Reversible, elapse-time indicator utilizing two solid electrolyte cells in which current of one polarity is applied to one cell to cause silver ions to move from the positive electrode to the negative electrode. When all the ions have been removed from the positive electrode after a predetermined specific interval of time, the cell resistance increases to trigger an alarm such as a lamp. While the first cell is timing out, the second cell is being charged from a zero time value by a current of an opposite polarity equal to the time begun within the first cell. When the time interval has elapsed, the cells are reversed so that the second cell now becomes the timing device and the first cell is being recharged.
A timer has as at least two timing intervals, at least one of which is switchable between different preset intervals by the user, between which tasks are to be performed by a user. Upon the expiration of each timing interval, the user is alerted that a task is to be performed. A display panel indicates the number of days remaining in one of the timing cycles and may temporarily be switched to indicate the number of days remaining in the other timing interval. A particular use for the timer of this invention is to remind a user to service a humidifier. Another particular use is to remind a user of chores to be performed to maintain indoor or outdoor plants.
The present invention provides a method and apparatus for monitoring the operation of a mobile machine. The machine includes a mobile communicator adapted to communicate with a remote monitoring station. The method includes the steps of receiving a configuration message from the remote monitoring station via a wireless communication link, comparing at least one of a current machine position to the configuration information a current machine time of operation to the configuration message, and sending an alarm message to the remote monitoring station in response the comparison.
