The single-channel Model 4040 is used 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.
This instrument accepts an exceptionally wide range of waveshapes and voltage levels. Its analog-input threshold level is selectable to accommodate signals from 250 mV to 100 V, thus guaranteeing reliable triggering when the input is at the low end of the frequency range.
Capacitive coupling of 0.1 μF and/or 10 μF is provided for low-frequency inputs, to eliminate false triggering by signal noise or any DC offset (positive or negative) that exists for the frequency signal. For "zero-velocity" sensors, nominal ±5 VDC excitation is supplied.
When you know the manufacturer-supplied full-scale rating of the frequency source (or the highest frequency expected to be measured), the Model 4040 can be quickly and easily calibrated by issuing a special FREQUENCY CALIBRATION (FRQ) command through the Interface Port or optional Model 10P80D Extended Keyboard. A precise 2.048000-MHz crystal frequency reference ensures accuracy of all calibrations.
For a 4000 Series instrument based on both the Model 4040 and the Model 4078 AC Strain Gage Instrument, and dedicated to the measurement of torque, rpm, and horsepower, see the Model 4K/HP Horsepower Instrument.