I have the above circuit roughed out and seems to work but have problems with the Q2 transistor blowing.
the circuit is powered by 12V and a sounder circuit connected to H3.
1.5v is used to turn on the Darlington pair which in turn powers up the timer circuit.
Pin 3 of U1 gets triggered and then makes alarm sound for set time.
Is the Darlington pair correct or any better way of doing it.
I can get circuits working but im no electronics engineer but just need a helping hand.