# dynamo hum - help me build a light system



## aljee (Aug 27, 2009)

Hi,

So for father's day, i got an alfine generator hub!
Now, i am planning a lighting system.
My goal is somewhat ambitious: I have 4 things i would like to power:
-endor star 3up based flood light
-cree 1up q5 xr-e based spot (separate housing/circuit from flood - detachable to mount in helmet for curvy/hilly night rides)
-endor star 1up red taillight
-charger for my iphone (for long bike camping trips) - want to do this circuit on my own, but am also interested in devices like the Dahon "biologic reecharge"

The bike is a cross check. It is my everything bike that will be used from year-round commuting to bike camping/touring.

I have put together a few cree-based battery powered lights. They are fantastic. Now i am starting down the road of basic electronics - bridge rectifiers, super capacitors, etc... it seems i have much to learn

I found this excellent resource: http://pilom.com/BicycleElectronics/DynamoCircuits.htm#Basics
that i will barrow many ideas from.

i will update this thread as i progress (slowly). 
If anyone has any suggestions/comments/resources to share, it will be most appreciated.

Thanks!
Alan


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## znomit (Dec 27, 2007)

Why endor stars?
They are really really really floody and not as efficient as other LEDs.


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## ktronik (Dec 23, 2006)

Hey,

as a Xcheck owner & dynamo light builder, I can say GO FOR IT, you will love it...

but, be very careful with hooking up sensitive electronic equipment (iphone) to a modified AC waveform, EX a rectified AC wave from from a dynamo hub. it may show / look like DC output on a mult-meter, but it is far from a pure DC waveform and may hurt your iphone if hooked up directly after the rectifier stage

Martins circuits are a great place to start, with a basic 3 LED string.

have fun

enjoy

Ktronik


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## aljee (Aug 27, 2009)

Thanks for the feedback.

znomit - i was thinking endor star because i wanted to diversify. i am still learning a lot about efficiency. it's sounds like you would think i would be throwing away light/energy? perhaps another cree based light with a wider optic would be a better choice.

ktronik - thanks for the tip. i was thinking yesterday instead of making a circuit to directly connect the phone, i would make a battery charger and use that to charge the phone (with no connection to the hub while the phone was charging).


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## OldMTBfreak (Apr 8, 2006)

All you need for the phone is a moderate filter; me I'd prolly use a TL431 as a shunt regulator. This would be after the voltage doubler and rectifier bits. The phone has is own battery charger/regulator. I don't hear of too many ppl having trouble with the charger in their phone. As to the LED's; XPG's are much efficient than endor's. Reason is age, the XPG's are newer. Here's an example. http://forums.mtbr.com/attachment.php?attachmentid=550644&stc=1&d=1276888222
The better efficiency will greatly contribute to your project's success. I'll put that last bit a different way. You only have a finite amount of power, you will have to use it wisely. lol James


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## aljee (Aug 27, 2009)

"You only have a finite amount of power, you will have to use it wisely"

thanks, this is what i am trying to get nailed down before i go choosing parts. with a dyno hub (3W, 6V) i should have 2 amps to 'spend'. what happens if you go over? according to the page i linked to (Martin's), it sounds like you will feel more drag? 
much to learn...


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## znomit (Dec 27, 2007)

aljee said:


> "You only have a finite amount of power, you will have to use it wisely"
> 
> thanks, this is what i am trying to get nailed down before i go choosing parts. with a dyno hub (3W, 6V) i should have 2 amps to 'spend'. what happens if you go over? according to the page i linked to (Martin's), it sounds like you will feel more drag?
> much to learn...


For the LEDs is basically 500mA constant current once you get up to speed. You can peak your circuit to supply more but 500mA is a good estimate of what you'll see. You can get about 12W max out of the dyno (right Kerry?). I feel no drag on 3 LEDs but 5 its perceptable.

For a flood definitely use cree XPGs. There are plenty of optic choices.

I run an AA battery helmet light alongside the dyno lights. Very simple and effective.


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## ktronik (Dec 23, 2006)

Good idea 'freak' & good idea for the battery before the iphone, this will smooth out the DC for you 'load'

I have got 12w out of the hub, but only with a peaky, 'not ideal' power curve...good thing is you can tweek the power output & where it 'sits' quite easily with martins circuits, so a great place to start.

But I would recommended starting with a NIMH battery (rather than lipo) if you go that way...

