A device comprising: a microprocessor; an input port; an input selector coupled to the input port configured for selecting a voltage divider (140, 130, 120) of a plurality of voltage dividers (140, 130, 120); an output selector coupled to the plurality of voltage dividers (140, 130, 120) configured for coupling the selected voltage divider (140, 130, 120) of the plurality of voltage dividers (140, 130, 120) to an output port; a switching circuit (190A, 190B, 190C) disposed between the output selector and the plurality of voltage dividers (140, 130, 120) configured for selectively coupling the selected voltage divider (140, 130, 120) of the plurality of voltage dividers (140, 130, 120) to either the output selector or to a calibration bridge; the calibration bridge coupled to the switching circuit (190A, 190B, 190C) and a voltage reference source and configured for providing first and second signals to a null detector circuit; and a plurality of calibration adjustment circuits (145, 135, 125), each calibration adjustment circuit (145, 135, 125) coupled to the microprocessor and to a predetermined voltage divider (140, 130, 120) of the plurality of voltage dividers (140, 130, 120); the null detector circuit; wherein in a first configuration an electrical signal at the input port is coupled to the output port via the selected voltage divider (140, 130, 120) of the plurality of voltage dividers (140, 130, 120); and in a second configuration the selected voltage divider (140, 130, 120) of the plurality of voltage dividers (140, 130, 120) is coupled to the calibration bridge and automatically calibrated with the calibration adjustment circuit (145, 135, 125) of the plurality of calibration adjustment circuits (145, 135, 125) associated with the selected voltage divider (140, 130, 120) of the plurality of voltage dividers (140, 130, 120) by a calibration routine in execution upon the microprocessor. a microprocessor; an input port; an input selector coupled to the input port configured for selecting a voltage divider (140, 130, 120) of a plurality of voltage dividers (140, 130, 120); an output selector coupled to the plurality of voltage dividers (140, 130, 120) configured for coupling the selected voltage divider (140, 130, 120) of the plurality of voltage dividers (140, 130, 120) to an output port; a switching circuit (190A, 190B, 190C) disposed between the output selector and the plurality of voltage dividers (140, 130, 120) configured for selectively coupling the selected voltage divider (140, 130, 120) of the plurality of voltage dividers (140, 130, 120) to either the output selector or to a calibration bridge; the calibration bridge coupled to the switching circuit (190A, 190B, 190C) and a voltage reference source and configured for providing first and second signals to a null detector circuit; and a plurality of calibration adjustment circuits (145, 135, 125), each calibration adjustment circuit (145, 135, 125) coupled to the microprocessor and to a predetermined voltage divider (140, 130, 120) of the plurality of voltage dividers (140, 130, 120); the null detector circuit; wherein in a first configuration an electrical signal at the input port is coupled to the output port via the selected voltage divider (140, 130, 120) of the plurality of voltage dividers (140, 130, 120); and in a second configuration the selected voltage divider (140, 130, 120) of the plurality of voltage dividers (140, 130, 120) is coupled to the calibration bridge and automatically calibrated with the calibration adjustment circuit (145, 135, 125) of the plurality of calibration adjustment circuits (145, 135, 125) associated with the selected voltage divider (140, 130, 120) of the plurality of voltage dividers (140, 130, 120) by a calibration routine in execution upon the microprocessor.