You'll need some kind of relay system. In order to drive the louder alarm, it needs the higher voltage supply, and to control it you need to interface to it using a relay or similar arrangement.
Someone with more expertise might be able to suggest a way to push the 3v supply up to 9v, but I'm guessing it would be more trouble than it's worth.
Then, dear Whovian, all you need is to use this voltage (via a 1k resistor perhaps) into the base of an NPN transistor like a BC548 with it's emitter tied to the 0V of the clock and your 9V source. The new load is placed between the +9V and the collector of the transistor.
This assumes that the output is at 0V and rises to 3V when the alarm is going off.
Then, dear Whovian, all you need is to use this voltage (via a 1k resistor perhaps) into the base of an NPN transistor like a BC548 with it's emitter tied to the 0V of the clock and your 9V source. The new load is placed between the +9V and the collector of the transistor.
This assumes that the output is at 0V and rises to 3V when the alarm is going off.
Ever wonder why we say that? I mean most of us do, even with oceans separating us.
I don't think I've ever heard a person say "Then the alarm went on".
Chris