Isolated capacitive liquid level probe

A measurement device comprising a circuit which comprises a measurement circuit and a sensing circuit, the measurement circuit having a first and a second transformer, the measurement circuit being connected across the sensing circuit such that a coil of the first transformer and a coil of the second transformer are connected to the sensing circuit, the sensing circuit being floating and fully isolated and comprising two elongate electrodes which are spaced apart from one another uniformly along their lengths and the measurement circuit being connected to measure the impedance across the two electrodes in which the coil of the first transformer that is connected to the sensing circuit is oppositely connected or oriented or handed to the coil of the second transformer that is connected to the sensing circuit, whereby any signal generated in one of those coils caused by a change in any external magnetic field relative to the sensing circuit is in anti-phase with a signal generated in the other of those coils caused by the change, the coil of the first transformer that is connected to the sensing circuit being connected to one of the two elongate electrodes of the sensing circuit, and the coil of the second transformer that is connected to the sensing circuit being connected to the other of the two elongate electrodes of the sensing circuit.