Seismic Monitors, Geophones Circuits

Deer Repellent/ Seismic Sensor - Here is a simple sensor which can detect the seismic vibrations caused by a person or large animal walking nearby. A representative application for the sensor is a deer repellent for the vegetable garden. When a deer steps near the sensor a loud buzzer or beeper sounds for a few seconds startling the would-be vegetable thief away. The sensor also makes an effective intruder detector to catch trespassers as soon as they step on the property!

Seismic Alarm - My original "Deer Repellent/ Seismic Sensor" recommended using a speaker with a weight glued to the cone as a vibration sensor but it recently occurred to me that the speaker could supply the mass itself. By gluing a standoff to the center of the cone, an inexpensive 2", 8 ohm speaker becomes a vibration sensor with a natural resonance below 100Hz which is quite good. My implementation is shown below.

Feedback Circuit:

Filter Circuit for the Earthworm Seismic Data Acquisition System:

Low Cost Feedback Circuit Boosts Efficiency: 01/21/99 EDN-Design Ideas / PDF contains multiple circuits - scroll to find this circuit

Low Cost Seismometer:

Optoelectronic Horizontal VBB Seismometer (Figures):

Seismic Detector: The piezoelectric element of a kitchen gas lighter is used in this simple, yet effective seismic detector.

Shackle ford Gundersen Seismometer Sensor Electronics:

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