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Varying current

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by Gregory, Dec 15, 2014.

  1. Flyback

    Flyback Well-Known Member

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    yes you're right, but as you know, the led string voltage of that is only 22v as you indeed noted.
    I think Gregory has a fixed load, as in the one that Greg posted earlier on in this thread.
    Is load modification a possibility for Greg?
     
  2. ronv

    ronv Well-Known Member Most Helpful Member

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    Since you have an infinite heat sink (the ocean) something like this might work. The FET and sense resistor would need to be mounted to the case, but the circuit is easy.
    If it is likable we can discuss dimming. :D
     

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  3. Flyback

    Flyback Well-Known Member

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    Regarding the ccled circuit above, with vin=42v,and iled=7A, and Vled=30v, As you know we see 75W dissipation in the fet and 5w dissipation in the sense resistor. (as shown in the below schematic). I appreciate that you already know this, and that we must present Greg this circuit in case Greg does not want to lay out a pcb......though that is a fair bit of power there....We possibly hope nobody accidentally switches it on when its on dry land.

    Having said that, at vled=30v, and iled = 7A, there is 210W dissipation from the LEDs alone, so I suppose an extra 75W is not so bad.

    You have to suspect that at these dissipations of the led bank, non sharing of current will creep in and the leds will go bang
     

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  4. dave

    Dave New Member

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  5. tvtech

    tvtech Well-Known Member Most Helpful Member

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    Hi Cicero

    My heart just want's to burst when I see something good coming out of South Africa. Having you here and active and posting makes me proud.

    Me, very Negative :mad:. But I have probably been around the fodder here too long....Eight Years is a long time stuck in the midst of this...

    Elon Musk (South African) and Tesla released this Video that is busy going Viral....

    Warning...strong language.

     
    Last edited: Jan 29, 2015
  6. Flyback

    Flyback Well-Known Member

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    Tvtech, wow, that is awesome, but also, It would be too dangerous to allow on the road.
     
  7. ronv

    ronv Well-Known Member Most Helpful Member

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    Yes, I understand, but I have little hope of him being able to build the switcher.
    The battery voltage will quickly drop from 42 to 37 so in the long run not so bad.
    Yes, I suspect if out of the watter the whole thing would be melted plastic. :woot:
     
  8. Flyback

    Flyback Well-Known Member

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    Youre right, it all depends on whether Gregory can get the PCB done.
    I suspect that firstly Gregory should use one of your linear circuits and just check that that led load doesn't actually blow up when its carrying 7A due to non current sharing between the paralleled led strings.
     
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  9. tvtech

    tvtech Well-Known Member Most Helpful Member

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    So good to see you helping and not asking questions Flyback:)

    Believe in yourself. Always.

    Regards,
    tv
     
  10. tvtech

    tvtech Well-Known Member Most Helpful Member

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    Double post..grrr

    Deleted.
     
  11. Gregory

    Gregory Member

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    FLYBACK could you post the buck lead driver in jpg or PDF as I can not open the file asc. Post 94
    Thank you.
     
  12. Cicero

    Cicero Active Member

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    Gregory...you need to download LTspiceIV. Its a free circuit simulation program, and its damn great! It opens acs files.

    http://www.linear.com/designtools/software/
     
  13. Cicero

    Cicero Active Member

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    Nice to be part of this small community that's so knowledgeable. What's great is that people have different expertise, and levels of experience, so its a fantastic place to learn.

    Haha, what a vid.

    I'm the same as you at times, South Africans like to complain, but can be a patriotic bunch as well at the same time.
     
  14. Flyback

    Flyback Well-Known Member

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    just got to this thread, it has for some reason stopped auto telling me that this post (or any other) has new replies....ill post you the schem.
    -gmail has started putting "watched threads" in the spam folder of gmail, I need to work out how to correct that...ok sorted now, just click "not spam"
     

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    Last edited: Feb 1, 2015
  15. tvtech

    tvtech Well-Known Member Most Helpful Member

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    Heya Cicero

    Stuck here we are. But some great people out there that more or less know our stuff here.

    I am a bit of a rebel here...so don't worry about me. Man on a Mission. That's my way.

    Regards,
    tv
     

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