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L.E.D. Power supply question HELP!!!

Discussion in 'Electronic Basics' started by Abad, Nov 20, 2003.

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  1. Abad

    Abad Guest

    I wish to make a ring of LED's to put around a camera lens. What woul
    dbe the best way to figure out how much power and how to power this
    ring? Would there be a way to put a dimmer on there as well?

    Any help greatly appreciated!

    Abad
     
  2. Robbie Banks

    Robbie Banks Guest

    This all depends on what power source you have available and the colour of
    LED's you wish to use.

    For example with a 12v supply, you can put 5 red LED's in a series with a 47
    Ohm resistor, thus you could prbably make the ring with 15 or 20 LED's and
    therefore 4 strings. IF you wish a different colour you have to look at the
    forward voltage and work out how many you can put in series together with
    your power source. With 5V you will be limited to either 1 or 2

    I'd personally run it from a transformed power supply to 12v DC and design
    the strings accordingly.
    You probably want to use an astable vibrator of some sort using a 555 timer
    to run the LED's. You can dim this by varying the duty cycle of the
    vibrator. Or, you can place a variable resistor in series with the LED
    strings and change this to dim the LED's

    Hope this helps. But, as they say there are many ways to skin a cat so I'm
    sure there will be other solutions you prefer

    Robbie
     
  3. Is this for macro photography?
    Have you looked at the Nikon adapter that does this? It might give you some
    idea how to proceed, and also I doubt you could build one for less than what
    they cost from a camera shop, unless you are looking for coloured light or
    something odd like that.
     
  4. See URL http://www.photoprojects.net/index8.html

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    ###Got a Question about ELECTRONICS? Check HERE First:###
    http://users.pandora.be/educypedia/electronics/databank.htm
    My email address is whitelisted. *All* email sent to it
    goes directly to the trash unless you add NOSPAM in the
    Subject: line with other stuff. alondra101 <at> hotmail.com
    Don't be ripped off by the big book dealers. Go to the URL
    that will give you a choice and save you money(up to half).
    http://www.everybookstore.com You'll be glad you did!
    Just when you thought you had all this figured out, the gov't
    changed it: http://physics.nist.gov/cuu/Units/binary.html
    @@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@@
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  5. Really bad advice. Pulsing the LEDs while the shutter is open will
    result in an exposure that's incorrect.

    Obviously he won't need red LEDs for a camera.

    --
    @@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@,@@[email protected]@[email protected],@@[email protected]@[email protected]@[email protected]@
    ###Got a Question about ELECTRONICS? Check HERE First:###
    http://users.pandora.be/educypedia/electronics/databank.htm
    My email address is whitelisted. *All* email sent to it
    goes directly to the trash unless you add NOSPAM in the
    Subject: line with other stuff. alondra101 <at> hotmail.com
    Don't be ripped off by the big book dealers. Go to the URL
    that will give you a choice and save you money(up to half).
    http://www.everybookstore.com You'll be glad you did!
    Just when you thought you had all this figured out, the gov't
    changed it: http://physics.nist.gov/cuu/Units/binary.html
    @@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@@
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  6. Louis Bybee

    Louis Bybee Guest

    Bad Link?

    Louis--
    *********************************************
    Remove the two fish in address to respond
     
  7. John G

    John G Guest

    Good Link
     
  8. David Wood

    David Wood Guest

    Check out National Semiconductor's dedicated circuits for powering
    white illumination LEDs. They offer lot's of control and versatility.
     
  9. Louis Bybee

    Louis Bybee Guest

    Works now. Didn't work when I tried it earler.

    Possibly it was busy?

    Thank you.

    Louis--
    *********************************************
    Remove the two fish in address to respond
     
  10. Let's move on from whether or not the link works to comments on the
    contents of the link.



    --
    @@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@,@@[email protected]@[email protected],@@[email protected]@[email protected]@[email protected]@
    ###Got a Question about ELECTRONICS? Check HERE First:###
    http://users.pandora.be/educypedia/electronics/databank.htm
    My email address is whitelisted. *All* email sent to it
    goes directly to the trash unless you add NOSPAM in the
    Subject: line with other stuff. alondra101 <at> hotmail.com
    Don't be ripped off by the big book dealers. Go to the URL
    that will give you a choice and save you money(up to half).
    http://www.everybookstore.com You'll be glad you did!
    Just when you thought you had all this figured out, the gov't
    changed it: http://physics.nist.gov/cuu/Units/binary.html
    @@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@@
     
  11. Robbie Banks

    Robbie Banks Guest

    Not apparent from post if it's a still's camera/video/cctv. Or the app of
    the camera. Lighting, SFX. So all input is valid.

    Cheers
    Robbie
     
  12. I don't know about that. White LED's send out a mixture of blue (from
    the chip) and yellow (from a fluorescent dye in the plastic) light. So
    adding some green, orange and red LEDs may be necessary to get correct
    representation of colours.

    Has anybody ever tried to make a truly white light by mixing different
    LEDs like that?

    In the catalogues I found LEDs with the following wavelengths: 400, 420,
    440, 470, 490, 503, 520, 565, 590, 605, 615, 625, 632, 660 nm. Beyond
    470 nm those would be superbright LEDs. So apart from a gap around 540
    nm (which is unfortunately where the human eye is most sensitive) the
    entire visible spectrum is covered. Interesting would be the range
    between 450-650 nm, which is about the range of the human eye.
     
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