I did say it was goofy. :)
Wiki says IrDA has specs up to 1 Gbit now, but I don't know if you can actually do that. When it was on a lot of laptops and printers I think it was in the dialup modem/ISDN speed range, like up to a few hundred kbits or so. You don't *have* to use IrDA but there may be pre-existing code and hardware (especially on the PC side) for it.
Matt Roberds
thinking
not
Have you looked at RFID? It won't handle that kind of power but will handle the comm.
Of course it would really help if you could get the power down below 1% of what you are using now.
?-)
Yup. I wonder how hard it would be to find optically black epoxy that's IR-transparent? It can't be that hard - it's what they enclose some of the IR LEDs and phototransistors in.
-- Tim Wescott Wescott Design Services http://www.wescottdesign.com
You mean the resin base? For example here:
-- Regards, Joerg http://www.analogconsultants.com/
It won't handle 10kbaud. If IR is an option that may be best because it comes without all this FCC rigamaroo. RF via magnetic coupling is also possible if one can stay below the usual class B limits.
Power for the unit itself? 200mW isn't really much for non-contact power transfer.
-- Regards, Joerg http://www.analogconsultants.com/
I needed to find a material that was opaque to the IR LEDs I was testing a few years back so I tried all sorts of weird things. Most of the "black" inks I tested -- permanent markers, standard ink-jet printer ink, toner from a laser printer, even some "pigmented" inks -- let my IRs shine through just fine. I did find two items that blocked IR well:
1) The local grocery store sells its fresh-cooked ribs and rotisserie chicken packaged in a black plastic "tub" with a transparent plastic cover. The black bottom material is opaque to IR. 2) My daughter knew I was looking for "black" stuff, so she brought me a jar of old black acrylic paint from Pittsburgh. This stuff also worked well, though I don't know if I can assume that all acrylic paints behave the same way.I did not try one of those "paint markers" since, at the time, I didn't know they existed. Those are another possibility.
Oh, and a digital camera, even one which supposedly blocks IR, may help you "see" whether or not IR light is passing through a substance. Look at the LCD display whwhile someone points a TV remote at the lens and presses a few buttons; if no-one is handy, rig up a clamp or weight to keep the remote transmiting.
Hope this helps...
Frank
--
The overwhelming message taught in American schools, public and
private, is that no group is superior to any other. In America,
embracing yourself as you are -- feeling secure about yourself -- is
supposed to be the key to a successful life. People who don't live in
the present are missing out on happiness and life itself. Whatever
kernels of truth may underlie these propositions, the irony is this:
America still rewards people who don't buy into them with wealth,
prestige, and power.
-- Amy Chua, Jed Rubenfeld / The Triple Package
Anything carbon-based works fine. It's just the organic dye blacks that are leaky in the IR. That's why the really old advice to use exposed photographic film to view eclipses was quite good with B&W film but disastrously bad with colour film.
My favourite is Krylon #1602 Ultra Flat Black, which you can get at Grainger or Fastenall. (They don't sell it in hardware stores anymore on account of the VOC regs.)
That stuff is also a spectacularly good index match to fused quartz or acrylic, so it does a really good job of controlling internal reflections.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
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