Design Con 2015
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


Flash Poll
Top Comments of the Week
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)
EE Life
Frankenstein's Fix, Teardowns, Sideshows, Design Contests, Reader Content & More
Max Maxfield

Want to Present a Paper at ESC Boston 2015?
Max Maxfield
8 comments
I tell you, I need more hours in each day. If I was having any more fun, there would have to be two of me to handle it all. For example, I just heard that I'm going to be both a speaker ...

Martin Rowe

No 2014 Punkin Chunkin, What Will You Do?
Martin Rowe
Post a comment
American Thanksgiving is next week, and while some people watch (American) football all day, the real competition on TV has become Punkin Chunkin. But there will be no Punkin Chunkin on TV ...

Rich Quinnell

Making the Grade in Industrial Design
Rich Quinnell
13 comments
As every developer knows, there are the paper specifications for a product design, and then there are the real requirements. The paper specs are dry, bland, and rigidly numeric, making ...

Martin Rowe

Book Review: Controlling Radiated Emissions by Design
Martin Rowe
1 Comment
Controlling Radiated Emissions by Design, Third Edition, by Michel Mardiguian. Contributions by Donald L. Sweeney and Roger Swanberg. List price: $89.99 (e-book), $119 (hardcover).