Alt-BEAM Archive

Message #06745



To: "'beam@sgiblab.sgi.com'" beam@sgiblab.sgi.com
From: Wilf Rigter Wilf.Rigter@powertech.bc.ca
Date: Thu, 14 Oct 1999 13:57:03 -0700
Subject: [alt-beam] Re: Phototransistor switch


oops

I forgot to mention the reason for discussing phototransistors in this
context is that you can cut one of those surplus slotted photo interrupters
in half to separate the photo transistor and IR emitter for use in other
applications like Shannon's SE

So the photo switch can be used for feelers or leg stops etc but can also
cannibalized for parts for photo detectors and IR beacons.

regards


Wilf Rigter mailto:wilf.rigter@powertech.bc.ca
tel: (604)590-7493
fax: (604)590-3411

> -----Original Message-----
> From: Phillip A. Ryals [SMTP:phillip@ryals.com]
> Sent: Thursday, October 14, 1999 10:11 AM
> To: beam@sgiblab.sgi.com
> Subject: RE: Phototransistor switch
>
> OK, that sounds really cool. I'm going to go ahead with the switch thing.
>
> It sounds like Bob was talking about the bot's ability to track light
> though.



6746 Fri, 15 Oct 1999 10:16:47 +1000 [alt-beam] Re: 3904s/3906s & 1381 static sensitive? beam@sgiblab.sgi.com Elmo Hi Steve

You can consider almost every electronic component to be static
sensitive, its just that some are more so than others. Most of the time
you wont kill a component even with a nasty big static zap from your
finger, but every time you touch a static sensitive component (even if
you dont feel a zap) you are shortening its life span. I have a 1381
that i zapped when i dropped it on the floor and picked it up without
static protection. Its worked for about a month after that, but recently
it died for no apparent reason.

The cheap and nasty way to protect yourself is to make sure you touch
something like a filing cabinet or your PC's case before picking up any
components. This will ground you but only for a very short while. Every
time you move your body through the air your picking up more static
charge.

A better method is to buy yourself a rubber backed static mat to sit
your components on. It wont ground you but it will disapate any static
on your body over a much wider area, and help to keep you and your
components at the same voltage potential (thats what causes that zap,
when you and something else are at different voltage potentials). You
can also get a wrist strap and ground wire which plugs into the earth
line on your power socket (umm....do you guys in the states/Canada even
have an earth line on your power sockets?....from memory you only use a
two prong power socket....not three). Wrist straps are great because
they make sure that your at ground at all times.

Once you have your robot together its a bit safer becuase there are more
point on which to discharge and any discharge isn't usually directly
into one component, plus you have resistors and caps to help disipate
any charge.


Hope this helps

Elmo





Steve M wrote:
>
> I ordered the usual parts for a photovore a while back from Digi-Key and
> they said that the aforementioned parts were static sensitive. Is this true?
> I've never heard that before, and I haven't seen any 'bots that are
> static-proof or anything. Does anyone know how to static-proof your
> workstation (or yourself) during bot construction?
> Steven
>
> ______________________________________________________
>


6747 Thu, 14 Oct 1999 21:37:50 -0400 RE: Phototransistor switch Phillip A. Ryals
> OK, that sounds really cool. I'm going to go ahead with the switch thing.
>
> It sounds like Bob was talking about the bot's ability to track light
> though. Anyone seen one like this in action? I'm curious because where I
> am, all I can seem to find are Phototransistors. Nowhere around here
> carries photodiodes. I had given up on making a photovore mainly because
of
> lack of parts.
>
> So what's the general concensus? Has anyone else tried it? What kind of
> results?
>
> par
>
>
> -----Original Message-----
> From: owner-beam@sgiblab.sgi.com [mailto:owner-beam@sgiblab.sgi.com]On
> Behalf Of Wilf Rigter
> Sent: Thursday, October 14, 1999 8:47 AM
> To: 'beam@sgiblab.sgi.com'
> Subject: RE: Phototransistor switch
>
>
> Hi Phillip,
>
> It's in the beam archives and well worth repeating
>
> Back on June 06 Bob Shannon wrote:
>
> From: Bob Shannon [SMTP:bshannon@tiac.net]
> Sent: Sunday, June 06, 1999 9:42 AM
> To: beam@sgiblab.sgi.com
> 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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