LED Dynamo Bike Light...easiest way to get decent output?

LED Flashlights – General Info
1

A couple years ago I got a dynamo hub for my bicycle and made a very simple led headlight out of some cheap leds from ebay and a pcb from radioshack and hooking it up to my hub. I was able to put the makeshift led light bank into an old bicycle light housing and it looks great and matches my bike. But, it’s not very bright.

I would like to replace it with something brighter but hopefully still vintage looking to match my bike. Is it feasible to hook up an XM-L T6 to my dynamo light with schottky diodes or something? Could I take the drop in out of a flashlight and mount it in an old light housing and wire it up? Or would it be more complicated than that?

Can anyone give me some pointers or ideas on how I can get a brighter light that can still be powered by my dynamo hub?

2

Hi and welcome to BLF! By all means stick around and enjoy the site, but I think you will get more answers on dynamo lights over at mtbrforums:

http://forums.mtbr.com/lights-night-riding/

3

I am using circuit 7 with 2 XM-L T6 lights on my old bike (hub dynamo).
http://www.pilom.com/BicycleElectronics/DynamoCircuits.htm

It works very good.

4

Cool! Do you have any photos of your setup? I feel like that circuit is over my head. Do you think I could make something work with 1 T6 and simpler circuit? I’m not looking for amazing brightness. Just hoping to get better that what I currently have.

5

Maybe this will help

http://nordicgroup.us/s78/mr16LED.htm

6

We're glad to have you onboard, flammenwurfer!

7

Your first link is very promising! Looks like he just hooked an MR16 bulb up directly to his dynamo hub. Sounds extremely simple as long as I can figure out way to mount it. I wish he had some beam shots.

He also says you can use a 4 or 3 led mr16 bulb. I wonder which will actually be brighter? Would a 3 led one be brighter because it’s only spreading the same power to 3 leds instead of 4?

8

Hahaha, thanks raccoon city. Nice images. :slight_smile:

9

This will also work, just connect the pins to the dynamo, and the wires with a powerled (or 2-3 leds in series):
http://dx.com/p/mr16-1-3w-650-700ma-constant-current-regulated-led-driver-8-40v-input-13557?item=64

I have bought 2 very cheap Ultrafire 501 flashlights with an XM-L drop-in and took the driver out of the drop in.
The leds are connected as in circuit 7, the self-made “driver board” is in the old bikelight to keep it dry.
I use the switch of that bike light to switch it on or off.

10

Very interesting. Do you have any photos of your setup?

So are you saying I could get that led driver you linked to, and hook it up to my hub and then the driver directly to a standard XM-L T6? What kind of light output would that create from a dynamo hub?

11

Now you’ve got me thinking. Could I also wire in an ultracapacitor to keep the light on briefly while stopped? Maybe I could use a p60 flashlight and hide the driver and ultracapacitor in the body where the battery should be and mount it on my handlebars.

Edit: I’m also curious as to whether an XM-L T6 is going to be brighter than one of the 3 led bulbs.