I have a solar powered watch that works great during the summer, but
during the winter I don't get out as much and the sun is not as
strong.  I would like a way to charge my watch without having to buy
new equipment.  What is the best way to do this?  I assume a light
bulb will work, but do I need a certain wattage?  Will a black light
work better?

Hi gr8fuljeff-ga 

Yes, light bub will work, and work better than black light.

 Black light,  
http://science.howstuffworks.com/black-light1.htm 
as well as day-light fluorescent
http://www.sitincomfort.com/daylibrliths.html
use special phosphors and filters to shape the light spectrum to
appear certain way to the human eye.

Photocell in the watch, as well as plants, have different characteristics
then human eye, so any such shaping just wastes some energy.
Total energy, rather then special shape of spectrum, is the determining factor.

That, delivered energy, depends on wattage of the source, it's efficiency,
and distance to the target (the watch).
 So, if you use 40W incadescent bulb at 1 meter distance and it is not enough,
 you can about quadruple delivered energy by 
       a) decreasing the distance to .5 m and  
       b) by switching to (more efficient) CFL bulb. 
You can do both and increase the delivered energy about 16 times.
http://www.sitincomfort.com/daylibrliths.html

Here is the same info in feet rather then meters
http://www.sitincomfort.com/daylibrliths.html

Hedgie

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Clarification of Answer by hedgie-ga on 08 Dec 2004 17:38 PST

Sorry, 
That second link, using custom units, was supposed to be:
http://www.theledlight.com/lumens.html


See also
http://www.natmus.dk/cons/tp/lightcd/lumen.htm