Patent ID: 7301352

Claim:
A sensor circuit having a first Part, the first Part comprising: an operational amplifier equipped with an inverting input, a non-inverting input, and an output, a plurality of resistance-based sensors electrically connected to one another in a parallel configuration having first and second sides across which a voltage can be applied wherein the voltage so-applied will be identical across each of the sensors, the first side of the parallel configuration connected to a connecting junction, and the second side of the parallel configuration connected to a ground terminal, a feedback resistor connected between the operational amplifier output and the connecting junction, a variable voltage source and a first series resistor connected in series between the ground terminal and the connecting junction wherein a voltage at the output of the operational amplifier can be adjusted to zero by adjusting the voltage output of the variable voltage source, and a constant voltage source with a constant voltage source first end connected to the non-inverting input of the operational amplifier, and a constant voltage source second end connected to the ground terminal.