# Thread: Beginner's Guide to explain simple LED flashlight.

1. ## Re: Beginner's Guide to explain simple LED flashlight.

Thanks for this post. If no one minds, I would like to use the diagrams to teach my young'ns. I understand the technology but can't explain it worth a darn.

2. ## Re: Beginner's Guide to explain simple LED flashlight.

We like to share what we learn from here.

3. ## Re: Beginner's Guide to explain simple LED flashlight.

We like to share what we learn from here.
I appreciate all of the knowledge shared here. A lot of the info is over my head but I read it anyway. This post breaks it down to the basic level which makes it a great tool for beginners.

4. ## Re: Beginner's Guide to explain simple LED flashlight.

Thanks for this, it will help me a lot in deciding which flashlight to buy as my very first high quality LED light!

5. ## Re: Beginner's Guide to explain simple LED flashlight.

is there any comparison chart of pwm boards to their efficiency?

6. ## Re: Beginner's Guide to explain simple LED flashlight.

AMC7135 board
http://www.candlepowerforums.com/vb/...eply&p=2405842

Originally Posted by Drewfus2101
1050mA version:

1400mA version:

Pretty good boards, as long as your in they're small voltage range. DX recommends that you stay within 3.6V to 4.5V. I read that is because between 4.6V to 6.0V (which it can take up to 6.0V) it gets very hot. In my testing I used a small fan to keep the board cool so this did not affect me.

These are a great alternative to resistors, even though resistors are cheaper. The best thing to do here is order 20 of the 1400mA version and you can remove each of the black AMC boards and each one you remove will cut down the output current by 350mA. I tested this and it does work.

Where these boards beat resistors is that these give you a semi-regulated output. If you use resistors and alkalines (for example) the flashlight will never be brighter than when you first fire it up. After that, the batteries will start to dim. If you chose your resistor based on the fresh battery voltage, as the batteries start to drain, your output will drop. With these, as long as your voltage stays above about 4.0V you get the full output. The 700mA version should need a lower voltage and the 350mA an even lower voltage. So that semi-regulation is worth the extra money to me. I can't tell you how much time and headache direct drive / resistors / alkalines have caused me.

I definitely love a good boost/buck convertor more than these, but these things are not bad little boards. I thought others could benefit from these numbers.

7. ## Re: Beginner's Guide to explain simple LED flashlight.

The efficiency or brightness of Led will be improved ~30% every year.
Well... not quite.

(The source for the below is Do The Math, an IMO extremely interesting blog that looks at energy and physics from a mathematical perspective. Well worth a read!

The units used below are the lumen [lm], watt [W], and nanometer [nm].)

The theoretical maximal luminous efficacy for any light source, regardless of technology, is 683 lm/W. This would be a monocromatic source emitting at 555 nm ("laser green"), and it would not get warm, no matter how bright it was or how much power it used, since all the supplied power would be converted into useful photons and "beamed away".

For a white light, the theoretical maximal efficacy is lower, since the sensitivity of our eyes gets lower the farther from 555 nm we come, and white light is a mixture of wavelengths between ca 450 nm (blue) and 660 nm (red).

To make a long story short (see the link above for details), a white light source with "ideal efficacy" and a color temperature of 5800 K could reach 310 lm/W maximum (and would have a CRI of 94). At 2800 K, we could reach 370 lm/W (and the CRI would be 87). Again, these would not even get warm, regardless of brightness, since they are 100 % efficient.

Let's look at a modern LED - the Luxeon T. At a reasonable CRI of >80, and a "typical" current of 700 mA, it has a luminous efficacy of around 100 lm/W. That's not that far away from the theoretical maximum!

In fact, at 30 % improvement per year, we would hit the theoretical maximum in only 5 years! 100 [lm] * 1,30^5 = 371 lm!

It's pretty amazing really that we have light sources today whose efficacy can only be doubled twice before we hit the absolute theoretical maximum, regardless of technology!

8. ## Re: Beginner's Guide to explain simple LED flashlight.

thats what I was searching for, thanks

9. ## Re: Beginner's Guide to explain simple LED flashlight.

bitnick,

Thank for the good article, we will learn something about it.
It is my roughly estimation only for beginner understand the concept.

11. ## Re: Beginner's Guide to explain simple LED flashlight.

Thanks for the helpful diagrams and explanation. I'm researching prior to buying a decent LED flashlight to replace the el-cheapo units I have bought in recent years as they have all failed, probably due to "You-get-what-you-pay-for" quality issues. :-)

It would be so nice to have a new flashlight that will last me many years without reliability issues.

12. ## Re: Beginner's Guide to explain simple LED flashlight.

