schematic http://www.perceptiveart.com/Arduino/Clock04_schem.jpg I am making a clock, using 6 rather large 7 segment blue displays. I am wondering 2 things.
1) Do I need a bypass capacitor on the 12V supply for each UDN2981 chip?
2) How can I control the dimming of the whole thing at once? I identified 3 options as potential solutions: A - a transistor at point A (on the schematic), controlled by the Arduino by PWM (which would in turn be controlled by a potentiometer via the Arduino) B - a potentiometer at point B (12V supply) C - some sort of voltage regulator at point B.
3) Any corrections or suggestions to my schematic are welcome.
Any help would be greatly appreciated. Thanks in advance.