Subject:
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IR Sensitivity - Was: 1.5/2.0 infrared problem
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Newsgroups:
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lugnet.robotics.rcx
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Date:
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Thu, 23 Oct 2003 03:26:43 GMT
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Viewed:
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6622 times
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In lugnet.robotics.rcx, Chris Masclet wrote:
> In lugnet.robotics.rcx, Chris Masclet wrote:
> > Hi I've got two RCX: a 1.5 and 2.0 version.
> > I' ve got a problem with IR emiter/reicever.
> > The 1.5 version seems to be more sensitive to reflected infrared and its
> > good to use !
> > But the 2.0 RCX is less sensitive and for example doesn't receive reflected
> > message from my remote control or 1.5 RCX.It has to be exactly in the axle
> > to receive IR.
> > Does anybody know about it?
> >
> > CHRISMAKER
>
> we ' ve told about this thing with Philo few days ago cause he had the same
> problem.
>
> So I' ve made several tests with 4 RCX: 2 RCXv1.0 and 2 RCXv2.0 .
>
> It seems RCX emitter is the same in 1.0 and 2.0 versions.
> But 2.0 receiver is less sensitive than 1.0's one..........
>
> This is a weird thing!!!
I think there might be an explanation for this and I've been meaning to post on
this topic, but never seem to have gotten around to it! :-)
I've opened up my RCX 1.0 and the IR receiver has the markings "TSOP 1138" on
it. After looking this part number up, it appears it is an IR receiver
sensitive to a 38KHz IR carrier. This is the "normal" carrier for RCX messages.
However, my RCX 2.0 has an IR receiver with "TSOP 1176" markings. I couldn't
find any info on this part, but knowing that a TSOP-1140 is an IR receiver for a
40KHz carrier leads me to extrapolate that the IR receiver in my RCX 2.0 is
sensitive to a 76KHz carrier (double the 38KHz carrier).
Now, as has been mentioned here before, the Spybot and Manas remotes send IR
messages using a 76KHz IR carrier. My RCX 2.0 can receive these messages just
fine, while my RCX 1.0 struggles to receive these messages even with the remote
a few inches from the RCX.
While the TSOP-1176 is also apparently sensitive to a 38KHz carrier (otherwise
it couldn't receive normal RCX messages), it may be with less sensitivity than
the native TSOP-1138. This could be the reason for the observed differences in
IR reception between the different RCX versions.
Mark
BTW, the TSOP-1176 part is also used as the receiver in Spybots and Manas motor
units.
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Message has 4 Replies:
 | | Re: IR Sensitivity - Was: 1.5/2.0 infrared problem
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| chip 1138 / chip 1176 Strange... 38 + 38 = 76 What does that mean? Rob "Mark Riley" <markril@hotmail.com> wrote in message news:Hn6xKJ.1o68@lugnet.com... (...) its (...) reflected (...) axle (...) same (...) post on (...) on (...) messages. (...) (...) (21 years ago, 23-Oct-03, to lugnet.robotics.rcx)
| | | Re: IR Sensitivity - Was: 1.5/2.0 infrared problem
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| (...) Hello Mark, Thanks for your answer, this will keep me from dismantling once again my RCXs ! So it seems that LEGO modified RCX2.0 to get better compatibility with Spybots/Manas. Now a question remains, why did they increased carrier frequency (...) (21 years ago, 23-Oct-03, to lugnet.robotics.rcx)
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Message is in Reply To:
| | Re: 1.5/2.0 infrared problem
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| (...) we ' ve told about this thing with Philo few days ago cause he had the same problem. So I' ve made several tests with 4 RCX: 2 RCXv1.0 and 2 RCXv2.0 . It seems RCX emitter is the same in 1.0 and 2.0 versions. But 2.0 receiver is less sensitive (...) (21 years ago, 23-Oct-03, to lugnet.robotics.rcx)
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