Alt-BEAM Archive

Message #03167



To: Beam List beam@corp.sgi.com
From: Matt Procopation proc@home.com
Date: Mon, 10 May 1999 19:43:28 -0700
Subject: [alt-beam] Photodiode question



I've got this FLED photovore (from the schematic that's been
floating around the mailing list lately) popping around on my
desk, and it appears that it's not acting photophilic at all.
When I breadboarded the circuit, it seemed to work just fine,
but since it's been given a body, it just goes whereever it pleases.
At first I thought I might just have the motor leads backwards,
and that it might be photophobic, but it doesn't look like it.
The only thing that I can think of is that the photodiodes don't
have the same face pointing forwards.
Looking head on at the bot, they're arranged like-

[] []
/ \ / \
a c c a
(a=anode, etc)

Now, these aren't solarbotics-type photodiodes; they don't
have one face that is obviously rounded, they're basically
symmetrical rectangular prisms.
So, do photodiodes usually have one face that is the most
sensitive? If so, I probably just need to flip one of them around.

_ _
Matt

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