Abstract: A geophone is disclosed that has a cylindrical housing closed at one end by a bottom and at the other end by a top. A magnet assembly and a coil-mass are located in the housing. Springs support the coil-mass for axial movement relative to the magnet assembly along the longitudinal axis of the housing. A pair of coil terminals are mounted in the upper end of the coil-mass adjacent the top of the housing. A pair of eyelets extend through the top of the housing and outside geophone terminals are attached to and extend through the eyelets into the housing. A pair of pigtails connect the geophone terminals to the coil terminals.

Abstract: A seismic detector assembly is disclosed that includes a housing and a seismic detector or geophone located in the housing. The geophone has a pair of external terminals that are positioned asymmetrical to the longitudinal axis of the geophone. A printed circuit board having conductive strips for connecting the terminals to leader cables is located in the housing above the geophone. The printed circuit board has a pair of asymmetrical openings through which the asymmetrical terminals can extend only when the printed circuit board is oriented in one position relative to the geophone. Marks on the printed circuit board indicate which conductive strip should be connected to which terminal and the proper orientation of the printed circuit board relative to the truck that receives the output of the geophone.

Abstract: A seismic detector housing assembly is disclosed having a housing open at one end, a seismic detector having an outer case with generally flat end walls, and a pair of terminals extending out of the case through one end wall located in the housing with the terminals extending outwardly from the open end of the housing. A seal member of elastomeric material having openings, through which the terminals extend, covers the end of the detector and closes the open end of the housing. A PC board for connecting the terminals to leader wire conductors covers the seal member. A cup-shaped cap is attached to the housing to enclose the terminals and an outer edge to engage the PC board and compress the seal member into sealing engagement with the cap and the housing.

Abstract: Disclosed is test apparatus included in a cable transmission system having intermediate local data units spaced along a cable, one connection to the cable also being to a master or control station. At each data unit, there is an input differential amplifier with two input terminals for application of at least one local data signal. A test signal is applied to the data unit via a transmission connection from the master station to a first element of a voltage divider connected to one of the two input terminals of the differential amplifier. A switch at the data unit is connected for disconnecting the data connection from the other input terminal of the differential amplifier. A second switch at the data unit, provides a connection to a conductor leading to the master station for connecting earth ground to the data unit local circuit common.

Abstract: A waterproof housing assembly for a geophone is disclosed that includes a housing having an elongated cavity. A geophone is mounted in the bottom portion of the cavity. A two conductor takeout cable extends into the cavity that has a first section where the outer sheath and insulation are stripped from the two conductors part of the way back from the end. A second section of the cable adjacent the first has the outer sheath removed from the insulated conductors. A body of elastomeric material is located in the cavity. It has a first pair of spaced openings through which the uninsulated first section of the cable extends to be connected to the geophone, a second pair of spaced openings connected to the first pair in which the second section of the cable is located, and a single opening connected to the second pair in which a portion of the sheathed cable is located.