Beginner's Guide to explain simple LED flashlight.

[download]

Here is a "Beginner's Guide" to explain simple LED flashlight concepts.
To show how it works.

1. Reflector or Lens - used to control beam pattern, change angle of projection.
The reflector profile is the most important aspect in if the beam if tightly focussed or spread out to give flood light. Deep reflectors typically create a tight spot and shallower reflectors a flood beam. The reflector surface finish then goes towards smoothing out the beam (using a textured surface) or reducing losses (with a mirror finish) but potentially having artefacts in the beam.
Flashlight Beam Patterns
http://www.youtube.com/watch?v=f4L1uIcbalQ#t=43
Reflector vs. Optics: Light Loss
http://www.candlepowerforums.com/vb/showthread.php?151836-Reflector-vs-Optics-Light-Loss


2. LED - Light-emitting diode, the modern Led is much brighter than Incan bulb and life span is much longer too. The efficiency or brightness of Led will be improved every year.
for more details, please take a look:
Commonly Used LED Emitter Index
http://www.candlepowerforums.com/vb/showthread.php?270419-Commonly-Used-LED-Emitter-Index
Bin Coding: Color, Flux and Vf Charts and Links for Popular White LEDs
http://www.candlepowerforums.com/vb...or-Popular-White-LEDs&highlight=color+binning


3. Heatsink - Cooling is required to remove the waste heat produced by Led. Consequent heating according to workload.
Brighter = Hotter. Nowaday the metal body of flashlight use as heatsink.
easy explanation asked for aluminium/Copper/silver, pls
http://www.candlepowerforums.com/vb...luminium-Copper-silver-pls&highlight=Heatsink
Heat Management Issues
http://www.candlepowerforums.com/vb...Management-Issues&highlight=current+regulated


4. Electronic Driver - control the power and signal to led.
The driver play a very important role here, because the led need ~3-4V only, but the battery capacity will drop according to life.
The driver can control the brightness by varing by current (or PWM)
eg. 1.5V AA battery boost driver (step-up) to ~3V to Led. or 2x Li-ion 8.4V battery buck driver (Step-down) to ~3V to Led.
eg. 3 diffenent power level - High, middle, low.
The basics of LED drivers
http://www.candlepowerforums.com/vb/showthread.php?444096-The-basics-of-LED-drivers
Driver board list / regulator board list
http://www.candlepowerforums.com/vb/showthread.php?188227-Driver-board-list-regulator-board-list
Led amperage basic question
http://www.candlepowerforums.com/vb...ge-basic-question&highlight=current+regulated
PWM - What is it, How does it work and how to detect it.
http://www.candlepowerforums.com/vb...es-it-work-and-how-to-detect-it&highlight=pwm
Constant Current vs. PWM dimming Revealed
http://www.candlepowerforums.com/vb/showthread.php?70073-Constant-Current-vs-PWM-dimming-Revealed
(PWM control) AMC7135 Specs Inside **UPDATE**
http://www.candlepowerforums.com/vb...cs-Inside-**UPDATE**&highlight=amc7135+driver


5. Battery - AA, AAA, CR123, Li-ion 18650 .......
Battery Shoot Out
http://www.candlepowerforums.com/vb...ronics-Batteries-Included-Threads-of-Interest
Before jumping to Lithium battery, please see: The dangerous side of batteries
http://www.candlepowerforums.com/vb...d-Close-Calls-The-dangerous-side-of-batteries


6. Switch - Control On and OFF, change power level
Forward Clicky:
- light comes on before it clicks
- momentary on (when the light is OFF you can half press the switch to flash the light ON)
- you cannot use the switch to change mode (in certain multi-mode lights) without completely turning off the light
Reverse Clicky:
- light come on after it clicks
- momentary off (when the light is ON you can half press the switch to momentarily turn the light OFF)
- you can use the switch to change modes (in certain multi-mode lights) while the light is turned on
Twisties:
- Turn the of head or tailcap, like MiniMag


Useful Link:
Simple guide to using a DMM for measurements
http://www.candlepowerforums.com/vb...-Simple-guide-to-using-a-DMM-for-measurements
Please remind me if anything can explain things more effectively. Thanks!

