Abstract: An inverting amplifier which drives headphones via an output capacitor includes: an operational amplifier, an input resistor having a first terminal via which an audio signal to be amplified is received, and a second terminal connected to an inverting input terminal of the operational amplifier; and a feedback resistor having a first terminal connected to an inverting input terminal of the operational amplifier, and a second terminal connected to the output terminal. A reference voltage source generates a bias voltage Vb, and supplies it to the non-inverting input terminal. A discharging path includes a discharging resistor and a first switch arranged in series between an output terminal of the reference voltage source and an fixed voltage terminal. A second switch is arranged between the output terminal of the operational amplifier and a node on the discharging path where the electric potential is higher than it is at the discharging resistor.

Abstract: An inverting amplifier which drives headphones via an output capacitor includes: an operational amplifier, an input resistor having a first terminal via which an audio signal to be amplified is received, and a second terminal connected to an inverting input terminal of the operational amplifier; and a feedback resistor having a first terminal connected to an inverting input terminal of the operational amplifier, and a second terminal connected to the output terminal. A reference voltage source generates a bias voltage Vb, and supplies it to the non-inverting input terminal. A discharging path includes a discharging resistor and a first switch arranged in series between an output terminal of the reference voltage source and an fixed voltage terminal. A second switch is arranged between the output terminal of the operational amplifier and a node on the discharging path where the electric potential is higher than it is at the discharging resistor.

Abstract: A zero-crossing detector detects a zero-crossing point by monitoring an amplitude of an audio signal, and generates a zero-crossing detection signal that becomes a predetermined level for every detected zero-crossing point. A timer circuit counts a clock signal, and generates a timing signal that becomes a predetermined level every time a predetermined unit transition time elapses. A volume setting unit receives the zero-crossing detection signal and the timing signal, and transits the volume from a current value to a target value in a step-wise manner. Every time the timing signal becomes the predetermined level, the volume setting unit changes the volume by a predetermined width at a transition timing at which the zero-crossing detection signal becomes a predetermined level immediately thereafter, and repeats such process to execute volume transition from the current value to the target value.

Abstract: The variable-order delta sigma modulator of the invention is capable of setting an optimum order in relation to a sampling frequency to be used, when using one out of plural sampling frequencies. As to the delta sigma modulator of the third order or higher, in a combination of two arbitrary continued integrators constituting the modulator is furnished a means that connects or disconnects the circuit on the second integrator side at the part of connecting the first integrator and the second integrator, or a means of switching the relation of connections. Connecting or disconnecting the circuit through the means and switching the relation of connections will set the order of the delta sigma modulator into an optimum order in relation to a sampling frequency.

Abstract: The variable-order delta sigma modulator of the invention is capable of setting an optimum order in relation to a sampling frequency to be used, when using one out of plural sampling frequencies. As to the delta sigma modulator of the third order or higher, in a combination of two arbitrary continued integrators constituting the modulator is furnished a means that connects or disconnects the circuit on the second integrator side at the part of connecting the first integrator and the second integrator, or a means of switching the relation of connections. Connecting or disconnecting the circuit through the means and switching the relation of connections will set the order of the delta sigma modulator into an optimum order in relation to a sampling frequency.

Abstract: The variable-order delta sigma modulator of the invention is capable of setting an optimum order in relation to a sampling frequency to be used, when using one out of plural sampling frequencies. As to the delta sigma modulator of the third order or higher, in a combination of two arbitrary continued integrators constituting the modulator is furnished a means that connects or disconnects the circuit on the second integrator side at the part of connecting the first integrator and the second integrator, or a means of switching the relation of connections. Connecting or disconnecting the circuit through the means and switching the relation of connections will set the order of the delta sigma modulator into an optimum order in relation to a sampling frequency.

Abstract: The variable-order delta sigma modulator of the invention is capable of setting an optimum order in relation to a sampling frequency to be used, when using one out of plural sampling frequencies. As to the delta sigma modulator of the third order or higher, in a combination of two arbitrary continued integrators constituting the modulator is furnished a means that connects or disconnects the circuit on the second integrator side at the part of connecting the first integrator and the second integrator, or a means of switching the relation of connections. Connecting or disconnecting the circuit through the means and switching the relation of connections will set the order of the delta sigma modulator into an optimum order in relation to a sampling frequency.

Abstract: In a one chipped digital signal processing and amplifying block, in addition to a conversion operation of music related signals, by supplying clocks to an A/D conversion circuit and a D/A conversion circuit through operation of a control circuit, a conversion operation for speech related signals having a lower frequency than a predetermined frequency for the music related signal is caused and data exchange with an external circuit or an external device is performed via a digital interface, thereby, both music related and speech related signals are processed by the one chipped digital signal processing and amplifying block.

Abstract: A voltage output device outputs an analog voltage obtained by dividing a supply voltage with a plurality of resistor elements. The resistor elements are individually connected in parallel with fuse elements and switching transistors. The fuse elements have a resistance sufficiently lower than the resistor elements. The voltage output device also has a controller that controls, in accordance with an input signal fed thereto, the on/off states of the switching elements. The fuse elements connected in parallel with the transistors that are turned on remain intact without blowing, and the fuse elements connected in parallel with the transistors that are kept off blow. The fuse elements blow when a current higher than a predetermined value is passed therethrough, and this permits adjustment of the value of the output analog voltage.

Abstract: A recording and reproducing apparatus of the present invention has a magnetic head used for both recording and reproduction. To perform the changeover between recording and reproduction in a short period of time, a first recording amplifier for supplying a recording signal is provided at one end of the magnetic head, a second recording amplifier for supplying a recording signal of a phase opposite to that of the recording signal supplied to the one end of the magnetic head is provided at the other end of the magnetic head, and a reproduction input amplifier connected to the both ends of the magnetic head is provided. The same bias voltages are supplied through first and second resistors connected to the both ends of the magnetic head.

Abstract: A device for collecting oil floating on the surface of water which comprises a main body made of non-ventilative and flexible sheet material and transformable from a flat configuration to a three dimensional configuration and vice versa, a first nozzle with a valve operatively connected to the main body, and a plurality of hollow elements made of non-ventilative and flexible sheet material and adapted to cooperate with each other to forcibly transform the main body to a three dimensional configuration when compressed air or gas is supplied thereinto through a second nozzle with a valve operatively connected thereto.