Abstract: An output circuit of a vacuum-tube amplifier is disclosed. An output circuit of a conventional vacuum-tube amplifier has shortcomings that a front end amplification unit uses a coupling condenser or a transformer to output an AC signal to an output node, a bias voltage of a cathode of a vacuum tube is varied in response to an input signal in an output buffer and, when the bias voltage is higher than a voltage set by a bias resistor, signal attenuation by the difference between the bias voltage and the set voltage is generated. To solve these shortcomings, the output circuit of the vacuum-tube amplifier includes a front end amplification unit for amplifying an input signal using a vacuum tube and an output amplification unit for power-amplifying the output signal of the front end amplification unit using a vacuum tube.

Abstract: An output circuit of a vacuum-tube amplifier is disclosed. An output circuit of a conventional vacuum-tube amplifier has shortcomings that a front end amplification unit uses a coupling condenser or a transformer to output an AC signal to an output node, a bias voltage of a cathode of a vacuum tube is varied in response to an input signal in an output buffer and, when the bias voltage is higher than a voltage set by a bias resistor, signal attenuation by the difference between the bias voltage and the set voltage is generated. To solve these shortcomings, the output circuit of the vacuum-tube amplifier includes a front end amplification unit for amplifying an input signal using a vacuum tube and an output amplification unit for power-amplifying the output signal of the front end amplification unit using a vacuum tube.

Abstract: An output circuit of a vacuum-tube amplifier is disclosed. An output circuit of a conventional vacuum-tube amplifier has shortcomings that a front end amplification unit uses a coupling condenser or a transformer to output an AC signal to an output node, a bias voltage of a cathode of a vacuum tube is varied in response to an input signal in an output buffer and, when the bias voltage is higher than a voltage set by a bias resistor, signal attenuation by the difference between the bias voltage and the set voltage is generated. To solve these shortcomings, the output circuit of the vacuum-tube amplifier includes a front end amplification unit for amplifying an input signal using a vacuum tube and an output amplification unit for power-amplifying the output signal of the front end amplification unit using a vacuum tube.

Abstract: A surface acoustic wave position-sensing device comprising a piezoelectric substrate, a nonpiezoelectric plate, two surface acoustic wave transducing units and a controlling system connected with the units. Each unit consists of interdigital transducers (IDTs). The thickness of the piezoelectric substrate is larger than three time an interdigital periodicity of the IDTs. The thickness of the nonpiezoelectric plate is smaller than the interdigital periodicity. Each of the IDTs is placed such that the finger direction thereof is slanting to that of the IDTs by an angle .alpha.. When an electric signal is applied to each of the IDTs a SAW is excited on an area, and transmitted to an area, in contact with the IDTs of the upper end surface of the piezoelectric substrate through the nonpiezoelectric plate. The controlling system senses a touch with a finger by the generation of the electric signal at one of the interdigital transducers.