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Thread: Id'ing bulbs for acceptable voltage, consequences when wrong

  1. #1
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    Default Id'ing bulbs for acceptable voltage, consequences when wrong

    Ok, I have seen the thread on identifiing emitters, that's a start.
    My problem- Everytime I have seen a new mo-better LED bulb, I decided to try one.
    Many of the bulbs came with a sticker on them with the Q5 (or whatever) and voltage range, altho some don't.
    It was not so hard to keep up with for a while, and I started using a Sharpie to mark the info on some.
    My record keeping is worse than my memory, as I open the lights to change batteries (or gaze at bulb for info), they are mostly naked now.
    I cannot find the stickers, maybe many over-heated and fell off, but some remain.

    That leaves me with 2 questions for anyone in the know:
    1) Do you find that you can ID most bulbs by the emitter type.
    2)By doing so, can you identify what the voltage needs (range) are/is.
    3)Ok I lied, I have 3-- It would seem that using a 3-4 volt rated bulb in a 6-9 volt light would burn out the light very quickly.


    I have one Q5 (says 6-18v) that is very dim, no matter what I use it in. Does this mean it is damaged or just faulty.
    Thanks in advance for any info. I will attempt to do better logging these as I acquire them, is too late for the ones I have.
    And to make the matters just a little worse, I have unscrewed a few of these playing with the different reflectors (size,shapes, etc...)
    Just hoping there is an easy way to test/id just what thse are. Just a newbi with too many hobbies to take it too seriously,
    Thanks...

  2. #2
    *Flashaholic* Gunner12's Avatar
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    Default Re: Id'ing bulbs for acceptable voltage, consequences when wrong

    Most of the LEDs used in lights now are Cree LEDs. Their XR-E, XP-E, and XP-G emitters can all be rated at the Q5 flux (output) bin. These LEDs have between 3-3.7v forward voltage. Forward voltage is the the voltage LED needs at a certain current. Usually batteries are usually below or above the forward voltage of the emitter, so a circuit (driver) is needed to lower or raise the voltage to the appropriate level. The driver also determines the current to the LED and the current determines how bright the LED is. You can't tell what voltage the driver needs just by looking at which LED the light uses. You also can't tell how bright the light will be by what voltages the driver takes.

    For example, there are some powerful boost drivers that push 800 mA to the LED from a 1.5v source. There are also some lower current, say 350 mA, buck drivers that lower voltage to the LED, say from 6-18v to 3.2v for the LED. Assuming we have two identical LEDs. The one attached to the 800 mA boost driver will be brighter then the one driven by the 350 mA buck driver, even though the buck driver takes a much higher voltage.

    The Q5 that seems dim could mean that the driver isn't pushing the LED hard, the LED is being cooked to death, or there's a large amount of resistance somewhere which sucks power away from the LED. It's hard to tell what the problem might be.

    Some drivers can take a short period of running outside of specs, but this is not usually the case. It might be a good time to get into modifying lights. Buy your own drivers and LEDs and swap them in for the broken ones. You'll need a soldering station and basic tools (pliers, screwdrivers, etc.) assuming the lights are too hard to open.

  3. #3
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    Default Re: Id'ing bulbs for acceptable voltage, consequences when wrong

    You could use csshih's "Commonly Used LED Emitter Index" to try to visually identify what emitter it is (XR-E, XP-G, K2 etc), then search for that emitter's data sheet; this should give you a graph of forward current vs forward voltage, eg. if you want to drive it at 700mA, the graph will show a typical forward voltage for this value. The various bins of the emitter (eg. Q5) don't tend to have different voltages/currents, it's just a grading of how much light it gives for said current, and/or it's tint.

    As Gunner said, most torches have drivers of some sort in them, unless it's direct drive or using a simple resistor, so that complicates things.

  4. #4
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    Default Re: Id'ing bulbs for acceptable voltage, consequences when wrong

    Thanks guys, I'll try to put this knowledge to use. I have the tools (pretty much) but the hand dexterity of an ape, I can drive a nail tho (if it's a big one) I had seen the emitter index, and thought maybe I could kinda use that, but without understanding of the electronics (driver/circuit) didn't push it any farther. Then received a few bulbs from kleidomain (sp?) that were labeled 3-4v, then they replied "these were mislabeled, is ok to use up to 18v". I believe I'll limit my flashlight building to more of just assembly of packaged parts, soldering, yes I have done- just on a larger scale than fine electronics. I do appreciated your replies, will prolly just buy my emitter assemblies from Malkoff and the like from here on. At times I really need a reliable light more than the few extra lumens that I could maybe squeeze out.
    Flashlights of today are so much better (and less simple) compared to the lights we had when I was young. Thanks...

