Hey guys! (don't ask why i'm posting at 5 in the morning, im on winter break)
During this semester of school, i was assigned the task of desiging, building, and testing a working human powered flashlight in a team of 3 other students. We are the M.E. Allstars and our project was based off a hand crank design, using capacitors as energy storage, and L.E.D.s for light. We were given a small d.c. motor as our generator and a $100 budget, then we were on our own. Our professor (who is an engineer, and a great guy) showed us the machine shop, and helped us along the way (no i didn't want to leave the shop...ever). During the first few weeks we designed the light, what gears we would use, lights, caps, ect... this must have taken the longest. one of themost difficult things was choosing what we were going to use and stick with it, lol. we were all in charge of different things, i designed the gearing in PRO/e, and built the gearbox, the team leader made the hand crank (which i tweeked, heheh) and the motor mount, and took care of ordering parts, the other two guys built the curcuit and modeled the rest in CAD. in the end we came together very well, everything worked better than expected and we got "Best in Show" after we had a design demo in the hallway. Ours' was one of the 3 that actually worked out of the 9 class projects!
the final specs for the light are:
2 25 farad 2.7 volt caps, charged in parallel (to shorten charge time, our design called for a 30-45 sec. charg time) and discharge in series (to run our 3.5v leds. we had originally though of using 4 10 farad and one 3 farad to give us our run time of 5 mins, but digi-key was out of stock(i didnt do cap calcs, so i dont know where thoes numbers came from) so we went with 2 25 farads instead. one charge of 45 secs give a run time of 45 mins!! way over what we needed. heheh
A 107:1 gear ratio to run our gen at 10000 rpms with a 100 rpm input, other teams used really extreme ratios like 400:1. and they stripped gears and broke shafts, muhahaha.
3 11000 mcd leds with a mag light reflector for stray light.
our switch was the most expensive part, $15! its a 4pdt rocker switch.
case is rapid prototyped withour veryown R/Per
my uncle has an engraver (mini cnc mill) to put out team name on the handle (everyone loved it!)
i did my parts on my mill, lathe,and dremel at home.