Bullnose LED Bike Light and Dynamo USB Charger

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Picture of Bullnose LED Bike Light and Dynamo USB Charger
bullnose dynamo close.jpg
USB Charging Station.jpg
LED Toggle.jpg
headphone jack.jpg
USB charging station2.jpg
Dynamo 111009.jpg
 This bike has a dynamo front hub that is wired to LED lights.  In addition there is a power output via a female USB plug.  You can charge your phone, ipod, GPS or any USB powered device.  

In this design, the USB charging station can be unplugged when not in use. When charging the devices can be kept in your pocket or backpack.

The charging station has four AAA rechargeable batteries wired parallel to the female USB that provide a secondary energy storage and once charged can power a USB device independent from the bike. 

You can use the dynamo to power the lights or the USB but not simultaneously.  A toggle switch on the bullnose handlebars turns the front lights off.
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Step 1: Circuits

Picture of Circuits
 There are quite a few circuits and great LED tutorials on Instructables. Just check out some resources to get your bearings.

LED for beginners:
try out different circuits... blinking, back light, combinations =>
As the front wheel turns it creates alternating current (AC) power.  The 'bridge' is a rectifier that converts the AC dynamo power to DC power. The bridge is made up of qty(4) 1N5818 diodes.

Bike Light Encapsulated in Epoxy

The battery pack absorbs any power not consumed by the USB device.

qty(4) 1N5818 Diodes
qty(8) White LEDs
qty(1) Battery Pack

Step 2: USB Charging Station

Picture of USB Charging Station
phone jack.jpg
phone jack insertion.jpg
USB charging station2.jpg
 I purchased the 4-AAA batter pack and female 1/8" phone jack from radio shack for $3.  I cut the female USB jacks out of an old computer.  

First I wired the battery pack and USB devices in parallel.

Next I partially disassembled the battery pack and wired the phone jack.  I arbitrarily used the Left channel of the phone jack as DC positive. You just have to be consistent when you work on the handlebar connection.

I drilled a 1/4" hole in the lid for the 1/8" jack to stick through.

I have 2 questions....

1) will this work if the dynamo is turned the opposite way?

2)Do you know any sites that i can order form(preferably amazon) that i can find usb receptacles?


pls reply fast

panigrc2 years ago
Dear hydronics,

at first I want to congratulate you for this very usable instructable.
Because I want to built it I have some questions.
I don't know much about electronics but I've searched a lot until I found your instructable and I've seen lots of designs.

I am looking for ways to improve your circuit so here are my questions:

1) Why do you have the second pair of LEDs in series and not in parallel?
2) Why do you use a resistor ?
3) Why don't you use a capacitor (I 've read here that using a capacitor improves the lighting and decreases flickering
4) Is it possible to have the batteries connected always with the LEDs so even if the dynamo isn't working the LEDs would remain ON.

I would be glad if you (or someone) could answer my questions.

Thank you in advance :)
Where would i Put an LDR in addition to the switch?
Excuse the Newbe question.

about the hub is it easy to connect the spokes onto it?
siggivara4 years ago
Exelent stuff.
Does this react/protect against overcharging? I'm a little worried about excess power frying whatever device I'm charging.
hydronics (author)  siggivara4 years ago
 the battery pack absorbs excess energy while peddling... I suppose it does the same thing once the device is charged... start cheap, go big, good luck. -tom
peteoc5 years ago
this isn't wanting to charge my iphone 3gs, any ideas? I've taken a photo of my breadboad setup.

I'm powering this using a 6V DC adapter for testing purposes.
peteoc peteoc5 years ago
a better quality image can be found at
(removed by author or community request)
IPod and iPhone need a "signal" so they know it is OK to charge, they need about 2.7 Volts on D- and 2 Volts on D+
You could modify the charger to make it work with iPod/iPhone by following this schematic:
That should make it work with your iPhone/iPod.
peteoc peteoc5 years ago
I've been researching this more and it appears iPhones require reference charges on pins 2 & 3.
On pin 2 it requires 2.5v and 3 requires 1.8v - It appears these reference voltages are only required to tell the phone to start charging, once the phone has started charging these voltages can be removed.

I'm going to sort out my setup first and will post a more detailed instructable.
hydronics (author)  peteoc5 years ago
 yea... it should work...your board looks good. 

couple things to check of course.
-the led should be unplugged for usb charging
-maybe check you got the voltage at the USB pins
-finally the diodes are supposed to convert from AC to DC (the dynamo produced AC current)  you indicated you have a DC source and the DC should pass through the diodes. It obviously passes through to light the LED, eh?

let me know when you figure it out.
peteoc5 years ago
Sorry to drag up the past however I'm looking at a possible solution to charge my iphone while out on long hauls. I assume it's possible to simply drop the LEDs from the circuit diagram and go forward with just the USB section?
hydronics (author)  peteoc5 years ago
let me know if you have any questions. look at the circuit diagrams, follow the links, etc... as we say in Portland, "do it better"

Have fun.
DaveG205 years ago
Hi there, great idea! how long does it take you to charge your 4 AA batteries while riding at a normal pace?
hydronics (author)  DaveG205 years ago
 i'v no idea. The battery pack is used as a buffer when running my ipod. It absorbs the excess electricity generated by the hub but not used by the ipod.  I don't use the battery pack as a standalone device... although you could!
hydronics (author) 5 years ago
yea, as soon as I finished I wanted rear lights too.  I'll have to hack those in shortly. The nights are getting longer.
henkmans5 years ago
 What a super cool idea! I thought of it too, except for the fact that I have a ramshorn steer
tevers945 years ago
Thats a pretty cool idea.  I might try that except for rear lights.