K


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## OldMTBfreak (Apr 8, 2006)

There have been posts in the past about rectifying and regulating the dyno hubs. Whip up that circuit. Get the data sheet for a TL431, wire it as a shunt regulator (5 volt of course). The shunt regulator will ground all the spikes heading for your phone. If you use three 5W led's, you'll have plenty of light. Are you gonna run a tail light? It won't draw as much current as the headlight. You will need to experment with the "peaking cap" for absolutly best results. I would guess you only need 2 or 3 watts to charge the phone. So, this is what you need: 1W tail light, 3W phone charger, 7-8W for the head light. 12W total, this looks good to me. I think you'll have good luck. I wouldn't worry with charging a battery and then using that battery to charge phone, more steps. If you want to be lazy, a 7805 will give you 5 volts. It's not quite as efficient thou.


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## aljee (Aug 27, 2009)

*Finally*

I am resurrecting this project. It never really died, but you know how life is some times.

so, this time around, i am going to keep it a bit simple and just do one light. going with the 3up cree xpg from led supply. putting the batter charger deal off till i am successful with this.

Got my wheel parts: 


got most of my light guts (using Martin's circuit #7): 


as i said, i am using this LED: https://ledsupply.com/creexpg-w417.php
i will be using my same simple housing design:


since i wasn't able to walk in a buy a smaller 4700mF cap, i will make a break-out box to house the innards and make a short version of my battery light housing. thinking of using a patch kit box for the circuit and will water proof it as well as i can. i can then make a smaller light housing.

i was hoping to get some advice on the optic. this light is intended to be mainly for commuting, but with some road night riding thrown in. i am looking for a bright but wide beam. the 'hood' and angle will hopefully keep it out of my fellow commuter's eyes.

anyone have an opinion on this? : https://ledsupply.com/10510.php

thanks for any help!


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## vroom9 (Feb 24, 2009)

That lens might be a bit broad for the relatively small amount of light you will be producing. You might to use the narrow spot lens. In this size the term narrow is relative. It's narrow for the size of the optic, but still a lot broader than larger optice named "spot". I'm guessing the narrow is still a 20 or degree wide beam, but I'm not sure on that exact number.


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## aljee (Aug 27, 2009)

thanks for the tip. i think i will pick up both the narrow and elliptical to experiment since they are only a couple bucks. 

i expect this light to get to 500-600lm per the spec sheet and mA generated by this circuit. do you think that is too small?


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## mattthemuppet (Jul 16, 2004)

I think that would be a bleedin' amazing amount of light for a mtb light, let alone a commuter. I've been getting by on 50lm or so for years, so 500lm would be literally like light and day


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## Bobblehat (Dec 1, 2007)

Alan ...... depending on what you've used previously you are going to be totally "stonked" at what a triple xp-g will put out from a dynamo! :thumbsup:

I've just finished this (for old shimano hub dyno on errand/commute bike) .....



















..... twin xp-g - regina ..... Martin's circuit 7 with a slight adjustment courtesy of Ktronic's and Znomit's experiments. :yesnod: :rockon:

OK Reginas get the best out of xp-g's (or nearly?) for throw, but even with elliptical or wide optics you're going to get a lot of light out of a triple for commuting use ..... you might even need to throttle back!

Using 3 xp-e R2's Ktronic was getting close on 600 lumens using a bipolar equiv of 200uF at 20kph or 700 lumens at 28kpm using a 100uF bipolar equiv. Xp-g's should give you even more!

Znomit's experiments were showing very similar proportionally equivalent results using 2 xp-e's.

I've used 2 x 470uF electrolytics as a substitute for the 220uF bipolar, as in Martin's #7, and according to my rough calcs, I'm getting close to 500 lumens at peak (approx 20kph), out of 2 xp-g's, and that's got to be around 440 lumens OTF at 90% reflector efficiency ...... it's a lot of light for a commute especially with the reginas putting most of it tightly on a bike path width circle about 6m in front of the bike. With this and good spill, you're definitely going to get noticed by on-coming traffic! See my better-half's comment on the 2nd thread linked below!

If you want a bit more detail ... have a look at my posts here ..... (there's 3 link's in one of the posts to Martin's pages - Znomit's and Ktronic's threads)

and about half way down here

OK ...... so 400-500-600-700 lumen ain't much if you're inclined to hare down a singletrack at high speed (Vroom9?) ..... but you want it for road/commute use ....yes?

GO FOR IT!


