Yes, I would like for the alarm to stay on for a while after the door is opened and after the door is closed, Maybe for five or ten minutes.
The problem with the design of the alarm as it is now is, When the door opens, the alarms sounds off but all you have to do is close the door to stop the alarm because the magnet opens the reed switch on the alarm.
if you need 5 till 10 minutes than i would use a 4060 timer ic instead of a 555
i will post you a shematic today but I am very busy at my work now so it could take a while
Thanks for the schematic. Would it be possible to downgrade the voltage required to something around 3 to 6 volts, because thats around what the alarm uses and I have no idea how to make 16 to 20 other than compiling a bulky mess of D or AA cells?
5 a 6 volt is fine (instead of the 7812 use the 7805) but it will effect the timing so you have to tweek a bit with the outputs or capacitors/resistors
also your relais should be a 5v one
you can make a power supply feeding from the net
transformer, bridge rectifier , capacitor feed it in the 7805 and there you go