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.
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.
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!