Basic LED questions Please help me. lol

[SuPpAvIlLiN]

Hey guys. I am just really getting into custom lights and I have a million question still.
#1My first most basic on is how bright is the led its self not in a certin light. For instance How bright is a XM-L? Does it have a default brightness or can the maker have it so it goes as bright as he wants (atleast to its max)

#2-Is the LED and the little cercut board one in the same? Or can the little LED drop be placed on any circut board

 

[Gunner12]

LEDs can be driven at different levels for different output. For example, an XM-L at 100 mA would be dimmer then the smaller XP-C at 500 mA. The XM-L is rated to 3 A though while the Xp-C is rated to 500 mA. They are simply a diode with no other circuitry (LED = Light Emitting Diode), white LEDs are blue LEDs with a yellow phosphorous on them. They don't have any settings, modes, or anything like that. They also don't have much protection, so you can easily kill one by running too much current, voltage, or both through it. Also, LEDs have a fairly narrow range of working voltage, too low and they won't light, too high and they will try to draw too much current (and if you power supply can send that current, then they will burn themselves to death). Because of the lack of protection, you can overdrive the LED for more output, but this is not recommended unless you have a good heatsink to remove the heat.

As said before, the LED is simple the Light Emitting Diode, the light source, the LED can be matched with any driver that sends out the right voltage and current. For example, say I have a driver that takes 3v in and outputs 3-3.7v @ 350 mA. I can attach any high power LED on to that that will take the current and voltage. Luxeon Rebel, Seoul P4, Cree XR-E, XP-C, XP-G, XT-E, XM-L, Luminius SST-50, SBT-90, CST-90, Nichia 219... all those will work on the driver. So yeah, the LED will work on any circuit board as long as the board is outputing the right current and voltage.

Feel free to correct me if I'm misleading or wrong, still learning myself.

 

[SuPpAvIlLiN]

Ok thank you, that is exactly what I was asking. So each LED is pre made to only go so bright,but can be mixed with any Circut board. I now know what question to ask thanks to you, I didnt even know where to start,I think im almost there.
-Is the circut board "The Driver"
-And what makes the driver take 3v? and put out 3-3.7v and what is 350ma.

 

[Thr3Evo]

I have a pretty good deal of CRS syndrome so I tend to keep handy (preferably in my phone for quick access) the manufacturer released PDF for most of the cree emitters. Here is one for the XM-L die you questioned. http://tinyurl.com/8gs4jbf
Read these and you will have more than just a basic knowledge of what these tiny monsters are capable. And once you have an understanding of what the emitter itself is capable of look into any of the AMC7135 based drivers, everyone seems to say they do a good job at "driving" these led's.

What I would recommend to get you started in the "modifying flashlights" department is to do some searches on here for the following basics to get you started.

1. Host
2. Power source
3. Emitter and Reflector depending on what your looking to achieve (flood or throw are main)
4. Driver/Circuit that will extract the power and feed(regulate things) the emitter.
5. and defn. NOT least, a way to keep these emitters at or close to optimal temperature.

Basic and one of the most imp things to remember with the high power led's ...everything needs to be carefully controlled. Current, Temperature, Moisture and Voltage should definitely be considered prior to any purchases.

And speaking of purchases ... keep a close eye on your bank account...YOU HAVE BEEN WARNED lol

 

[hoffmyster86]

yes the 'curcuit board' is the driver.(the electronics on it..).

theres step up (booster) and step down (buck) curcuits, that eather up the volts as in a step up, or step down and or control amps, or volts and amps.

have a read up on the LM317, theyre very simple to rig up. (and there is a dual LM317 curcuit that does amps and volts in step down.)

basically a simple resister 'resists' current flow, the higher it is the more resists the flow of current. a regulator does it in a slightly diferent way by changing voltage to keep the current constant, but thats simplisticly put. (and..there is a varience in current on battery sourced stuff, although its within peramiters usualy, a higher voltage input alows for the varience in out to be acomadated, e.g. a 5v input and a 4volt ourput will only work untill the battery runs low enough and cant allow for the votage rising to keep the amps 'constant')

volts sort of span a wire..surface or what ever substrate (the air in lightning is charged that hi the volts directs the amps to ground) and conects and gives a posative to ground or negative arrangement that lets or forces electrons to 'flow', the more volts the easier the current flows, or more usualy the more current flows. with the simple resister thees a voltage drop accross it (put the meter befor and after as close as posable) and a current that flows, in basic electronics change the volts and the curent changes, i.e. theres a 'fixed' relasionship for that curcuit, ohms law. up the volts the magnetic feild/flux or what ever you'd call it is stronger and more amps are aloud to flow. lower the volts and the electrons find it harder to travel from hole to hole along the wire. thats for DC btw.

add other compoinents like coild capaciters etc, things change, apply a AC current or signal current then thngs are different because the voltage, and there for the current is changing from maximum negative to zero to maximum posative.. its called impedence then (resistance).


in english its electrons flowing to the holes, as in flows from posative to negative poles, in american its holes flowing from negative to posative or some such petty arguement of how you look at it, eather way posatives posative, and negatives negative.. it'll pop if you get those mixed up lol. the 'electricty current' flows from a posative to a negative.

scan the net, theres umpteen peoples interpretasion of what it does, i think the secret is finding the one that suits your way of thinking, but eather way you'll need the basics or you'll be forever backtracking to see wtf they are on about. It's self defeating not to.

