tlc555

I'm trying to make a circuit that has two timing modes (45 minutes and 1.5 hours). Pin 6&7 need to be connected to different RC circuits. I'm using a SPDT switch to control which RC circuit is connected to pin 6&7 but the RC circuits are connected together at VCC and Gnd. What is the correct way...

Hi, I have an application, where external and internal power is available. I'd like the internal power to be supplied for, approximately, 1 minute after external power is removed. I have been trying to use a TLC555I combined with a relay, but the correct solution alludes me... Can someone...