Subject:
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RE: LEGO light sensor schematic
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 30 Apr 1999 15:39:32 GMT
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Viewed:
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972 times
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> > Anybody cut one of these rotation sensors open yet? A guy in Japan
> > (Sasuraibito) has discovered what he thinks is the circuit for the LEGO light
> > sensor. He also gave me permission to publish the image and circuit on my
> > page.
> > http://www.plazaearth.com/usr/gasperi/lego.htm
>
> Hmmm. Not to be overly critical, but that circuit wouldn't do a darn
> thing. We have an OpAmp connected to nothing that is set to oscillate for
> no reason, diode pairs that won't supply power to the circuit, an optical
> sensor that is biased backwards and lots of transistors set to act as diodes.
> I think he needs more work on the sleuthing, that can't be correct.
Hmmm, Michael is usually pretty careful about what he posts and he
has just a little experience with this kind of thing :-). In fact, Michael's
own powered sensors look a lot like this one.
From left to right:
The diode pairs that don't do anything are just a bridge rectifier in an
unusual schematic form.
The no-connect op amp is connected that way to conserve power it is half
of a pair...
When the RCX stops powering the circuit, the cap hold the internal supply up enough to keep the emitter and detector working, and
the right hand op-amp
drives the transistor to simulate an impedance which draws current through
the diodes on the far left of the diagram.
It looks like it works to me, and I'll bet Michael thinks so too, or he
wouldn't have put up the link.
Dennis, this is NOT a flame, but please be careful and know what you are
criticizing before you do it...
Cheers,
Ralph Hempel - P.Eng
--------------------------------------------------------
Check out pbFORTH for LEGO Mindstorms at:
<http://www.bmts.com/~rhempel/lego/pbFORTH/default.html>
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Reply to: rhempel at bmts dot com
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Message has 1 Reply:
 | | Re: LEGO light sensor schematic
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| In lugnet.robotics, Ralph Hempel writes: (I wrote) (...) [snip] (...) I've done a few myself, but I'll admit I'm not an analog guru. (...) Except all of the anodes go to the wires out, in 2/3 of the pairs this is correct, but one of those pairs (...) (25 years ago, 30-Apr-99, to lugnet.robotics)
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Message is in Reply To:
| | Re: LEGO light sensor schematic
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| (...) thing. We have an OpAmp connected to nothing that is set to oscillate for no reason, diode pairs that won't supply power to the circuit, an optical sensor that is biased backwards and lots of transistors set to act as diodes. I think he needs (...) (25 years ago, 30-Apr-99, to lugnet.robotics)
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