edu>, Roy Roberts
<rroberts@hmc.edu> wrote:
>marlowe@io.com (marlowe) wrote:
>> The highway near my house in Houston has just installed those
electronic
>> highway signs that show up all over the country. To be precise,
these are
>> permanent, tall, and have bulbs as pixels.
>
>Interesting tidbit: for some reason, those signs (at least those on
the Long
>Island Expressway) don't operate by turning the bulbs on and off, but
>instead shutters are used.  I have no idea why.

This prolongs the life of the bulbs --- turning an incandescent
light on and off subjects the filament to some pretty extreme
temperature-cycling, and the bulb lasts a lot longer of you
don't do that. I can imagine that changing burned out light bulbs
in hundreds of highway signs would be pretty costly.

Or so I hear.

ObHack: ... well ... let me see. I live in a kind of networked house;
we use duct-tape-and-phone-wire technology. Most of the actual
computing power is on an Ethernet in the basement, in particular my
NeXT slab, off of which I've hung an old vt320 which sits on the
breakfast table, upstairs.

The terminal uses a weird vaguely RJ-11-like connector for its serial
port, and the slab uses a mini-DIN-8, and for some reason I couldn't
find a 50-foot mini-DIN-8-NeXT-RS422-to-DECconnect-RS423 cable at the
local Radio Shack.  I did, however, have a 2-foot
DECconnect-to-DECconnect cable (easily halved), 50 feet of 8-conductor
phone cable, and a mini-DIN-8 plug.

Right now you're thinking, "So he made a custom cable. Big deal." No,
that's not my hack (though my hack isn't all *that* much better). I made
the custom cable some months ago and it's been working fine since. The
stub of the DECconnect cable, and the 50-foot phone station cable, both
have miniature pins and sockets crimped on to their ends to make it
easier to rearrange the connections. The two cables were originally
taped to a spare piece of lumber to keep the connections from pulling
apart, but this is bulky, and occasionally someone bumps the connectors
and the terminal stops working.

But if I put the pins into a real connector, I wouldn't be able to
rearrange them easily --- they lock in. Looking about one afternoon
after stuffing the pins back in, I noticed near me some manila folders,
a large needle, and an X-Acto knife. Springing into action, I cut a
rectangular piece from the folder. Along each side, I put eight holes,
smaller than the connector pins, through which I then forced said pins,
each cable going to one side of the rectangle, and the pins and sockets
connecting across the middle and held in by the fact that the
connectors were too large to go back out through the holes.

Fine and dandy, but not very robust. I then rolled the cardboard up
into a tube (with the connectors parallel to the sylinder's axis),
and cut a hooked tab and a slot to keep it that way. I used the needle to
thread a loop of thread through each cable sheath and through the center
of the tube as strain releif, so that the connector could take some tension
without ripping the cardboard. Finally, I wrapped another tube of cardboard
around the whole thing. The result: a small, sturdy, custom cable
splice, easily rearrangeable, a little larger than a DIN but a whole
lot easier to put together.

Or at least a whole lot more fun...

--
        William "Wim" Lewis * wiml@netcom.com * Seattle, WA, USA

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