
A $5 Lamp Powered Solely by Gravity - TannerLD
http://enpundit.com/a-5-lamp-powered-solely-by-gravity/
======
ColinWright
Previously submitted and seriously doubted:

<http://news.ycombinator.com/item?id=4889266>

In that thread[0] revelation[1] said:

    
    
        At perfect efficiency, this seems to give you about
        55mW for a hour, if I asked Wolfram correctly (for
        20kg lifted one meter) - [2] - So probably a hoax.
    

[0] <http://news.ycombinator.com/item?id=4889426>

[1] <http://news.ycombinator.com/user?id=revelation>

[2]
[http://www.wolframalpha.com/input/?i=20+kilogram%E2%80%90for...](http://www.wolframalpha.com/input/?i=20+kilogram%E2%80%90force+meters+in+milliwatt+hours)

~~~
tonyarkles
If you read some of the followups and tweak the math a little bit, it works
out reasonably well. Instead of 20kg and 1m, 20lb and 2m, which comes out
about the same (49.42mWh). If you have to lift it every half hour, that's
100mW for a half hour. That's more than enough power to get a useful amount of
light out of an LED.

For example, this LED uses 68mW <https://www.sparkfun.com/products/531> and is
marketed as "so bright that it hurts to look directly at them"

~~~
ars
It's hurts to look at it because it's focused into a very narrow beam. Very
bright sure - in one tiny spot, and totally useless to illuminate a room.

They even include a photo of the beam pattern - it's almost as focused as a
laser.

(You can tell on an LED by looking a the top - round tops are focused, flat
ones spread out.)

~~~
tonyarkles
That's fine! It's enough to read a book or do homework after the sun sets.
We're not talking first-world style lighting; we're talking about a $5 light
that is better than sitting in the dark because you have no electricity and
ran out of kerosene to burn.

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dsl
Not to nitpick, bit it's not powered by gravity, it is powered by people going
over every 30 minutes and lifting a weight back up to its top position.

EDIT: Apparently people don't understand that using gravity to generate energy
is a thing, and the title "Powered Solely" suggested someone found a way to do
that.

~~~
tarice
People couldn't lift the weight without consuming energy from food. Doesn't
mean that it's powered by food.

The machine converts gravitational potential energy to electromagnetic
radiation. People generate the gravitational potential energy by lifting the
weight using kinetic energy, which was likewise created by converting chemical
energy.

It's easier just to say "Gravity" because, without gravity, it wouldn't work
with its inanimate weight.

~~~
emiliobumachar
I suppose it all ultimately comes from solar energy, which, in turn, comes
from nuclear fusion.

~~~
njharman
And the nuclear fusion is started if not powered by the heat and pressure
caused by, wait for it...

GRAVITY!!!

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Lagged2Death
Some people get excited by F1 racing, the Bugatti Veyron, or stuff like the
latest iPhone, telling you they are technology enthusiasts or engineering
fans.

But if you ask me, it's always at the low end of things - like this project -
where the really inventive, exciting engineering happening.

Sure, something like an F1 car is impressive after a fashion, but considering
the price, yeah, well, it _better_ knock my damn socks off or it just looks
stupid. Unlimited budgets do not make for impressive engineering, really.

Making something that is truly, spectacularly useful like this for $5 ot $10?
That is genuinely impressive.

~~~
ZeroGravitas
_"To define it rudely but not inaptly, engineering is the art of doing that
well with one dollar which any bungler can do with two after a fashion."_ \--
Arthur M. Wellington

~~~
CamperBob2
My favorite way of expressing the same thing: "Anyone can design a bridge that
will stand up. It takes an engineer to design a bridge that will _barely_
stand up."

Not sure where this came from -- Douglas Adams, maybe?

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NathanKP
Maybe I'm stupid for asking but what is the advantage of this over a spring
powered wound clock? My wristwatch can tick for two days on a wind, and while
it isn't as cheap as this gravity powered wound clock I'm sure it could be
made cheaper. There is nothing special about this invention; purely mechanical
"gravity powered" clocks have existed for centuries in the form of old
grandfather clocks etc.

~~~
morsch
The advantage of this lamp over a spring powered wound clock would be that it
emits light. The disadvantage is that it's comparatively poor at keeping the
time.

