La Crosse WT-5431 Digital Atomic Projection Alarm Clock



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La Crosse WT-5431 Digital Atomic Projection Alarm Clock
with Wireless Indoor Outdoor Thermometer

Radio Controlled Atomic clock Wireless Thermometer Displays Remote Temperature Digital Thermometer Displays Indoor Temperature Atomic Clock Displays Time Wireless Thermometer Displays Outdoor Temperature Atomic Clock Displays Date Atomic Clock Displays Day Of Week Digital Thermometer Selectable for Fahrenheit or Celsius  
For definitions of the feature icons, please click any icon.

The La Crosse WT-5431 Digital Atomic Projection Alarm Clock calibrates itself to the world's most accurate clock every night by receiving WWVB radio transmissions. These transmissions contain time information from the U.S. atomic clock source, operated by the U.S. Commerce Department near Boulder, Colorado. The built-in antenna ensures reliable signal reception up to 2000 miles (3200km) from the WWVB transmitter.

La Crosse WT-5431 Digital Atomic Projection Alarm Clock
Click to Enlarge

The WT-5431 atomic projection clock is titanium in color and features gracefully rounded styling accents. Its LCD display shows time of day, date, time zone, and indoor and outdoor  temperature (selectable). The time and outdoor temperature are also projected, although not simultaneously, on the wall or ceiling.

This atomic clock has dual alarm settings with adjustable snooze. A TX6U remote transmitter for outdoor temperature reporting is included with the clock. Designed for table or shelf placement, the clock can be powered from the included ac adapter or optionally from three AA batteries.


  • Accurate to 1 second per million years
  • Sets automatically to WWVB radio signal (manual setting is also possible)
  • 12/24 hour time display (hour, minute, second)
  • Calendar display (day, month, date)
  • Three projection modes: time only, outdoor temperature only, or alternating between the two
  • Projection is continuous with ac powering
  • Projection is initiated via pushbutton and 3 seconds in duration with battery powering (pushbutton projection is also available with ac powering)
  • Projection auto-focusing for display from 3 to 6 feet away; maximum projection distance is 6 feet (2 meters)
  • Projected display can be rotated 360 in 90 increments for proper viewing
  • Projector case rotates 180 to further orient the projected display
  • Three different intensity settings for projected display, plus an "off" setting. With battery powering, "off" is the only option; the intensity is not adjustable and the projection is via pushbutton (not continuous).
  • Dual alarm settings with adjustable snooze function
  • Time zone setting (13 available) with map display for U.S. time zones
  • Daylight saving time ON/OFF option
  • Indoor temperature display in either F or C
  • Outdoor temperature display (via 433 MHz transmission) in either F or C
  • Electro-luminescent backlight for LCD display (2-second duration)
  • Integral base for table/shelf/desktop placement
  • Atomic clock powered by ac adapter (included) or by three AA 1.5V alkaline batteries, with normal life of about 1 year
  • Remote wall-mount temperature transmitter powered by two AAA 1.5V alkaline batteries, with normal life of about 1 year


  • Indoor temperature measuring range:
    41 to 140F with 0.2F resolution
    (5 to 60C with 0.1C resolution)
  • Outdoor temperature measuring range:
    -21.8 to 157.8F with 0.2F resolution
    (-29.9 to 69.9C with 0.1C resolution)
  • Temperature checking intervals:
    Indoor: every 10 seconds
    Outdoor: every 5 minutes
  • Transmission distance:
    maximum 82 feet (25 meters)
  • Clock dimensions:
    5.07 inches (12.9 cm) wide
    3.66 inches (9.3 cm) high
    2.0 inches (5.1 cm) deep (including base)
  • LCD display dimensions:
    2.5 inches (6.35 cm) wide
    1.5 inches (3.8 cm) high
    Time number height: 0.75 inch (1.9 cm)
  • Remote transmitter dimensions:
    1.625 inches (41 mm) wide
    5.5 inches (138 mm) high
    1 inch (25.4 mm) deep
  • Power source:
    AC adapter (included):
    120Vac, 60Hz input
    6Vdc, 100mA output
    Optional: three 1.5V AA alkaline batteries

The La Crosse Technology WT-5431 Radio Controlled Atomic Projection Alarm Clock with Temperature Display:

The La Crosse Technology Radio Controlled Projection Atomic Alarm Clock with Temperature Display maintains its incredible accuracy by automatically tuning into the WWVB radio signal. The built-in antenna ensures reliable signal reception up to 2000 miles (3200km) from the WWVB transmitter. As a result, the La Crosse Technology atomic clock will calibrate to the atomic clock not only throughout the mainland U.S. but also in much of Canada. You need only insert the batteries, wait until the signal is received, and program the desired additional settings. In locations outside of WWVB range, the LaCrosse atomic clock can be manually set and will provide the high degree of accuracy of any quality quartz clock.

In a nutshell, here's how the the La Crosse clock works: The atomic clock's antenna is specifically tuned for optimal reception of the 60 kHz time signal. The time signal received on the antenna is demodulated by an onboard receiver, which sends the information to the clock's CMOS microprocessor for decoding. Once your atomic clock has automatically set its time for the first time, it ensures continuing accuracy by automatically tuning into the WWVB radio signal once per day at midnight. As long as your atomic clock is kept within transmitter range, it will continue to display the absolutely precise time, automatically adjusting for summer time/winter time changeovers if the daylight savings time option is ON. Should you move your clock out of transmitter range for an extended period of time, the atomic clock will continue to operate as a highly accurate quartz-controlled clock. Upon re-entering the transmitter range, your clock will correct itself again to the precise WWVB time signal.

Radio-controlled Time:

The NIST (National Institute of Standards and Technology, Time and Frequency Division) maintains a radio station, WWVB, in Ft. Collins, Colorado. The WWVB radio station derives its signal from the NIST atomic clock in Boulder, Colorado. A team of atomic physicists is continually measuring every second of every day, to an accuracy of ten billionths of a second per day. These physicists have created an international standard, measuring a second as 9,192,631,770 vibrations of a Cesium-133 atom in a vacuum.

WWVB (the stations identification just like any other radio station) continuously broadcasts time and frequency signals at 60 kHz. The carrier frequency provides a stable frequency reference traceable to the national standard. There are no voice announcements on the station, but a time code is synchronized with the 60 kHz carrier and is broadcast continuously at a rate of 1 bit per second using pulse width modulation. The time code contains the year, day of year, hour, minute, second, and flags that indicate the status of Daylight Saving Time, leap years, and leap seconds.

Availability: Exact quantity available will be displayed in the shopping cart, after you click the button below.

lacrwt5431padRegular price: $59.95padSale price: $34.98, 2/$68.00, 5/$167.50, 10/$330.00pad

La Crosse TX6U Remote Sensor/TransmitterLa Crosse TX6U Remote Sensor/Transmitterpad
The La Crosse TX6U is the more common remote temperature only sensor for the La Crosse Technology weather instruments. The La Crosse Technology TX6U does not have a display of its own. The TX6U uses 2 AA batteries, and is excellent for use for extended periods of operation in cold temperatures. In harsh climates, the alkaline batteries in the TX6U may be replaced with Lithium batteries for extended low temperature operation.
Availability: Exact quantity available will be displayed in the shopping cart, after you click the button below.

lacrtx6upadRegular price: $22.95padSale price: $16.95pad

If the order button is there, but the shopping cart page indicates that there are no units available, then we are temporarily out of stock.  The item should be available in a day or two.  Our inventory control system tries it's best to keep us from allowing the sale of something we don't have on the shelf. 

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