Andy,
Thanks for the help. All my components are spec'ed for operation between 3 and 18V. So I should be good from that standpoint. Also all the resistors for the LEDs are sized for 12V. If I did use a regulator I would probably go with 8V, that way as the battery output decreased as it was drained, 8 AAs even close to death should probably still give enough voltage for an 8V regulator to work. If I went with the 8V reg I would either resize the LED resistors or just take the hit in brightness. I know the battery output should be relatively smooth under normal operation, I just wasn't sure about the transient effect on battery voltage the extra current draw from turning on the 40 LEDs all at once would be. Would the supply voltage dip momentarily? Would that screw up the logic ICs? From your post, it sounds like I shouldn't worry about it too much. I was planning on testing the circuit before I made the boards but I haven't received the LEDs in the mail yet and I kind of want to get moving on it. As for as the diode to protect the 555. Should I just place it between ground and the 555? I am exploring Mikebits' suggestion of multiplexing the LEDs. I hadn't though of it before so my board really wasn't laid out to add that functionality. It is creating quite a bit of backwards work for me but it truly is the best solution in my opinion and in Mikebits' too. Anyway, please keep the thoughts coming everyone. Thanks!