Alt-BEAM Archive

Message #09057



To: beam@sgiblab.sgi.com
From: Bruce Robinson Bruce_Robinson@telus.net
Date: Tue, 11 Jan 2000 17:15:52 -0800
Subject: [alt-beam] Re: walker questions


blake marks wrote:
>
> i have mechanical stops now,, but there just nasty looking. i
> just wanted to know if there was a better way to do it.

1) As Jim said, springs that try (gently at first) to pull the
legs back to centre.

2) Contact switches that short out the appropriate Nv in your bicore
or microcore. Use a resistor (e.g. 5k) in series with the switches.
The switches are located in place of mechanical stops. They
have the same effect, but they stop the motor electrically instead
of mechanically.

Bruce



9058 Tue, 11 Jan 2000 17:19:22 -0800 [alt-beam] Re: Nv speed? beam@sgiblab.sgi.com Bruce Robinson blake marks wrote:
>
> I have a question.... is it possible to change the speed that it
> takes for one Nv process to travel through a loop. how would you do
> that???

To speed it up, use smaller resistors. If you want to speed it up in
just one Nv, use a smaller resistor in just that Nv.

If you want to change the speed "on the fly", place a resistor in
parallel with the existing one, but ground it only when you want the
speed to increase.

Bruce



9059 Tuesday, 11 January 2000 9:55 Re: Just Another Newbie beam@sgiblab.sgi.com Chia
>then just ask them for broken ones, scrap ones - the may sell it to you for
>10 for $5?
>--------------------------------------------------------
>Daniel Chia:
>danndom@mbox5.singnet.com.sg
>Robotics Web Page(unfinished):
>http://home.crosswinds.net/~danstryder/
>"It takes 99% sweat and 1% ingeniuty to have success" - Thomas Edison
>---------------------------------------------------------------------
>
>----- Original Message -----
>From: Mike Kulesza
>To:
>Sent: Thursday, January 06, 2000 12:13 PM
>Subject: Re: Just Another Newbie
>
>
>> the only other thing
>> >is to scavenge motors from busted pagers (juest ring up your local pager
>> >company and ask politely).
>>
>>
>> Last time i called up a few pager repair shops they didnt know what i was
>> talking about when i said "pager motors." I went through the prcess of
>> explaining to them that they are the little thingies that make your pager
>> vibrate - theyre still clueless!!!
>> ______________________________________________________
>>


9060 Tue, 11 Jan 2000 17:31:50 -0700 [alt-beam] Re: New(?) FLED variant beam@sgiblab.sgi.com Senior Any FLED will do too. But they are a bit harder to find than flashing
LEDs. :)
No, just kidding. FLED is an acronym for flashing LED, and any flashing
LED will do, so a green one will work.

-Kyle

Bumper314@aol.com wrote:
> > Nope, any flashing LED will do.
>
> Well right...but what about green FLEDs
>
> Steve



9061 Tue, 11 Jan 2000 17:42:34 -0800 (PST) [alt-beam] re: parts source beam@sgiblab.sgi.com Max Inggal I hope that all you guys can see that of course Dave
is going to say that his motors are better. But I
have to say that most of us don't want to shell out 10
bucks for a little pager motor. So Dave don't take
this the wrong way but is there any possibility of
lowering the prices? They're a bit steep. I'd rather
spend 3 bucks for a motor that'll last a year than 10
bucks for one that will probably last the same.
__________________________________________________
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9062 Tue, 11 Jan 2000 17:51:51 -0800 (PST) [alt-beam] re: parts source beam@sgiblab.sgi.com Max Inggal some of the really effiecient motors that I've seen
are the Port Escape motors. Tilden used them for the
motors for the legs on his famous bot walkman. The
motors are the little black rectangle boxes. I looked
up how much they were. They're $200 bucks a motor.
The other really tiny and really effiecient motors I
think they were called smoovey motors or something.
They ran from $60-$500 for a motor. Super effiecient
but super expensive.
__________________________________________________
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Talk to your friends online with Yahoo! Messenger.
http://im.yahoo.com



9063 Tue, 11 Jan 2000 18:08:01 -0800 [alt-beam] Re: BEAM VIDEO was Solar Powered Camera's "'beam@sgiblab.sgi.com'" Wilf Rigter

BEAM circuits are very similar to the older analog type video technology
still used in simple B/W TVs and 20 years ago all televisions used analog
beamlike circuits for decoding video signal.

So it's not surprising that it is fairly simple to use BEAM circuit blocks
to convert video into digital or analog signal suitable for interfacing with
other beam circuits. In the example suggested by Dennison below, The video
signal is converted into a 2x2 matrix which corresponds to the average
light level of a quadrant of a video frame. The attached block diagram shows
the general concept of such BEAM video decoder.

A composite video signal (ie a sugar cube camera output) is processed by a
sync separator to produce Horizontal and Vertical sync pulses as well as a
DC restored video signal. This circuit requires some 2N3904s and a few
passive components. The H and V sync signals each trigger a Hsync Nv and
Vsync Nv (74HC14) respectively which are adjusted to time out at a point
corresponding to the horizontal and vertical midpoint of the screen. The
signals are connected to one half of a 74HC139 (Z bridge) which generates 4
control signals corresponding to each screen quadrant. These 4 Q signals are
used with four 4066 analog gates to route the video signal to one of 4 Nu
(74HC14). The analog voltage on each Nu cap corresponds to the average video
signal of that quadrant This can be used to "influence" a central pattern
generator like a microcore. A digital signal can be generated with a one bit
A/D converter also know as a comparator or Schmitt trigger. If the video
level on the Nu cap is above the trigger level of the comparator, a LED
turns on. A bright light moving from one quadrant to the next, will turn on
the corresponding LEDs indicating the relative position of the light.

This concept can be scaled up to a low resolution "gray scale" (or red
scale) monitor (ie 8 by 8 LED matrix) which can also be easily made with a V
and H chains of 8Nvs each buffered with HC240 LED drivers which can drive
64 LEDs in real time. The video signal is "sliced" by a comparator the
output of which drives the HC240 tristate enable lines. No Nu stages are
needed to measure the average video since your eyes will do a visual
integration of the LED light level. Any old video signals can be used for
experimenting with this concept including a camcorder or VCR video output.

regards

wilf

<> <>


> -----Original Message-----
> From: Dennison Bertram [SMTP:dibst11+@pitt.edu]
> Sent: Tuesday, January 11, 2000 10:07 AM
> To: beam@sgiblab.sgi.com
> Subject: Solar Powered Camera's
>
> Hey, look at:
>
> http://www.mpja.com/allpict.asp?dept=125
>
> You should see the "sugar Cube" Camera. It runs on 5v 10ma, a power level
> easilly provided by a solarcell. Any ideas? Possibly, Hey Wilf! think you
> could come up with something to interpret video signals? What would be
> MOST
> interesting is if we could find away to interpret the general LIGHT level
> of
> a quadrant of the cameras vision. IE LEFT, RIGHT, UP, DOWN. That way we
> could then use cameras as light level inputs to say, a head. I'm thinking
> that analog wise, this might be a little difficult.
>
> dennison



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