Soiltest, Inc., has developed an inexpensive and compact MD-5 Engineering Seismograph. It can be used by one or two operators to determine depth and classification of subsurface materials.
The battery-powered, all solid-state instrument weighs only 10 lbs. and measures 11 in.×5 in.×10 in. Power supply is a 6-volt battery, rechargeable by a built-in charger or external AC or DC source.