 

[ianfield]

The quick answer: power LEDs are usually integral with a ceramic or metal substrate that can be screwed down to an aluminium heatsinking part of the main assembly - the LEDs you find on a PCB are usually soldered in/on and can be unsoldered. This broadly applies to low power LED torches, and almost all equipment front panels with indicators.

The first rule you *MUST OBEY* when connecting up an LED; you have to regulate the current through it *NOT* the voltage across it. The simplest way is a series resistor calculated fron max current indicated on datasheet and the max voltage to be applied(less the LED Vf) this is wasteful as some energy is dissipated as heat in the resistor. There are PWM converter chips you can build a constant current driver, there may also be off the shelf driver modules - at a price!

 

[Gunner12]

Also read up on some basic electronics, kinda like circuits 101. There are a bunch of videos about that online, either recorded from college classes, or short tutorials. Physics 2 videos might also help, since they also teach some basic electrical stuff (voltage, current, resistor, capacitor, inductor).

 

[SuPpAvIlLiN]

Ok, thanks guys, it looks like I have enough here to keep me busy for a while.

 

[SuPpAvIlLiN]

WHat about this, ok, I have a Haiku, say the led burns out, can I un screw the brass led housing out of the reflector and screw in any other led? Will the light work? And what if the led +housing came from a twisty type light and was going into a light with an electronic switch?

 

[Gunner12]

You'll have to desolder and remove the old LED, then resolder a new LED. Make sure to clean the surface the LED sits on and apply thermal paste for the new LED. Very few light probably have a screw in LED, I can't think of one off the top of my head. The modes and stuff are determined by the electronics of the light and not the LED. I'm not sure about the electronic clickie part or how the Haiku is wired up.

The LED would have to have similar characteristics, both optically and electronically to the current one for the swap to work well. Most white and blue LEDs have similar electrical properties, so you'll just have to find one with the right optical properties.

The microcontroller of the driver would have to be programmed and wired up to the electronic clickie for that to work.

 

[ianfield]

You'll have to desolder and remove the old LED, then resolder a new LED. Make sure to clean the surface the LED sits on and apply thermal paste for the new LED. Very few light probably have a screw in LED, I can't think of one off the top of my head. The modes and stuff are determined by the electronics of the light and not the LED. I'm not sure about the electronic clickie part or how the Haiku is wired up.

The LED would have to have similar characteristics, both optically and electronically to the current one for the swap to work well. Most white and blue LEDs have similar electrical properties, so you'll just have to find one with the right optical properties.

The microcontroller of the driver would have to be programmed and wired up to the electronic clickie for that to work.

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For a "star" pattern power LED there should be one or more screws about M3 securing the LED to the flashlight bulkhead (for want of a better word) that also provides the ground connection, the other terminal is a solder pad on top the "star" mounting plate.

CPU heatsink paste is suitable for the joint between the LED & the aluminium mounting - you can also get cheaper white (magnesium oxide/silicon grease) heatsink paste used for power transistors etc in general electronics work - if you're really stuck, you can get away with translucent silicon grease, but don't leave the joint dry!

A well designed electronic LED light should last pretty much forever as the electronic circuit provides the best drive conditions for the LED, these often run on only 2 cells - which only provide sufficient voltage for the LED Vf with the help of a boost converter.

3-cell lights should have a current limiting resistor, in which case the LED should have a decent life expectancy but you're always wasting battery power in the resistor.

The last 3x D-cell light I bought has no resistor, so the upto nearly 1.6V of fresh cells gives the LED a VERY finite life expectancy! To mitigate this as best I could, I used NiMh cells as their slightly lower terminal voltage is at least less harsh on the LED.

As this light was used strapped to the handlebars of a bicycle, it didn't take long for vibration to fatigue and snap the wire from switch to LED. When I replaced this wire I made it a bit longer and coiled a loop in the recess where the LED mounts - the loop relieves stress & the extra length adds at least some resistance to protect the LED.

 

[Gunner12]

Good point, I thought that he meant the LED + star was one big threaded thing. If it is on a star that is secured by screws, then yes, remove the screws, and you should be able to swap the LED out for another one. Gotta look up internal pictures of the McGizmo after work and see how the LED is mounted.

 

[ianfield]

Good point, I thought that he meant the LED + star was one big threaded thing. If it is on a star that is secured by screws, then yes, remove the screws, and you should be able to swap the LED out for another one. Gotta look up internal pictures of the McGizmo after work and see how the LED is mounted.

