The first 555 is a slow oscillator, the second one is a fast oscillator. The second one produces the tone in the buzzer (loudspeaker) and the first one makes it go on and off slowly. If you miss out the first 555 it will give a contuinuous tone instead of going on and off repeatedly.
The first 555 is a slow oscillator, the second one is a fast oscillator. The second one produces the tone in the buzzer (loudspeaker) and the first one makes it go on and off slowly. If you miss out the first 555 it will give a contuinuous tone instead of going on and off repeatedly.
Thanx a lot Brian! But, the Buzzer I have already produces sound in beeps(I connected across a DC battery), i.e., it doesnt produce a continuous sound.. So, I think, there is no need of first Timer IC..
Now, what does second timer IC exactly do to produce a sound? I know the working of Timer IC, but cant understand why buzzer needs pulses, if it can be operated on DC(i.e. signal from collector of Second Transistor)?