I am trying to interface six 12v, 5w halogen bulbs with an Arduino using six TIP121 transistors each connected to a PWM output of the Arduino. They should each flicker randomly.
The problem I ran into is that when I connect the TIP array to the Arduino, all lights flicker together (so all have the same brightness at the same time) instead of separately. Its not a code problem, the code works perfectly when I connect small bicycle lamps directly to 5v and the separate PWM pins, I used this code: http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1192693288#6
For the TIP array I used the Tom Igoe example at http://itp.nyu.edu/physcomp/Tutorials/HighCurrentLoads
and multiplied it by six like in the attached image (only three shown but you get the idea)
Now is the question, what am I doing wrong?
Thanks for all help and advice!