The Public Seismic Network of San Jose

serving

 Santa Clara County and Santa Cruz County

http://www.PublicSeismicNetwork.com

Aptos PSN Station


Display / AMP Geophones Lehamn Outside Seismic House Lehman Seismograph

Emon Data Collection

 

Rack mounted amplifier and filter cases

Data Collection

 Software:

  • Name - EMON by Ted Blank

System: AT1 /2

  • Normal sampling rate: Samples Per Second - 3.949
  • OS - DOS3.3

System: ATE/N/Z

  • Normal sampling rate: Samples Per Second - 63.875
  • OS - DOS3.3

Amplifiers:

Designer: Pet Rowe

Two gain stages op-27  overall gain

Min - 2,985    1.3DB

Max - 51,740   67.3DB

Filter: Low pass 10Hz   3-poll butterworth

 Specification:

Model:

  • Geo Space HS10

Functional Sensitivity         ( 10%)     2.99 V/ips                          Natural Frequency                ( 10%)    1 Hz

Coil Resistance                 ( 10%)    400 ohms

Coil Inductance                     360 mh

Damping Factor         ( 20%)       .031

Damping Constant              1178 2862

Displacement Limit                     0.5 in

Inertial Mass                             33 oz  

Orientation Angle            5

Mechanical

Height                    5.40 in

Diameter                4.38 in

Weight                   9.75 lbs  

 

Specification:

 Case:

  • 10 Sq Ft work area
  • 20 Cu Ft volume
  • Airtight seal
  • 2- Lehman cement mounting pads 2x2x4-feet
  • Full cement floor
  • Interior insulation 2-inch Styrofoam top/sides
  • Exterior 1/2-inch plywood with removable top
  • 2-inch PVC cable pass through to garage interior
  • Outside rain drain to remove standing water
  • Metal roof 4-feet above wooden box to block wind/rain (not shown)
Specification&Design:

 Lehman boom:

Boom: Aluminum 1-inch sq

Boom length: 30cm

Initial mass: 80 oz

Pre Amp / coax driver gain: 1889

Amp/Coax power supply: +/- 12V steady supply with UPS backup provided from the seismic rack supply via the PVC cable pass through tube.

 
Specification&Design:

 Lehman upright support:

Base Plate: Aluminum .75x10x12-inch

Height: 20-inches

Mounting: (3) 3/8-inch 1000 lb cement anchor

Leveling: (2) 2-inch 8-32 hex head machine screw

Upper pivot : #10 machine wire from upright to turnbuckle.

Lower yoke wire: From lower turnbuckle  to boom cross bar .035 steel aircraft cable.

Lower pivot: Hardened point in cupped 8-32 hex head machine screw

 

Specification&Design:

 Lehman detail:

Top Photo:

Damping Magnets:   1.5Hx1.75W1.75D-inches

Flag: brass 8x2x.25-inches

Middle Photo:

Manufacturing process: Hand wound

Pickup coil 25mm diameter plastic wire frame x 10mm  x 15mm

Magnet: cow magnet

Magnet Wire size: 52 gauge

Coil Resistance: 12.5K ohms   

Lower Photo:

Manufacturing process: Machine wound

Pickup coil 14mm diameter plastic wire frame x 10mm x 7mm

Magnet: 1.375Wx.75Hx.75D

Magnet Wire size: 38 gauge

Coil Resistance: 71.5 ohms

 

           


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Webmaster Public Seismic Network of San Jose   WWW Since August 1997 - BBS Since January 1990 - Last Update Jan 26, 2014 Professor Stephen Hammond
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