Subject:
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Re: detecting goal objects at a distance
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 31 Dec 1999 18:38:02 GMT
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Viewed:
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911 times
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In lugnet.robotics, Uwe Denzer writes:
> Mario Ferrari wrote:
>
> > Does any of you have suggestion on what kind of IR led is more appropriate
Well, I do now! I bought three last night. I got a GaAs IR LED that was
clearly made for a remote control application. The good news is that when it
is pointed at the LEGO light sensor it pegs at 100%! Unfortunately it's higly
directional (it seems to be an LED behind a lens, rather than embedded in a
diffusing material). I chose it because it claimed to be a 3v part, which made
battery selection easier. I'm going to exchange it for one of the 5-6v LEDs
with a standard diffuse plastic body.
To power it I got 3v lithium watch batteries (biggest I could find, about the
size of a quarter). If I go with 6v LEDs I'll need two of them sandwiched
together. I plan to use 1/2" heat-shrink tubing to hold the batteries together
with electrodes (aka wires soldered to a loop of large gauge copper wire).
> > to make such an object? Do I need any additional circuit, or just a LED and
> > a battery (and the proper resistor) are enough?
They make some LEDs with builtin resistors now. You should make sure you know
what kind you've got.
> I imagine that - even if using such an IR LED as a beacon - roomlight etc. • will
> still be the major problem.
The LEGO sensor is far more sensitive to IR already, even without a filter.
That's why I was choosing it (although being invisibile to humans is a nice
side-effect).
> So, I'm pretty sure that a quite simple means at the detector side would
> simplify such a project dramatically: an optical IR filter.
You can get these (as well as so-called Hot Mirror filters to block IR) at any
camera store.
--Ben
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Message has 2 Replies:
 | | Re: detecting goal objects at a distance
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| Thanks a lot Ben! I'm going to look for some of those IR LEDs and make some experiments. Mario (...) appropriate (...) it (...) higly (...) a (...) made (...) LEDs (...) the (...) together (...) and (...) know (...) etc. (...) filter. (...) nice (...) (24 years ago, 3-Jan-00, to lugnet.robotics)
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Message is in Reply To:
| | Re: detecting goal objects at a distance
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| (...) I imagine that - even if using such an IR LED as a beacon - roomlight etc. will still be the major problem. So, I'm pretty sure that a quite simple means at the detector side would simplify such a project dramatically: an optical IR filter. (...) (24 years ago, 31-Dec-99, to lugnet.robotics)
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