LED-Day-Drive-Light for Your Bicycle




Introduction: LED-Day-Drive-Light for Your Bicycle

If you check the modern cars, driving on our streets, you will realize that they all have a Day-Drive-Light with LEDs.
The critics mean, if everyone drives with light during the day, we survey the cyclists, because they only turn on their light, if it gets dark!
Ok, nice point. We bikers need bright enviroment-friendly light, too Hm, we all like LEDs! (You do, i´m sure ^^ ) LEDs on our bikes! Great idea!
So, I thought "Why, don´t build a LED-Bike-Day-Drive-Light?".

I started "developing" 6 months ago and realized that it is relative easy to do!
I wanted a light, that is bright enough to be seen on daylight.
In addition it should be possible to turn on both "light-systems"  (the main-system: front-light, and rear-light, I hope you got them, but it is not necessary for this Instructable;  and the new day-light-system)
And the most important point: it have to use the dynamo and NO BATTERIES.
Here on instructables.com are a lot of these battery lights, but if you ask me we all should never use batteries for a bike light! We have only the one planet... And we all should realize that good (longlasting) batteries aren´t cheap on long time. So, hey! A (Hub-) Dynamo is the best way if you ride your bike often. In my opinion good Bikers make their light  in an environmentally friendly manner!

So, here are the advantages of the
... makes biking safer
... looks great, everyone is looking at you!
... you can turn on your ordinary light and the Day-Drive-Light
... LED-light makes fun!

Ok i wrote to much. LED´s start!

PS: please read the complete Instructable before you start. Some informations are necessary for the complete LED-Light      :D

Step 1: What You Need:

What you need is here.
The Circuit is easy, so you don´t need a lot of parts. The main circuit is not my invention (but would be great  ^^ ) if you are interested you can find the developer here (german page)

Soldering Iron and equipment

2x SCHOTTKY Diodes

2x Capacitors 2200µF/ 16V

(you can use caps from 16 V on, but it is better if they make more Volts)

Your HighPowerLEDs.
I used "AVAGO MOONSTONE LEDs" partnumber is: ASMT-MW62-NFH00

- > Some information for your LED-selection:
Our Driving-Circuit drives the current of the Dynamo to (low-cost-) LED-friendly 300-320 mA.
If you want to build it like I did: You can use 4 0,5W LEDs (2x2 parallel and the two pairs in series)
But you can also use 1 W LEDs (if you do so, you have to connect each LED in series. A Dynamo is able to drive ca. 3 1W LEDs)

In Addition you need a Dynamo. A HUB-DYNAMO is perfect.
Sorry, if I don´t write how much it costs, because you can use desoldered material for the driver-circuit. The most expensive parts are the LEDs.  

Step 2: Build the Driving-circuit

Now, we build the circuit.
Before you start you should search for a place, where you want to install the Circuit. If you got one build your circuit, but build it in a way you can install it later! I installed mine in the bar of the steering-weel and secured it with a Cap i found in a toy.
I hope you can install your Circuit in the same way i did. It is the perfect place!
Pictures say more than 1000 words...
( Ohh, an old but true saying... xD)

Don´t connect the circuit-entry (the left site on the circuit-picture) with your dynamo now! (Read The "Really Important Information")
You have to connect the LEDs first!!!

1. the Capacitors could be destroyed and
2. if you then reconnect the LEDs with the Circuit all the Current in the Capacitors destroys the LEDs suddenly !!

(If this is the problem; means you moved the wheel but have not connected LEDs, turn your Multimeter on the highest Voltage-Range and connect it with the Circuit on the LED-side, first. Then the Multimeter unloads the capacitors. After 5 Minutes you can connect the LEDs )

-> that means, if you want to use a switch, you have to connect it between the dynamo and the circuit and not between circuit and LEDs (But it is an Day-drive-light, isn´t it? Why to turn it off?)

Step 3: Install Your LEDs

OK, the most interesting step!

Now, I have to ask you: Where do you want your LEDs?
Left and Right of the Front-Wheel?
On your Steering-Wheel, like I did?
Or somewhere?
Try to find out!
The important point is: The circuit delivers ca. 300 mA. You know, that LEDs don´t "work" with voltage but with current. The Voltage adjusts itself then.

That means:
...your LEDs should have Specs of 300 mA (350mA) if you drive them (up to three) in series.
...your LEDs should have Specs of 150 ma if you make 2 pairs of 2 parallel-connected LEDs  and the Pairs connected in series. (I used this way)

If you did, install them and solder the Wires to the Circuit-exit (the right side of the circuit).

I protected the LEDs with transparent Lacquer against water.  Then I made two Housings. They break the light and protect the LEDs, too.
On the pictures can you see them.

Step 4: Finish

Ok now we got the circuit and the LEDs. You have connected them to the circuit.
That´s all we need!
Last Step: Connect the Circuit to your Dynamo.


Wohhaa we got the LED-bike-day-drive-light!!

Now you can ride your bike with wonderfull bright LED-light! Your friends will like it.
I hope it was a fun for you to read and build this.
If you like it, please vote for me.

See you on the street.
Led the sun shine!!

