Originally Posted by
flammenwurfer
I don't know a lot about this but your explanation makes sense carrefour. I don't remember exactly, but I think the leds I'm using were rated 20-30ma.
So if I want the light to stay on for short period of time when stop, what would be the easiest/simplest way of accomplishing that? In another thread I saw somebody mention using a supercapacitor in their setup. Is there a way to use one of those to keep the light lit up briefly when I stop at stop signs and such?
If they are 20-30mA, then you will need at least 15 pairs of leds.
In theory supercaps are the way to go if you want a stand light. However (1) I have not tried them myself... (2) from what I believe to understand about them it would not be as easy to use them to keep the light going for a while after stopping cycling.
Let me clarify a bit. You should not expect that a supercap will keep all 25 leds on for let's say a stop at a red light. The way to go is to only run 1 led for the stand light. All very easy to do with electronics for experts, but that is not me.
I would just go with batteries : dynamo, bridge, 4 AAs, leds. But with batteries you may have to add resistors (very cheap) in the circuit to avoid over-currenting them. This is where you use Ohm's law.
Also take into account that if you plan to use the light only once every x months your batteries will be empty. No problem to charge them with the dynamo while cycling, but the question is if your lights will work properly at the beginning. The batteries may take all the current till they reach a minimum level of charge. Best way to find out is to try.
I second Unterhausen in getting a or some power leds. I think that
www.pilom.com has some very simple, but great ideas for that.