Alt-BEAM Archive

Message #11548



To: beam@sgiblab.sgi.com
From: SG sparkyg@seark.net
Date: Wed, 08 Mar 2000 22:21:46 -0600
Subject: [alt-beam] BeamANT vs other photovoric circuits



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oops...
fergot to send the circuit.



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Attachment: photovor1.gif

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11549 8 Mar 00 23:24:42 CST [alt-beam] Re: nv's and nu's beam@sgiblab.sgi.com Steven Dang What is the difference between the schematic of the nu neuron that u encl=
osed
and the nu neuron at the robotics tek FAQ
http://people.ne.mediaone.net/bushbo/beam/nvnet.html#NvSensors
I see the scematic difference, but what is the differences in function an=
d the
way they work.

Steven

> The basic Nv neuron responds to a rising input by switching it's
> normally high output to a low one for a varying amount of time. Given a=
n
> input that goes from high to low to high again, on the low-to-high
> transition, the output will go from high to low. After a delay
> (determined by the resistor and capacitor values), the output will
> switch back to high. This allows you to chain Nv neurons together and
> have a signal travel slowly along the chain.
> =

> The basic Nu neuron responds to a prolonged change in input. If a high
> signal is applied to the input, after a delay, the output will switch
> from high to low and will remain low as long as the input stays high.
> =

> One essential difference is that the Nv responds immediately to an
> input, and sends the output for a time duration: The delay occurs AFTER=

> the output is sent. The Nu responds to an input after a delay and sends=

> the output continuously. The delay occurs BEFORE the output is sent.
> =

> > ... But i don't know what the schematic of each of these are. Could
> > someone clarify this for me.
> =

> See attached. The only difference between the two is that the capacitor=

> and resistor are swapped. Each one also has a variation where the
> resistor (Nv) or capacitor (Nu) is connected to Vcc instead of ground.
> =

> I'll be interested to hear what the rest of the BEAM community has to
> say about this (I'm taking notes ... watch for a future web page). Also=
,
> any critique of the diagrams will be appreciated.
> =

> Bruce



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11550 Wed, 08 Mar 2000 21:25:01 -0700 [alt-beam] Re: tiny limit switches beam@sgiblab.sgi.com Senior

> Richard Caudle wrote:
>
> Evening all.
> BTW, I have put four of the HPV's together and tried out different
> combinations of photodiodes, IR LEDs, and phototransistors for the
> eyes. In the dark (I hooked up a 9V battery to them), the ones using
> the IRLEDs and the phototransistors exhibit negative phototropism. In
> the light, it's positive! Would that classify as emergant behavior?

Really? this is quite interesting! Maybe not too useful though... Unless
you want your robot to head off and hide when it gets dark so it can
sleep! Isn't there a bot somewhat like this, that had something special
about it sensors, in the microvore contest? Anyone remember?

Theres an interesting topic to explore, with all this beamant stuff!

Kyle



11551 Wed, 08 Mar 2000 22:42:27 -0800 [alt-beam] Re: nv's and nu's beam@sgiblab.sgi.com Bruce Robinson Steven Dang wrote:
>
> What is the difference between the schematic of the nu neuron
> that u enclosed and the nu neuron at the robotics tek FAQ
> http://people.ne.mediaone.net/bushbo/beam/nvnet.html#NvSensors
> I see the scematic difference, but what is the differences in
> function and the way they work.

I showed the most basic form of the Nu. It is a remarkably flexible
device with countless variations possible.

The BEAM Tek site shows a specific application of the basic Nu. The
resistor controlled by the sensor switch will activate the Nu after a
short delay (or several very short contacts). The larger resistor will
very slowly deactivate the Nu. So, bump into something for a few
seconds, and the Nu goes active, and stays active for several seconds
(long enough to back well away from a wall, for example.)

Diodes are often used to make the cap charge much more rapidly then it
discharges, or vice versa.

If you look at Tilden's original patent, you'll see three variations on
the Nu.

Although my basic diagram shows one input through one resistor (the
simplest form), in practice you will often find several inputs,
sometimes through diodes, and often through different resistors. In
fact, you will sometimes have a tough time actually identifying a
complex Nu neuron in a circuit.

Bruce



11552 Wed, 08 Mar 2000 22:51:19 -0800 [alt-beam] Re: Diodes in microcores beam@sgiblab.sgi.com Bruce Robinson Flaming Headphones wrote:
>
> Thanks Bruce,
> I think I'm going to stick with the schematic Chiu has drawn and
> not try to modify it to be PNC-less. I'll probably try that on another
> walker, but not my first.
>
> So for the diode then, would a regular LED do the trick? Or do I need
> something special?

I'm hardly qualified to answer that one. My first conventional PNC
didn't work, until I put 5 diodes in parallel. Now there is no logical
explanation for THAT (a couple of the masters shook their heads over
that one), but when I built it as shown, extra pulses started "leaking"
back into the micorcore. (Yes, I had bypass caps on my supply. Yes, my
unused inputs were grounded. Yes, I had a stable power supply.)

This is what prompted me to invent a better PNC, and then Wilf did his
usual magic and made that a whole lot simpler.

My advice is, try it on the breadboard. If it doesn't work, try a
regular diode. If THAT doesn't work, use Wilf's circuit.

Bruce



11553 Wed, 8 Mar 2000 17:06:16 +1100 Re: Quick-Change components "Sathe Dilip"
>
>
> "Feser, Jason" wrote:
> >
> > Yup. They are pin sockets. I've managed to melt about 1000 of them out
of
> > old pc hardware with a pencil torch, but you can buy em' if you want.
Dave
> > sells them over at http://www.solarbotics.com.
>
> I have a pencil torch but never thought of this use. Have you tried
> salvaging ICs, transistors etc. What is the mortality due to heat if
> one is quick enough? I have read on another newsgroup about someone
> using a barbecue to remove components enmasse. This person claimed not
> to lose that many due to heat.
>
> Dilip
> ----------------------------------------------------------------------
> The early bird may get the worm, but the second mouse gets the cheese.
> ----------------------------------------------------------------------

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