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Summary of Contents for Extech Instruments LT40
- Page 1 USER GUIDE White LED Light Meter Model LT40 ...
- Page 2 Introduction Congratulations on your purchase of the Extech LT40 LED Light Meter that measures light from white LED light, fluorescent, metal halide, high‐pressure sodium and incandescent sources. The LT40 can measure light up to 400,000 Lux (40,000 Fc). The LT40 offers an overload indication, low battery indication, Data hold, maximum/average/minimum hold (MAX/MIN), Zero adjustment, auto power off with disable function, and auto ranging features. This instrument is shipped fully ...
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Page 3: Meter Description
Meter Description Photo detector (remove protective cover to expose sensor) Display (LCD) Control push‐buttons Power Button: ON/OFF Battery compartment and tripod mount are located on rear of instrument Push‐Button Description Lux/Fc units selector Calibration and ZERO button Maximum/Average/Minimum memory button Data hold button LT40-EU-EN v1.3 9/13... -
Page 4: Operation
Operation Power ON‐OFF Press and hold the Power button for at least 2 seconds and then release to power the meter. To power the meter OFF, momentarily press the Power button. Taking Measurements 1. Switch the meter ON and remove the sensor’s protective cover to expose the light sensor dome. The display should switch ON, if not check that batteries are installed and fresh. 2. The meter measures the intensity of the light (illuminance) that strikes the sensor dome in foot candles and lux units (1 fc = 10.76 lux), displaying this measured value on its LCD. 3. Position the meter and light source so that the light strikes the sensor dome straight on (perpendicular) with as little an angle as possible. 4. The meter’s display can show a value up to 3999. However, for readings that represent measurements higher than this, the meter uses x10 feature (right‐most decimal point flashing). For example, to represent a measurement of 39,999 the meter will display 3999 with the right‐most digit flashing. Auto Power OFF To save battery life, the meter powers down automatically after approximately 12 minutes of inactivity. Enable/Disable Auto Power Off While the meter is ON, press and hold the Power button for at least 2 seconds (and then release) to disable the Auto Power OFF utility; the Clock symbol will switch OFF. To enable the Auto Power OFF utility, repeat this process. LUX/FC Button Press the LUX/FC button to toggle between Lux and FC (foot‐candles) measurement units. LT40-EU-EN v1.3 9/13... -
Page 5: Max/Min Button
2. Press the “MAX/MIN” button again to switch from “MAX” to “AVG”, where the meter will show the average measurement value. The “AVG” icon will be displayed above the displayed value. 3. Press the “MAX/MIN” button again to change the mode from “AVG” to “MIN”, where the meter will show the minimum value measured. The “MIN” icon will be displayed. 4. Press the “MAX/MIN” button again to switch from “MIN” back to “MAX”. 5. To exit this mode, hold the “MAX/MIN” button for at least 2 seconds. The MAX/AVG/MIN icons should all be switched OFF when the unit returns to the normal operating mode. Data ‘Hold’ Button Press the HOLD button to freezes the current reading on the LCD. Press the HOLD button again to release the reading. CALIBRATION and ZERO Buttons 1000 LUX Calibration Prepare a 2856 K/1000 Lux light source and face the meter’s sensor perpendicularly toward the light source. Simultaneously press and hold both the “CAL/ZERO” button and the power button for at least 2 seconds. Release the buttons when “CAL” is displayed on the LCD screen. Press and hold the “CAL” button for 2 more seconds, and the LT40 will power down. The meter is now calibrated. ZERO Calibration Ensure that the protective cover is attached to the light sensor. Power the meter and the LCD should display ‘0’. Momenarily press the “ZERO” button for the zero adjustment and the CAL icon will switch ON. The CAL icon will switch OFF when the calibration has been completed. If the protective cap is not covering the sensor when the ZEO calibration is started the LCD display will read “CAP”. In this case, please cover the sensor with the cap and restart this procedure. LT40-EU-EN v1.3 9/13... -
Page 6: Battery Replacement And Maintenance
When the meter is to be stored for long periods, please remove the batteries and store them separately. Batteries can leak and cause damage to the meter’s components. Avoid areas of high temperature and humidity when using this instrument. Battery Replacement and Maintenance Cleaning and storage 1. The white plastic sensor dome should be cleaned with a damp cloth when necessary. Use only a mild soap if needed. Do not use solvents, abrasives, or harsh detergents to clean the dome. 2. Store the meter in an area with moderate temperature and relative humidity. Battery Replacement When the battery power decreases to a critical level, the low battery symbol “ ”will appear on the LCD. Replace the 2 x 1.5V AAA batteries located in the rear battery compartment. The battery compartment slides easily downward for removal. Ensure that the compartment cover is securely fastened before using the meter. 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. Battery Safety Reminders o Please dispose of batteries responsibly; observe local, state, national regulations. o Never dispose of batteries in a fire; batteries may explode or leak. o Never mix battery types; install new batteries of the same type. LT40-EU-EN v1.3 9/13... -
Page 7: Specifications
60 ±6% 80 ±25% General Specifications Sampling rate 2.5 times per second (digital display) Photo detector Silicon photo‐diode with spectral response filter and cosine correction Operating conditions Temperature: 5 to 40 C (41 to 104 F); Humidity: < 80% RH Storage conditions Temperature: ‐10 to 60 C (14 to 140 F); Humidity: < 70% RH Low battery indication “ ” appears on the LCD when battery voltage falls critically low LED Type White LED light can be accurately measured Power supply 2 x 1.5V ‘AAA’ batteries Battery life Approximately 200 hours Auto Power OFF Meter switches OFF after 12 minutes of inactivity Dimensions 133 x 48 x 23 mm (5.2 x 1.9 x 1”) Weight 250 g. (8.8 oz.) including batteries LT40-EU-EN v1.3 9/13... - Page 8 200‐750 20‐75 Medical Exam Room 750‐1,500 75‐150 Show Window, 750‐1,500 75‐150 Operating Room Packing Table 1,500‐3,000 150‐300 Storefront, Show Window 5,000‐10,000 500‐1000 Eye Inspection Spectral Sensitivity Peak sensitivity wavelength: 550nm; Deviation from comparative luminosity standard: JIS standard C1609‐1993. LT40 WAVELENGTH (nm) Copyright © 2013 FLIR Systems, Inc. All rights reserved including the right of reproduction in whole or in part in any form www.extech.com LT40-EU-EN v1.3 9/13...
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