Retrofitting LEDs in a Dynamo Bulb

Hello , again ,

As you know there are several instructables on building Bike Lighting systems ,but , hey i wanted to post my own .

After a couple of hours searching instructables ,I haven't saw a proper Bulb-Led conversion , i've just saw some spam or ones with incomplete instructions .

Now i will show you how to retrofit an LED array into a Regular Light bulb , which i think is brighter cleaner , and lotsa times cooler .

As a Bonus i used this LED array in my Bike's Dynamo, Voila, Much more output and half the Power .

Step 1 Materials 'N' Tools

For my Array I used 3 LEDs but you can use up to 5 (well you can really use more , but there is not enough space...)

The List:

Quantity---------Description
3-5 White Ultra-Bright LEDs (mine were 4900mcd)
1 Used, Burnt or Spare Screw-type Bulb
5-10 CMs(2-5inches)of Small Gauge Wire (mine came from an IDE cable,which is 26AWG)
1 Small Piece of Scrap circuit board (mine had a Dotted design,which is pretty Common)

Tools
-The Usual Soldering Equipment ( Soldering iron , Solder , Helping Hands, Sponge ,Etc)
-Needle or fine tipped Pliers (mine are rusty, That's Why i used my Multi-tool)
-Small Cutters
-A round file
-Hobby knife (i used A hobbico body and a X-acto blade)
-Hot glue and hot glue gun
(Not shown but handy to have )
-A fine tipped Permanent marker
-6 Volt supply and alligator clips
-A Small alligator clip

Comments

[danbb]

<strong>Good project, but fails</strong>. I built this project and the end result basically looks just like <a rel="nofollow" href="http://www.ccrane.com/lights/flashlight-led-conversion-bulbs/3-led-flashlight-replacement-bulb.aspx">this $22 bulb</a>this $22 bulb. (I simplified it by soldering each negative to the base and running the anode down the middle. I installed it on my Brompton (which has a 6v dynamo) and it works great for the first hundred yards. Then it dims, dims, dims, fails. I removed the bulb after a few hours, checked it on some batteries and it worked fine. After re-installing it the same thing happens... I get about a mile and it's dead. What's going on?<br/>

[acaz93]

I'm not quite sure what is really happening with your light .
What I can say from my perspective may not be the Real answer ,
the problem , i'm not quite sure, it's thet the dinamo doesn't produce enough current to light every thing properly , what could be happening ( which i think impossible due to the air flowing around the dynamo ["air friction] )It's that the coils from within the dynamo produce some heat and it affects the energy production , OR the array doesn't properly convert the current to light .

May I ask , is everything connected properly ?
is the resistor in?
how did you made the LED wiring?

[luigi2999]

according to wikipedia, those dynamos produce AC. Leds are only capable of running on DC, so you might need a rectifier diode.

[danbb]

Hi ACAZ93. Thanks for commenting. I simply built the unit as described (all three + to the tip of the base, all three - to the edge of the base). When I tried it initially (without the resistor) it lit up with batteries and the dynamo... no problem. So, knowing nothing about electricity or LEDs, I assumed (!) that the light would continue to work, even after several minutes of use. I will install a resistor and then put a few miles in on the bike to see if it solves the problem.

[acaz93]

If the resistor wasn't the cause of the issue , I recommend adding a smoothing buffer capacitor and a zener diode . Try with the resistor and tell me if it corrected the problem see ya !

[SteveMcCraft]

This is very interesting. Thanks a lot! But I have read, that LED need a resistor to survive longer. How long has your construction worked? best to you Steve

[acaz93]

over 3 months so far , yeah it needs a resistor to work the guarantee 10,000 hrs (that's described in the last step ), It's really robust ,someone dropped by bike and a bump appeared in the case but the LED bulb was intact. Thanks , Have a nice week!

[SteveMcCraft]

OH yes - now I have read the last page. All ist there. I am sorry for asking. Is it difficult to add a high Cap for making it light even without riding for a short time - but where and how? Allt the best Steve

[acaz93]

Yes! but you will need a Zener diode and really high cap (I mean like 0.55 F ) if you ive a day i'll make a schematic

[AndyGadget]

(For Fluorescente) Here's a simple circuit which should smooth the dynamo voltage, charge up a battery and get over the main failing of a dynamo - namely the lights go off when you stop moving. I haven't made this (no dynamo), but it should work, and fit in a small box between the dynamo and lights. Let me know if you try it.

[AndyGadget]

err . . . here it is.

[fluorescente]

Oh wow that seems a step further, thank you! I'll study it but since I'm too novice I don't know if I... heh

[slorge]

The new "green" idea uses Compact Fluorescent Light Bulbs, but don't those thing contain mercury? Wouldn't LED's be a much better idea? I'm very ignorant when it comes to circuitry. Any idea on how to do it to a regular 40, 60, or 100 watt light bulb? I'm sure it would be done approximately the same way, but with a bit more circuitry, but I wouldn't know where to begin.

[acaz93]

It will consume less than 2 watts , the problem is the step down regulation , using leds in series may not be the solution , something using a triac or transformer or better , use a rectifier ,a Transformer , regulator ,fuse , capacitor resistors and some more things

[acaz93]

_{3.47 Thats an abuse}

[Patrik]

Another issue that might come up with hooking LEDs directly to a generator - what if you're racing downhill and are suddenly generating far more that your nominal 6V / 75mA? You coudl over-design your LEDs and resistors such that you'll never exceed the max current even at yoru maximum speed. But then the LEDs will under-perform >90% of the time. One option might be to put a zener diode across the generator to clip the excess voltage. And in that case, you might as well rectify the generator voltage as well. Good luck fitting all that into a little bulb socket though..

