Understanding the flashlight theory

Hi as the name says I'm a n00b.
I came here and looked about for 5 days and got more confused then I gained understanding.
I am trying to I understand the principles and math behind the ability to construct a flashlight that puts out high lumen with minimal power. I'm not asking for people to tell me I'm just asking for advice on where I should start reading on design and the math (optics and electrical) stand point. As I scouted website I found a lot of conflicting info. For you guys this is cake. For a n00b it's like walking into a physics lab with a kindergarden education.. I understand the +/- to load to switch. But conversions and cree and heat sinks and new lighting and omg im lost. Can y'all be kind and not call me names or flame me and just say look here to start. I tried on my own. I have read multiple time over years (mod can verify by searching ip, though I'm also learning up python so it will be random)

Something like this? http://www.flashlight-blog.com/p/how-does-led-work.html

or something else?

CREE and Nichia are popular brands of emitter chips. Lettering indicates generations so for example when you see Nichia 219 B or C... the C is the newest. For CREE an example would be XP-G or XM-L the xml is the newer.

You'll see all kinds of Kelvin numbers indicating the tint color. Higher numbers indicate closer to white called "cool" while lower numbers are headed towards the "warm" direction.

CRI means how well it can accurately portray colors lit by the beam.

Heat sync is like a radiator. As the LED heats up it tends to dim. Heat sync methods are a way of sucking the heat away from the light source and expelling it to the outside of the light.

Hope that at least helps you understand what you are reading at times.

:wave: Noobish. :welcome:

No one should be unkind to you. CPF is a huge resource, and very overwhelming at first.

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~ Chance

Selfbild did some videos about a lot of aspects of flashlights hereh is the first
https://youtu.be/-N0JTHqw0zQ
I hope it will help you. And if you still have some questions after that you can always ask.
Enjoy.

Been here yet: http://www.candlepowerforums.com/vb...nner-s-Guide-to-explain-simple-LED-flashlight ??

I'm a perpetual semi-noob myself and can contribute some generalities. Sorry no great links as you asked.

For highest lumens (total light emitted) the question leads to the most efficient leds and power circuits.
For highest lux (concentration of light focused on a specific area, and the ability to illuminate distant objects) it leads to learning about die size, reflectors, and lenses.

And of course you can have a design that is strong with both.

As for efficiency, in general the newer leds are more efficient than the older ones, and as efficient as leds are, they don't like heat, and their efficiency suffers as they heat up. Too much heat and they break, so heat sinks are an essential part of any design that puts out very much light at all.
Your most efficient led light for most lumens for the least power might be multiple modern leds that are kept cool, and driven to considerably less than their full potential.
But if you want the light to throw far as possible, then multiple leds works against you.
For throw what you want instead is the smallest, brightest led with the biggest reflector or lens to "collimate" the light from "a point" into as close to a parallel tube of light as possible.


On top of that, some of us feel that we see better with lower frequency light that's more towards the "warmer" yellow/orange range and away from the "cooler" bluer tints, but the bluer lights are always more power efficient for putting out more visible light per watt.
But again, some people find that extra visible light of the cool emitters results in more glare and squinting, and less actual seeing.

mbw_151 said:

Been here yet: http://www.candlepowerforums.com/vb...nner-s-Guide-to-explain-simple-LED-flashlight ??

Click to expand...

Yeah, there it is.

Another idea
(As you want to learn by your own)
Read the datasheets - they show most aspects, from electrical to tint to mounting to application recommendations...

Cree offers good Info on that, search f.e. for
Cree xp-g2 datasheet (that's the "small" led), or
Cree xm-L2 datasheet


Just one direct recommendation:
Forget heatsinks.
Led, put on a "thermal mounting plate" - as thick as possible to get heat away from the led - and this in direct contact with Metal body of the light, which thus Acts as "heatsink".
That is actual way to build a high power LED light

Is Noobish even listening ?

It would be nice to know if any of this is in the right direction...

LeanBurn said:

Is Noobish even listening ?

It would be nice to know if any of this is in the right direction...

Click to expand...

He's new to the hobby; probably still has a life. Let's be patient and give him a day or two to get back to us.

~ Chance

Also his first posts will be screened so he may have responded but it not appear yet. This was a frustration I had when starting.

Here's some info as I understand it from one noob to another.

XML and XPG are 2 different platforms.
In terms of progression it is as follows.
XML -> XML2
XPG -> XPG2 -> XPG3

XM series emitters are 5x5mm
XP series emitters are 3.5x3.5mm

XPG and XPL emitters are the same size but XPL's have a much higher lumen output, this is because the light emitting surface is the same size as that of an XML.
XPL's also come in 2 distinct varieties. HI and HD
HI is high intensity, these have a flat lens and project more of their light out sideways. These work well in throwers as 'more light' is 'collected' by the reflector and concentrated into the hotspot.
HD is high density, these have a domed lens as per 'normal' LED's, they work better in floody lights as the light it projected more evenly so 'less light' is 'collected' by the reflector and more exits out of the front 'undirected' creating a brighter spill and a more diffuse, dimmer hotspot.

Hope that's useful for you.

^^ Don't know about OP but it sure helped me.
Thanks!!

No problem. That info came to me when searching how well a nichia would work in a larger reflector thrower. Never did find an answer to that question but I found (and then fact checked) a lot of info about Cree LED's.
A bit more info on that is even though the XPL and XML have the same size emitter on different sized board the reason the XPL will out throw an XML is because the XPL has a smaller dome due to the size constraint of an XP sized footprint. As a result the light is effectively being emitted from a smaller point meaning more of it is in the focal point of the reflector.

^^ Good 101 info.