 

[shelm]

i think you have got the basics right, you seem to have a clear understanding as a beginner.
so what's your question please?

 

[KILLER_K]

Good job and this will help people. I like it when it is very simple and easy on the eyes.


He is just adding it to help others out. Plus allowing others to add stuff to the help section of it.

Here is a "Beginner's Guide" to explain simple LED flashlight concepts.
To show how it works.

i think you have got the basics right, you seem to have a clear understanding as a beginner.
so what's your question please?

 

[subwoofer]

Nice looking diagram.

A couple of minor things come to mind:


In the LED section I would not compare an LED to a CPU. If anything the better computer analogy would be to compare the LED to the screen. The LED is the output device not the controlling device.


Reflectors and if they are smooth or textured are not the only factors affecting the beam. The reflector profile is the most important aspect in if the beam if tightly focussed or spread out to give flood light. Deep reflectors typically create a tight spot and shallower reflectors a flood beam. The reflector surface finish then goes towards smoothing out the beam (using a textured surface) or reducing losses (with a mirror finish) but potentially having artefacts in the beam.

The Aspheric lens creates a great deal of loss of output as it typically focuses only the directly emitted light and cannot meaningfully include light collected by a reflector. The tight pencil beam is fun and light-sabre like but is of little practical use.

Just an initial reaction. Nice idea for new CPFers to find.

 

[subwoofer]

Oh, one other thing, the reverse vs forward clicky thread you link to is a bit confused why not simply say:

Forward Clicky:
- light comes on before it clicks
- momentary on (when the light is OFF you can half press the switch to flash the light ON)
- you cannot use the switch to change mode (in certain multi-mode lights) without completely turning off the light
Reverse Clicky:
- light come on after it clicks
- momentary off (when the light is ON you can half press the switch to momentarily turn the light OFF)
- you can use the switch to change modes (in certain multi-mode lights) while the light is turned on

 

[download]

When I first saw the Led flashlight, I wanted to find how it works, but no a single post to show in simple way.
That is the reason I want to make it for a long time. Especially here CPF have millions useful posts can tell the story.

i think you have got the basics right, you seem to have a clear understanding as a beginner.
so what's your question please?

 

[jabe1]

When I first saw the Led flashlight, I wanted to find how it works, but no a single post to show in simple way.
That is the reason I want to make it for a long time. Especially here CPF have millions useful posts can tell the story.

I think Shelm missed your join date, post count, and doesn't know your M@g modding history.

Nice job, you show the basics very clearly. I do understand the CPU comment, both gain efficiency at about the same rate over time.

 

[Norm]

I've made this a sticky.

Norm

 

[download]

KILLER_K, subwoofer & jabe1,

Thanks for your input.
Hope we will make it even better.

 

[Obijuan Kenobe]

Is it something to illustrate how the body of the light is used as the negative path?

obi

 

[download]

Picture added,

Is it something to illustrate how the body of the light is used as the negative path?

obi

 

[jabe1]

Under the Electronic Driver designation, note that an LEDs intensity is varied by current (or PWM) and not voltage.

 

[AZPops]

Nice! Thanks for taking the time to do this!

 

[T-3]

Very nice of you to take the time to post this. Helps broaden the understanding of someone like myself who lurks here once in a while!

 

[erikesp]

This is great for those of us new to this hobby. Great visual aid helps me quickly understand the relationship between all components. Thanks for posting .

 

[Mid Atlantic]

Thanks big help

 

[stevethumb21]

That was surely a big help ! I was teaching my kids the other day and got a question about LED flashlights. I searched all over the net didint find anything easy to grasp. Got to your blog and I found the wanted piece of wisdom. Thanks again. Keep sharing .

 

[ericabrinyte]

I like your diagram, it helps a lot for a rookie like me:nana:

 

[filb]

Fantastic. Well done. Easy to understand for us new to the LED flashlight building/modding

Thank You

 

[Lomandor]

I've made this a sticky.

Norm

What is a sticky? Is it a cpf function that allows me to easily bring this page up for reference? Cheers.