Originally Posted by
mmeiser
== secondary recharging power packs ==
On a related side note I've been reading up on resisters. Apparently it's become extremely popular for people to make external secondary battery packs for the iPods, mp3 players, iPhones, Android pones and other smartphones which are well known for being ridiculously power hungry.
The key is that everything is standardizing around USB for charging and syncing. This is a great thing since one can theoretically make a secondary battery pack that will power multiple devices. The key element to these simple battery packs is a resistor. For example Radioshack sells a 5-volt resistor for $1.47. This resistor with theoretically knock anything up to 35 volts down to 5-volts which is the USB standard for power. Therefore it's theoretically possible to create a little black box or battery pack that you can connect anyting from a 4AA battery pack, to a 9-volt or a 6-volt to and get clean consistent power to your light, camera, mp3 player or smartphone. Been meaning to build one, but haven't had the time yet. I guess I've been to busy reading / writing on special topics on forums and mailing lists passive aggressively.
I think you mean regulator, not resistor. You can use a network of resistors to get a desired voltage, but a regulator is a much better way to go. For example:
http://www.radioshack.com/product/in...howFullReviews
Even better, some nice folks have done all the design, PCB fabrication, kitting, illustrated instructions, and packaging ideas for you. Do a search for "Mintyboost" or as posted recently on a local email list by a local hardware hacking group:
The Mintyboost, created by Limor Fried of Adafruit in Brooklyn, is a rechargeable booster pack for USB powered devices. Now, rather than running out of juice on the airplane or bus, you can bring your own power. This is for version 3 of the device which works on all kinds of gadgets including GPS units, iPhones, iPods, & Android phones.
Links:
http://www.ladyada.net/make/mintyboost/compat3.html
http://www.adafruit.com/index.php?ma...products_id=14
The recommended packaging is intended for AA batteries for recharging a phone or MP3 player, but there's no reason you couldn't use the kit with larger