i have build this:
but it doesnt quite work as ia expect....
well the problem is at IC1C & D
it was suppose to make a brake so that it will not sound contnous, but the problem is that i only get a delay, i mean that sometimes when i connect the power to it is takes about 20-30 seconds till it starts to sound.
what could be the problem?
o, and at J2 the buzzer is connected.
Pin 8 of IC1 should be at logic low for oscillator to work. Here you have connected it to Vdd. Try connecting it to Vss and see if it solves your problem.