help wanted

Discussion in 'The Projects Forum' started by j taylor, Nov 13, 2012.

  1. j taylor

    Thread Starter New Member

    Nov 4, 2012
    Hi i am new to the forum and would like some help with a project i am trying to build , I have four high power led s that i want to run from a 12v battrey however the leds have a forward voltage of 3.5v max at 1000ma , i would like to run them in strings of two connected in seires which means using a buck converter to step the voltage down also i would like to be able to dimm the whole setup using pwm 0% to 100% which i have already built my problem is that i have no idea which buck regulator to use and even less of an idea how to put pwm into a buck regulator or what components to use with the buck regulator to get the best from my power supply any help would be welcome
  2. spinnaker

    AAC Fanatic!

    Oct 29, 2009
  3. DickCappels


    Aug 21, 2008
    I like this circuit. You can change it to 12 volts by doubling the inductor. watt whi...t/1 watt white LED power supply circuit.shtml

    When paralleling the LEDs, make sure the LEDs have equal forward voltage drops. If they aren't equal, they will not share the current equally, but you can improve the current sharing at the cost of efficiency by placing a small resistance in series with each string.
  4. j taylor

    Thread Starter New Member

    Nov 4, 2012
    Hi guys and thanks for your input but not sure these ciruits are quite what i wanted 12 volt from a battrey is just not enough voltage to run four of these leds to there full potential so my thought was to wire them in serise two at a time so each pair only needs 6 volts useing a buck converter to give me six volts at up to 1amp from my 12volt battery but i want to build the buck converter myself and also incorparate a pwm for dimming although i am knew to electronics i can solder and make pcb sand read a schmatic but am not good with the maths so any help would be much appreshated .