Page 3 of 5 FirstFirst 1 2 3 4 5 LastLast
Results 21 to 30 of 48

Thread: driving your LED(No resistors allowed)? Read this

  1. #21

    Default

    So to make sure you are giving a constant current (brightness) the driver will change the voltage to give what the LED wants. That's why a III on a "V" setting works, or a III on the K2, etc...
    ONLY on downconversion of voltage. Not upconversion. That requires a circuit called a charge pump and from what I know they are not built into a buckpuck, a CF board, or Ultra's board.

    Don't try to simplify this for people. You will get their LED's fried.

    If you take a Crystal Focus board, boot it up and power on with a luxeon V. Then hit the ignition switch again (powering down the blade, but the board is still alive) replace with a red luxeon III, and power on... the LED will fry.

    Don't do it to prove me wrong, you will lose your LED.

    Why?

    Because when Erv' made the CF board, he did build it to regulate current YES. But.... the way he did it is on first power on it detects and sets the required voltage for THAT LED to hit the requested current value in the file. If you "hot swap" the LED's and re-ignite the blade, then your CF board will go straight back to the voltage it just detected before to hit that 1 amp value... 6.85v on a Lux III. Which fries it. The work around is you MUST reset Erv's board when you swap an LED.

    A buckpuck will work for hot swap. But it works differently. Just like you have assumed, it drives entirely based on current and it detects each time. Not on the first boot like a CF board.

    Now for the ultra board? I really don't know what it would do. It depends on how it's built. I will ASSUME that since it has a "setting" for luxeon V that it will go for an average current for an LED with that high forward voltage. But it could still go either way based on how Alex designed it.

    So short story... don't simplify it too much for people. You cannot leave some parts out or some LED's will get fried. You can't leave out a low voltage input with a high end board will result in a dimmer LED. You'll then get all kinds of questions asking why that's going on.
    Edwin Tracy (Eandori)

    - Official Plecter Labs USA station for repairs and firmware upgrades, Ultrasound soon!
    - Occasional completed Lightsabers for sale there!

  2. #22

    Default

    An LED is a diode...it has a resistance. A resistance is volts per ampere.
    Carefull with that statement...

    An LED is NOT the same thing as a resistor. A resistor has resistance just like a diode yes. But a resistor is totally linear response. Take a 1 Ohm, apply 1v across it and you get 1amp. Give it 5v and you get 5amps. Give it 7v and you get 7amps. Etc. Linear.

    A Diode is not the same. They don't conduct current until their forward voltage is met. Then their "resistance" drops off very fast. Not linearly at all. I even drew up some graphs to illustrate this but I don't have a working online storage to upload them to ATM.

    Novastar made a big post talking about using LED's without a resistor. While that can work, it's easy to destroy your LED. It's NOT a resistor, and it does NOT act the same way. If you really know what you are doing... go for it. If you don't, then make sure you learn basic electronics or be willing to risk your Luxeons.
    Edwin Tracy (Eandori)

    - Official Plecter Labs USA station for repairs and firmware upgrades, Ultrasound soon!
    - Occasional completed Lightsabers for sale there!

  3. #23
    Council Member
    Jedi Council Member
    xwingband's Avatar
    Join Date
    Nov 2005
    Location
    The training simulators, duh!
    Posts
    5,899

    Default

    Eandori, I understand but you're complicating it and I think we can simplify it so people at least grasp it.

    I wasn't saying anything about hooking up a lux III on a board with a setting for lux V. Yeah that will fry the LED.

    NOOOO!!!! Thereis not a driver in the world that will have you set up a voltage. That's what I'm getting at. You'll set it at the amperage and the driver gives it what it wants.

    Yes, hook a V up to a CF then go to a III and it'll fry. That's a by product of the CF not a driver. Change the situation to any other driver and that won't happen... like Yoda was telling people that they could run their V on other settings to be brighter.

    Everyone was like, "Doesn't that send less voltage?" No... it sends what it wants at that current.

    Like this:
    ONLY on downconversion of voltage. Not upconversion. That requires a circuit called a charge pump and from what I know they are not built into a buckpuck, a CF board, or Ultra's board.

    Don't try to simplify this for people. You will get their LED's fried.


    No one needs to know this... a micropuck does up conversion. So I didn't explain every technicality... no one will fry an LED because I told them to to use a V setting. Why? Because NO LED driver sets the voltage before hand.

    So sure I didn't explain avalanche fall of a diode. Most people can follow the volts per amps of an ohm to realize that you can't send a fixed voltage... because even though I didn't state it you have to accept that the voltage is uncertain or even dynamic if you see it depends on something else.

    I'm firmly with Novastar to say *within reason*. I'm talking about the volts of the LED anyway. For now I'm ignoring batteries with the qualifier that you have "enough" and within reason (not above what your driver can handle).

