| Deflection vs. Voltage Figure 1.0 Bend Sensor® Voltage Divider: For a simple deflection-to-voltage conversion, the Bend Sensor® device is tied to a resistor RM in a voltage divider configuration. The output is described by the equation: VoUT = (V+) /[1+ Rm / RBend Sensor®] In the shown configuration, the output voltage increases with increasing deflection. If RBend sensor® and Rm are swapped, the output swing will decrease with increasing deflection. These two output forms are mirror images about the line VoUT = (V+) / 2. The measuring resistor, RM, is chosen to maximize the desired deflection sensitivity range and to limit current. Suggested op-amps for single sided supply designs are LM358 and LM324. FET input devices such as LF355 and TL082 are also good. The low bias currents of these op-amps reduce the error due to the source impedance of the voltage divider. A family of DEFLECTION vs. VoUT curves is shown in Figure 1.0 for a standard Bend Sensor® device in a voltage divider configuration with various RM resistors. A (V+) of +5V was used for these examples. |