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This active audio audio system use three TDA2052 chips and 5 speakers ( one woofer, two tweeters and two midranges ) .For this TDA2052 active audio system we need dual 20 volts power supply and five volts supply for the stand by function.To the input of the every audio IC chip is placed an audio filter for filtering the audio signal for used speakers ( low pass for woofer , high pass for midranges and tweeters ) Active Audio System Circuit Diagram The subwoofer plays the 20 to 300 Hz frequency range, while the remaining 300 Hz to 20KHz are sent to two separate channels with stereo effect.If one of the amplifier is affected by clipping distortion the others amplifiers are not affected .

Many of our costly appliances require three-phase AC supply for operation. Failure of any of the phases makes the appliance prone to erratic functioning and may even lead to failure. Hence it is of paramount importance to monitor the availability of the three-phase supply and switch off the appliance in the event of failure of one or two phases. The power to the appliance should resume with the availability of all phases of the supply with certain time delay in order to avoid surges and momentary fluctuations. The complete circuit of a threephase appliance protector is described here. It requires three-phase supply, three 12V relays and a timer IC NE555 along with 230V coil contactor having four poles. Relays RL1 and RL2 act as a sensing devices for phases Y and B, respectively. These relays are connected such that each acts as an enabling device for the subsequent relay. Therefore the combination of the relays forms a logical AND gate connected serially. The availability of phase R en...