Hearing aid circuit having an output stage with a limiting means
First Claim
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1. A hearing aid circuit, comprising:
- an output stage connected via an earphone and a battery to an adjustable limiting circuit means for limiting a maximum acoustic output level of the earphone;
said limiting means being electronic and comprising at least one first controllable semiconductor;
controllable component means comprising a programmable electronic resistor for operating the semiconductor as a current-traversed switch given deactivated electronic limiting, and for operating the semiconductor as a current-traversed, variable resistor given activated electronic limiting;
the first controllable semiconductor comprising a control terminal which is connected to the controllable component means; and
for electronic limiting approaching zero, the first controllable semiconductor being supplied via the controllable component means with a current which allows the first controllable semiconductor to become transmissive due to overdrive.
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Abstract
A hearing aid circuit has an output stage which is connectable via an earphone and a battery to a circuit that has an adjustable limiting means for electrically limiting the maximum acoustic output level of the hearing aid. The limiting means is electronically designed such that a reduction in the maximally obtainable acoustic output level of the earphone in the zero position of the limitation is avoided. At least one first controllable semiconductor is operated with an adjustable component part as a current-traversed switch given a deactivated electronic limiting, and which can be operated as a current-traversed, variable resistor in the circuit given activated electronic limiting.
71 Citations
15 Claims
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1. A hearing aid circuit, comprising:
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an output stage connected via an earphone and a battery to an adjustable limiting circuit means for limiting a maximum acoustic output level of the earphone; said limiting means being electronic and comprising at least one first controllable semiconductor; controllable component means comprising a programmable electronic resistor for operating the semiconductor as a current-traversed switch given deactivated electronic limiting, and for operating the semiconductor as a current-traversed, variable resistor given activated electronic limiting; the first controllable semiconductor comprising a control terminal which is connected to the controllable component means; and for electronic limiting approaching zero, the first controllable semiconductor being supplied via the controllable component means with a current which allows the first controllable semiconductor to become transmissive due to overdrive. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A hearing aid circuit, comprising:
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an output stage connected via an earphone and a battery to an adjustable limiting circuit means for limiting a maximum acoustic output level of the earphone; said limiting means being electronic and comprising at least one first controllable semiconductor; controllable component means for operating the semiconductor as a current-traversed switch given deactivated electronic limiting, and for operating the semiconductor as a current-traversed, variable resistor given activated electronic limiting; the first controllable semiconductor comprising a control terminal which is connected to the controllable component means; the controllable component means and at least a first resistor being connected to form a first voltage divider means having a voltage tap which is electrically connected to the control terminal of the first controllable semiconductor and at which a voltage of the battery is divided; and the first resistor of the first voltage divider means comprising a second controllable semiconductor having at least three terminals whose control terminal is connected to a voltage tap at a second voltage divider which is formed of a series circuit of two resistors having a fixed value of resistance and of a third semiconductor which has a voltage-dependent non-linear value of resistance. - View Dependent Claims (13)
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14. A hearing aid circuit comprising:
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an output stage connected to drive an earphone; an adjustable limiting circuit means connected to control and limit a maximum acoustic output level of the earphone; said limiting means comprising at least one controllable semiconductor; circuit means for operating the semiconductor as a switch when deactivated electronic limiting is not desired, and for operating the semiconductor as a variable resistor when electronic limiting is desired; said circuit means comprising a programmable electronic resistor connected to control an input of said controllable semiconductor; and remote control means for adjusting the programmable electronic resistor by high frequency signals transmitted from a remote location external to the hearing aid circuit. - View Dependent Claims (15)
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Specification