New Amplification Method for Depth Recording

By placing a field-effect transistor (FET) directly on or near the test object and by supplying the source and drain from low-ohmic points, which follow the potential of the measuring signal with respect to earth, it is possible, with ordinary wires, to connect the test object with FET to the actual amplifier, which is placed at some distance from the test object. This is especially useful when it is not possible to place a complete amplifier close to the measuring point and when the size of a shielded or coaxial cable, used to connect a remote amplifier, causes difficulties.