Subject:
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Re: Elimating the need for the IR tower
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 10 Jan 2001 20:50:59 GMT
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Viewed:
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396 times
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John Barnes wrote:
> I have been following this thread for a while and it suddenly
> crossed my mind that the originator of the thread may have
> had a slightly different requirement than the current thread's
> interpretation is addressing.
>
> I traced out the circuitry in the tower a couple of months back
> to make sure it didn't have any clever tricks up its sleeve.
> It doesn't!
>
> On the receiver side it is super simple. It uses one of the integrated
> IR receiver demodulator devices which have become so common
> these days.
>
> The transmitter side is simply a 38kHz oscillator gated by the transmit
> data. The only reason it has its own battery is because it pushes a
> fair amount of current through the transmit IR LEDs when set to long
> range mode.
>
> There is a simple timer circuit that keeps the power applied for a certain
> period after the last activity allowing for response data to be received from
> the RCX.
>
> It was my experience that if the range between an IR LED and the RCX
> receiver can be kept to less than a couple of inches, as was the case in
> my UHF repeater brick, then the modern high efficiency IR LEDs will
> work just fine with only a milliamp or so of drive.
>
> The upshot of all this is I think you could build a cable which plugs into
> the PC's serial port and which hides the 38kHz oscillator on a small
> board in the DB9 hood. The other end of the cable would have a small
> transparent
> "blob" which houses the IR LED and the IR demodulator device. This cable
> end would be placed in close proximity to the RCX's business end and
> away you go. (I almost wonder about using one of those small sized transparent
> suckers for the RCX end. I think enough power can easily be scavenged from the
> RS232 control signals. The Lego tower already does this to obtain its negative
> supply for its RS232 transmitter transistor on the TX data line back to the
> PC.
> (The tower doesn't use any RS232 transmitter/receiver chips, just transistors.)
>
> I wonder if there is enough interest in something like this to make it
> worth building and publishing the details (assuming it works ;)
>
> JB
If it worked it would be great to be able to connect a super short version to a
PALM or Pocket PC type device. If it could be transmitting and receiving all the
time you could do some wonders with it.
Dean
--
Coin-Op's For Sale!: http://www.akasa.bc.ca/tfm/coin-op.html
Dean's Lego Workshop: http://www.akasa.bc.ca/tfm/lego_wr.html
Vancouver Lego Club: http://www.akasa.bc.ca/vlc
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Message is in Reply To:
 | | Re: Elimating the need for the IR tower
|
| I have been following this thread for a while and it suddenly crossed my mind that the originator of the thread may have had a slightly different requirement than the current thread's interpretation is addressing. I traced out the circuitry in the (...) (23 years ago, 10-Jan-01, to lugnet.robotics)
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