First post - Homebrew Seoul P4.

[marcopolo]

Hi all, nice to meet you!
be gentle - it's my first time.

I ride MTB trail and would like to build a very bright light for my bike!
After reading many posts here on P4's homebrew I was wondering if you could check my shopping list and answer a few questions for me.

Here it is:

Some Seoul P4 u-bin 220Lm emitters (use emitter or star?)
Large heatsink
Couple of 1000mA buckpucks
Reflector/collimators
Batteries
Housing/clamps etc... ....forgotten anything else?

Would these collimator lenses be suitable? they are suspiciously like the 7 segment lenses on the new Lupine Betty light:

http://www.anglia-lighting.com/prod...&opticsFor=Seoul+Semiconductor+&button=Submit

Which beam - the 25deg?

Another question concerning load/regulation. If I use 7 emittters, should I use a 28v battery (charger I might have to make myself) and use just one buckpuck or should I use a 16v battery with 2 buckpucks- 3 series emmiters on one buckpuck and 4 series emitters on the other? Is it less efficent to use 2 buckpucks rather than one?

How would I dim the lights / switch off individual lights?

Many thanks.

Marco.

 

[marcopolo]

I have spent a few hours trawling and have found the answer to one of my questions - on dimming: External pot into buckpuck,

But my other questions, especially the one about sharing 7 emittters across 2 buckpucks or just using one buckpuck at 28v - I have looked and looked and can find no similar post.


Pleeeeeeeese help!!

Marco.

 

[marcopolo]

Bumb. Help. 175 views and no help - is that a record?

Have I asked a stupid question? One where the answer is blindingly obvious? I need educating!

Marco.

 

[NovaNath]

Just registered so i could help you.
Check out this data sheet:
http://www.leddynamics.com/LuxDrive/datasheets/3021-BuckPuck.pdf

I think it's saying that the max output is 32v.

If you want to run 7 emitters at say, 4.5v ea @ 1A
then 7 x 4.5 = 31.5v
Board needs 2v more than the forward voltage pulled by the leds:
33.5v, which excedes the V(out)max, so two boards needed.
Still with me?

By the way, electronics isn't my strong point, so this could be quite wrong.. best to read the data-sheet your self!

1500 lm could be overkill?!

Good luck
Nathan

Edit: Also, be patient when you're asking for help. People quite often don't post so much during the week

 

[TheFunkyMonkey]

Haxe a look at this marcohttp://forums.mtbr.com/showthread.php?t=372269

 

[marcopolo]

Many thanks for the info. 2 buck pucks it is then and i'll use NiMH 16 cells - 22.4v to 19.2V should be enough to do 4 & 3 on 2 buckpucks.

1500 lumins I would not say is overkill on a wide angle lens. Agreed that on a helmet light narrow beam I could get away with 500lm but the stuff I am riding is getting more technical and I dont want the shadows washed out from a high angle headlamp - prefer bar mounts - without having to 'wiggle' my bars to see round the corner!

I've been with someone with 20% overvolted 20W 36deg MR16's which were kicking out 1500 lm and they were perfect for technical trail riding.

Marco.