Linear output bridge circuit

A digital set point circuit comprising:

• a pair of input terminals;
• a pair of output terminals;
• a bridge circuit having at least first, second, third and fourth impedance arms, said first and third impedance arms being connected together and to one of said input terminals, said second and fourth impedance arms being connected together and to the other of said input terminals, said first and second impedance arms being connected together and to one of said output terminals and said third and fourth impedance arms being connected together and to the other of said output terminals, said circuit containing sensor means;
• one of said impedance arms comprising at least a most significant digit selector switch for switching between a plurality of digital set point devices;
• and,
• another of said arms comprising a characterizing switch interlocked with said most significant digit selector switch, said characterizing switch for switching a plurality of characterizing devices, each characterizing device having a value associated with each digital set point device for providing an approximation of the operating characteristic of said sensing means to provide a substantially linear output from said bridge.