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The 741 is a versatile device and it can be used in the design of a wide variety of sound-effects generators. This circuit produces a siren. The siren can be used in conjuction with other circuits. The siren can be used as the alarm output of a home or automobile security system. Before discussing the circuit operation, let us see the description and working of 741 IC. An operational amplifier, often referred to as an Op Amp, is a very high gain & high performance amplifier designed to amplify AC and DC signal voltage. As shown in Figure 1 the operational amplifier has two inputs and only one output. One input is called the inverting input and is denoted by a “–” sign. A signal applied to this input appears as an amplified but inverted phase signal at the output. The second input is called a non-inverting input and is denoted by a “+” sign. A the output as an amplified signal which has the same phase as that of the input signal.