I suspect the world would be better if that percentage were even greater.
Make an Instant-Charge Screwdriver | Popular Science
Ben Tongue’s article on using a supercapacitor to hold energy harvested from an antenna tuned to strong local broadcast system got me thinking about supercapacitors again. Digging around uncovered a link to a DIY project (very simple) for creating your own electric screwdriver powered by supercaps. (I think they are a bit cavalier with the charging circuit, which basically just dumps the current from a USB port into the caps without any leveling or the like, but shrug….) One interesting thing that I found was that SparkFun apparently carries 10F (yes, 10 farad) 2.5 volt supercaps for around $5. Neat!
Make an Instant-Charge Screwdriver | Popular Science
Addendum: Here’s an even simpler project to power a flashing LED.
Comments
Comment from Doug Weathers
Time 10/25/2009 at 2:21 pm
I wouldn’t use my computer’s USB port to power this critter, but any USB wall-wart power supply ought to do the trick without risking expensive damage. For example, my iPod charger has a USB port on it, and I believe you can also purchase universal chargers at Radio Shack that sport USB ports. They also exist in 12v versions for charging your gizmos in the car.
Or I suppose you could use an old USB hub (externally powered of course) you don’t want any more because it’s only v1, or because it’s crappy.
Thanks for the pointer!
Comment from Kenneth Finnegan
Time 10/25/2009 at 9:21 am
And as usual, Digi-Key has an equivalent part, for less. Using first class, Digi-Key shipping for small orders end up being ~$2.50, as opposed to SparkFun adding $2 to whatever it costs them.
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=589-1002-ND
I hadn’t thought of looking for super caps though. I’ll add a few of those to my next order, and have some fun with an RC > 1 hour.