Even though, there are plenty of "Dynamo Bike Light" instructions on this site, I thought I would share mines.   The great news, there are NO resistors in my circuit.    It has a fixed 5 volt output, so you can ride as fast as you want without worrying about burning out the LEDs.  Also, since this has a 5v output, you can hook up virtually any high-powered (CREE/Luxeon) LED flashlights (typically rated 4.5v - 8v).  I use this circuit to power a CREE RC-G4 Flashlight , which i bought  from DealExtreme for $17. (It's very bright, but I will most likely upgrade to SSC P7  900-Lumen LED Flash Light, not bad deal for $38.67).

I will also hook up a USB connector plug to charge my BlackBerry Phone and Ipod.  Most USB devices are rated 5v , so with this circuit like this, you will never need to deal with a solar charger to charge your phone, GPS, ipod, recharable batteries, or to power any standard USB device.  

Please refer to Step 1, Step  2, Step 3 & Step 4 for further details..

FYI: This is a work in progress, and I will update my instructions as my project progresses.  Please bear with me given my hectic schedule and feel free to contact me if you have questions regarding where to get the parts or accessories.   And don't forget to leave feedback and suggestions.   

Thank you for visiting & Have a Happy and Safe riding!


RussoF6 days ago

yup, it works, i just tested with an "usb wall charger" i connected the usb wall charger to the dynamo and then my phone into the charger, perfect.

RussoF7 days ago

cool, i have a question, what if i get one of those "usb wall chargers", its says: input ac 100-240v, output dc 5.0v == 500mA

Doesnt it do the same thing? convert AC to DC to charge the phone or whatever, im thinking, all i need to do is set the wire from the dynamo to the wall charger and connect an usb cable to whatever device. Would it work?

Or maybe, i could buy one of those small crank dynamo with usb and connect the wire to the crank thing, could this work?

pgamage6 months ago
i have got some problems in making the voltage regulator.. how can i fix any problems in circuitry?
RoyalR1 year ago

Hi Sonnet...beautiful idea...
Have you completed it already ?

doppiej1 year ago

Is it possible to add a battery in-between?

I would like to have the dynamo charge the battery and the battery to power the lights and for example other equipment.

Nexus dynamos add resistance only when you are using the light or drain power as far as I know but maybe you have short circuit somewhere
devDee2 years ago
I am working on a similar idea , the only difference is I have very low speed of cycling, around 15 rpm. So please suggest an appropriate dynamo and what changes do i need to make in the circuit to get a constant output of 5V at low speeds. please help!!
bogyman573 years ago
Good stuff Maynard!

I'm "eagle-ing" it as we speak...

Some questions though:

Just where in the circuit (schematic) does the "big-ass-capacitor" fit?
Have you looked into Supercapacitors yet?
I've had an interest in them, but haven't found much in this niche...

kebabacool3 years ago
Another question/idea; wouldn't it be possible to put a little stack of rechargeable batteries (4x1.5V) between the rectifier bridge and the regulator in order to store some energy and feeding the regulator when not cycling ?? Therefore having some power feeding the lights when not moving.
kebabacool3 years ago
Wouldn't it be possible to use the whole bridge rectifier made of power LED as a taillight ?? Pilom suggest using one of the LED from the bridge as a taillight but why not the four of them ??

Cheeeeers !!
jmynhier3 years ago
thanks for the instructions, I have one question though. why not drill two holes in the side of the flashlight body for the wires to exit and integrate the rear on/off/mode switch of the flashlight into the wiring?

Also check out the new crop of "on/off" hub dynos. In the off position the magnets are disengaged and there is no drag, much like a bottle dyno. I have provided links to three of them below.




Malhecho3 years ago
good job i wouldnt put this on my lowrider but i wanted something for my mountain bike.
carlos66ba3 years ago
A very nice idea. I recommend you take a look at switched regulators (dealsextreme have quite a few, and they are not expensive at all). They do not loose energy to heat like a regular linear regulator (like the one you built). Sometimes they are called buck-boost (or something like that). Check them out!
sgomes3 (author)  carlos66ba3 years ago
Thank you. A great suggestion indeed. I will do a search on DX to inquire more about it. If you have a direct link or the part number, it would greatly help.

zazenergy3 years ago
This looks really awesome. As a regular cyclist I know I could use something like this. I do think your Instructable could benefit from some more detail. I'm happy to help if you have any questions!
sgomes3 (author)  zazenergy3 years ago
Thank you. Yes. I am not 100% done yet. I got a bit too excited and published it soon. This circuit could benefit any touring or commuting cyclist, especially when winter is around the corner and it will be dark outside :)

I will break it down to more steps with more explanation. I am not an expert on electronics by any means, but this circuit seems to work well (took me less than an hour to build). so far, I have not burned any LEDs yet (I rode 2 hrs non-stop). I have yet to stress test it, and hook up a USB device to charge. I will update the instructions as time progresses. Hopefully, it will hold up to my expectations.