Audio amplifier
AssigneeTokyo Shibaura Denki Kabushiki Kaisha
InventorHideki Sakano
Life of this patent
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Abstract
An audio amplifier having an auxiliary terminal for connection of a feedback line to the grounded terminal of a loudspeaker and including a circuit for protection against voltage overload on the amplifier and loudspeaker if the auxiliary terminal is inadvertently connected to the ungrounded terminal of the loudspeaker, or in case of malfunction of the feedback circuit. The protection circuit includes a signal generator activated by the closing of a power switch for producing a check signal for circuiting through the terminals of the loudspeaker to the auxiliary terminal and a controller sensitive to the voltage at the auxiliary terminal for controlling a switch for disconnecting the feedback line, if the voltage at the auxiliary terminal exceeds a predetermined value.
Claims13
An audio amplifier for connection to a pair of terminals of a loudspeaker through like individual extension wires comprising:
- a line input terminal;
- a line amplifier having an input terminal connected to the line input terminal;
- a line output terminal for connection to one of the terminals of the loudspeaker through one of the extension wires;
- a grounded terminal for connection to the other of the terminals of the loudspeaker through the other of the extension wires;
- an auxiliary terminal for connection to the grounded terminal of the loudspeaker;
- a positive feedback circuit connected between the auxiliary terminal and the input terminal of the line amplifier;
- and
- apparatus for protecting the line amplifier and loudspeaker from damage by voltage overload including:
- (a) a first switch in the positive feedback circuit between the auxiliary terminal and the input terminal of the line amplifier;
- and
- (b) controller means sensitive to the voltage at the auxiliary terminal for opening, or maintaining open, said switch when the latter voltage exceeds a predetermined value.
Dependencies are inferred from the claim text.