461950 Datasheet, PDF (5/6 Pages) Extech Instruments Corporation. – Panel Mount Digital Tachometer

Meter and Sensor Operation
Meter Operation
Mount and wire the meter as previously described. The Model 461950 Panel Mount
Tachometer was designed to measure and display RPM in the following ranges:
Ranges
5 – 999.9 rpm
1000 - 9999 rpm
10,000 - 99,990 rpm
Resolution
0.1 rpm
1 rpm
10 rpm
Accuracy (of rdg)
±(0.05% + 1 digit)
Extech sensors generate pulses that are counted by the meter and converted to RPM. The
meter computes RPM values based on the number of pulses detected in a given period of
time and provides an RPM display on the 4 digit (9999 count) LED.
Operation of the Proximity Switch Model 491955
The Extech Proximity Switch Model 461955 connects directly to the tachometer's input
terminals and measures up to 36,000 RPM (600 Hz). Proximity switches detect magnetic
(ferrous) objects as they pass the sensor, sending a pulse, one for each pass, to the
meter. The pulse LED on the switch lights with each pass. The meter then calculates RPM
and updates the LED display.
Operation of the Photoelectric Sensor Model 461957
Extech Photoelectric Sensor Model 461957 connects directly to the tachometer's input
terminals and measures up to 6,000 RPM (100Hz). When the sensor is properly powered
(by the voltage on terminal 3 of the meter), the green power LED (on the sensor) will
switch on.
Photoelectric sensors generate a light beam that is interrupted by an object as it passes
through the beam. Each time the beam of light is interrupted a pulse is transmitted to the
meter and the red status LED on the sensor blinks. The meter then calculates and displays
the RPM based on the number of pulses received in a specific period of time.
The sensitivity adjustment screw on the sensor may have to be adjusted so that one pulse
is generated for each interruption of the light beam. If the red LED turns on less/more than
once for each interruption of the beam, adjust the sensitivity screw.
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Model 461950 Version 2.0 March 2005