| 摘要 |
A distance measuring device that can be easily retrofit to a recreational vehicle includes a sensor unit that easily attaches to the wheel of the vehicle, a counter unit 12 for processing the sensor signals, a display unit 13 for providing a numeric display of the distance traveled, a reset unit 14 for allowing the vehicle operator to reset the count to zero and to initiate a timing cycle, during which timing cycle movement of the vehicle must either start or continue, and a time limit unit 16 for automatically resetting the timing cycle to lengthen the cycle under appropriate circumstances. The timing cycle will terminate when no sensor signals are received during the timing cycle, and as a result, the counting circuits and the sensor will be driven low to clear memory and preserve power. In the new embodiment, a display present unit 50 can be used to cause a predetermined count to be displayed on the display unit 13. An increment/decrement select unit unit 51 can then be used to cause the display to decrement from the predetermined count.
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