Dimming/fading a 50w ebay LED with PWM

hey everyone,

so i'm trying dim led (see attached pics).

i have circuit set illustrated led doesn't fade. driver makes loud buzzing noise when using  under 255 pwm, light output stays same. i've tried 220ohm , 1kohm resistor on base same results.

here code i'm using test, i'm sure hardware issue.

this same circuit worked fine on led strip have.

any suggestions?

thanks,

-raul

code: [select]

int ledone = 9;  // pin led attached to
int brightness = 55;    // how bright led is
int fadeamount = 1;    // how many points fade led by


void setup()  {

  pinmode(ledone, output);

}

// loop routine runs on , on again forever:
void loop()  {

  // set brightness of pin 9:
  analogwrite(ledone, brightness);

  // change brightness next time through loop:
  brightness = brightness + fadeamount;

if (brightness == 255){
  delay(5000);
}


  // reverse direction of fading @ ends of fade:
  if (brightness == 55 || brightness == 255) {
    fadeamount = -fadeamount ;
  }     
  // wait 30 milliseconds see dimming effect   
  delay(100);                           
    }


that weird. .

all can think of transistor under full saturation, i'd stick 10k on base of transistor , try.

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