A cheap homemade infrasound detector

A cheap and simple device for recording infrasound is presented. Costs for this project are in the order of 150 EUR. A subwoofer converts the pressure variations created by infrasound into a voltage signal, a homemade preamplifier is used for magnifying the signal amplitudes to a detectable level. Finally, a commercial data logger acts as second amplifier stage and allows data storage at sampling rates of up to 500 Hz via USB port. Using a subwoofer with a 10 inch membrane, the resulting detector offers excellent sensitivity down to frequencies of Hz. The excellent suggestion of using a subwoofer as detection element has been proposed by Oona Räisänen (Low-frequency exploration microphone, The device presented here is a refined design based on this idea.