The is a simple and less expensive amateur long-period seismometers by using PIC microcontroller and other new chips, such as switched capacitor filters. Long-period seismometers are useful for detecting and analyzing distant teleseismic activity (worldwide). Main part of the project is PIC 14000, MAX7401, and AD8628. The PIC controls A to D, time integration, etc. MAX7401CPA works as filter chip (8th order, low pass, Bessel, switched capacitor filter). As amplifier, it uses AD8628 auto-zero low noise, precision, rail-to-rail output, op amp.
David Saum, the designer, said that the project board is designed to work with a 9 k ohm pickup coil. But, it can also uses for other pickup coils. Amplification is single stage, low noise, 1100x voltage. For data logging, helicorder display, data export, you need to download Amaseis (freeware).
Project Documentation and Schematic