Abstract: An alarm assembly specifically designed to warn sleeping occupants within a dwelling structure as to the occurrence of earth tremors such as those caused by relatively serious earthquakes wherein an activating member is movably positioned relative to a supporting base and is sensitive to such earth tremors to the extent of being displaced within a predetermined range of movement and into activating engagement with a switching assembly also mounted on said base to cause operation and/or activation of preferably an audio alarm to awaken the sleeping occupants.

Abstract: A speaker system having a magnet and voice coil are mounted within a dome-shaped enclosure in such a way as to be capable of transmitting sonic vibrations and audio waves through a liquid medium or solid structure, the dome-shaped enclosure cooperating with the magnet and voice coil in such a way as to greatly enhance the waves and sonic vibrations generated to the other medium or structure.

Abstract: An improved geophone for seismic prospecting is disclosed which features plural magnets of varying mass oscillating with varying frequencies within one or plural coils whereby the frequency response of the geophone may be optimized.

Abstract: A passive mass-spring type of sensing device or other such device for monitoring a particular parameter, for example mechanical vibration, is disclosed herein. This device utilizes an electrically conductive coil having a given impedance disposed within a magnetic field in a way which results in relative movement between the coil and the field corresponding to the particular parameter being monitored, whereby to produce a monitoring signal in the form of a voltage which also corresponds to the parameter being monitored. The device includes a circuit arrangement for electronically damping the relative movement recited above in a substantial way while, at the same time, maintaining the monitoring signal at a measurable value.

Abstract: An electrodynamic transducer has broadband operation and is suitable for erwater use. The transducer has a flexible rubber seal to assist in keeping the unit watertight. New features include a large flared air passage, a coil of wire that is rectangular in cross section and is routed through the center of a hollow centering shaft. In addition, a piston is machined out of beryllium copper with the piston attached to the shaft at the dome center and the skirt spider center. The transducer is designed to operate with the magnet having its outer pole piece in contact with the seawater.

Abstract: A seismometer comprising a permanent magnet fixed to a supporting plate, a thin flexible blade, one of whose ends is embedded in a support which is itself fixed to the supporting plate and the other end of which carries a coil which moves freely in the air gap of the permanent magnet, and an electronic amplifier which amplifies the electromotive forces induced in the coil by a displacement of the coil in the air gap of the magnet.This seismometer can be used more particularly in connection with the safety of the nuclear reactor in the case of an earthquake.