Seismic detectors

The piezoelectric element of a kitchen gas lighter is utilized in this simple yet effective seismic detector. The piezo element must be positioned vertically, with one end firmly grounded. A loose package containing 2-3 pounds of fine gravel should be placed on top at the opposite end. The high voltage lead connects to the integrated circuit (IC), which is situated close to the piezo element. The entire assembly is acoustically and electromagnetically shielded. A three-core shielded cable transmits the signal to the rest of the circuit and to the power supply (+/- 15V). The SB140 diodes used in this circuit are of the Schottky type, and pin 8 (substrate) of the IC should be connected to ground.

The seismic detector employs a piezoelectric element, which generates a voltage when subjected to mechanical stress, making it suitable for detecting vibrations and seismic activity. The vertical orientation of the piezo element is crucial as it maximizes the sensitivity to ground vibrations. The weight of fine gravel applied on top enhances the mechanical coupling, ensuring that even minor seismic events produce a measurable response from the piezo element.

The high voltage lead from the piezo element connects to an integrated circuit (IC) designed to process the signal generated by the piezoelectric element. This IC is strategically placed near the piezo element to minimize signal loss and interference. The use of a three-core shielded cable is essential in preserving the integrity of the signal as it travels to the rest of the circuit and the power supply. The shielding protects against electromagnetic interference, which could otherwise compromise the performance of the detector.

Power for the circuit is supplied at +/- 15V, providing sufficient voltage for the IC and associated components to operate effectively. The inclusion of SB140 Schottky diodes ensures fast switching and low forward voltage drop, which is beneficial for signal processing applications. The connection of pin 8 of the IC to ground is a standard practice that helps stabilize the IC's operation and ensures proper functioning within the circuit.

Overall, this seismic detector design is straightforward yet effective, leveraging the properties of piezoelectric materials and careful circuit design to monitor seismic activity reliably.The piezoelectric element of a kitchen gas lighter is used in this simple, yet effective seismic detector. The piezo element must be placed vertically, one end solidly to ground. A 2-3 pound weight of fine gravel in a loose package should be placed on top at the other end. The high voltage lead goes to the IC, placed close to the piezo element. Th e whole box is acoustically and electromagnetically screened. A 3 core shielded cable brings the signal to the rest of the circuit and to the power supply (+/- 15V). The SB140 diodes are Schottky type and pin 8 (substrate) of the IC should be connected to ground. 🔗 External reference