Model 10A40 Single Channel Frequency Conditioner
This single-channel conditioner is for measurement of flow, rpm, and other phenomena that can be sensed by pulse transformer transducers with two-wire isolated windings (tachometer pickups, turbine flowmeters, etc.), transistor or logic-circuit drivers, “zero-velocity” (true digital output) sensors, and similar frequency-generating transducers. The 10A40 accepts a wide range of wave shapes and voltage levels, either grounded or floating—though it is not recommended for measuring frequencies under 25 Hz without special modification.
The “Smart Schmitt” input threshold automatically adjusts to accommodate signals from 10 mV to 200 V. Nominal ±5 V-DC excitation is supplied for use with a “zero-velocity” sensor. Capacitive coupling of 0.1 or 10 μF is provided for low-frequency inputs, to eliminate false triggering by signal noise and/or any positive or negative DC offset that exists for the frequency signal. A special trigger-level control guarantees reliable triggering when the input is at the low end of the voltage range.
The System 10 Central Processor controls frequency-range selection and applies an appropriately calculated scaling factor to each measurement, if desired, following initial entry of a special FREQUENCY CALIBRATION (FRQ) command. This convenient “calculated” calibration technique can be used when the manufacturer- supplied full-scale rating of the frequency source (or the highest frequency expected to be measured) is known. A precise 2.097152-MHz crystal frequency reference ensures accuracy of all calibrations, whether “absolute,” “calculated”, or “two-point” (“dead-weight”).