Extech Instruments 461920 User manual

USER MANUAL
Model 461920
Laser Photo Tachometer and Counter
AdditionalUserManualTranslationsavailableatwww.extech.com

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Introduction
Congratulations on your purchase of Extech's Mini Laser Photo Tachometer, Model 461920. This
Tachometer provides non-contact RPM and count measurements. The laser pointer beam
provides accurate long distance measurements for photo tachometer measurements. This meter
is shipped fully tested and calibrated and, with proper use, will provide years of reliable service.
Meter Description
1. Photo Tachometer sensor and laser source
2. MEASURE button
3. MEMORY button
4. MODE button
5. AC Power Adaptor
6. Battery compartment (rear)
CAUTION: Rotating objects can be dangerous. Use extreme care.
WARNING: Do not directly view or direct the laser pointer at an eye. 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.
Laser complies with: FDA 21 CFR 1040.10 and 1040.11, IEC 60825-1 (2001-2008) Edition 1.2
EN 60825-1:1994/A11:1996/A2:2001/A1:2002

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Meter Operation
RPM Measurement Mode
1. To set the units to RPM, Press and release the MEAS button and press the MODE button until
RPM appears on the display.
1. Apply an appropriately (0.5”/12mm) sized square piece of reflective tape to the surface of the
object under test.
2. Point the meter toward the device under test at a distance of 2" to 20" (50 to 500mm).
3. Press the Measure button (MEAS) and align the laser light beam straight on with the reflective
tape.
4. Verify that the ((( ))) Monitor Indicator appears on the LCD when the reflective tape passes
through the light beam.
5. When the Measure button is released the last reading will remain in the display for 5 to 10
seconds before the Auto Power Off feature turns the meter off.
6. With the meter OFF, press the MEM (memory) button to recall the MAX, MIN and LAST rpm
values.
COUNT Mode
1. To set the units to measure Counts, Press and release the MEAS button and press the MODE
button until REV appears on the display.
2. Point the meter toward the device under test at a distance of 2" to 20" (50 to 500mm).
3. Press the Measure button (MEAS) and align the laser light beam to the objects being counted.
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 in the display for 5 to 10
seconds before the Auto Power Off feature turns the meter off.
6. With the meter OFF, press the MEM (memory) button to recall the last count (REV) from the last
measurement period.
Measurement Notes
1. Bright ambient light may interfere with the reflected light beam. Holding the tachometer closer to
the target or shading the target area may be necessary in some cases.
2. The non-reflective area must always be larger than the reflective area.
3. If the shaft or rotating object is normally reflective, it must be covered with black tape or paint
before the reflective tape is applied.
4. 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 reflective tape squares to
calculate the actual rpm.

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Battery Replacement
The low battery indication appears as “ " on the display. To replace the batteries, loosen the two Philips head
screws securing the rear battery cover and lift the cover off. Replace the 9V battery and replace cover.
Never dispose of used batteries or rechargeable batteries in household waste. As consumers, users are legally
required to take used batteries to appropriate collection sites, the retail store where the batteries were purchased,
or wherever batteries are sold.
Disposal: Do not dispose of this instrument in household waste. The user is obligated to take end-of-life devices to
a designated collection point for the disposal of electrical and electronic equipment.
Specifications
Time base Quartz crystal
Display 5 digit LCD display
Laser light source Class 2 laser < 1mW power; Wavelength is 630 to 670nm
Detecting Distance 2 to 20" (50 to 500 mm)
Sampling Time 0.5sec (over 120 rpm)
Tachometer accuracy ± (0.05% reading + 1digit)
Memory Last reading and MIN/MAX readings
Operating Conditions 32 °F to 122 °F (0 °C to 50 °C); RH 80% Max
Power Supply Internal 9V battery or external AC Adaptor (6 to 9VDC) (Part# UA100-240)
Power Consumption 45mA DC approx.
Weight 5.3oz. (151g)
Size 6.3x2.3x1.6" (160x58x39 mm)
Parts Reflective Tape Part# 461937
Range Specifications
Range Resolution Accuracy (%reading)
Photo Tachometer 2 to 99,999 rpm 0.1 rpm (<1000rpm)
1 rpm (>1000 rpm) ± (0.05% + 1d)
Counter 1 to 99,999 REV 1 count ± 1 count
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