[sdiy] Presets on a laser

[Richard Wentk]

At 12:02 12/11/2004 -0500, Glen wrote:
>At 07:16 AM 11/12/04 , Richard Wentk wrote:
>
> >>Wireless doesn't always have to mean radio transmission. Could you perhaps
> >>use a modulated IR link for your laser?
> >
> >Too slow. You're lucky to get more than 1MHz out of a laser.
>
>How much bandwidth do you need for your laser controller application?

Okay. Sorry. Crossed wires. :-)

For current laser controllers 10kHz per channel is more than you need. 
Analogue intensity modulation works up to 30kHz, supposedly, but there 
aren't many situations where you need that. A single laser head needs 
separate X and Y signals, and the fancy ones (which I don't have, because 
they're *way* too expensive for my budget) have separate RGB control levels 
as well. So that's 5 channels at 10kHz or so.

IR would carry that, but the problem with IR is it's line of sight, and the 
range is very poor.

What I have at the moment is a USB extender which gives up to 50m via a 
couple of converters that run USB into and out of CAT5 cable. (The XY 
signals come from a modified USB DAC next to the head.) That's actually 
fine for most halls. But it would be good to be able to run wireless. 
Wireless USB is going to be Next Year's Big Thing, but there's no hardware 
for it yet, and the range is still on the low side for what I need.

So it would be good to find an off-the-parts-shelf wireless solution that 
can multiplex a handful of channels onto a digitally modulated FM signal 
using legal frequencies, with a range of up to a mile or so for when I find 
the money for a monster god 50W city show head. :-)

>That could get interesting at a Pink Floyd concert, with their history of
>using of both synths and crashing airplanes onto the stage.   :)
>
>You could even make their flying pig dance around in synchronization with
>the synth.  :)

Or vice versa. :)

Richard