Hello,
I'm doing a small project and I'm stuck. I want to control brightness of 90v 185mA LED strip with my Arduino Uno. I used bd941 transistor in series with LED strip and I'm sending signal form arduino PWM digital pin to 100om resistor and then to transistor base.(in datasheets for transistor hfe is 40) I was able to fully light up and down my LED but when i tried to modulate signal and lower the brightness of led it was at first barely visible change(brightness is lower but it is barely visible change) and at certain point led diodes start to blink fast and then transistor starts to worm up. I'm using arduino pin at fullest arduinoWrite(pin, 255) and when i want to down brightness i lower number 255 by 25. So after maybe 6 times lowering when number is 100 led strip starts to blink. I could stop at 5 but i didn't accomplish to lower brightness.
I hope someone can help me with this, I'm new at electronics and I'm really bad at reading datasheets for transistors, I'm not even sure that I'm using right one.
I'm doing a small project and I'm stuck. I want to control brightness of 90v 185mA LED strip with my Arduino Uno. I used bd941 transistor in series with LED strip and I'm sending signal form arduino PWM digital pin to 100om resistor and then to transistor base.(in datasheets for transistor hfe is 40) I was able to fully light up and down my LED but when i tried to modulate signal and lower the brightness of led it was at first barely visible change(brightness is lower but it is barely visible change) and at certain point led diodes start to blink fast and then transistor starts to worm up. I'm using arduino pin at fullest arduinoWrite(pin, 255) and when i want to down brightness i lower number 255 by 25. So after maybe 6 times lowering when number is 100 led strip starts to blink. I could stop at 5 but i didn't accomplish to lower brightness.
I hope someone can help me with this, I'm new at electronics and I'm really bad at reading datasheets for transistors, I'm not even sure that I'm using right one.