Discussion in 'The Projects Forum' started by knowtankyou, Mar 17, 2016.

  1. knowtankyou

    Thread Starter Member

    Feb 29, 2016
    if someone unsoldered the on/off pin and put an NPN transistor with Collector on the pin, and the emitter soldered down to the pad of the board could I effectively get PWM control? I would use the input to the buck converter for powering the PWM 555 circuit.
    thanks( i realize I need to regulate the 555 chip power down under 15 V)
  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
    Thats a Lm2596 variable regulator chip, just set the desired voltage and feed that to the 555 circuit.
  3. knowtankyou

    Thread Starter Member

    Feb 29, 2016
    sorry dodgy, i didn't explain the whole picture.
    This is an LED Driver, and I am going to set the current output to a level appropriate for the LED and I want to add PWM dimming to the unit.
    I understand that just adjusting the current level of the LM2596 isn't the best choice because the color can shift when I get down in the 5%-40% light output range.
    My reading seem to indicate setting 600ma for a 750ma rated LED is OK but then I need to start PWM dimming to avoid color shift.
    The question is how to best achieve PWM with the LM2596 board. I hope to not add a Mosfet if I can avoid it.
    thanks and have a great weekend.