Alt-BEAM Archive
Message #06744
To: beam@sgiblab.sgi.com
From: Bob Shannon [SMTP:bshannon@tiac.net]
Date: Thu, 14 Oct 1999 12:11:00 -0500
Subject: Wow, ever tried this...
If you want to try something strange...HOT OFF THE BENCH!
Get a three terminal, NPN phototransistor. I'm using some surplus GE parts
(non-standard markings).
Simply replace the 2N3904 with the phototransistor in the standard 1381 SE.
Think about a photopopper, and now start getting rid of all the extra parts
you
no longer need!
I've heard of a photovore in Chiu's last contest that replaced the
photodiodes
with phototransitors and got some interesting behaviors as a result. I have
some SYMETs
that have phototransistor sensors on them, and its amazing to see that a
phototransistor
with a built-in lens (they often look just like LEDs) can actually 'see'
contrasts at well
over 4 meters in range!
The point here is that the optics of the phototransistor are a major factor
in
the behaviors
it will produce. Its not easy to know what the phototransistor is
responding to
if its optics are that good.
If you alter the optics of the phototransistor (sandpaper, or a dremel tool
can
be used!)
there are profound changes in the sensors response. Also the small metal
can,
three lead phototransistors have very different optical properties, and
produce
different behaviors.
An interesting photovore can be made with 2 'Photosensitive SE's', and by
mounting the
phototransistors under small shadow 'brows' you can get some very complex
behaviors!
Without a 'unicore' no less! What should we call this thing?
I can't wait to play with the UJT/SCR SE circuit, and some LASCR's I found.
Now back to making it move in an interesting, new way!
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