~~~
NathanKP
True, but my question is if a clock winding mechanism can keep going for days
without need of winding could a clock winding style mechanism be more
efficient than a gravity weight powered one.

~~~
morsch
SCNR. I suppose the advantage of clock winding mechanisms is that they can
deliver (mechanically) a constant, relatively low level of power. Compared to
an LED, a wristwatch uses _very_ little power (about 1µW according to
Wikipedia). Of course this lamp may be more comparable to a grandfather clock
than a wristwatch; I don't know how much power a grandfather watch requires,
but the energy you store winding it up can't be that high since it's not that
much work, and the strength of the mechanism is that the stored energy is then
delivered over a long time, ie. days.

Also, with clocks, you get to skip the conversion of the energy completely.
That immediately gets you a much higher efficiency than this lamp, which is
potential energy converted to electricity (losing heat), converted to light
(losing heat). Of course energy transmission losses still apply, ie. it's not
free to get the mechanical energy from the spring to the hands of the watch.

------
joeyh
I use kerosene lights by choice in the winter in weeks like this one when
there is no sunshine. So, here's my firstish world problems take on it. May
not apply to people for whom a gallon of kerosine is a significant fraction of
their monthly income.

I have a hard time seeing myself using something like this, except as task
lighting. I'd be fine to have to lift a weight if I was only going to be using
the kitchen for 30 minutes (it could even serve as a useful timer), or
similar. But getting up every 30 minutes rules out using it anywhere I need
longer duration light for eg, reading.

Also, anywhere I could use this, I could use any of the many inexpensive crank
LED lamps available everywhere, which run for similar amounts of time.

The pity is that, with the right design, this could support a longer cord for
a further lift distance, so it'd run an hour. Or multiple weights used in
sequence or parallel so it can be primed for even longer (iirc that's how my
grandparent's cuckoo clock worked). From what I can see, it's not designed to
be very hackable, and something like this needs hackability.

The LED light is the other problem with it; I'd much rather have a well
ventilated kerosine light than blue tinged LED for almost any task. (I'm
curious to see studies about kerosine health risks however.) Since this light
cannot be moved, it has to illuminate the whole area, and its light doesn't
seem up to it, so I'd be doubtful about eg, reading by it either.

~~~
geophile
This idea just hit me, and it's so powerful I'm still reeling. What if someone
built a battery-powered weight lifter that would go off every 1/2 hour? You
wouldn't have to keep getting up to do it yourself!

Not sure if I should patent this, or just donate it to the greater good of
mankind.

~~~
K2h
are you proposing propetual motion? if you have the energy to lift the mass,
you have the energy to power the light directly and bypass the losses of
setting up the dravity weight again.

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obilgic
First thing I thought when I saw the title was: Linux, apache, mysql, php...

~~~
bmelton
I'm not sure why you were downvoted, as I bypassed the article probably at
least a couple times before realizing that it didn't say "Lamp Server" and
just said "Lamp".

~~~
rijoja
"A $5 LAMP Server Powered Solely by Gravity", if I read that I would have
clicked instantly.

------
degobah
Technically powered by the effort of lifting it.

~~~
mmanfrin
Technically powered by the food eaten to lift it.

Technically powered by the sun.

Technically shut up with useless pedanticism.

~~~
Jach
It's not very useless. The title suggests a perpetual motion machine, so I was
wondering what that was doing on HN. Knowing you have to lift it first (from
the article or from the comments) is important to know and lets one think this
isn't necessarily made up.

~~~
mmanfrin
You _infer_ a perpetual motion machine, they say it is 'powered by gravity'.

~~~
mayanksinghal
Which is something I infered as well, and probably many others. The title is
confusing and that is all the OP was pointing at, so you know, be nice - he
wasn't trying to undermine the achievements, if any.

------
jstsch
Similar in concept to the Waka Waka light, except that's powered by a solar
panel (and some quite nifty electronics):

<http://www.wakawakalight.com/>

------
eliben
As always, the devil is in the details here. Does this lamp produce enough
light for a family to be motivated to actually lift it every N minutes (e.g.
does it produce enough light to read comfortably, or to cook a meal)? Is it
durable enough to survive in essentially outdoors conditions in terms of heat
and humidity? If the answers to these questions are positive, it's certainly a
great invention. If not, back to the drawing board.

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antidoh
As we all argue over whether this is powered by gravity, or food, or nuclear
fusion, somewhere in a dark hut someone is lifting a weight to attend to the
baby that just woke up in the middle of the night.

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praveenhm
This is not a new idea. Cuckoo clocks, which is common in germany, works
without a battery. we need to pull up the weights everyday.

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tessellated
I don't seem to be in the target audience but the first question that came up
is: How much noise does it make?

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cr1st1an
I don't quite understand HOW does it turn the weight into energy. Could
someone enlighten me?

~~~
RandallBrown
the weight is on a string. That string is connected to a crank that turns a
generator as it falls.

~~~
cr1st1an
Oh, and as I understand, the amount of weight is important due the resistance
of the crank?

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lttlrck
It's not powered 'solely by gravity'

It's powered by a human lifting the weight.

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bobowzki
If it's real, I wonder if the gears are noisy...

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chrisringrose
Pretty cool idea.

