Subject:
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Re: IR Collision avoidance
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Tue, 25 Feb 1997 06:51:29 GMT
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Original-From:
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Richard Vannoy <richardv@NOMORESPAMabac.com>
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Reply-To:
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RICHARDV@ABAC.avoidspamCOM
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Viewed:
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2231 times
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Bill Rose wrote:
>
> Chris or anyone who cares to respond,
OK.
> You put your message on the mailing list concerning the IR avoidance. I
> have a question about the hardware also. How are the leds powered? Are you
> pulsing them some way or what? I guess the decoder is what is wired into
> the digital ports? Am I right about this? I just don't catch how you are
> powering the leds.
The transmitter is basically a modulator made from two 555 timer chips.
One timer does 200-1000 Hz (we use 500) while the other does 38 KHz. On
a scope, the output looks somewhat like..
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----------- ----------- ----------- ----------
^ ^ ^ ^
One complete cycle The high of each cycle
of 500 Hz pulses the 38KHz
The tone decoder (receiver) demodulates the signal. If is senses the
38KHz signal it puts out a logic one (or zero depending on design) that
can go to any available digital port. The port is processed like...
hit = digital(7)
If the receiver is getting hits, hit will be a one, if not hit will be
zero. Then program the bot from what you want to happen for each case.
The LEDs are in series with the collector of the transmitter output. We
put a current limiting resistor in the circuit which allowed us to tweak
the LED for good range from several inches to about 5-6 feet.
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Message is in Reply To:
 | | IR Collision avoidance
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| Chris or anyone who cares to respond, You put your message on the mailing list concerning the IR avoidance. I have a question about the hardware also. How are the leds powered? Are you pulsing them some way or what? I guess the decoder is what is (...) (28 years ago, 24-Feb-97, to lugnet.robotics.handyboard)
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