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5-10 watt led circuit needed.

Discussion in 'LEDs and Optoelectronics' started by brittonv, Apr 11, 2015.

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  1. brittonv

    brittonv

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    Apr 11, 2015
    I need a led circuit that will pull between 5 and 10 watts.

    I was going to put a 1.8k resistor with a diode and led... however. Not really sure if that is the right way to go.

    The reason I want this is I have a low power device that doesn't pull enough power to trigger an alert. Please don't focus on the why, it's complicated and long....
     
  2. chopnhack

    chopnhack

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    Apr 28, 2014
  3. brittonv

    brittonv

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    Apr 11, 2015
    Truth, I am not sure...

    But here is some more information... I purchased some aquarium dosing pumps. I also purchased an aquarium controller that uses TRIAC outlets to switch the dosing pumps off and on based on a program.

    The problem is the dosing pump draws so little power that the TRIAC outlets can fail leaving them powered ON as the current draw is so low they can't detect it. In effect it bleeds current to the pump, leaving it in a constant on state, killing the whole aquarium.

    I opened the dosing pump and it is very simple, 2 wires to the motor. I contacted the manufacture who stated that for the TRIAC outlets to function properly the connected device needed to draw a minimum of 5 watts.

    So that is where this post came from. I could just put a high watt Resistor and a fuse, but thought it would be great if I could add an LED as well to 'see' when the pump is on as it turns very slowly and a red LED would be great feature to me.
     
  4. KTW

    KTW

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    Feb 22, 2015
    That sounds like a mismatch between the pump and controller.
    Which triacs are in there now?
    How may watts does the pump operate on?
     
  5. brittonv

    brittonv

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    Apr 11, 2015
    yes it is a mismatch, a mismatch I am looking to solve by increasing the wattage drawn by the dosing pumps.

    All I am looking for is a 120v Circuit design that will allow me to power a LED light and a resistor that will disapate 5-10watts.
     
  6. BobK

    BobK

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    Jan 5, 2010
    Use one of the 7W 120V bulbs used in night lights, and in the old days as Xmas tree lights.

    Bob
     
  7. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    OK, 7W from 120V would require a 1.9k resistor. You could connect a pair of 5W LEDs in inverse parallel in series with this.

    The problem is that the whole thing would be live and thus dangerous. I would recommend you simply power a low wattage lamp as well as the pump. If you use a LED bulb, you may achieve the same effect but in safety.
     
  8. BobK

    BobK

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    I guess I was unclear, that is exactly what I was suggesting.

    Bob
     
  9. brittonv

    brittonv

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    Apr 11, 2015
    Here is what I came up with. Any faults in this circuit? Problem with using a light bulb is in the event of a bulb failure, I no longer use enough power to trigger the TRIAC to turn off potentially. Thus the pump could continue to run and over dose my tank.

    LED Circuit.png
     
    Last edited: Apr 16, 2015
  10. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Bob, we were typing at the same time I think.

    Brittonv, use a LED bulb, they have a very long lifetime. As an alternative, two 25W bulbs in series will likely never burn out.

    The problem your having is almost certainly caused by the snubber network across the triac. I had exactly this problem when driving a small motor. The easy fix is to remove the snubber network. This will make the device unsuitable for switching heavy loads, but won't leak so much power to a light load.
     
  11. brittonv

    brittonv

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    Apr 11, 2015
    So there is nobody that can help validate the circuit design?
     
  12. BobK

    BobK

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    I believe that direct connection of LEDs to mains is not allowed to be discussed on this site.

    Bob
     
  13. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    It's bad because the wiring is live everywhere and because you have no reason not to use a safer alternative (especially around water!)
     
  14. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    My first post in this thread gave you an answer (except I'd change the recommendation to 1W LEDs), and then I recommended something easier, faster and safer (and possibly cheaper). I'm not sure what else you want.

    edit: Oh and I also told you what was likely causing the problem and how to fix it.
     
  15. brittonv

    brittonv

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    Apr 11, 2015
    Steve, I'm am sorry for lashing out.... You are trying to help... so sincerely, Sorry!
     
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