Operation - Extech Instruments LT40 User Manual

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
Power OFF utility, repeat this process.
LUX/FC Button
Press the LUX/FC button to toggle between Lux and FC (foot‐candles) measurement units.
will switch OFF. To enable the Auto
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