[OLPC India] more thoughts on dynamo..
Ajay Kumar
ajay at classapart.org
Tue Oct 23 19:30:35 EDT 2007
Arjun,
Very cool pictures. And a great prototyping system. I hope the final
assembly would be lower to avoid all the sheer damage. Actually, if you
use bicycle / motorcycle chains instead of the belts, the sheer might
be even less. Would save a lot of downtime in my opinion. Way to go!
Arjun Sarwal wrote:
>
> Though, we have a general idea of the characteristics of the dynamo,
> it'd be great if someone could help us by providing with specific and
> detailed characteristics of the dynamo.
Unfortunately I don't have direct answer to your question, if you are
asking for the rpm-voltage characteristics that is. But do have a few
questions though. (I know I am sounding like an pain in the .... but
nevertheless...) . What exactly do we plan to do with the dynamo?
Listing some cons of the various things that come to my mind.
* Dynamo DC
o --> Chopper + step up Circuit + Ripple filter
+ --> DC jack of OLPCs
+ --> Battery --> DC jack of OLPCs
# [Not good for this battery, as you will never
drain it completely and hence will die out soon.
but could work like the below circuits if we
offer the battery some protection.]
o --> Zener Bypass (connected to a bulb/LED. If the bulb
lights, please adjust speed)
+ --> DC jack of OLPCs
# [Wasted power in the shunt circuit. Otherwise
very good.
# Only works when the animal is available.]
+ --> Battery
# --> DC jack
* Will damage this battery soon. (Or am I
unnecessarily paranoid?)
# --> Chopper + Step up circuit (includes the filter)
* I am happy for now with this thought.
But I guess you must have tried other options as well. Would love to
hear your thoughts. Did you get a chance to consider an off the shelf
inverter? I know it takes away the entire fun of creation ( which
incidentally is so central to OLPC kool factor). Just a thought nonetheless.
On another day of brainwave, I was thinking of using the induction
generator. Briefly :
Cow Power + [mini invertor / ups / oscilator]
--> Induction Generator
--> (optinally a few capacitors to improve power factor and stability)
--> The laptop ac adaptor.
= less variables to consider.
The cowpower of course could be easily replaced with the rotary
playplatforms, and the induction generator would not complain, by
changing voltage or anything else. Not many other things to consider in
the circuit. What am I missing here? I am sure there has to be something.
Kind Regards,
Ajay
> Hi,
>
> In our design, we are using a dynamo taken from a Fiat car - in Mumbai
> these Fiats are used as Taxis and are quite common.
>
> Though, we have a general idea of the characteristics of the dynamo,
> it'd be great if someone could help us by providing with specific and
> detailed characteristics of the dynamo.
>
> thanks,
> Arjun
>
> On 10/22/07, *Sameer Verma* <sverma at sfsu.edu <mailto:sverma at sfsu.edu>>
> wrote:
>
> Arjun Sarwal wrote:
> > Hi Jaya,
> >
> > We plan to drive a dynamo (taken from an old Fiat) through a system
> > of belts and pulleys using cows/cattle.
> >
> > Some initial pics here
> > http://dev.laptop.org/~arjs/cp1.JPG
> <http://dev.laptop.org/%7Earjs/cp1.JPG>
> > <http://dev.laptop.org/%7Earjs/cp1.JPG>
> > http://dev.laptop.org/~arjs/cp2.JPG
> <http://dev.laptop.org/%7Earjs/cp2.JPG>
> > <http://dev.laptop.org/%7Earjs/cp2.JPG>
> >
> > We are currently working on finalizing the mechanical and electrical
> > design aspects.
> >
> > regards,
> > Arjun
> >
>
>
> Way cool!!!
>
> This reminds me of the days (almost in a previous life) when I
> would go
> to my grandmother's place and run a pair of oxen to draw water
> using a
> persian wheel. Of course, we were no where close to doing this on a
> daily basis, but it was quite the task. Minding oxen that go around a
> circular path for hours is a bit mind-numbing. However, it
> produced very
> low rpm, but steady power. Do you guys know if this will be used to
> charge a bank of batteries directly, or will it be used to store
> energy
> and use it later.
>
> Burning biogas from cow dung will require a lot more in the way of
> infrastructure. We have had one at my grandmother's since the mid
> 1970s.
> We have had to change the drums several times because they rust
> easily.
>
> http://sameerverma.org/blog/?postid=122
> <http://sameerverma.org/blog/?postid=122>
>
> I suppose you could pipe the gas into a diesel generator (which are
> fairly common) with the appropriate carburettor to mix biogas and air.
>
> On a related note, I wonder if someone has looked at the Play Pump
> project where they use merry-go-rounds in school to pump water into an
> overhead tank. Kids supposedly love to go to school because they
> get to
> play in the morning before going to class and every spin of the
> merry-go-round pumps water!
>
> A play pump like setup could be used to charge batteries just like
> Arjun's cow power effort.
>
> http://www.pbs.org/frontlineworld/rough/2005/10/south_africa_th.html
> <http://www.pbs.org/frontlineworld/rough/2005/10/south_africa_th.html>
>
> Sameer
>
> --
> Dr. Sameer Verma, Ph.D.
> Associate Professor of Information Systems
> San Francisco State University
> San Francisco CA 94132 USA
> http://verma.sfsu.edu/ <http://verma.sfsu.edu/>
> http://opensource.sfsu.edu/
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>
>
>
> --
> Arjun Sarwal ( arjun at laptop.org <mailto:arjun at laptop.org> )
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