circuit produces the sound of a beeper like the one
in pagers which produces a "beep-beep" sound.
Basically the circuit consists of a 555 timer oscillator
which is turned ON and OFF periodically.
IC(left) oscillates at about 1Hz. The second IC is turned
ON and OFF by the first IC.
The first IC determines how fast the second IC is turned
ON/OFF and second IC determines the tone of the final
By varying the VR1, the changeover rate
can be adjusted. By varying VR2 the tone can be adjusted.
If you know something about electronics, you can try
replacing the 2nd 555 IC circuit with a piezoelectric
buzzer. This saves one IC and associated components
but the buzzer cannot give a loud sound as the speaker
and also its tone cannot be varied.