Alt-BEAM Archive

Message #13412



To: beam@sgiblab.sgi.com
From: BUDSCOTT@aol.com
Date: Thu, 13 Apr 2000 22:26:58 EDT
Subject: Re: photocells, from the litter?


Okay, the best cells you could probably scavange are going to be calc cells,
but, big but, your gonna need at least two if you want your FRED to be
active, where the calc cells have a comparable voltage to some of the
suncerams, they don't have anywhere near enough current to be really good
with any FLED applications. I tried to make a solar engine out of a calc
cell, it popped every 30 seconds in sunlight, with two 470uF caps, 470uF! So
my suggestion is to go to walmart, buy two or three solar powered calculators
and just use them in parrallel!

-Spencer

<http://www.botic.com/users/beamstop>

not a robot scientist
not a college major
not a grad student
not a professor
not a very organized person
just Spencer (isn't that impressive enough?)



13413 Thu, 13 Apr 2000 22:45:39 EDT mallorca beam@corp.sgi.com bumper314@aol.com Hello,
does anyone have pics of that nice solar walker named mallorca (i think
it was called that), one of the original beam bots.

steve



13414 Thu, 13 Apr 2000 22:31:59 -0600 Re: Shipping times :p beam@sgiblab.sgi.com Dave Hrynkiw At 03:40 PM 4/13/00 , Gabriel DeVault wrote:
>Just wanted to say that solarbotics shipped faster than digikey to santa
>cruz, CA. The order was also perfect and everything was
>packaged beautifully. Hats off to solarobtics, excellent service :)


Why thenkyou, thenkyoubeddymuch!

Regards,
Dave

---------------------------------------------------------------
"Um, no - that's H,R,Y,N,K,I,W. No, not K,I,U,U, K,I,_W_. Yes,
that's right. Yes, I know it looks like "HOCKYRINK." Yup, only
2 vowels. Pronounciation? _SMITH_".
http://www.solarbotics.com



13415 Thu, 13 Apr 2000 23:38:02 -0700 Re: mallorca beam@sgiblab.sgi.com Bruce Robinson Bumper314@aol.com wrote:
>
>... does anyone have pics of that nice solar walker named mallorca
> (i think it was called that), one of the original beam bots.

Hi, Steve. That's one of Brian Bush's machines, I believe. I put the
link on the BEAM Web Index when I first built the site. It'll be on the
walker page.

http://www3.telus.net/rfws/bwi/

Bruce



13416 Wed, 14 Apr 1999 23:39:19 +1000 Re: Core-less walker beam@sgiblab.sgi.com "Ben Hitchcock" On the 245:
Ground pins 1,10 and 19.
Tie pin 20 high.
Connect pins 2&3, 4&5, 6&7, 8&9, 11&12, 13&14, 15&16, 17&18.

Now run lines from the output of inverter 1 to pin 17, output of inverter 2
to pin 15, output of inverter 3 to pin 13.

Now attach motor 1 to pins 2 and 4, and motor 2 between pins 4 and 6.

All pin numbers refer to the 245. I'm going to attempt to get a rudimentary
'getting stuck' detector into the circuit, otherwise I'd draw a picture for
you now. More to come next week.

Ben

----------
>From: "William Cox"
>To:
>Subject: Re: Core-less walker
>Date: Fri, 14 Apr 2000 10:48
>

