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Which is better for led

Discussion in 'General Electronics Discussion' started by mrel, Nov 4, 2019.

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  1. mrel


    Jul 2, 2008

    Have led operates from 10.5 to 12.9 volts and current up to 1.68 amp.

    Should i use 2 . 2 ohm resistor to limit current so don't burn the led, or use current regulator to limit. current.

    If use a current regulator use more power ( run the battery down faster) since the current regulator need power to function.

    If only use 2 . 2 ohm resistor less circuit to build,

    Don't know what wattage the resistor should.

    Enclosed is a circuit for current limit..

    Mrel IMG_20191104_041417.jpg
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    Nov 17, 2011
    Not with your circuit. Power dissipation is (for practical purposes) the same as for a resistor. The IC circuit will give better regulation and better protect the LEDs from overvoltage at the input.
    It depends on the input voltage of your circuit. Power dissipation is: Pdiss = (Vin-Vled)/Iled = (Vin-Vled)²/R
  3. duke37


    Jan 9, 2011
    The leds are specified for voltage and current, perhaps they have a control circuit built in. Red leds can need a voltage of 2V or so and other colours more. There may be several leds connected in series to get up to 10V.

    Leds can be driven using PWM pulse width modulation. Say you have a 24V power supply and rapidly switch it on and off with on time at 50% of the total time then with a resistive load it will appear as a lower voltage source with negligible loss of power.

    You can get buck covertors which will reduce voltage and boost convertors which will increase voltage, They can be over 90% efficient. It depends on what battery you wish to use.
  4. Audioguru


    Sep 24, 2016
    How will you cool your high power LED?
  5. Harald Kapp

    Harald Kapp Moderator Moderator

    Nov 17, 2011
    @jaksonlee : What do you want to tell us? How is this related to the original question? I'm inclined to treat such posts as spam unless you give me agood reason to let it stand.
  6. davenn

    davenn Moderator

    Sep 5, 2009

    It is
    I will delete this post from him but give him a chance to redeem himself
  7. bertus

    bertus Moderator

    Nov 8, 2019

    Do you have a datasheet for the mentioned led?
    The given 1.68 A is a strange value.
    Never use a device on its absolute maximum allowed rating.
    Also the cooling of the led must be garanteed, otherwise the led will have a short life.

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