Calculating times based on starting point

This one is beating me up... I can't find it in search mainly because I don't know what to search for.

I am trying to add 505 minutes to a time. Say I start with 7:30 am - then I need to add 505 to it, but I need to skip a few minutes here and there throughout the day. So - here's how it works on paper:

7:30 - 8:30 = 60
8:40 - 11:30 = 140
12:00 - 2:30 = 150
2:40 - 4:20 = 100
6:10 - 6:55 = 55

See? I need to skip over ten minute periods at 8:30 and 2:30, and thirty minutes at 11:30.

Now I know that 7:30 today plus 505 minutes equals 6:55 tomorrow. But I just can't come up with a formula that will determine that for me. Does anyone have any suggestions? Right now I have a lookup table with precalculated values, but this isn't as elegant a solution as I would like to come up with. Plus, everyone who has a copy of the workbook would have to recalculate their takt times in the lookup table (the 505 minutes) every quarter.

Yes, I'm a n00b when it comes to excel, so take it easy on me please. Thanks a lot for any help.

Sorry, I wasn't clear in my post. I'm skipping the period between 4:20 pm and 6:10 am. So overnight isn't included. Sorry about the miscommunication. I'll go try A1+time now.

Ok, I see that my calculations were wrong, I just did those in my head real quick as an example. But you get my point - somehow I need to add 8:25 to a time but add in the periods that aren't included in the takt time.