  5. #5
    Flashaholic* AnAppleSnail's Avatar
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    Default Re: Id'ing bulbs for acceptable voltage, consequences when wrong

    Quote Originally Posted by JohnG7 View Post
    ...but without understanding of the electronics (driver/circuit) didn't push it any farther. Then received a few bulbs from kleidomain (sp?) that were labeled 3-4v, then they replied "these were mislabeled, is ok to use up to 18v".
    Your question is not about LEDs, but about LED drivers. It sounds like you are trying to identify P60 dropins. In this case, it's going to be quite tough. For what it's worth - an etcher or engraver is GREAT to label dropins. Malkoff does (or used to) use one to write the voltage ranges on his.
    My biggest light-hog is my camera.

  6. #6
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    Default Re: Id'ing bulbs for acceptable voltage, consequences when wrong

    Yes, you are way more right than wrong. I don't know what I don't know. And yes P60 dropins are about 90% of what I've been concentrating on. To really complicate things, I have a box of PentegonLights, some with the large reflector (and of course non-working). I sorta like these lights (the chair-leg style hosts) but finding easy fixes for these to a newbie like me is challenging. This too is where part of my origonal problems listed started. I started disassembling some of the drop-in p60 LED assemblies (and the large reflectors) trying to find stuff that would throw some light, was kinda fun (and IF I had followed your tip on etching/engraving the parts), I might not have got things quite so mixed up. On the bright side (no pun intended) I ended up with some working heads. Since I really don't understand the geometry (don't have a clue ) I have some really bright lights now, but I guess due to the fatter reflector, they all put out lot'sa light- they just don't throw light far. They will light up a room well (I guess spill) but no distance. Did get one of the smaller heads that will throw a beam great, and just a little splash/spill- I dunno the proper terms, but am having fun without wasting huge amounts of $$. With you guys patience and knowledge, I'll be smarter than your average 2 year old golden retriever before long... Thanks Guys. I gotta keep it kinda simple...
    Last edited by JohnG7; 08-09-2012 at 09:47 PM. Reason: keyboard got stupid on me:)

  7. #7
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    Default Re: Id'ing bulbs for acceptable voltage, consequences when wrong

    You are going to have to experiment. I feel your pain, as I have some older lamp assemblies that I have removed the LED/driver from. Start out with low voltage input, and work up from there. I have a light meter so that helps, so when I notice a reasonable output I know I have the correct voltage. You have to go by guessing in a dark room with bounce off the ceiling; a dark bathroom is best. Good luck. In addition to marking the LED/driver, get a light meter if you intend to continue being a flashaholic. A reasonably priced light meter can cost no more than some of the P60 dropin's out there, and you will have fun using one to test out your lights.

    Bill

  8. #8
    *Flashaholic* Gunner12's Avatar
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    Default Re: Id'ing bulbs for acceptable voltage, consequences when wrong

    Usually, larger reflector = more throw, but if the reflector is textured, it would provide a wider and smoother hotspot.

    One thing you could try is swapping reflectors for optics or lenses. Those can throw more then a reflector at the loss of spill light. They will turn the lights into spotlights without much spill beam so it'll be hard to see in your peripheral.

    If you really need throw, you'll probably need to get away from P60 lights and buy something with a large reflector.

    Bullzeyebill has noted one way of testing the drop-in. Slowly ramp up voltage until the drop-in hits a reasonable output, and that should be the lower end of the driver's input voltage. Usually drivers are fine with lower voltages below spec, but will fry at higher ones.

    Also, for many of the drop-ins, the LEDs are mounted on stars with solder pads and many drivers come with wires pre-soldered. All that needs to be done is soldering the right wires to the right pads, applying a bit of thermal paste, or thermal epoxy for a more permanent bond, and attaching the driver to the pill. The driver is usually attached by solder, this is done by bridging the gap between the outer metal ring of the pill and the outer round trace of the driver. The pill is the metal pert that holds both the LED and reflector.

    Good luck with your drop-ins!

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