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7 LEDS - 4 PWM DRIVERS

Discussion in 'General Electronics Discussion' started by Jgray152, Sep 5, 2016.

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  1. Jgray152

    Jgray152

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    0
    Sep 5, 2016
    I am trying to design a custom LED light used primarily with my Full Spectrum Camcorders.
    [​IMG]

    The sinkpad above can have leds wired in series or individual. I want to build 4 PWM circuits for 3 different LED circuits that will be on the board. 3 PWMS will control 3 separate LED circuits. The Forth PWM will control the brightness of all 7 LEDs as a whole. So you can customize the brightness if UV vs VISIBLE vs IR and then use the forth main pwm to control the overall brightness.

    PWM CIRCUIT 1 = LED Circuit One - 3 IR LEDs 3w ea. 1.3v - 1.6v Fwd voltage (In series)
    PWM CIRCUIT 2 = LED Circuit Two - 3 UV LEDs 3w ea. 3.4v - 3.8v Fwd Voltage (In series)
    PWM CIRCUIT 3 = LED Circuit Three - 1 Green LED 3w ea. 3.3v - 3.9v fwd voltage
    PWM CIRCUIT 4 = Main Brightness Control for all three at same time.
    Battery Powered: 4x 18650 Batteries in Series

    The LEDs I would like to keep at a max of 1w. With all 7 LEDs being used, 7 watts of power im sure is plenty and would also like to keep the heat down. This light I want to last between 5-8+hrs or more depending on brightness. There will be 4 control knobs on the outside of the case a long with buttons to turn of IR, UV and GREEN separately depending on my needs.

    I am a little lost when it comes to the circuit design and need some help as most circuits I see online don't deal with this specific design.

    Please Note: I have been soldering for many years, building very very very simple circuits, nothing with chips like 555 or transistors etc. I have a lot of "why" questions in my head when it comes to figuring out how to wire up these chips and figuring out what capacitors to use or how to drive high power LEDs with a ne555 which can only handle about 200ma from what I read. Maybe I should use a difference chip instead. I don't want to use Arduino

    Any direction would be greatly appreciated!

    If I can figure this out I honestly wouldn't mind paying someone to build a complete circuit with the schematic so I can replicate it as I need.

    Thank you!
    Justin
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,411
    2,779
    Jan 21, 2010
    It sounds overly complex. I would just use 3 PWM circuits.

    Use a microcontroller to multiply the individual brightness by the overall brightness to determine the mark space ratio.

    7W for 5 hours is 35 Wh. That's not a huge amount of power. Would it be operating near any audio recording equipment?
     
  3. Jgray152

    Jgray152

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    Sep 5, 2016
    Yes the camcorders will be recording audio. Might have other recording devices around
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,411
    2,779
    Jan 21, 2010
    Recording audio does not play well with PWM or switch mode power supplies.

    You will have to be very careful about radiated noise out you may have to decide between light and sound.
     
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