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## aljee (Aug 27, 2009)

awesome, thanks for the links!

one thing i notice on diy light forums is the variance in the idea of 'bright'. 
granted, i am still learning and have a long way to go, but it seems like 500+lm might even be too bright. there has been a lot of dialogue lately about commuting lights in town being way too bright, angled wrong, etc. so my goal here is to balance REALLY bright light that plays nice with others. 
so yeah, i admit that i was sort of wondering about the phrase "relatively small amount of light you will be producing", but then thought it IS pretty small light when you compare to the multi-thousand lumen beasts i have seen come out of the forums. but for a dyno, for commuting, for road work, 500+ sounds bright to me. i think a supernova e3 is less than 300, and that is considered darn bright. 

mountain bike lights serve a very different purpose than road/commuter lights and i see that get confused with a good deal of commuters in town. i would like to apply dyno lights to mtb, on my pugsley and eventually on my el mariachi (when i get one )


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## Bobblehat (Dec 1, 2007)

Build it as is ....if on a remote chance you find it too bright (Nah! you'll love it!) you could ......

a) rob some current from the front to drive a rear light ....

b) alter the circuit to a voltage doubler to get the light to come on at a lower speed, but at a max of about half the lumens of the full rectifier circuit. (Martin's #'s 8,9,10)

c) both!

...... and ....


d) still got the option to use the switch to revert back to full rec for those mad moments!

Just allow a little more space when you build the housing to add the extra components later from your initial build (switch and 2 caps) ...... my mkII dynolight will probably do all of these!


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## mattthemuppet (Jul 16, 2004)

aljee said:


> one thing i notice on diy light forums is the variance in the idea of 'bright'.
> granted, i am still learning and have a long way to go, but it seems like 500+lm might even be too bright. there has been a lot of dialogue lately about commuting lights in town being way too bright, angled wrong, etc. so my goal here is to balance REALLY bright light that plays nice with others.
> so yeah, i admit that i was sort of wondering about the phrase "relatively small amount of light you will be producing", but then thought it IS pretty small light when you compare to the multi-thousand lumen beasts i have seen come out of the forums. but for a dyno, for commuting, for road work, 500+ sounds bright to me. i think a supernova e3 is less than 300, and that is considered darn bright.
> 
> mountain bike lights serve a very different purpose than road/commuter lights and i see that get confused with a good deal of commuters in town. i would like to apply dyno lights to mtb, on my pugsley and eventually on my el mariachi (when i get one )


well, a single XP-G at 350mA (100lm OTF?) is waaay better than my old Cateye commuter LED light and at 1A (250lm OTF?) simply blows it into the weeds, so I think I triple would do very nicely indeed!


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## aljee (Aug 27, 2009)

*set back*

i think i might have fried my brand new xpg. :madman:

my lack of basic electronic knowledge might have caught up with me. i was trying to test my circuit with my wheel in the truing stand. i twisted it up and connected the led, but no dice. 
i then untwisted everything and started over with the very basic rectifier bridge + LED, still nothing. 
in short, between the diagrams and schematics, i got confused and didn't realize that the side of the bridge with both negatives actually make a positive. so....i figured out at work and will try again this evening.

*question from a newb*: if you accidentally run a reversed polarity to a new xpg, is it.....dead? 

i read somewhere that it should be fine unless it was a lot of voltage, but it might kill some of the new LED's. oh well, an expensive lesson learned.


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## klynk (Apr 18, 2010)

aljee said:


> if you accidentally run a reversed polarity to a new xpg, is it.....dead?


It's fried, yes. You should never reverse polarity with LEDs :nono:


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## aljee (Aug 27, 2009)

frick.


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## aljee (Aug 27, 2009)

i am so pissed at myself. this lesson stings.:madmax: 

i have an extra battery powered led that needed some work. i can at least use that for spare parts till the replacement 3-up arrives.

poops mcgee.


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## znomit (Dec 27, 2007)

aljee said:


> i am so pissed at myself. this lesson stings.:madmax:
> 
> i have an extra battery powered led that needed some work. i can at least use that for spare parts till the replacement 3-up arrives.
> 
> poops mcgee.


They can actually handle 5V reverse
http://www.cree.com/products/pdf/XLampXP-G.pdf


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## aljee (Aug 27, 2009)

maybe there is hope then.


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## aljee (Aug 27, 2009)

ok, good news everyone. it isn't dead, got it to fire up last night. haven't isolated the problem, but it works, so that's good. now to just finish the wheel up, find some housing and put it all together. exciting!


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## BrianMc (Jan 5, 2010)

There is nothing so fine as a Lazarus light returned from death at your own hands! Oh what a feeling, what a rush...(dating myself, there.) :thumbsup:


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## aljee (Aug 27, 2009)

ok, so i got the light working!
dyno power is where it is at. :thumbsup: 
for the rear light, instead of making my own, i caved and picked up the toplight line plus because it was so inexpensive. i am really pleased with it so far.

so back to the dyno light. i tried both the narrow and elliptical carclo optics from led supply. i decided to stick with the narrow optic. much better for swifter riding, and i would be on the fence about which one i would chose for my cargo bike.

