I'm building a 555 sweeper circuit with 4017's in series triggering various colored 10W LED's for signage. Using a 12V 1A power supply. I thought the 555 and 4017 could handle the 12V no problem, but the LED's are drawing anywhere from 500mA to 900mA through those chips and the 555 is getting very hot. Not only that, but the oscillation seems to either go insanely fast or just freezes no matter what I set the duty cycle. So I'm thinking I should use transistors to handle the higher current draw of the LED's and keep a lower current for the timer circuit part of it. Running at 12V and 500mA to 900mA what would be a good transistor for this application?