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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Mon, 3 May 1999 16:43:35 GMT
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Viewed:
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916 times
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In lugnet.robotics, lego-robotics@crynwr.com writes:
> Just to clean up the schematic a bit you could flip R1 (75R) to the right
> side of the Q4. I would also bring R8 (12R) in line with the LED.
> This would then be a more standard drawing of a current source.
OK, I fixed that and in the process discovered they should be PNPs.
3Hp83 is a BC857 GP PNP from Philips. Looks better now.
> Is the detector a photo diode or a photo transistor?
I think photo diode used in photovoltaic mode. It looks like it pushes the
voltage down from that established by the LED.
> > http://www.plazaearth.com/usr/gasperi/light.htm
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Message has 2 Replies:
 | | Re: LEGO light sensor schematic
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| (...) [snip] I'm happy to see that some of my concerns have been born out with these changes, it looks more like a happy little circuit now. (...) Are we sure that the photodiode is located in the schematic correctly? It doesn't look like its biased (...) (25 years ago, 3-May-99, to lugnet.robotics)
| | | Re: LEGO light sensor schematic
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| Michael, Is your light sensor still in pieces? I was wondering if you could find a moulded Lego part number for the upper half of the brick. -John Van Michael Gasperi <gasperi@alynk.com> wrote in message news:FB614n.JBF@lugnet.com... (...) (25 years ago, 6-May-99, to lugnet.robotics)
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Message is in Reply To:
| | Re: LEGO light sensor schematic
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| (...) Ah... much better, I figured one or two components were backwards. Just to clean up the schematic a bit you could flip R1 (75R) to the right side of the Q4. I would also bring R8 (12R) in line with the LED. This would then be a more standard (...) (25 years ago, 3-May-99, to lugnet.robotics)
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