    So maybe my title is incorrect, but I wanted to get at the LED only to combat a lot of absurd posts that could done away with if what a driver does for the LED is understood. It's like the misnomer of Corbin's board as a "3W driver"... it leads people to think it'll only work for a III and the other misinformation that III=3W (Red III anyone? 6W K2's?etc...).
    Last edited by xwingband; 02-22-2008 at 06:07 AM. Reason: formatting
    RED LEADER Standing by!

  4. #24

    Default

    I think mostly we are agreeing with each other, but I would definitely like to see us both using the same terminology.

    NOOOO!!!! Thereis not a driver in the world that will have you set up a voltage. That's what I'm getting at. You'll set it at the amperage and the driver gives it what it wants.

    Yes, hook a V up to a CF then go to a III and it'll fry. That's a by product of the CF not a driver. Change the situation to any other driver and that won't happen... like Yoda was telling people that they could run their V on other settings to be brighter.
    Actually, that is exactly how CF drives an LED. From what Erv' directly told me, it senses current on the first boot, records the voltage at that current, then from that point on powers up to that voltage. I think it's done that way for reasons of timing. It takes time to power up his board to the requested current in the config file. So rather then "detecting" that with each blade power on, he simply does it just the first ignition after reset.

    Is a buckpuck (sold on this website) different then a micropuck? I'll have to go look at the specs for those, but I was not aware they are built with a charge pump for voltage up-conversion. I know Erv's board does not have that. He directly told me.

    I'm firmly with Novastar to say *within reason*. I'm talking about the volts of the LED anyway. For now I'm ignoring batteries with the qualifier that you have "enough" and within reason (not above what your driver can handle).
    This is exactly the problem. You want to have your cake and eat it too. *within reason* would require that the user you are informing has some basis of understanding. They know what is reasonable. One cannot stay within reason, when they don't know what truely would be reasonable.

    Somebody that does not understand how an LED works, how a resistor works, Ohm's law, and how batteries work like you, me and Novastar will probably NOT be very good at doing something "within reason."

    If I was trying to adjust the timing of my cars engine, and barely understood how the engine worked, how could I ever do something "within reason?"
    Edwin Tracy (Eandori)

    - Official Plecter Labs USA station for repairs and firmware upgrades, Ultrasound soon!
    - Occasional completed Lightsabers for sale there!

  5. #25

    Default

    Here is the PDF for a micropuck: http://www.leddynamics.com/LuxDrive/...-MicroPuck.pdf

    Here is the PDF for a buckpuck: http://www.leddynamics.com/LuxDrive/...1-BuckPuck.pdf

    You mentioned the micropuck does voltage up conversion. That seems true, but only to a point. It says on the datasheet that the maximum power is 1.5w
    Absolute Maximum Ratings
    Input Voltage. . . . . . . . . . . . . . . 3.0V 2 DC
    Output Voltage. . . . . . . . . . . . . . 8.0V 2 DC
    Output Power . . . . . . . . . . . . . . . 1.5W
    With a max power output of 1.5w, and a driven current of 350mA, that gives a maximum upconverted voltage of 4.29v. I don't see that called out on the specification for minipucks, but it must be true if the reported maximums are correct. Driving a Luxeon V seems way out of range for a minipuck from what I see.

    I just even did a quick test with my power supply and my green lux V. At about 5v, the LED was allowing about 300mA to flow. That's right about 1.5watts. So based on specs on the datasheet, I would expect either the minipuck to drive the lux V at 300mA at 5v, or if there is no limiter it will be overdriving itself (running beyond the listed max spec.) It's important to note something like that so sabersmiths don't buy components they can't use or overdrive their stuff without knowing it.

    For the BuckPuck, this is what I see in the specification about upconversion. (page 3)
    Fixed Current Drive

    The fixed output versions of the 3021 are designed to supply their rated current to one or more LED junctions. For example, a 350 mA rated unit will drive up to six Luxeon* I LEDs connected in series. Due to the nature of the buck regulator, the input voltage must always be higher then the total forward voltage drop of the LED junction(s) connected in series (2.0V for DC models, ~4.0V for AC models).
    Quick note, a luxeon V at 1 amp is probably around 7v forward on the LED. So your buckpuck driving it would require a minimum battery voltage of 9v while under load to hit that 1 amp on the Lux V.

    So it's verified. Buckpuck does not upconvert, micropuck does... but to a small limit.
    Last edited by Eandori; 02-22-2008 at 12:20 PM.
    Edwin Tracy (Eandori)

    - Official Plecter Labs USA station for repairs and firmware upgrades, Ultrasound soon!
    - Occasional completed Lightsabers for sale there!

  6. #26
    Council Member
    Jedi Council Member
    xwingband's Avatar
    Join Date
    Nov 2005
    Location
    The training simulators, duh!
    Posts
    5,899

    Default

    Yup, I think we're on the same page, just differing on how much is "just enough knowledge to be dangerous". LOL

    I'd simply like for a person to be able to look at a few numbers and be able to solve the "will this work?" question.

