Loudspeaker Protection circuit

Posted on Jul 17, 2012

The protection circuit output amplifiers and speakers, has some interesting features such as isolating the speaker from the amplifier output when shown a continuous trend in output or when the temperature gets too much cooler while providing a time delay and the connection of the speaker amplifier, to avoid passing them, the known irritating noise from the charge-discharge power supply capacitors. It consists of a binary comparator [IC1], transistors Q1-2 and indicative LED D5-6. The power circuit can be made from the positive trend [point A] to the main power supply, which is stabilized by the D3 and R17, at +15 V. Point B is connected to one of the secondary AC power adapter.

Loudspeaker Protection circuit
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Just close the power switch AC, then an alternating voltage appears on terminal B, is rectified by D2 and supplies a negative voltage through R9, in Q3, it cuts off and begins to charge the C4 through R10-11. So long as the duration of the load capacitor, the input [+] IC2B the comparator is at a low level compared to the input [-]. The output of IC2B, has a low level, so that Q4 remains off and remains off RL1, the D6 is on. Once the C4 charge, the state changes IC1V activates the RL1, the speakers connected to the amplifier, the D6 off. When power is interrupted throughout the process is reversed, and the speakers disconnected, without going through annoying noises. If the circuit works as a problem occurs at the output voltage of the amplifier, it's a relaxation of RL1 and protect the speakers. This is done with the help of Q1-2. The audio signal from the output of the amplifier leads to point D, the changing trends led to earth via the C1-2, generating a non-polar capacitor. Ongoing trends, greater than +1.7 V or below?? 4.8V, directly activate the Q1 or Q2, respectively. By enabling transistor lowered the level of [+] input IC1B, thereby apodiegeiretai and RL1. Another area that gives us protection circuit is thermally protected. This is done by using a sensor temperature of RTH, which is a resistance type PTC (positive temperature coefficient), and is mounted onto the heatsink, where they are and the power...

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