Extech Instruments 461920 User manual
USER MANUAL
Extech Mini Laser Photo Tachometer /
Counter — Model 461920
Introduction
1
Congratulations on your purchase of the Extech Mini Laser Photo Tachometer
/ Counter, Model 461920. This instrument provides non-contact RPM (rota-
tions per minute) and Count (revolutions) measurements. The laser pointer al-
lows for accurate measurement targeting. This instrument is shipped fully
tested and calibrated and, with proper use, will provide years of reliable
service.
Additional User Manual Translations available at www.extech.com
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Safety
3
CAUTION
Rotating objects can be dangerous. Use extreme care.
WARNING
Do not directly view the laser beam or point it toward the eyes.
Low power visible lasers do not normally present a hazard but may present some potential
for hazard if viewed directly for extended periods of time.
See laser safety information below and on meter label.
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Meter Operation
4
4.1 RPM Mode (Rotations per Minute)
1. To set the meter to measure RPM, press and release the Measure but-
ton and then use the MODE button to select RPM on the display.
2. Apply an appropriately sized square piece of reflective tape (typically 0.5
in. [12 mm]) to the surface of the object under test.
3. Point the meter toward the device under test at a 2 to 20 in. (50 to 500
mm) distance.
4. Press and hold the Measure button and aim the laser at the reflective
tape.
5. Verify that the monitor indicator (()) appears on the display when the re-
flective tape passes through the light beam.
6. When the Measure button is released, the last reading will remain on the
display for approximately 5 seconds, and then the meter will switch off.
7. With the meter OFF, use the MEM (memory) button to recall the MAX,
MIN, and LAST RPM readings.
4.2 COUNTER Mode (Revolutions)
1. To set the meter to measure Counts, short press the Measure button
and then use the MODE button to select REV on the display.
2. Point the meter toward the device under test at a 2 to 20 in. (50 to 500
mm) distance.
3. Press the Measure button and aim the laser at the object under test.
4. Verify that the monitor indicator (()) appears on the LCD when the object
passes through the light beam.
5. When the Measure button is released, the last reading will remain on the
display for approximately 5 seconds, and then the meter will switch off.
6. With the meter OFF, press the MEM button to recall the final count value.
4.3 Measurement Notes
• Bright ambient light can interfere with measurement accuracy. Hold the
meter close to the target, or shade the target area, if necessary.
• The nonreflective area must be larger than the reflective area on the object
under test.
• If the shaft or rotating object is inherently reflective, cover it with black tape
or paint before applying the reflective tape.
• To improve repeatability of low RPM measurements, apply additional
squares of reflective tape. Divide the reading shown on the display by the
number of pieces of tape to calculate the actual RPM.
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Battery Replacement
5
The low battery indicator appears on the display when the battery needs
replacing. To replace the battery, open the rear battery compartment by re-
moving the two Phillips head screws. Replace the 9 V battery observing cor-
rect polarity. Secure the battery compartment cover before using the meter.
Do not dispose of used batteries or rechargeable batteries in house-
hold waste.
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Specifications
6
6.1 General Specifications
Time base Quartz crystal
Display type 5 digit (99999) LCD
Laser type Class 2 laser ≤1 mW power @ 630 to 670 nm
Detection distance 2 to 20 in. (50 to 500 mm)
Sampling time 0.5 seconds (> 120 RPM)
Reflective tape Replacement part no. 461937
Memory Recall the MIN, MAX, and LAST readings for RPM
measurements
Recall the final count value for REV measurements
Operating conditions 32 to 122℉(0 to 50℃); RH 80%, maximum
Power supply 9 V battery or optional AC Adaptor (part no. UA100-240)
Power consumption 45 mA DC; typical
Weight 5.3 oz. (151 g)
Dimensions 6.2 x 2.3 x 1.6 in. (160 x 60 x 42 mm)
6.2 Measurement Specifications
Range Resolution Accuracy
Tachometer 2 to 99, 999 RPM 0.1 RPM (< 1000
RPM)
1 RPM (> 1000
RPM)
± (0.05% of reading
+ 1 digit)
Counter 1 to 99,999 REV 1 count ± 1 count
#NAS100117; r. AA/86449/86449; en-US 6
Two-year Warranty
7
FLIR Systems, Inc. warrants this Extech brand instrument to be free of
defects in parts and workmanship for two years from date of shipment (a six-
month limited warranty applies to sensors and cables). To view the full war-
ranty text please visit: http://www.extech.com/support/warranties.
7.1 Calibration and Repair Services
FLIR Systems, Inc. offers calibration and repair services for the Extech
brand products we sell. We offer NIST traceable calibration for most of our
products. Contact us for information on calibration and repair availability, refer
to the contact information below. Annual calibrations should be performed to
verify meter performance and accuracy. Product specifications are subject to
change without notice. Please visit our website for the most up-to-date prod-
uct information: www.extech.com.
7.2 Contact Customer Support
Customer Support Telephone List: https://support.flir.com/contact
Technical Support:https://support.flir.com
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#NAS100117; r. AA/86449/86449; en-US 8
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5
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