Figure 6
Signal conditioning circuit. The device is powered by nine volt batteries. The regulator adjusts the excitation voltage to the bridge to 5 V. The half-bridge consists of the variable piezoresistances along one arm and the adjusting resistances on the other arm that are used to balance the output when no tension is applied. The output signal is amplified and is calibrated so that 1 gm tension = 1 mV; thus a millivoltmeter can be used for 1:1 reading of grams of tension sensed by the device. The battery low component of the circuit is given at bottom.