Sensitivity: 1500V/m/sec over a bandwidth of 120 seconds to 50 Hz Configuration: Non-Galperin design with three force feedback sensors in Z, N-S, and E-W directions
WinSDR updated every 5 minutes. YDivisor = 6, Filtered 0.002 Hz - 0.07 Hz, 100 samples/sec
The Yuma Force Balance Broadband Verticle (FBV) Seismometer is the second in a series of three designs: the Inyo, the Yuma, and the still experimental Napa Seismometer. Each design is less than half the size of the preceding model, but each retains the same basic design principles of an astatic leaf-spring suspension and broadband force balance electronics.
Dave Nelson of Palos Verdes, California, created the instrument's electronic and mechanical designs and has continued to perfect them over the years in a close collaboration with Brett Nordgren of Berkeley Heights, New Jersey. Brett, described as a Feedback Control System "guru", has produced dozens of white papers and spreadsheets which provide a detailed theoretical underpinning for these instruments. Brett has also provided supberb CAD drawings which allow anyone to reproduce these seismometers. Dave and Brett make available critical parts such as the 17-7 Precipitation Hardening Stainless Alloy leaf-springs, circuit boards, Kapton flexures, and high leakage resistence, (~20,000 MegOhm) capacitors. Brett and Dave are active on an email listserver along with a community of builders and people interested in the fascinating subject of Seismology. All are more than happy to assist the new builder. For more information email Brett at: .
These Yuma Seismometers are located approximately 3 miles South of Princeton, NJ in central New Jersey, Mercer County. It is located between the physiographic provinces of the Coastal Plain and the Piedmont. They are underlain by the Pennsauken and Stockton Formations. These regions consist of sedimentary rock such as siltstone, shale, sandstone and conglomerate6. The instruments are located in the basement of a two story dwelling on a concrete surface in a quiet residential neighborhood. The Amtrack and NJ Transit NorthEast Corridor high speed line is located about two miles North-West of the instrument location.
Larry Cochrane has designed an extremely cost effective 16 bit scanning A/D board which is well suited for Seismology. He is the auther of WinSDR and WinQuake, display and analysis earthquake software which use his hardware. His software runs on x86 hardware running Windows and under Wine on Linux. See Larry's website for further information on his hardware and software.
PSN-ADC-USB Version III Board, Firmware V1.6
This photo shows how the Yuma is made up from simple parts which could conceivably be made with a hacksaw, electric drill and file. The robust design allows for adjustments so extreme accuracy is not required. These particular parts were fabricated with a small Grizzly lathe and milling machine. At this stage there are dozens of holes and thread taps remaining to be done. Note: these parts represent two Yuma Seismometers.
Fabrication complete with one Yuma test fitted
Completed Yumas with main electronics, center of gravity weight, balance adjustment weights, sensor plate, and leaf-springs.
Yuma is installed in gas tight (IP67) Hammond enclosure, IP67 DB-15 connector with warpless design fittings. Note, the bottom cover of the case was drilled and tapped to allow for top mounted retaining knobs.