Breaking News
Comments
Newest First | Oldest First | Threaded View
<<   <   Page 2 / 2
ost0
User Rank
CEO
re: GravityLight – What a GREAT idea!
ost0   1/7/2013 8:26:47 AM
NO RATINGS
Simple and Genious! :)

RWatkins
User Rank
Rookie
re: GravityLight – What a GREAT idea!
RWatkins   1/6/2013 11:02:00 PM
NO RATINGS
Well, based on the calculator at http://convert-to.com/159/energy-units.html 100 ft-lb = 135.58 J, and by my calculations a 3V LED powered by a 100% efficient generator that draws 20 mA will stay lit for 37.7 minutes. I would estimate for the 3-LED system shown with a 50% efficient power conversion system would give about 6 minutes of light per 5 foot 100 pound lift. That is some big bag to hold 100 lb. The Gravity Light web page talks about a 20-pound weight, and says 18 to 30 minutes of light output per lift. I agree something seems a little off...

Steven.Herrrick
User Rank
Rookie
re: GravityLight – What a GREAT idea!
Steven.Herrrick   1/5/2013 2:30:25 AM
NO RATINGS
Has someone done the math on this? a 20 pound bag lifted 5 feet has 100 foot-pounds of potential energy. At an efficiency of 20%, how long will a 20ma LED provide light?

Paul A. Clayton
User Rank
CEO
re: GravityLight – What a GREAT idea!
Paul A. Clayton   1/4/2013 8:29:28 PM
NO RATINGS
There was an article on this at The Register a few weeks ago: http://www.theregister.co.uk/2012/12/12/deciwatt_gravity_light/ One advantage of this device is that, other than the LEDs (I think), it is relatively low tech and could be mostly manufactured or at least assembled locally (an economic advantage, not just a hand-out but partly a hand-up) and quite possibly maintained/repaired locally. I still think that the child-powered (merry-go-round) water well pumps are a little more clever in terms of exploiting an abundant energy source and providing fun.

<<   <   Page 2 / 2


EE Life
Frankenstein's Fix, Teardowns, Sideshows, Design Contests, Reader Content & More
Max Maxfield

What's the Best Traveling Toolkit?
Max Maxfield
Post a comment
A few years ago at a family Christmas party, I won a pocket knife as part of a "Dirty Santa" game. This little scamp was a Buck 730 X-Tract. In addition to an incredibly strong and sharp ...

Rishabh N. Mahajani, High School Senior and Future Engineer

Future Engineers: Don’t 'Trip Up' on Your College Road Trip
Rishabh N. Mahajani, High School Senior and Future Engineer
9 comments
A future engineer shares his impressions of a recent tour of top schools and offers advice on making the most of the time-honored tradition of the college road trip.

Larry Desjardin

Engineers Should Study Finance: 5 Reasons Why
Larry Desjardin
41 comments
I'm a big proponent of engineers learning financial basics. Why? Because engineers are making decisions all the time, in multiple ways. Having a good financial understanding guides these ...

Karen Field

July Cartoon Caption Contest: Let's Talk Some Trash
Karen Field
151 comments
Steve Jobs allegedly got his start by dumpster diving with the Computer Club at Homestead High in the early 1970s.

Top Comments of the Week
Flash Poll
Like Us on Facebook
EE Times on Twitter
EE Times Twitter Feed

Datasheets.com Parts Search

185 million searchable parts
(please enter a part number or hit search to begin)