This entire circuit of beeper cum visual indicator is build and fabricated around two timer ICs and is configured in an astable multivibrator mode. The frequency generated by IC1 is controlled by capacitor C1. The output from pin 3 of IC1 is given to input pin 4 of IC2 and base of voltage amplifier transistor T1 through resistor R4. Flashing light
is connected to collector of switching transistor T2 and grounded through resistor R7.