    I don't think it's a horrible leap to look for the typical forward voltage of the LED, the max voltage your driver can handle, and what amperage the LED wants. From there you should be able to answer some basic questions.
    RED LEADER Standing by!

  7. #27

    Default

    Now that we have a huge a convoluted thread about this....

    Perhaps we should email back and forth, come up with a condensed version of what is written here and repost/sticky it.
    Edwin Tracy (Eandori)

    - Official Plecter Labs USA station for repairs and firmware upgrades, Ultrasound soon!
    - Occasional completed Lightsabers for sale there!

  8. #28
    Council Member Novastar's Avatar
    Join Date
    Mar 2007
    Location
    San Jose / San Francisco, CA
    Posts
    4,082

    Default

    Aww MAAAAAN!!

    You guys went all Angry Video Game Nerd on the thread... lol!!

    Sorry to say, Edwin, but... X HAS YOU ON THIS ONE!! If you over-complicate it for the basic users, the repetitive current questions will continue to pour in. If people are told to try to match the LED current and fwd v as best as they can... that is safe and "within reason".

    I even pointed out that giving a Lux III Red-O like 7.2v is just plain ridiculous, and if you're not doing a driver, it's just LED homicide, hahahahh.

    Maybe the Bard's advice here (Hamlet's advice to the troupe of players he encounters in Hamlet... which is really Bill Shake speaking out through his own text):

    "Suit the word to the action, action to the word."

    ************MODIFIED FOR LED NERDS:************

    "Suit the LED to the current, current to the LED."

    or...

    "To LED... or not to LED... that is the question!" hahahaha

    'Nuff said.

    ~~ GREYTALE NOVASTAR (Writer, Director, Choreographer, Sound Designer, Actor, Saber Designer, Vocal Artist)
    ~~ Balance of Power, EP I: "Into The Lion's Den"
    ~~ Balance of Power, EP II: "Ashes of The Phoenix"
    ~~ The Crystal Focus Sound CD Compendiums... are HERE! ~~
    ~~ Nova & Caine's Staged Combat System... comin' SOON!
    ~~ Crystal Focus Wiring Guide

  9. #29

    Default

    I don't care if "X-wins", I'm not trying to "win" a debate and I never was trying to "win" a debate.

    I wanted to help people without years of experience and training in electronics build better sabers. That's my goal. I have a steady job, a good family. I don't need to win debates on a message board to boost my ego. That's not what it's about.

    The facts stand and everything I said in this thread is 100% correct. If you take Xwings earlier comments then you will have people frying LED's and wondering why their setup is getting dim on a board that was "supposed" to keep it bright.

    Sorry Novastar, but that's why there's an entire degree focused to the study of electronics. Because sometimes you CAN'T simplify it without throwing out needed details.
    Edwin Tracy (Eandori)

    - Official Plecter Labs USA station for repairs and firmware upgrades, Ultrasound soon!
    - Occasional completed Lightsabers for sale there!

  10. #30
    Council Member Novastar's Avatar
    Join Date
    Mar 2007
    Location
    San Jose / San Francisco, CA
    Posts
    4,082

    Default

    I was speaking mainly in jest, but... I'm not all about any egos here.

    I am not saying nor did I ever that you weren't 100% correct. I think X-wing also agrees that the facts are the facts...

    I just think perspective can be important, especially when many saber builders... simply do not have the degree, resources, tools, experience, and/or "troubleshooting/repair order of operations skills" that you might have from your extensive degrees and line of work.

    Anyhow... I do understand what you mean... if someone asked me to just "simplify how to put together BOP I or II"... I don't know how short I could keep the descriptions... but I do believe it is possible for me to tell people in a BASIC way... "here's the general idea".

    But yes... the "uber" folks such as you or X-Wing or whomever else will CERTAINLY be working with the details, as THAT is what separates the designers from the DIY "just for fun" folks.

    [begin humor mode] I mean, egos? Come on. Maybe some people think that sabers make them cool. Whatever. They're not cool. You think I'm cool? I'm not cool. Look at me. I've got a flubbin' sink tube in my hand, I'm tryin' to be a wannabe jedi. That's not cool. You want cool? Oh look, I'm waving it around with a stick O' light shoved into it and postin' videos in the dark on youtube. I feel cool, just like an idiot with a fistful of dooku. [end humor mode]

    *sigh* hehheheh. Alright, it's not that funny. I can't be funny ALL of the time. Well... unless I'm naked. That'd be funny. Well... sort of.

    Just not in BOP III. :O
    ~~ GREYTALE NOVASTAR (Writer, Director, Choreographer, Sound Designer, Actor, Saber Designer, Vocal Artist)
    ~~ Balance of Power, EP I: "Into The Lion's Den"
    ~~ Balance of Power, EP II: "Ashes of The Phoenix"
    ~~ The Crystal Focus Sound CD Compendiums... are HERE! ~~
    ~~ Nova & Caine's Staged Combat System... comin' SOON!
    ~~ Crystal Focus Wiring Guide

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •