How do I use a String Potentiometer (A.K.A.: String Pot; Yo Yo Pot; Draw Wire Transducer) with an eDAQ Low Level Board (LLB) or Bridge Board (BB)?

The Wiring described is for an un-conditioned 3-wire potentiometer. This wiring diagram can be used with any simple potentiometer, string pot, angular or linear displacement potentiometer.

It does not apply to yoyo or displacement type transducers that have conditioned outputs, such as, 4 to 20 mA or 0 to 5 Volt output.

For your potentiometer based transducer, use 5 or 10 Volt excitation and wire as illustrated. When using 10 Volt excitation, the resistance of the potentiometer must be greater than 350 Ohms. The Bridge Board and LLB provide Bi-polar excitation which means that the output of the Potentiometer will be around zero Volts when the pot's wiper is centered and the signal should swing close to the excitation voltage rails.

In TCE for the Bridge Type use "Diff Ampl". Although the pot is a resistive device, DO NOT use Bridge Types of Full or Half Bridge.

For calibration in TCE the best method of calibration is use sensitivity readings from the manufactures calibration data sheet. The first entry into the LLB or BB calibration table could be an external value (typically zero) and the second entry a Defined Span from the manufacture's data sheet. If sensitivity data is not available, You can enter External Value and External Span in the calibration table. Again the first External Value calibration point will be zero. The External Span will require applying two known and precise displacement points (span) when prompted by TCE during the calibration process.