Help: what IC or transistor can i used to drive a 10+ LED and used PWM?
can i use 74hc595 or transistor BC547?
There is a library called ShiftPWM that allows you to do PWM in a sense manually over 595 shift registers. It keeps the Arduino awfully busy beacuse it has to continuously update the shift registers at high speed to get the PWM effect.http://www.elcojacobs.com/shiftpwm/
I still think a dedicated chip like the TI TLC5940 is the best choice. It removes both the electrical load and the computation overhead from the Arduino. They are fairly inexpensive on eBay. I got mine from a seller with a name like "hitechtools" and he was very, very professional and shipped fast.http://www.arduino.cc/playground/learning/TLC5940