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 Robotics / 4906
4905  |  4907
Subject: 
Re: LEGO light sensor schematic
Newsgroups: 
lugnet.robotics
Date: 
Thu, 6 May 1999 14:06:49 GMT
Viewed: 
1122 times
  
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...
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



Message has 1 Reply:
  Re: LEGO light sensor schematic
 
(...) Sorry about that, I glued it back together with liquid plastic cement. I don't think it can take another operation and survive. I can't remember seeing a number inside and I was looking in there when you wedge the pc board in place. You might (...) (26 years ago, 6-May-99, to lugnet.robotics)

Message is in Reply To:
  Re: LEGO light sensor schematic
 
(...) OK, I fixed that and in the process discovered they should be PNPs. 3Hp83 is a BC857 GP PNP from Philips. Looks better now. (...) I think photo diode used in photovoltaic mode. It looks like it pushes the voltage down from that established by (...) (26 years ago, 3-May-99, to lugnet.robotics)

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