Variable-phase resistive transducer, and method of operating same

A transducer for producing a digital output signal proportional to a change in a sensed physical parameter, comprising:

• a first pair of series-connected resistors;
• a second pair of series-connected resistors;
• the electrical resistance of at least one of said resistors being variable in response to a change in said sensed parameter;
• first excitation means for applying a first exciting alternating voltage at a particular frequency across said first pair;
• second excitation means for applying a second exciting alternating voltage at said frequency across said second pair;
• said first and second exciting voltages having identical waveforms but being shifted relative to one another by a constant phase angle;
• summing means for vector-summing the voltage existing at a point between the resistors of the first pair with the voltage existing at a point between the resistors of the second pair to provide a vector-summed output signal;
• and
• a counter operatively arranged to count the time difference between the occurrence of a distinguishing waveform event of said vector-summed signal and the occurrence of a like distinguishing waveform event of the exciting voltage referred to;
• whereby said time difference count will be a digital output signal proportional to the change in said sensed physical parameter.