I have an issue similar to this so I thought this the best thread for the question. Furthermore, I'm not sure this is even possible on the scale I need so this is what I need to find out. I need to know how to charge a capacitor to run an led flashing, or full on for 1-5 minutes, 30 sec maybe. Charged with a 9v batt or other power source. Right now I have what I believe to be 3mm leds, but would like to use 0.25mm Ultra-Thin 0603 SMD LEDs http://www.kingbrightusa.com/gapg1608.asp?gclid=CITb35bq2pYCFQOcFQodcAzy2A I'm thinking 3 parts possibly. LED, resistor, and a small cap. Otherwise I'm looking at 2 button cells, or a 3v batt that I'm not sure will be small enough. Here is the problem. I need to fit this little sucker inside of a cone shape approx .578 dia and 1.25" long. Weight and size is the issue. Is this possible?