One of the reasons why the speakers fail is that the amplifier fails and gives DC voltage to the output. The speaker protection circuit detects the DC voltage at the amplifier output and disconnects the speaker. The DC voltage detection level of the protection circuit is very low (0.7…1V) so that the speaker is protected from being exposed to high voltage.
The loudspeaker protection circuit is connected to the outputs of 2×200 or 1x400w amplifier circuits with a double contact relay, and no adjustments are required on the usable amplifier.
The relay in the speaker protection circuit connects the amplifier output and the speakers with a delay according to the set time.
In addition, I added a thermal fuse connection to prevent malfunctions that may occur due to overheating of the amplifier. The thermal fuse mounted on the cooler of the amplifier cuts the voltage of the protection circuit at high temperature, the relay contacts leave the speaker amplifier circuit, the thermal fuse value can be 70…75 degrees. This feature is optional, you can directly short-circuit it and use it.
Speaker Protection Circuit Diagram
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Published: 2021/09/20 Tags: analog circuits projects