Originally Posted by
Unknown Cyclist
Why do you say the voltage is doubled ?
As I understand it, a hub dynamo's voltage goes up proportional to teh bicycle's speed. My voltage is (almost) doubled because my wheel is small; it rotates a lot faster than the manufacturer intended. My small wheel makes about 105 revolutions per mile, while the dynamo is designed for a wheel that rotates something like 62 to 64 per mile. This is why some manufacturers make dynamos specially designed for small wheels; but they are much more expensive, and I don't have one of those.
Originally Posted by
Unknown Cyclist
If the LEDs are in series, the highest the current can reach is appr. 500mA and the voltage will be related to the current.
I'm glad to hear it, but I don't really understand. What's limiting the current to 500mA?
Originally Posted by
Unknown Cyclist
You will still need a rectifier and smoothing.
And heatsinking.
I understand the rectifier well enough, but not the smoothing. Frankly I'm not sure what smoothing is. How do I figure out how much smoothing I need? The heat sink I understand to some degree; but again, how do I figure out how much heatsinking I need?
Originally Posted by
Unknown Cyclist
How did you connect up the ones that melted ?
For the last two years I have used a home-made headlight using 5W, 12V halogen bulbs with, I think, an MR-11 base. The light was good, not great, but the system was durable; bulbs lasted about a year. At one point I bought two (rather expensive) LED bulbs that fit the same base, which gave a lot more light, but... well, the first one melted forthwith. Then I built a voltage regulator into the circuit, and... right, the second bulb melted too. I suspect I hadn't done the regulator right but, fed up, I went back to my halogen bulbs. At one point I had an off-the-shelf taillight with standlight function mounted to my mudguard, which was very nice, but... guess what? The leads to the LED melted.
Again: Thanks!