What I was aiming at covering and probably didn't do as clearly as I'd hoped - is that outright LED failure is fairly rare, if its in a 3-cell light with no current limit resistor and the user continually renews the battery for always ultimate brightness - this will shorten LED life, but it will get conspicuously dimmer before it fizzles out altogether.

An example of sudden failure was given re: the 3x D cell light I used on bicycle handlebars - the vibration broke a wire.

Excepting damage by abuse, a light with an electronic LED driver could easily outlive its owner - any such LED that failed in normal use would most likely be one of the rare cases of faulty manufacture.

 

[Gunner12]

Yeah, LEDs can be very hard if not physically abused. I'd say they are also likely to outlive the driver that supplies them, depending on the driver components and the LED current of course. High power LEDs to have to be heatsinked or they will fry themselves, but even many budget lights have decent heatsinking. McGizmos are also known to be tough and well designed and well built too. So, did you break a light? or just planning a swap/mod/upgrade?

 

[SuPpAvIlLiN]

I was was planing on swaping, And I think I have been using the wrong word, What I mean by LED is the whole assembly, the LED,the wires the threded metal and the battery connection thinger. So say you find another assembly that just happens to fit into another light but the light has a twisty activation and your assembly came from a electronic or clcky, would that work? Does the led assembly know what kind of switch it need? (Im not sure what the whole assembly is called LED,wires,metal parts)

 

[Gunner12]

LED + driver + part of heatsink = pill

To most pills, the switch doesn't matter, twistie, clickie, piston drive, etc. The microcontroller can't tell what kind of switch just from the power pads (the + and - pads on the driver).
Electronic switches are different though. The is a microcontroller (small, cheap, simple computer) on the driver board that changes the modes and stuff. For an electronic clickie, one of the pins of the microcontroller has to be connected somehow to the switch so it can detect when the switch is depressed.

Which light are you talking about with the electronic clickie? Some lights have part of the circuit in the tailcap to change modes, so you'll need both the head and tail for it to work well, or make and program your own switch of those lights.

 

[SuPpAvIlLiN]

Thanks, I have a Haiku with a electronic switch, E series Ti Ku trit switch. I think it is still a clicky? It makes a clicky sound?lol. I am a noob.
Thats another thing E series? Lights are very confusing to me, knives are so simple, Example-Blade,Handle.LOL
PS: That Pill lesson helped BIG time. Big time. Now I can talk. Thank you.

 

[Gunner12]

With a clickie, you press down, feel a click, and let go. imagine a retractable pen. With a electronic clickie, you have to hold it down to activate the switch, imagine a keyboard or other surface mounted switch.

I think the E series switch just means it can fit on Surefire's E series of lights.

Knives can be hard too. The type of steel, handle material, rockwell hardness, butterfly/fixed/folder/assisted opener, half tang, full tang, sharpening stones... etc.

 

[SuPpAvIlLiN]

yea, true, but I have collected knives for years and I am a scholar now,lol. It all seems so simple to me. But there is alot to lern there too.
Back to my torch confusion, how can a clicky work on a pill that is made for a piston? Because the piston pill needs pressure to push the pill itself.
And I dont understand how the clickies work either. like, the batteries are toucheing the pill the whole time,but when you click the tail cap the light turns on? Same goes for the electronic clicky.

 

[Gunner12]

Have you checked out the flashlight wiki(it does need to be updated)? Also, what about general searching (just "switch" might work)?

A switch on a normal light just cuts power or lets power through, just like a toggle switch on a wall. Most drivers only have two pads on the back of them. A positive (+) and a ground (-), those are for power. For example, a computer can't tell what type of keyboard is connected from the power cable alone, you'll need another pad/contact to check the keyboard, in this case, the USB cable. Detecting the communicating with a keyboard is much more complex then that of course but I hope that analogy makes sense (USB cable has two power lines, and two data lines).

A twistie and clicke work by disconnecting or reconnecting the battery from the driver, same with a piston switch in some lights (early McGizmo lights, I might be wrong on this). A twistie is pretty simple. Loosen the bezel, and one or both of the pads on the driver is disconnected, breaking the circuit and turning off the light. With a clickie, the same thing happens. Inside the clickie are little mechanical parts that disconnect or reconnect two metal pieces when you click the switch. It still works by disconnecting or reconnecting the power.

An electronic clickie is a momentary switch. It only lets current flow when it is being held down. There's usually a pad on the bottom of the switch connecting to one side, and a springy piece of metal on the other side. When you press the switch, the springy piece touches the bottom pad and lets current pass through the switch.

With a electronic switch, the power is always connected. There is a microcontroller in the light that detects when the switch is pressed, and reacts accordingly. This controller can also measure how long the switch is being held down, the time between clicks, and also time how long the light is on, and may other functions depending on the program. Some of the newer piston lights are also the same. The piston acts as the springy piece, and a third pad on the driver acts as the bottom pad of the switch.

With most piston lights, I don't think the piston actually moves the driver. Usually the battery sits in the piston, and the outer rim of the piston touches the driver when the piston is pressed down.

It's not magic, just very simple electromechanical things (to an engineer at least).