OKM GeoSeeker Mini

The OKM GeoSeeker Mini is a geoelectric survey instrument, not a metal detector. Two power electrodes inject a controlled current into the ground while two voltage electrodes measure the resulting potential difference — the classic Schlumberger four-electrode array — and the control unit converts current, voltage and electrode spacing into apparent ground resistivity in ohm-metres. Because water-saturated ground conducts electricity well and air-filled voids do not, the finished profile reads as a colour-coded section: blue where conductivity is high, as it typically is over a water deposit; yellow and white for ordinary soil; red where resistivity is high, as it typically is over a cavity or an impervious barrier. It cannot find gold, coins or buried metal — resistivity contrast is the only thing it measures. Everything runs from the control unit itself. On the 3.5-inch resistive touchscreen you set a maximum depth and choose three or five scan points, and the screen then tells you which numbered cable marker to move each electrode to for every reading; a measurement takes a minimum of 16 seconds per point and the completed 2D section is stored in 4 GB of internal memory, with no tablet, notebook or PC software involved. OKM states a maximum penetration of 100 m (328 ft) and is explicit about what that needs: 100 m of clear ground on each side of the scan point for the cable spread, a dry surface, and electrodes driven deep enough for solid contact — and it notes that the depths shown are maximum values, often deeper than the real target. At 4.5 kg the control unit doubles as the carrying case, with the four stainless-steel electrodes clipped into the lid, which makes the Mini the portable, self-contained alternative to the full 250 m GeoSeeker. OKM recommends a team of three, ideally five, because the electrodes are moved for every depth at every point. It suits well and borehole siting, village and farm water supply, cavity and void survey, and geotechnical ground checks.