Thank you for putting this information out there. Great overview. I am trying to learn more about creating drivers that are programmable. As I know NOTHING, I have a long way to go

13. ## Re: Beginner's Guide to explain simple LED flashlight.

This is a great post for total beginners like me who have just bought flashlights in the past and now want to start becoming an informed consumer. Thanks

14. ## Re: Beginner's Guide to explain simple LED flashlight.

Chalk this up to a noob observation but just looking at the diagrams you could not only modify but existing lights but build them given the right materials. Thank you Download

15. ## Re: Beginner's Guide to explain simple LED flashlight.

A really useful thread, a lot of terminology on this forum was passing my by and this will help my grasp. Thank you.

16. ## Re: Beginner's Guide to explain simple LED flashlight.

Thanks for all the info really appreciated. Should help me sort things out

17. ## Re: Beginner's Guide to explain simple LED flashlight.

Thanks for the great info, starting to really get into flashlights and this primer really helps.

18. ## Re: Beginner's Guide to explain simple LED flashlight.

This helps out alot. Thank you. Does the housing material matter?

19. ## Re: Beginner's Guide to explain simple LED flashlight.

Thanks for this. It's always good to know the basic workings of things.

20. ## Re: Beginner's Guide to explain simple LED flashlight.

I really like this post .you explain really well in nice way.

21. ## Re: Beginner's Guide to explain simple LED flashlight.

company should give some important and basic things about the usage and the improvement that are to be made when someone is using the lights of these kinds

22. ## Re: Beginner's Guide to explain simple LED flashlight.

Thnaks for sharing,I used flashlights for one year ,but I don't know it very well.

23. ## Re: Beginner's Guide to explain simple LED flashlight.

Thanks for the guide! I bet the senior members of this forum know all of this stuff by heart!

24. ## Re: Beginner's Guide to explain simple LED flashlight.

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
Reflector vs. Optics: Light Loss
http://www.candlepowerforums.com/vb/...ics-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 ~30% every year.
for more details, please take a look:
Commonly Used LED Emitter Index
http://www.candlepowerforums.com/vb/...-Emitter-Index
Bin Coding: Color, Flux and Vf Charts and Links for Popular White LEDs
http://www.candlepowerforums.com/vb/...=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/...light=Heatsink
Heat Management Issues
http://www.candlepowerforums.com/vb/...rent+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.
Driver board list / regulator board list
http://www.candlepowerforums.com/vb/...tor-board-list
Led amperage basic question
http://www.candlepowerforums.com/vb/...rent+regulated
PWM - What is it, How does it work and how to detect it.
http://www.candlepowerforums.com/vb/...&highlight=pwm
Constant Current vs. PWM dimming Revealed
http://www.candlepowerforums.com/vb/...mming-Revealed
(PWM control) AMC7135 Specs Inside **UPDATE**
http://www.candlepowerforums.com/vb/...amc7135+driver

5. Battery - AA, AAA, CR123, Li-ion 18650 .......
Battery Shoot Out
http://www.candlepowerforums.com/vb/...ds-of-Interest
Before jumping to Lithium battery, please see: The dangerous side of batteries
http://www.candlepowerforums.com/vb/...e-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

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

thanks for your information. if I don't have read your article, I will don't know a tiny torch with such specific information. in addition, it is common that a torch with replaceable battery, and there is a kind of torch with non movable battery , you can charge it after the battery runs out, and we can them when we are going to camp. do you think so?

25. ## Re: Beginner's Guide to explain simple LED flashlight.

thanks for you information...

26. ## Re: Beginner's Guide to explain simple LED flashlight.

Amy sunshine.
Thanks for your input, the rechargeable flashlight have extra circuit for recharging the battery.
Just like our cell phone nowadays.

27. ## Re: Beginner's Guide to explain simple LED flashlight.

do you have a flashlight? and where do you usually get it? from a real store or an online shop? and how do you judge a flashlight according to what factors. thank you...

28. ## Re: Beginner's Guide to explain simple LED flashlight.

Amy sunshine,

Sure I own dozens of flashlights. Got them from a real store and an online shop too.
Too many criteria to judge, like, build quality, material used, reliability, battery used, user interface, price..........

For beginner, Please take a look of the below posts, it is good starting.
http://www.candlepowerforums.com/vb/...Me-a-Light-For

http://www.candlepowerforums.com/vb/...-Updated-MK-II

29. ## Re: Beginner's Guide to explain simple LED flashlight.

How do they test the life span of the LED?Some is claimed to be 100000 hours,how to measure it?

30. ## Re: Beginner's Guide to explain simple LED flashlight.

feifei

We have some post discuss like below:
http://www.candlepowerforums.com/vb/...longevity+been

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