[leebryuk]

A moderately-cheap price dynamo has circuity to prevent this situation.

[acaz93]

a Dirt-cheap one does not , mine doesn't and it costed me 16 bucks

[acaz93]

I case i've used a Zener diode , I would have used a 3.9 diode ,a 470microfarad capacitor and a 75 ohm resistor

[acaz93]

Using a PVC tube and my drill , I've tested the array with Succesful results , even at maximum speed , the LEDs are complete , I've registered voltage of 6.65 volts and 0.451 A (open circuit ) the LEDs perform almost as brigth as when running slower (tested 5.46 volts , 0.496 A (open circuit)) the voltage diference is about 1.2 volts , I'm sure those little buddies can withstand that .

[Dungeonbrownies]

This looks petty solid, and its a clean looking job, but arent you afraid thats gonna burn out unless you put some resisters on it more than that tiny lil thing?

[acaz93]

Believe , it haven't burned and I did put Resistors (check Last step)

[gamer]

Very nice! But we have yet to see one that is done correctly.... USE RESISTORS! You would be able to protect your L.E.D.s by putting a resistor on each L.E.D., you would protect them from burning. Very nice and very detailed, though... -gamer

[gamer]

I read my comment over and I meant, "Use a resistor on each of the L.E.D.s"

[acaz93]

its correct to use a resistor in every single led , but to save space , (and respecting the ohm's law (volts by amps = Watts)) a single 1/2 ohm resistor will do easily the job
and Thanks BTW

[gamer]

A few comments: Ohm's law is (R x I = V) and maybe you meant "1/2 Watt"...

"(and respecting the ohm's law (volts by amps = Watts)) a single 1/2 ohm resistor will do easily the job"
Umm.... how to explain, basically, that isn't how it works... If you need more information, PM me and I'll explain in more detail.

-gamer

[acaz93]

sorry , it was a little typo , I meant 1/2 watt

[PKM]

Well written and well photographed- I like your "comic" style images!

The people already familiar with LEDs will know how to find the positive lead etc. but a simple project like this might be a good introduction to working with LEDs so a quick note about "current only flows one way, the longer lead is the anode, we want to wire in parallel" etc.

I'm not sure where you got the 75 from- you appear to be multiplying a voltage by something to get a resistance. Surely the equation you want is voltage / desired current = resistance? (Unless your LEDs want 1/75 A = 13mA...)

[acaz93]

Thanks PKM The 75 comes from the sum of the LEDs current (ie:each led consumes 25 mA ) so each led is 25mA , 25 by 3 (no. of leds of the array ) equals 75 , easy as that

[PKM]

OK, that much makes sense but I'm not sure you meant to multiply that by the voltage to determine the resistance you wanted. Then, if you wanted twice as much current you'd have twice as much resistance- that doesn't make very much sense does it?

Voltage multiplied by current gives you power- I think you wanted voltage divided by current, which gives you the resistance.

My calculations give 2.6V divided by 0.075A = about 35 ohms. (Remember milliamps are not a base unit, so you should convert to amps by dividing by 1000 before performing calculations with other units). As you are using 200 ohms your LEDs won't burn out, but they are not running as brightly as they could be. This online LED calculator agrees that if you are using a single resistor it should be around 35 ohms (rounded up to 39 as the closest common value and allowing for 5% tolerance).

Hope this clears up what I meant.

[acaz93]

It clears it up very well

I think i did the Equation bad ,
Resistance = Voltage divided by Current right ,

The E-calculator gave 33 ohms ,

thanks again PKM

[GorillazMiko]

SUPER AWESOME. I know that I am 1000,000,000,000,000,000% sure that I would have never thought of this idea. Great job, this got my 5/5 stars.

[steven123654]

Great project, well gone a lot better then how I do them.

[bumpus]

that would make a sweet fridge bulb, or for in a drawer in the shop or garage...awesome

[killerjackalope]

Really well explained project, great photos, definitely featured... This is one of the few times I've seen this explained so well, usually people skip over arrangements and all. Oh two things to watch out for, some dynamos (cheaper ones) don't have a particualr positive/negative wire, check with a multimeter first, I've seen red grounds in them before.

[acaz93]

Thanks , killerjackalope! as far as I know LEDs Are diodes by themselves , they can work in AC or DC my tests show that my dynamo for example , outputs 5.84 volts AC , and the LEDs lit just as well as with my 5.5 test PSU , the resistor does not have any polarity so , it could go in one rail or the other , and the LEDs won't fry . Thanks again !

[AndyGadget]

Ah yes, you've just reminded me. A bike dynamo pushes out AC - The LEDs are only using half the cycle. Putting this through a diode bridge would double the available current. (Although you don't really need that as too much would fry the LEDs.)

[killerjackalope]

Oh right, some newer ones are rectified anyway, if it's AC you could double the brightness by adding a second bulb with the reverse polarity of that one, enjoying double brightness without frying anything...

[acaz93]

mine is a cheapy one , and output AC

[killerjackalope]

you may aswell add a set of LED's in opposite direction, for no extra cost on the alternator you'd be getting double light output and a more consistent light...