Mountain Bike Reviews Forum banner

41 - 60 of 110 Posts

·
Registered
Joined
·
6,656 Posts
HEY HEY ITS HENDO said:
no, although the 20mm base is the same, the emmitter is substantially larger than say the xp-g, and so the reflector or optic wouldn`t fit or be suitable
Substantially larger than the Seoul Z-power P4? Those things are pretty huge.
 

·
A waste of time it is is
Joined
·
4,069 Posts
Curse you matthew.

I've only just finished building an xpg I'm happy with, have more optics on the way. I wasn't even going to go near the Xm-l for atleast 6 months.........

and then you go and post those pics. Can you give some dimensions of those wall shots please? ie, how far from the wall, how wide the beam pattern is
 

·
Registered
Joined
·
1,322 Posts
The view angle is larger in the XM-L than the MC-E. No magic way to focus that.
Without a larger diameter optic or reflector the XM-L should be a flood monster.
No scale on the photos. No mention of distance.:confused:
I appreciate someone taking the time to take pictures and post, but its doubtful that any sub 20mm optic will have any throw at all.
The XM-L will probably just turn out to be an MC-E sized XP-G.;) ,
(yes, without the annoying emitter cross in the beam:p )
 

·
Registered
Joined
·
4,488 Posts
matthewm said:
Something special is in the works. Attached is photos of a single CREE XM-L (low bin) and a four 'undisclosed' optics
Shouldn't tease us like this. :ihih: Do you have an XP-G with say, a regina or CXP, shot at the same spot, running at either 1 or 1.5 A? That would be a help to figure out how best to deploy this LED.

That would let you off the 'time out' step a bit sooner. :D

I'll take 'just' an MC-E with no cross and higher efficacy than an XP-G S2 bin. :thumbsup: The fact that there seem to be workable optics in existence or in the works and far enough along for testing is VERY nice to know. It suggests we shouldn't have to wait :cool: long to know which optics were used.
 

·
Registered
Joined
·
179 Posts
What does 'low thermal resistance 2.5 degC/W' actually mean? Is it an indication of the heat generated by the LED, so when drawing 10W it runs at 25 degrees, or am I completely misinterpreting?
 

·
Registered
Joined
·
744 Posts
JezV said:
What does 'low thermal resistance 2.5 degC/W' actually mean? Is it an indication of the heat generated by the LED, so when drawing 10W it runs at 25 degrees, or am I completely misinterpreting?
Thermal resistance is referring the resistance to transferring heat. The less resistance the better the LED transfers heat to the board. If you want to understand the C/W measurement then look up thermal resistance on Google and read the wiki or something similar.
 

·
Registered
Joined
·
752 Posts
JezV said:
What does 'low thermal resistance 2.5 degC/W' actually mean? Is it an indication of the heat generated by the LED, so when drawing 10W it runs at 25 degrees, or am I completely misinterpreting?
It means there will be a 2.5 degree increase in temperature for every watt of power dissipated across that thermal boundary. In this case they are talking about the boundary between the LED junction and the slug. There will be addition thermal resistances that have to be factored in for the junction between the slug / case / ambient that depend completely on the design of the bike light housing.

So, if the LED is dissipating 10W of power, the LED junction will be 25 degrees warmer than the the slug. You have to factor in the other thermal resistances to calculate the slug temperature based on the ambient air temp and ultimately the LED junction temperature. The absolute max junction temperature is 150 degrees C. But there is also a graph in the data sheet that shows how much lumen output drops as junction temp increases. For example, if you want to keep lumen loss due to heat to 10%, you have to keep the junction temperature below 75 degrees C.
 

·
Registered
Joined
·
1,322 Posts
Thanks for the graphics phb.

I was wondering what they would look like side by side. I was thinking that the emitter would be lower than the MC-E. This might give the Fraen FRC 35 mm reflector some problems. Might have to modify/thin the base some to get the emitter inside the reflector.
Nothing new to the DIY crowd, but the FRC narrow is hard to find. The last time I checked the only people with them in stock was Led-tech.
 

·
Registered
Joined
·
296 Posts
Discussion Starter #60
acezone said:
Welight,
Do you know when the boards will be for sale? im holding back untill i can get some mounted

Thanks ace
I have 5000 starboards inbound, just finishng layout on a 14mm Round
 
41 - 60 of 110 Posts
Top