GB398418A - Improvements in or relating to pressure wave or vibration generators suitable for use in submarine signalling and for like purposes - Google Patents

Abstract

398,418. Audible-signalling apparatus. FLORISSON, C. L., 11, Rue de Cronstadt, Becon-les-Bruyeres, and SOC. DE CONDENSATION ET D'APPLICATIONS MECANIQUES, 42, Rue de Clichy, Paris, both in France. March 2, 1933, No. 6438. Convention date, May 20, 1932. [Class 118 (ii).] In pressure waves or vibration generators for submarine signalling, echo-sounding or like purposes of'the type employing a piezo-electric crystal in an oscillatory circuit, the oscillatory circuit is shock-excited by the charging or discharge current of a condenser or the inductive " kick " generated upon opening the circuit of an induction coil. As shown in Fig. 1, a condenser 4 is charged from a source of supply 3 when the switch 6 engages contact 7. When the switch is moved into contact with contact 8 the condenser discharges through a coil 5 coupled to the coil 2 in circuit with the crystal 1, and the steep wave front of the discharge current shock excites the circuit 1, 2 to produce a damped oscillatory wave train. A resistance 9 is adjusted so as to render the shock circuit aperiodic or, if oscillatory, in a highly damped condition. In the modified arrangement shown dotted, shock excitation occurs by virtue of the steep wave front of the charging current of the condenser. In further modifications shock excitation may be produced by both charging and discharge currents and the coil 5 may. be dispensed with by utilizing a tapping on the coil 2. In the modification shown in Fig. 5, shock excitation is produced by the e.m.f. induced in the coil 10 when the switch 6 is opened. The switch 6 may be replaced by apparatus, e.g. a rotary or vibratory switch or a " relaxation " oscillating device and a morse key, adapted to interrupt the circuit at a desired frequency.