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    10 years ago on Introduction

    This is very cool. Thank for sharing this project. I need to give this a try.

    i use day lights but havent had the time to try and buld a dynamo type.one of my requirements would br to have goog lighting power when stoped , slowing and starting. 1 am not sure if a capacitator would store enough power
    presently i use a deal extreme green output 700lum , solo lithium battery , 3.7 vdc LC 18650 2400 mah, they are sold green , wish they blinked to save batteries . I use tire tubing to lash it to my basket, with a piece of fast back? it is the double sided velcro, that sticks to itself and had multiple uses on bikes. I use a small piece to lock my brake handles closed on the grips, so it helps with balance and not walking and falling, and also another obstacle for the thief. It is really hard to see on black grips.
    i like green since no one in the usa has a clue what it is , it also hits their side view mirrors, with a bright green glow.i am in nyc area so i have been using some kind of daytime light for a while, saw how many times someone who was opening the door , stopped,since they saw the earlier white led, but blinkys, forget the name but for the size they were great for being seen, not for seeing. i also had to make sure it was aimed at the side view mirrors, but the reflection back was easy to see. Air zound is the other survival tool, a 2 litter bottle wrapped in tape to make it stronger, was better than the original bottle. i only use it on vehicles, no pedestrians, that is what the bell and brakes are for. Very rude to use air zound on ped or other bicyclist unless they are really being a law breaking jerk. i still need to make a foolproof airzound horn button.
    Nice lights, daytime lights are real life savers on bikes. being seen in the daytime keeps you around to ride again, well except for the cell phone / texting drivers who are killing daily in this area.


    11 years ago on Introduction

    lovely simple scheme.
    Just in th elight of some questions: yes, the light will depend on the speed of cycling and may flicker a bit on low speed. For those interested to develop this schedule a bit further: check here


    12 years ago on Step 4

    Interesting... but you forgot the power source. I figured those LED's that you use will use up a-lot of power if useing just a 9 volt battery.


    Reply 12 years ago on Introduction

    hey mate could be, that I did not understand your question.
    The circuit is developed for a Hub-Dynamo, each modern bike should have.
    I don´t like that battery-lights much, they are weak and expensive with the time.


    12 years ago on Step 1

    great idea mate!

    does the circuit ensure uniform lighting or is it my bike speed dependent?
    if it does then how?

    ps: i am a high schooler and not a pro 


    Reply 12 years ago on Introduction

    no, the light-output depends on the speed. With my Hub-Dynamo I get 100% brightness on 15 km/h. Till 5 km/h the LEDs are flickering a bit.

    Have a nice day!


    12 years ago on Introduction

     can we modify the circuit and drive the lights from an accumulator rather than from the generator itself? 


    Reply 12 years ago on Introduction

    Hey Sfsreporter,
    hm, in my opinion, an buffering via accumulator is not the best idea...
    First, if you want it cheap, it will be really ineffectiv and you need alot of space (means a housing etc.) The expenditure is high...
    my LEDs have nice brightness for 10 km/h on. You cannot brighten the street but it is enough to be seen! (thats why I want a day-drive-light)
    To have more light (and less flickering) on lower speeds, you can easily connect capacitors (perhaps 4700 µF and more) parallel to the LEDs. I don´t now if it is better to connect a capacitor parallel to each LED or one for all of them, try simply.


    12 years ago on Introduction

    Hey dino,
    those "lenses" are the packing of the LEDs (they are delivered in plastic-pits; I cuted them halve).
    It´s ordinary plastic so don´t have scruples to use each plastic-packing you can find ; )

    See you on the road!


    12 years ago on Step 1

    thanks for the instructable.  I didn't see exactly what you used for the two lenses that the LEDs are mounted.   I like how it dispersed the light.  Did you make these or are they a part that you were able to obtain from scavenging, etc?


    12 years ago on Step 1

    Hi there, Nice job. You should really have something to limit the current so that you don't over drive the LED's.  I may have missed this part, I couldn't find it in the article?

    A good place to get cheap LED's and free shipping is dealextreme.com


    Reply 12 years ago on Step 1

    Hey, thank you.
    The circuit is a voltage-doubler. It doubles the voltage and halves the current. The voltage is not interesting for the LEDs, we drive them with current.

    We have to know, that a Hub-Dynamo supplies approximately 500 mA. (it is not a voltage-supply but a current supply)
    With the circuit you can halve that 500 mA now and you get at the most 250ma-320mA.
    Your LEDs will not get more current; also not, if you ride your bike with 50 km/h (I tested it ;D)


    12 years ago on Introduction

    Thank you.
    This will likely be my next headlight.
    Remember that a headlight should be pointed at car window level. Around here it might be an idea to make sure it angles up a bit for the SUVs (about 50% of cars here). The scatter from my 1 watt light lights the road to beyond my stopping distance. My first thought was to mount you idea to the fork but when I thought about it, handle bars are best especially in the day light. I ride through busy intersections a lot. Now I need turn signals with a quick connect to transfer the circuit to the trailer.


    12 years ago on Introduction

    They look bright! (Check your hyperlink to led-trieber.de)