Hello:

Im making a shift light using a comparator, multivibrator, and displayer. My question is on the breadboard, can i have the topmost rail be my 12V supply and the rail below that be my 5V supply? i checked with my dmm to make sure they are independent but the dmm made a beeping sound. personally i like my power rails to be the top 2 and use the bottom 2 for grounds. is this okay?

also, i have some 2x2.5mm clear leds and i was wondering if the line represents the cathode or anode?

thank you
tron

 

What kind of scale was the DVM on? The basic question is OK, you can have two voltage rails right next to each other, but the beeping bothers me.