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Sensors / Detectors: Seismic
Monitors, Geophones
Last Updated on:
Saturday, April 26, 2008 08:31 AM |
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Sensors / Detectors -- Main Page |
| Circuits Designed by Dave Johnson, P.E. : |
- Home Made Geophone Detects Foot Stomp
A home made geophone is made from a strong magnet, a coil of wire and a rubber band. The circuit is sensitive enough to detect the
vibrations of a nearby foot stomp. It could be used as an earthquake detector. (added 7/06)
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Human Traffic Footstep Detector
This circuit uses a surplus geophone to detect human footsteps from 100 feet away. It was designed for monitoring the Mexico/USA border. This preamp
part of the system draws about 50 microamps from a 12 volt supply. (added 12/04)
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Human Traffic Footstep Alarm
This circuit processes the amplified signals from the footstep detector circuit and activates a microprocessor when the circuit detects footsteps. At has an
adjustable sensitivity. (added 12/04)
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Links to electronic circuits, electronic schematics, and/or designs
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Deer Repellent #1: seismic sensor (added 8/03) |
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Filter Circuit for the Earthworm Seismic Data Acquisition System: (electronic circuit added 4/05) |
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Inexpensive seismometer project: (electronic circuit added 4/05) |
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Low cost feedback circuit Boosts efficiency: 01/21/99 EDN-Design Ideas / (added 11/05) To implement a step-up
converter with a current output, designers often simply connect the load in place of the top resistor in a resistive-divider feedback network. The bottom resistor then serves as a
current-sense resistor. Though simple, this approach is inefficient. Low efficiency results from the relatively high sense voltages—usually, 1.25V but as high as 2.5V for some ICs. A
switch-mode dc/dc converter configured as a 20-mA current source minimizes the efficiency loss by lowering the sense voltage to 200 mV (Figure 1). Advantages of this circuit include the
factor-of-six gain in efficiency; minimal board area; and readily available, low-cost components. Applications include battery charging, LED drive, and general-purpose current sources.... |
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Seismic Detector: The piezoelectric element of a kitchen gas lighter is used in this simple, yet effective
seismic detector. (added 4/03) |
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Shackleford Gundersen Seismometer Sensor Electronics: (circuit / schematic added 4/03) |
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