> Very nifty Ben. I might make one myself. Can you explain exactly how to hook
> it up the 245?
> -William
>
>
> ----- Original Message -----
> From: Ben Hitchcock
> To: beam
> Sent: Tuesday, April 13, 1999 5:39 AM
> Subject: Core-less walker
>
>
>> All,
>>
>> Yesterday I was toying with the idea of using the position of the feedback
>> pot to tell the bot to stop turning the legs. After a couple of
> iterations
>> I realised that I could do away with the micro (or bi) core altogether,
> and
>> just use the position of the pot to tell the walker which way to turn its
>> legs.
>>
>> I tested this circuit out today, and it appears to work. You have to use
>> schmitt triggers as the sensing elements, and I had to use a 74HC245 to
>> drive the motors themselves (a 74HC14 wasn't enough). This circuit will
>> work with hobby servos quite well because they have a feedback pot to tell
>> the driver what the position of the servo is.
>>
>> Problems with this circuit:
>> If a leg gets stuck then bad luck. The circuit will stall. This is to do
>> with the lack of timing elements in the circuit.
>>
>> Good points of this circuit:
>> Simplicity of debugging: You don't need to debug a complex Pulse
>> Neutralisation Circuit, or see how the process is walking around the core.
>> Just plug the leads in and go.
>> Simplicity of building: You don't need any more electronic elements than a
>> 74HC14 and a 74HC245. NO other components are necessary (apart from
>> batteries and wire)
>> No leg stops: I dislike the idea of using mechanical stops to prevent my
>> legs from going too far. This circuit does away with them altogether -
> and
>> your legs will NEVER go too far!
>>
>>
>> I would recommend this circuit for people who want to get into walkers,
> but
>> are frightened by the complexity of a full-on microcore or bicore. About
>> the only thing you can get wrong with this circuit is hooking up the
> motors
>> the wrong way - and then the only thing that happens is that the motor
> goes
>> to the end of its travel and stops. Reversing the leads makes them tick
>> along nicely.
>>
>> Right now I have two servos alternating on my desk, just the way that
> servos
>> should if they were on a walker. I haven't actually tested this by adding
>> legs and seeing if the thing moves, but it should work reasonably well.
>>
>> In the diagram I have omitted the 74HC245 driver for clarity. I regard
> this
>> circuit as a bit of a curiosity ("I did it because I can!") rather than a
>> functioning piece of BEAM evolution such as the FRED.
>>
>> If anyone's interested in developing this further then an idea might be to
>> use the remaining three inverters on the 74HC14 as a sort of 'getting
> stuck'
>> detector... if an output stays on for a long length of time then kick the
>> input over the other way. I haven't drawn this yet because I like the
>> simplicity of this drawing.
>>
>> Oh and another thing, to make the walker turn just bias one of the wipers
>> either high or low with a 5 k resistor and the gait will change perfectly,
>> not hitting any end stops or making the legs do cartwheels. Not bad,
> eh?:-)
>>
>> Any questions, comments?
>>
>> Ben



13417 Fri, 14 Apr 2000 09:02:53 -0500 Re: Core-less walker beam@sgiblab.sgi.com Scott Burns At 11:39 PM 4/14/99 +1000, you wrote:
> >> Problems with this circuit:
> >> If a leg gets stuck then bad luck. The circuit will stall. This is to do
> >> with the lack of timing elements in the circuit.

But if the legs are very flexible, the motors may continue to cycle while
the legs are stuck, and it might eventually work itself free.

Scott



13418 Fri, 14 Apr 2000 09:04:32 -0700 (PDT) Re: photocells, from the litter? beam@sgiblab.sgi.com "Leonardo Boulton F." Yes, since i will conect them in parallel, i will increase the current,
but not the voltage.... So i am planning to put a variable capacitor so
i can figure wich is the best time constant for charging this one....

--- TurtleTek@aol.com wrote:
>
>
> So you want to use calculator panels for a photovore, eh? I've
> tried it
> and yes, it works. However, not nearly as well as the Suncerams. Not
> only
> that, but the bot being powered was a 1381 photopopper....and I used
> two
> calculator panels. I have not built a FRED yet but here is my advice
> to you:
>
> Use two panels, wire them in parallel. Calc panels provide very
> little
> current. And try a smaller than usual cap. That should result in a
> fairly
> active bot.
>
> -Brien the TurtleTek
>

=====
I'm here... http://geocities.com/l.boulton

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13419 Fri, 14 Apr 2000 10:28:53 PDT Re: Shipping times :p beam@sgiblab.sgi.com "Jim Cook" Dave,
I just wanted to say that you do run a very nice polite and efficient
company. I have never had the care and customer support that you seem to
provide on a regular basis. There have been times (Before my interest in
beam brought me to you) that I used venders that wouldn’t even go half as
far as you do. Thank you again


Sincerely,
Jim Cook
beamboter@hotmail.com
http://www.geocities.com/boter_99


P.S. I was taught to praise in public and criticize in private.





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