Subject:
|
Re: Elimating the need for the IR tower
|
Newsgroups:
|
lugnet.robotics
|
Date:
|
Wed, 10 Jan 2001 20:50:52 GMT
|
Original-From:
|
John Barnes <barnes@sensors/StopSpammers/.com>
|
Highlighted:
|
(details)
|
Viewed:
|
398 times
|
| |
|
|
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
|
|
Message has 3 Replies:
 | | RE: Elimating the need for the IR tower
|
| (...) <snip> (...) <snip> (...) John, This would be neat in the short term, especially for little PDAs and such that don't have a standard DB9. But the biggest benefit (in my opinion) would be in classrooms. With a low power transmitter, there would (...) (23 years ago, 10-Jan-01, to lugnet.robotics)
| | | Re: Elimating the need for the IR tower
|
| (...) 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!: (URL) Lego (...) (23 years ago, 10-Jan-01, to lugnet.robotics)
| | | Re: Elimating the need for the IR tower
|
| (...) What I'm wondering, is could the timer circuit be eliminated? From previous posts, I know a lot of people would like to have their towers ready to recieve at any time, without it shutting down from lack of activity. People have been adding to (...) (23 years ago, 11-Jan-01, to lugnet.robotics)
|
4 Messages in This Thread:
 
- Entire Thread on One Page:
- Nested:
All | Brief | Compact | Dots
Linear:
All | Brief | Compact
|
|
|
|
