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PWM setup

Discussion in 'LEDs and Optoelectronics' started by NeilMac, Aug 28, 2018.

  1. BobK

    BobK

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    Jan 5, 2010
    Red LEDs are not 3.2 to 3.4V. The are typically 2.5V.

    Bob
     
  2. NeilMac

    NeilMac

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    Aug 28, 2018
    Their not red, UV-a / Royal blue / Full spectrum. (1W)
     
  3. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Your picture shows red. If you post a picture and something is clearly rendered incorrectly it would help a great deal if you say so.

    My advice about reading the forward voltage still stands. (Also about how you should calculate the string voltage and match it to the driver)
     
  4. NeilMac

    NeilMac

    26
    1
    Aug 28, 2018
    I got my 10W leds (IR850nm) working no problem.

    The 1W leds are still being a pain in the ass, tried three different drivers and incorporating 3-15 leds, best was four seconds of light before flashing. Even tried using just one type in a string.

    [​IMG]
    [​IMG]

    This amount produced the longest activation.
    [​IMG]
     
  5. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    We can do no more until you spend $5 on a cheap multimeter.
     
  6. NeilMac

    NeilMac

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    Aug 28, 2018
    Got a meter..
    33v (bouncing)(analog meter) with 12leds, 4x3 in parallel so the current is max of 1.05-1.14A.
    Still flashing and only the first three rows light up, fourth nothing.

    High Power LED Chip 1W.png
     
  7. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Great, you have a meter

    Now measure the forward voltage of each different type of LED.

    Also, don't put the LEDs in parallel. Odd things can happen.
     
  8. NeilMac

    NeilMac

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    1
    Aug 28, 2018
    So the led current and the driver current out put difference does not matter?
     
  9. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,160
    2,676
    Jan 21, 2010
    Yes it matters a great deal. If you need multiple strings in parallel then you'll need to ensure the current is equally shared. A resistor in each string will help.

    Something that drops a couple of volts should be sufficient. 2W 6.8Ω resistors should work fine (they will drop 2.4V at 350mA).

    So, what is the MEASURED forward voltage of your LEDs?
     
  10. NeilMac

    NeilMac

    26
    1
    Aug 28, 2018
    Haven't gotten back to it, a frustrating several hours this morning mix and matching, roasted Coffee Beans to relax for a bit before I get back to it :)
     
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