Extech Extech 461825 Manual

99 Washington Street
Melrose, MA 02176

Phone [phone]
Toll Free 1-800-517-8431

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User’s Guide

Combination Photo-Tachometer Stroboscope

Model 461825

Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176

FAX [phone] - TestEquipmentDepot.com

Introduction

Congratulations on your purchase of Extech’s Combination Photo­Tachometer/Stroboscope. This professional meter, with proper care, will provide
years of safe reliable service.

Meter Description

1. Tachometer Light Source

2. LCD Display

3. Measure trigger button

4. Memory Recall button

5. FINE adjust knob

6. COARSE adjust knob

7. Range/Function select switch

8. Stroboscope flash tube
Note: Battery compartment is on rear of

meter

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Operation

STROBOSCOPE MEASUREMENT PROCEDURE

Select the Stroboscope Function and Range using the Range/Function Select
Switch. The switch has four positions, three of which are stroboscope-dedicated
with white range numbers. The fourth position is Photo-Tachometer dedicated
and is labeled as such.

Speed Measurements.

1. Remove power to the moving object under test and affix a target mark on

the area to be measured.

2. Apply power to the moving object and press the stroboscope's Measure

Trigger Button.

3. Aim the Stroboscope light beam toward the marked area on the object

under test.

4. Use the FINE and COARSE adjust knobs to synchronize or "stop" the

motion of the object's mark. A single stationary image of the mark
provides actual speed measurement data.

NOTE: Care must be taken to ensure that the mark is providing a 1:1
measurement. This is done by checking that there is only one mark and not t wo,
four, or more stationary marks on the object under test. Two or more stopped
marks indicate "harmonic" measurements (2:1, 3:1, 4;1 etc.) which provide a
doubling, tripling, or quadrupling of the actual speed. A useful method of
avoiding harmonic measurements is to adjust the FINE/COARSE knobs until
two images (marks) appear and then lower the flash rate (via COARSE/FI NE
knobs) until a single, stationary image appears. This is the actual speed.

Inspecting a moving object.

Measure the speed of a moving object as described above and move the FI NE
adjust knob alternately higher and lower to visually inspect all areas of the
device.

3 461825 Ver. 1.2 03/05

Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176

FAX [phone] - TestEquipmentDepot.com

PHOTO-TACHOMETER MEASUREMENT PROCEDURE

1. Select the Photo-Tachometer function by moving the Range/Function
select switch to the PHOTO position.

2. Affix a small piece (approx. 0.5") of supplied reflective tape to the
object under test.

3. Press the meter's Measurement Trigger button and align the Photo­Tachometer light source with the reflective tape mark on the moving
object.

4. Wait until the Monitor Indicator appears in the upper left hand corner of
the LCD indicating that synchronization has occurred.

5. Release the Measure Trigger button only after the reading has
stabilized (approx. 2 seconds).

NOTE: To obtain better accuracy for low RPM measurements (less than 50
RPM) use more than one piece of reflective tape. Divide the meter reading by
the number of reflective tape pieces for accurate measurement data.

MEMORY RECORD AND RECALL

The 461825 can record Maximum, Minimum, and Last Reading for the period of
time during which the Measure Trigger button is held. These stored values can
then be read directly on the meter's display. The memory will automatically
erase after approximately 10 seconds of meter inactivity. Access the memory
data immediately after the measurements.

1. Follow the instructions for normal operation.

2. Release the Measurement Trigger button.

3. Immediately press the Memory Recall button once to display the Last
Reading taken during the measurement period. 'LA' will alternately
display with the data reading to indicate 'Last Reading".

4. Release and press the Memory Recall button again to display the
Maximum reading taken during the measurement period. 'UP' will
alternately appear with the data reading to indicate Max. reading.

5. Release and press the Memory Recall button again to display the
Minimum reading taken during the 30 second test period. 'dn' will
alternately appear with the data reading to indicate Min. reading.

4 461825 Ver. 1.2 03/05

Specifications

General Specifications

Custom LSI microprocessor based design

Circuit
Display Reversible, 0.4" (10mm) 5-digit (99999 count) LCD display
Measurement
units
Memory Recall Records/Recalls Max/Min/Last readings with memory push-

Operating
Temperature
Operating
Humidity
Power Supply Four 1.5V 'AA" batteries (UM-3 or equivalent)
Weight 0.66 lb. (300g)
Dimensions 8.5x2.6x1.5" (215x65x38mm)
Accessories Reflective tape and carrying case

RPM (revolutions or rotations per minute)

button
32 to 122oF (0 to 50oC)

< 80% RH

Electrical Specifications

Measurement Range

Resolution 0.1 RPM (<1000 RPM) and 1 RPM (> 1000
Accuracy ± (0.1% + 2 digits)

Sampling Time 1 second (> 60 RPM)
Photo Tachometer detection
distance

Stroboscopic Flash rate 100 to 100,000 FPM (flashes per minute)
Stroboscopic Flash adjust
range

Stroboscopic Flash tube type High efficiency LED lamp
Stroboscopic Flash duration 60 to 1000 microseconds (approx. 16% of

Stroboscopic Flash Color Orange

5 to 99,999 RPM for the Tachometer

100 to 100,000 FPM/RPM for the
Stroboscope

RPM)

2 to 6" (50 to 150mm) typical
Note: Detection distances up to 12"
(300mm) are possible depending upon
ambient light

Range A: 100 to 1,000 FPM
Range B: 1000 to 10,000 FPM
Range C: 10,000 to 100,000 FPM

period)

5 461825 Ver. 1.2 03/05

Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176

FAX [phone] - TestEquipmentDepot.com