Model 10A41-2C Dual Channel Frequency Conditioner
Employing a 1-MHz crystal reference, the two-channel Model 10A41-2C 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 10A41-2C 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” threshold level for each input channel may be individually selected via internal jumper connections, depending on the expected peak voltage input. This ensures reliable triggering when the input is at the low end of the voltage range. All ranges are protected against an overload of up to 200 V. Nominal ±5 V-DC excitation is supplied for use with a “zero-velocity” sensor. Capacitive coupling of 0.1 or 22 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. One of four separate filter bandwidths is available for each input channel: 1.25 Hz; 2.5 Hz; 5 Hz; or 12.8 Hz.
Per-channel bandwidth is selectable via internal jumpers. Each channel is normally preset for the 1.25-Hz bandwidth, which, while yielding the slowest response, also provides the widest dynamic range for high-frequency inputs (2% to 100% of full scale for the 1-kHz and 2-kHz ranges; 1% to 100% of full scale for ranges above 2 kHz). For faster response, you may select one of the higher filter bandwidths. 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 for a 10A41-2C data channel when the manufacturer-supplied full-scale rating of the frequency source (or the highest frequency expected to be measured) is known. The 1-MHz crystal frequency reference ensures accuracy of all calibrations, whether “absolute,” “calculated” , or “two-point” (“dead-weight”).