Have you any schematics?
----- Original Message -----
From: "Kenneth Alan Boyd Ramsay" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Friday, January 12, 2001 4:14 AM
Subject: Re: [SURVPC] Optical link for Or Botton's Network.
> While this thread interests me, I feel it is wandering a bit OFF-TOPIC
> for old computers. I have had some experience with optics and telescope-
> making as well as analog and digital circuits.
>
> From: Garry <[EMAIL PROTECTED]>
>
> > Yes, line of sight. Hmmm . . .
>
> > <dream mode>
> > A real challenge would be inventing some way
> > of "broadcasting" such a light-spectrum signal.
>
> I would suggest "beamcasting" as more efficient and secure. Laser diodes
> and sensors are now fairly cheap - even available in surplus 1X CD-ROMs.
> Lasers are monochromatic, so you only need thin, simple lenses (or
> mirrors). I would guess 3 or 4 inches (75 to 100 mm in diameter) would
> do nicely. The idea is to spread the beam so that most of it passes
> around raindrops, etc.
>
> With luck, you may be able to find appropriate lenses in surplus stores at
> a good price. Small lenses (like elements from a microscope, or eyepiece)
> could be useful in spreading the beam to the width of the big lens as if
it
> came from the focal point of the big lens, so that the beam out is
parallel.
>
> They should be solidly mounted - with means to make fine adjustments.
Given
> a parallel beam, the width of the lens, in the visual part of the
spectrum,
> I would suggest using a beaded slide projection screen behind the receiver
> to align them.
>
> Long lens hoods would also be a good idea, to keep out rain, etc., but
> removable for cleaning.
>
> Note: It is not a good idea to look into the beam - especially after dark,
> when your pupils are wide open.
>
> > I suppose with a little thought (or a lot) one
> > could devise a roughly circular array of emitters
> > and receptors . . . although finding a way to
> > multiplex that would require more engineering
> > skill than I have . . . alternatively, each channel
> > could simply be assigned its own frequency.
> > </dream mode>
>
> For multiple connections, unless you are broadcasting to the whole
> neighborhood, you would need separate transmitter/receiver pairs.
> Unless you modulate the diode output (complicated) or use multiple colors
> and filters, you can't use different frequencies. One frequency of light =
> one pure spectral color.
>
> > But, for what this design was intended, it's
> > brilliant: it takes the IrDA support circuitry
> > that's already on most newer mother boards
> > and routes it through a modified version of
> > that kind of hardware, taking advantage of
> > existing network drivers! Sweet.
> ~~ Garry
>
> As for the electrical connection to your computer, the COM port or a
network
> card should do nicely, too.
>
> ----- Original Message -----
> "Bob George" <[EMAIL PROTECTED]> wrote:
> >>
> >> Neat, but line-of-sight only. I suppose you could put up towers on the
> >> rooftops...
>
> Boyd Ramsay
>
> [EMAIL PROTECTED]
>
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