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Thread: Casio RED Led

  1. #51
    Join Date
    Jun 2009
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    Nebraska
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    168

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    Just ordered 3 samples...

    I'll post when I get them.


  2. #52
    Join Date
    Dec 2010
    Location
    Daytona Beach
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    OK, I got the thing tested with a flexdrive and battery. My question now is:

    I have two "D" cell batteries that put out 3v and jump around with the current from about 3.5W to a max of 5W. Would it be safe to connect Mr Phat to this hookup, WITHOUT a driver, seeing how it can stand much more current than these D's are putting out?
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    ....And, I may have found a host!!!! It's big and it's heavy!

    thanx
    ----------------------------------------
    Peace, the Blob

    Remember! If it works, fiddlewith it till it don't!

  3. #53
    Join Date
    Mar 2007
    Location
    North Iowa
    Posts
    249

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    I wouldn't try that. Those D cells might be able to put out a BIG surge before they pull down.

    HMike

  4. #54
    Join Date
    Dec 2010
    Location
    Daytona Beach
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    16

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    Anything I can put between the D's and the lamp to avoid any surges? A capacitor maybe?
    ----------------------------------------
    Peace, the Blob

    Remember! If it works, fiddlewith it till it don't!

  5. #55
    Join Date
    Jun 2009
    Location
    Nebraska
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    168

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    If happen to have a Farad or two at your disposal, it might work.

    Do you mean 3.5A-5A? Instead of Watts?

    Remember that diodes have ~next to zero ohms resistance when forward biased.

    It would be like short circuiting the batteries. Shorting cells has never been considered a safe practice.

    Get yourself a current limiting resistor network in there, and do some research on the maximum safe discharge current for the cell you're working with.

    You may have to settle for a lower current, get different cells, or you might just have to 'settle' for a driver.

    If you want that LED to last, you'll put a resistor in series with the circuit at the very least!


  6. #56
    Join Date
    Dec 2008
    Location
    Canada
    Posts
    972

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    Quote Originally Posted by Meatball View Post
    If you want that LED to last, you'll put a resistor in series with the circuit at the very least!

    Agreed.... LEDs are currrent devices and must
    have current limiting resistors in series or they
    will suck all the available current and blow...

    The other solution is to us a current limited
    power supply or driver.


    Jerry
    See the LaserBee II and all other LaserBee LPM products here....
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  7. #57
    Join Date
    Jun 2009
    Location
    Nebraska
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    168

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    Quote Originally Posted by lasersbee View Post
    Agreed.... LEDs are currrent devices and must
    have current limiting resistors in series or they
    will suck all the available current and blow...

    The other solution is to us a current limited
    power supply or driver.


    Jerry
    Maybe you can set me straight on this then.

    What is the difference between a current regulated supply and a current limiting supply?

    I don't want a supply that just shuts off when the current limit is reached..


  8. #58
    Join Date
    Dec 2006
    Location
    denver,co
    Posts
    1,078

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    Quote Originally Posted by Hemlock Mike View Post
    It's good to see optics info for this LED. Someone mentioned a driver....
    Look into the driver modules made by TI such as the PTH08T250W
    This small module is a switcher and can take 4.5 to 14 VDC input and put out 0.7 to 3.6 VDC at 50 AMPS !!!!!!!
    They also work good for LD bar assemblies.

    HMike

    Great find! That is a neat little module.

    I have a RGB set of these and the dev kit drivers. Remember that the slug is at + voltage so if you remove it from the tec you need to isolate it from the heat-sink. They get hot, so they need to be well cooled.

    As for powering them, At these currents you really need a switching adjustable current supply. At 10 amps you are going to need a HUGE, HOT, resistor. wasteful and just not a good idea. Unless you just go direct and count on the ESR of the cells to insure they don't destroy themselves ( also a bad idea ).

    These are the drivers that come with the luminus dev kit, well some of them.
    http://www.national.com/an/AN/AN-1793.pdf

    They work well and can be pwm dimmed and or modulated efficiently.

    Hemlock Mike's module would be a great place to start.

    chad


    When the going gets weird, the weird turn pro.


  9. #59
    Join Date
    Dec 2008
    Location
    Canada
    Posts
    972

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    Quote Originally Posted by Meatball View Post
    Maybe you can set me straight on this then.

    What is the difference between a current regulated supply and a current limiting supply?

    I don't want a supply that just shuts off when the current limit is reached..
    You have basically answered your own question...

    A Current regulated supply usually allows you to adjust the regulated
    current and is an electronic circuit with multiple components.

    A current limiting supply is usually preset to a certain current level and
    can be as simple as a single resistor.

    Jerry
    See the LaserBee II and all other LaserBee LPM products here....
    All LaserBee Laser Power Meter Products

    New 3.2Watt RS232/USB LaserBee II LPM REVIEW


    Always in stock and ready to ship....
    Subsidary:-Pharma Electronic Solutions

  10. #60
    Join Date
    Dec 2010
    Location
    Daytona Beach
    Posts
    16

    Default

    @ MB, yeah, I meant Amps, not Watts.
    @ LB, Cool! Got your Laserbee LPM last night! Set it up and it worked great on all my pointers.

    .........Amazing what one can learn just listening to you guys jibber jabber electronically.
    ----------------------------------------
    Peace, the Blob

    Remember! If it works, fiddlewith it till it don't!

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