Electronics newbie needs help with alarm circuit.

I'm very amateur at electronics. I'd like to construct an alarm that is basically a continuity alarm. It is two alarms in one and each is activated by the computer closing a circuit on a 9 pin serial port. The alarm can be muted by pushing the button, at which point that circuit is earthed through a flasher LED rather than the buzzer. Since the two alarms share the same buzzer, I have added a voltage regulator to it so it always receives the same power whether one or two alarms are active. There are a number of resistors which will need to be added for various components ofcourse. The whole assembly will be contained in and ABS project box and mounted onto a 1 rack unit panel. The flasher LEDs will be inside the box and are only providing a cheap and easy way of creating a flashing effect for the LED ring on the switch. I would also like to include a 0.5 second on 30 second off timer circuit that blips the buzzer as a reminder when muted but I'm not really sure how.

Advice and suggestions much appreciated. I'm sure there are errors in the cct as my knowledge is very limited.

**broken link removed**

edit: here is the switch incase it helps make sense of my diagram. It is an on/on latching push button with separate LED terminals.
**broken link removed**

edit: and the physical layout:
**broken link removed**

I suggest you begin by reading **broken link removed**. The serial port is very limited as to power available. Next try to better explain where you want to go with this project?

Ron