Extech Instruments LT250W User manual

User Manual

LT250W Light Meter

Bluetooth®Connectivity with the ExView®Mobile App

Table of contents

1 Introduction........................................................................1

2 Safety ................................................................................2

3 FCC Compliance .................................................................3

4 Product Description ............................................................4

4.1 Meter Description .......................................................4

4.2 Function Buttons ........................................................4

4.3 Display Symbols.........................................................5

5 Operation...........................................................................6

5.1 Powering the Meter ..................................................... 6

5.2 Auto Power Off (APO)..................................................6

5.3 Taking Measurements .................................................6

5.4 Changing Measurement Units ....................................... 7

5.5 Data Hold Function .....................................................7

5.6 LCD Backlight............................................................ 7

5.7 MAX/MIN Readings .................................................... 7

5.8 Bluetooth Operation ....................................................7

6 Maintenance.......................................................................9

6.1 General Cleaning .......................................................9

6.2 Battery Replacement...................................................9

7 Specifications................................................................... 10

7.1 General Specifications............................................... 10

7.2 Measurement Specifications ....................................... 10

7.3 Environmental Specifications ...................................... 10

7.4 Connectivity Specifications ......................................... 11

8 Two-year Warranty............................................................. 12

8.1 Calibration and Repair Services................................... 12

8.2 Contact Customer Support ......................................... 12

#NAS100076; r. AA/78957/78963; en-US ii

Introduction

Thank you for selecting the Extech LT250W Light Meter. This meter measures

illuminance and displays it in Lux or foot candle units on the backlit LCD. Light

is captured by the built-in domed photo-cell, situated at the top of the meter.

The meter includes Bluetooth connectivity, MAX/MIN memory, selectable unit

of measure, auto power off, data hold, backlit LCD, and tripod mount.

Using the Extech ExView mobile app, you can pair your smart devices with

the meter using Bluetooth. The app and the W Series meters were developed

together for seamless integration. Download the free app from the App Store

(iOS®) or from Google Play (Android™).

This quality instrument is designed to provide years of reliable service, high

accuracy and simple operation. Please visit the Extech website for additional

information and world-class support.

#NAS100076; r. AA/78957/78963; en-US 1

Safety

Please read all safety information before using this device

CAUTION

• Check for damage to the device’s housing, sensor, display, and battery compartment

before use. If obvious damage or abnormalities are noticed, please discontinue use

and return the device for service.

• Do not attempt to open the meter housing or access the sensor module. There are no

user-serviceable components in this device.

• Replace the batteries immediately after the low battery symbol appears. If the device is

to be stored for a period of months, please remove the batteries and store separately.

• Do not store the device in high temperature or humidity environments, in flammable or

combustible areas, or where a strong electromagnetic field is present.

• This device is CE certified.

#NAS100076; r. AA/78957/78963; en-US 2

FCC Compliance

This equipment has been tested and found to comply with the limits for a

Class B digital device, pursuant to part 15 of the FCC Rules. These limits are

designed to provide reasonable protection against harmful interference in a

residential installation. This equipment generates, uses, and can radiate radio

frequency energy and, if not installed and used in accordance with the instruc-

tions, may cause harmful interference to radio communications. However,

there is no guarantee that interference will not occur in a particular installation.

If this equipment does cause harmful interference to radio or television recep-

tion, which can be determined by turning the equipment off and on, the user is

encouraged to try to correct the interference by one or more of the following

measures:

1. Reorient or relocate the receiving antenna.

2. Increase the separation between the equipment and receiver.

3. Connect the equipment into an outlet on a circuit different from that to

which the receiver is connected.

4. Consult the dealer or an experienced radio/TV technician for help.

WARNING

Changes or modifications not expressly approved by the party responsible for compliance

could void the user's authority to operate the equipment.

#NAS100076; r. AA/78957/78963; en-US 3

Product Description

4.1 Meter Description

1. Light sensor

2. Backlit LCD (detailed below)

3. Function buttons (detailed below)

4. Tripod mount

5. Battery compartment

4.2 Function Buttons

Power / Bluetooth button

Long press to switch the device on. Short press to switch off.

With meter powered, long press to switch Bluetooth on/off.

Short press to switch the meter off directly from the Bluetooth mode.

MAX/MIN button

Short press to cycle through MAX/MIN readings. MAX/MIN memories

are cleared each time meter power is cycled.

Data Hold / Backlight button

Short press to freeze/unfreeze the displayed reading. HOLD will display

when data hold is active.

Long press to switch the LCD backlight on/off.

#NAS100076; r. AA/78957/78963; en-US 4

Product Description

Unit of Measure button

Short press to toggle Lux and foot candle (fc) units. Lux is the standard

measurement unit, Foot candle readings are calculated.

APO ON/OFF With the meter on, long press the power and Hbuttons to switch APO

on/off. The APO symbol is displayed when APO is enabled. APO is

reset each time the meter power is cycled.

4.3 Display Symbols

1. Bluetooth active

2. Illuminance measurement

3. Maximum and Minimum reading modes

4. Data Hold

5. Low battery symbol

6. Unit of measure symbols

7. x10 and x100 indicators (multiply reading)

#NAS100076; r. AA/78957/78963; en-US 5

Operation

5.1 Powering the Meter

The meter operates on three (3) 1.5 V (AAA) batteries, installed in the rear

compartment.

Long press the power button to switch the meter on. Short press the power

button to switch the meter off. If the meter does not switch on, check the bat-

teries for proper orientation.

When the low battery symbol appears on the display, replace the batteries

immediately to ensure accurate readings.

5.2 Auto Power Off (APO)

The meter switches off automatically five (5) minutes after the last button

press.

The default mode for APO is ON (the APO symbol indicates that APO is

enabled).

To switch the APO function off, with the meter switched on, long press the

power and data hold (H) buttons. The APO symbol will switch off, indicating

that the function is disabled. APO is reset each time the meter’s power is

cycled.

Repeat this process to switch APO back on manually.

5.3 Taking Measurements

1. Long press the power button to switch the meter on.

2. Hold the meter in hand, set it face-up on a table or desk, or mount it on a

tripod in the area under test.

3. For best results, allow the light to fully encompass the sensor dome. Also,

reduce the ‘angle of incidence’ as much as possible (angle at which the

light strikes the dome).

4. Read the illuminance reading on the LCD. If the x10 or x100 display ap-

pears, multiply the displayed reading by 10 or 100 to obtain the actual

measurement.

5. If the measurement is out of range, OL will appear on the display in place

of a typical reading.

#NAS100076; r. AA/78957/78963; en-US 6

Operation

CAUTION

Do not touch or otherwise obstruct the sensor.

Do not allow liquids to come in contact with the sensor.

5.4 Changing Measurement Units

Short press the LUX / FC button to toggle the displayed unit of measure (Lux

or foot candles).

5.5 Data Hold Function

Short press the Data Hold (H) button to freeze/unfreeze the displayed read-

ings. While Data Hold is active, HOLD will appear on the LCD.

5.6 LCD Backlight

Long press the backlight button to switch the display backlight on or off.

Excessive use of the backlight will shorten battery life.

5.7 MAX/MIN Readings

When the device is switched on, it begins tracking the highest (MAX) and low-

est (MIN) readings.

Short press the MAX/MIN button to step through the MAX/MIN memories.

MAX will show when the Maximum reading is displayed and MIN will show

when the Minimum reading is displayed. The memories are cleared each time

the meter power is cycled.

Press the MAX/MIN button again to exit this mode (MAX and MIN symbols

switch off when you exit).

5.8 Bluetooth Operation

Long press the Bluetooth button with the meter on, to switch Bluetooth on

or off. This communication symbol is shown when Bluetooth is on.

The Bluetooth utility allows you to remotely monitor readings on an iOS or An-

droid smart device using the Extech ExView mobile app designed for use with

this meter.

Download the ExView mobile app from the App Store for iOS devices or from

Google Play for Android devices. Instructions for mobile app use are available

from the ExView product page on the Extech website (link below).

#NAS100076; r. AA/78957/78963; en-US 7

Operation

http://www.extech.com

Switch APO off when using Bluetooth by pressing and holding the power

and Hbuttons for 2 seconds (the APO symbol will switch off). This will pre-

vent the meter from automatically switching off while you are logging data or

monitoring readings in real time on your smart device.

#NAS100076; r. AA/78957/78963; en-US 8

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