How-to Dynamo power my LED? (Electronics Help)

[Canabix]

Helloz,
I am planning to build a simple Dynamo-LED Light for my bike.
I have a wind-up Be-Seen front and back
I have a botched Cree Q5 powered by 4x Duracell 1.2v AA NiMh for back up.
.. but want this project to be my main Light. (save the planet Dynamo power)

INGREDIANTS:
[FONT=verdana,arial,helvetica][SIZE=-1]Dynamo ATB for left side 6V 3W for bike/ bicycles - £4.99[/SIZE][/FONT]
---
4x Schottky Rectifier Diode - 1N5818 - £1.12
2,200 uF Capacitor - £2.50
220 uF Non-Polarized Capacitor - Having trouble finding
---
Cree Q5 Drop-In - £6.46



PLAN:
Power = 6v/3w cheep Bottle Dynamo
Electronics = Perhaps this;
http://pilom.com/BicycleElectronics/dynamo1sb.gif
Lighting = Cree Q5 Drop-In, 3.7v - 18v


PROBLEMS:

Is the above circuit cosher? I don't know electrics well, does going down hill blow up the Capacitors/LED.

Will I need to run the LED at a lower % to reduce heat damage?

Is it possible to add a battery in thier some were.. NiMh? to suplement starting brightness and remove excess power.

I'm not to bothered about getting the MAX brightness out of the LED, i'm more interested in effeciency and life-span, 3.7v - 18v what does that mean? I am running the same Cree Q5 drop in another light with 4.8v NiMh and it seems to run fine.

 

[steveo_mcg]

Maplin will do you a capacitor, but 220uf is quite high for non polarised, you sure about your units? Normally that kind of capacity is in the electrolytic type which are polarised.

Though i could be wrong....

 

[znomit]

You shouldn't use a drop in. You need an LED without its own driver circuit.

For simplicity start with circuit 2. It works well when driving just one led.

 

[Canabix]

Interesting, I had a think over this.

1. To solve the 220 non polarized hunt I changed circuit to Piloms Circuit 7, 2 LED bottle dynamo. http://pilom.com/BicycleElectronics/DynamoCircuits.htm
2. The LED driver circuit problem, I realize now the driver wants to pulse the power supply but can't, and I have 2 ways around this.

• work out how to deal with this electronicly, I was thinking a tungsten filament in seiries would this work?
• buy a presoldered LED seperate.

I would prefer to just buy the LED seperate but from UK it seems hard to find a seller
I must find a suitable LED reflector lens stuff and what ever else is needed.

 

[Canabix]

I've decided on Cutter.com.au

Currant shoping list is at...

[FONT=verdana,arial,helvetica][SIZE=-1]Dynamo ATB for left side 6V 3W [/SIZE][/FONT]
--- £4.99

4x Schottky Rectifier Diode - 1N5818 - £1.12
2,200 uF Capacitor - £2.50
2x PC Elect 220uF 63V - VH43W - £0.52
47,000 Ohm 0.25w Resistor
--- < £5

2x XlampXPG R4 on a 10mm SRO
2x Lisa2 16 degree Optics
--- £27.72

Total nearly £50
Would be good to get the LED/Optics cost down a little. Cutter website is vast and will take me a day to get threw all these combinations.

 

[BrianMc]

Would be good to get the LED/Optics cost down a little. Cutter website is vast and will take me a day to get through all these combinations.

In case you haven't done this already, when you find an optic you like or want to know more about in Cutter's site, google it in this forum or check this one out.

There are some incredible beam shots of the XPG optics in both places to help you decide where you get the best bang for the buck. It feels like too much info at first, but it will come into focus and then gets addictive. :naughty:

 

[ktronik]

4x Schottky Rectifier Diode - 1N5818 - £1.12
2,200 uF Capacitor - £2.50
2x PC Elect 220uF 63V - VH43W - £0.52
47,000 Ohm 0.25w Resistor
--- < £5

better to use a 4700uF smoothing cap if you can, these can be found in a non low ESR version, the same size as some 2200uf caps. the 4700uf does a better job & has a higher ripple current rating as a bonus.

2/ 100uf bi-polar caps in parallel = 200uf could use that also...if you want to keep it really simple...

once you get it setup you will wonder why you did not do it sooner... :twothumbs

K

 

[Canabix]

Ok update time.

Using Circuit 6 (added switch) I have come up with ...Pic
All fits in the little box nicly and canabalized a USB extention cable for the lead, yeap the plastic optics is held in place with plastercine.

Most problems encountered so far are UK electronics shopping.
Maplin stock rubbish, had to go to 2 different stores to get all 4 schottky's. uk.rs-online.com sell everything under the sun but only sell to companys.

• 2x 470uF Low ESR unavailable, In fact I could only get 470uF in 1 format, Hi-Temp(105) high ESR.

• LED, I resorted to using the Drop-In with built in driver to reduce overall cost by 4x.

One would asume the poor capacitors will just not work to full efficency at higher frequencys, as for the driven LED, I do not know what problems that will cause.

But for the moment it's all working fine, cept the Alternator, had to cable tie it to the bike and it's running angle causes massive errosion of the alternators head, 1-2 more 3 hour trips and it will be gone.

 

[znomit]

uk.rs-online.com sell everything under the sun but only sell to companys.

I don't understand how the drop-in reduced costs so much? Regardless you should heatsink it somehow.

I use Farnell when I can't source bits locally.
http://uk.farnell.com/