日本音響学会誌
Online ISSN : 2432-2040
Print ISSN : 0369-4232
11 巻, 3 号
選択された号の論文の6件中1~6を表示しています
  • 森 栄司, 山内 巌
    原稿種別: 本文
    1955 年 11 巻 3 号 p. 149-154
    発行日: 1955/09/30
    公開日: 2017/06/02
    ジャーナル フリー
    An equipment developed for soldering large number of fine aluminum wire ends is described. The equipment consists of a metalic bar or horn with molten solder pot at one end and a magnetostriction oscillator as a means of producing mechanical vibrations of an ultrasonic frequency. When an end of a fine aluminum wire is inserted into the pot with molten solder the oxide film on the aluminum surface is destroyed by the cavitation errosion due to intense ultrasonic vibrations. The transducer (radiation area 30 mm x 30 mm) consists of pure nickel sheets-thickness 0. 125 mm-in lamination and insulated from one another. The soldering bar or horn is attached to one end of the transducer by silver solder. Considering the heat conduction from the heater to the transducer, the length of the bar or horn is taken as one wavelength for resonant frequency of the transducer here employed. Excitation of the transducer is produced by high frequency current through a coil (165 turns of copper wire) wound on one limb. The transducer is driven from a class C power amplifier (maximum output power about 30 W) using a type UY-807 tube fed by a master oscillator (plate tuning) using a type UZ-42 tube. The d. c. polarizing supply (about 1A;10 oersted) is fed to polarize the transducer, the polarizing coil being common with the exciting coil. The transducer is supported with a brass band at the nodal line of limb. Results of some experiments are as follows: (1) The driving power required by the transducer for successful soldering was sufficient at about 20 w. (2) Aluminum and its alloy were almost perfectly soldered without any fluxes. (3) The solders of Zn-Cd and Sn-Zn alloys are effective in protecting the aluminum from corrosion. (4) The materials of bar which made perfect contact with solder and proved effective at working temperature at about 300℃ were monel metal, chrome and silzin bronze.
  • 大庭 太郎
    原稿種別: 本文
    1955 年 11 巻 3 号 p. 155-163
    発行日: 1955/09/30
    公開日: 2017/06/02
    ジャーナル フリー
    The effective feedback quantity of the feedback amplifier that has a negative output voltage feedback and a positive output current feedback is controlled by its output current. In other words, the internal impedance of a feedback amplifier takes positive or negative sign according as the increment of the output voltage is larger or smaller than the voltage drop due to the internal impedance of the amplifier when the positive current feedback is removed. This paper deals with the analysis and experimental investigation on the above-mentioned phenomenon and it was revealed that this amplifier shows, under certain conditions, superior characteristic for the purpose of sound reproduction by loud speaker and other purposes as compared with usual negative feedback amplifiers.
  • 大野 壽彦
    原稿種別: 本文
    1955 年 11 巻 3 号 p. 164-173
    発行日: 1955/09/30
    公開日: 2017/06/02
    ジャーナル フリー
    The threshold values, the amplitude discrimination and the frequency discrimination of the vibratory sensation of the skin was measured by a moving coil type vibrator with a BaTiO_3 ceramic element. The frequencies ranged from 50 to 1000 cps. The amplitude was obtained from the output voltage of BaTiO_3 ceramic. The contact area of the vibrator with the skin was about 0. 7 cm^2. The threshold of vibration sensation of the skin was measured with several normal persons. The threshold amplitude was 10^&lt-2&gtmm at 60 cps, about 10^&lt-4&gtmm at 400 cps, and about 10^&lt-3&gtmm at 1000 cps. These thresholds changed only slightly with person (about ±5db), with parts of body where they were measured (about ±10 db), and with the constant pressure on the vibrator (about 2 db) which was usually about 100g weight. The threshold values of the acceleration were about 6x10^2mm per sec^2 and remained almost constant over the lower frequencies below ca. 300 cps. In the higher frequencies above about 300 cps the threshold value rised up about 20 db per octave. The amplitude discrimination of vibratory sensation of the skin at same frequency was measured by a vibrator which was able to produce two different amplitudes alternatively. Generally, the limit of the amplitude discrimination was about 2 db. The frequency discrimination of the vibratory sensation of the skin at the same amplitude was measured by a vibrator which could produce two sorts of frequencies alternatively. Generally, the limit of frequency discrimination is about 7%. The frequency discrimination under two different amplitudes was nearly the same as that obtained under two equal amplitudes. During the experiments of discrimination, the ears were masked by noise. These results of discrimination also show a little difference by persons, the parts of the body, the amplitude of vibration, and the frequency. Thus, as to the vibratory sensation of the skin it is concluded that one can obtain the amplitude discrimination and the frequency discrimination independently.
  • 五十嵐 壽一
    原稿種別: 本文
    1955 年 11 巻 3 号 p. 174-188
    発行日: 1955/09/30
    公開日: 2017/06/02
    ジャーナル フリー
  • 実吉 純一
    原稿種別: 本文
    1955 年 11 巻 3 号 p. 189-196
    発行日: 1955/09/30
    公開日: 2017/06/02
    ジャーナル フリー
  • 横山
    原稿種別: 本文
    1955 年 11 巻 3 号 p. 197-
    発行日: 1955/09/30
    公開日: 2017/06/02
    ジャーナル フリー
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