the circuit worked well, the flicker isn't an issue. it is pretty ugly with the breakout box though. so, i am thinking of a revised design:
1. use a pre-made rectifier
2. forget the tuning caps
3. use a super cap for a stand light
4. fit it all in the light housing (including switch
5. make housing out of aluminum (maybe used seatpost)
6. make a fork crown mount

this leads me to a couple questions
1. anyone have any idea how large that super cap is? my hope is that it isn't any larger than my housing (1in copper pipe, i forget what the ID is).
2. for the super cap, i was going to wire it parallel to one the led's. now, this is a 3-up star, so in theory i would have to solder it using the tiny solder spots on the star. can one wire a cap parallel to just one led on a 3-up?

i have gathered a lot of info regarding stand in this post

thanks for any help! i look forward to getting some beam shots up (letting my flat foot heal at the moment).


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## klynk (Apr 18, 2010)

aljee said:


> ok, so i got the light working!


Would you share any pics of the light itself?


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## aljee (Aug 27, 2009)

klynk said:


> Would you share any pics of the light itself?


yeah, sure, i was kind of holding off, to make something a bit more handsome in terms of mounting, but here you go






i don't have a good pic of the current state of switch 'tube', but here it is before i wrapped it up in electrical tape and sheathed it in bike tube (zip tied to the fork at the moment):


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## znomit (Dec 27, 2007)

aljee said:


> the circuit worked well, the flicker isn't an issue. it is pretty ugly with the breakout box though. so, i am thinking of a revised design:
> 1. use a pre-made rectifier
> 2. forget the tuning caps
> 3. use a super cap for a stand light
> ...


Your links are busted so we can't see what parts you're referencing. Stick with schottky diodes for efficiency.
The common supercap is as seen here in my 5up build. Note for scale the big hole is around 40mm and the little optic ~17mm


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## aljee (Aug 27, 2009)

ahh, thanks for telling me.
here is the super cap

and here is the rectifier (it is the schottky variety).

and thanks for the tips, i will also check out the 5.5v, 1F super cap you are using there.


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## znomit (Dec 27, 2007)

aljee said:


> ahh, thanks for telling me.
> here is the super cap
> 
> and here is the rectifier (it is the schottky variety).
> ...


The supercap dimensions are on the datasheet.

Note the rectifier is SMT so very very small (but otherwise a good choice).


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## Bobblehat (Dec 1, 2007)

aljee said:


> ok, so i got the light working!
> dyno power is where it is at. :thumbsup:


+1 on that Aljee! 

I was dead chuffed when I got the battery version of the Troutie/CK/Teapot/Hammond light working ...... but even more chuffed when I saw what a dynamo version could do. (Not that I'm saying the dynamo version is better ..... just very satisfying that the power source is your legs!)

Good to hear your opinion on the elliptical optics, because I had a hankering to try them instead of the regina reflectors .... guess it's suck-it-an-see if you like it :thumbsup:

I'd like to hear why you think you would abandon the tuning caps .... have you done a test with and without? I just built the circuit with tuning caps, so have no comparison myself.

Also, what prompts you to say you will go with a pre-made schottky next time ... is it just the size and not a performance issue that makes the difference?

Hey! Who needs handsome when its dark! Your light pics look good to me!


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## znomit (Dec 27, 2007)

Bobblehat said:


> I'd like to hear why you think you would abandon the tuning caps .... have you done a test with and without? I just built the circuit with tuning caps, so have no comparison myself.


If you look at the performance chart on Pilom.com you see the boost is generally in a lower speed range. So you get more light at 15kph but the same at 30-70kph. You don't need the extra boost unless you spend a lot of time in that speed range(be useful for a commuter).
They do take up a fair amount of space too.


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## aljee (Aug 27, 2009)

Bobblehat said:


> Good to hear your opinion on the elliptical optics, because I had a hankering to try them instead of the regina reflectors .... guess it's suck-it-an-see if you like it :thumbsup:
> 
> I'd like to hear why you think you would abandon the tuning caps .... have you done a test with and without? I just built the circuit with tuning caps, so have no comparison myself.
> 
> ...


yeah, the optics are cheap enough to just test out. to me it is worth the first-hand experience.

pretty much all the stuff i listed is to make a tighter unit with a stand light. the schottky rectifier is just to get the size down. i might change my mind on the tuning caps. this is all on my fast(er) bike, so i might not need them. at the very least, i would like to get the switch box smaller if i do keep it.

and thanks for the compliment. in general, i have been trying to get away from a lot of accessories. the swing grip is nice and functional (and i got it for super cheap), but i will go without, when i get the chance. most of my riding is commuting, but my goal is endurance racing (if my foot ever heals).

and big thanks to znomit for sharing the knowledge. i have been looking over your past posts, very inspiring work!


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