Force Balanced Uniaxial Broadband Seismometer


Model EP-105-U

The EP-105-U is an uniaxial that is designed as a versatile, very compact, lightweight, and very rugged broadband seismic sensor. Unlike traditional seismometers, they are based on proprietary electrochemical transducer technology that provides many advantages over the conventional electromechanical (mass) seismometers. In particular unlike other sensors, the EP-105-U noise curve is essential flat starting from about 5Hz toward the longest periods. Each sensor element in EP-105-U is equipped with an efficient electrodynamic force-balancing feedback.

The instrument is offered in two application-dependent versions. The standard EP105-(LN) is the reduced noise version. An optional model, EP105-SM has a higher clip level and is used for strong motion applications. Both versions have the same dynamic range, which is shifted up by approximately 10db in the ‘SM’ relatively to the standard ‘LN’ version.

The EP105-U has an exceptionally rugged design and easily deployed in the field. It DOES NOT require mass lock for transportation, mass centering, special installation equipment, or technical installation procedures. The units are operational over a wide range of installation tilts. An optional inclinometer may be installed. The EP105-U seismometer provides low cost of ownership, REQUIRING no maintenance over the life of the instrument. Three and five-year extended warranties are available.

  • Passband 0.033 Hz to 50 Hz,
  • Low Power
  • No Mass Centering or Mass Locks
  • High Sensitivity
  • 142dB Dynamic Range
  • Rugged
  • Maintenance Free
  • Waterproof
  • Operates over a wide tilt
  • OBS and Borehole Configurations
Operating principle: Electrochemical motion transducer with force-balancing feedback
Output signals: Horizontal or Vertical specify at time of order; very broad passband, velocity flat response
Output signal swing: 10 V single-ended; (20 V p-p)
Dynamic Range: 142 dB
Bandwidth: 0.033 Hz - 50 Hz;
Self-noise: LN -160dB; SM -148dB on the USGS NLNM
Generator constant: Standard: 2000 V/m/s; Opt.: 350 - 20,000 V/m/s
Mass Centering: NONE REQUIRED
Maximum installation tilt 12
Mechanical resonance >150 Hz
Waterproof: Submersible (1m)
Temperature range: Standard: -12 to + 55 C
Others optional
BasicEP-105 Configuration The standard configuration includes mating connector and calibration sheets
Sensitivity Option option -Sxxxxx
(x specifies sensitivity)
Recorder Options DR-4000,
Supplies and Accessories Sensor Cable
General Spares None

S Printer Friendly Format For Specifications

Case diameter 120 mm
Case height: 160 mm
Weight (Al housing) 3 kg
Connector 8-pin circular
Power - Standard 10 - 15 Vdc; 12 Vdc nominal
Supply current Standard: 10 mA


ep105 noise

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