Model AA30-4 Four Channel AC LVDT Conditioner
is a four-channel conditioner for measurement of displacement, force, pressure, and other parameters obtained with a linear variable differential transformer (LVDT) or variable reluctance transducer. Based on the synchronous carrier-demodulator principle, the AA30-4 supplies regulated, remotely sensed AC excitation for each active transducer channel—thus allowing direct measurement of thickness (when two separate inputs are summed) or of taper (when their difference is calculated). It then demodulates, filters, and amplifies the resulting signals to produce system outputs precisely proportional to LVDT core displacement.
The AA30-4 automatically adjusts to the signal phase shift of the transducer in use, thereby insuring optimum sensitivity and linearity. Unlike the Model 10A30-2C or 10A31-4, the Model AA30-4 does not require special cabling to accommodate “long-stroke” LVDT's (full-scale range of ±1 inch or greater). Also, the AA30-4's enhanced linearity correction lets it accommodate a wider range of displacement transducers. Like most Daytronic “Advanced Analog” (“AA”) cards, the AA30-4 features optional PROGRAMMABLE LOW-PASS ACTIVE FILTERING for the removal of unwanted high frequency measurement-signal components. Selectable analog filtering is offered for the AA30-4F1 from 0.2 through 200 Hz in 16 steps—or, if desired, a fixed filter of either 10 or 50 Hz for all channels may be specified at the time of order.
When the AA30-4 is used in System 10, its filter cutoff values are set by means of an on-board 16-position switch for each channel. A nominal ±5-V ANALOG OUTPUT is produced by each active AA30-4 input channel, for purposes of real-time signal monitoring. Each of these “Auxiliary Outputs” is available on a corresponding mainframe wire-wrap pin. Each output may be individually set, if desired, to represent the prefiltered value of the corresponding input. Separate excitation for each channel uses remote sensing of excitation voltage and is slaved to a common System Reference Voltage. The result is consistently stable ratio metric measurement, unaffected by possible power-supply drift. A “Slave Excitation” input is available if the user wishes to provide an external excitation voltage and frequency instead of the AA30-4's internal supply.