PASCO ME-8930 SMART TIMER - Manual (Page 10)

Smart Timer 012–06734A
6
summary of the mode suggested for a given experimental activity can be found on page 5
(Quick Cross-Reference for Suggested Activities and Smart Timer Modes). Refer to the
timing diagrams in Table 1 (pages 8 and 9) for a detailed look at how the Smart Timers
times events on its input(s) and an explanation of how speed and acceleration calculations
are performed internally.
The following are detailed descriptions of the Smart Timer’s modes of operation.
Time Modes
One Gate: In One Gate mode, timing begins when the beam is first blocked and
continues until the beam is blocked again. This mode can be used to measure the speed of
an object as it passes through the photogate. If an object of length L blocks the photogate
for a time t, the average velocity of the object as it passed through the photogate was L/t.
Fence: In Fence mode, the timer measures the time between successive interruptions of
the photogate. Timing begins when the beam is first blocked and continues until the
beam is unblocked and then blocked again. The Smart Timer can remember ten such
interruptions and will allow the user to scroll through the times using either the Select
Measurement or the Select Mode keys. Pressing the Start/Stop once will allow another
measurement type to be selected. Pressing it twice begins a new Fence Mode
measurement. Note that once a measurement has begun with an initial block of the
photogate, the Smart Timer will continue to time until ten interruptions are counted before
stopping the measurement and displaying the result. Pressing Start/Stop will stop the
measurement, and any recorded times will be displayed.
Two Gates: In this mode, the Smart Timer measures the time between blocking two
photogates. This mode is useful for not only air tracks and Dynamics Tracks but also with
the ME-6810 Time-of-Flight Accessory. In this mode, you must plug the photogate you
expect to encounter first into input channel 1, and the second photogate into input
channel 2.
Pendulum: In Pendulum mode, the timer measures the period of one complete
oscillation. Timing begins as the pendulum first cuts through the beam. The timer
ignores the next interruption, which corresponds to the pendulum swinging back in the
opposite direction. Timing stops at the beginning of the third interruption, as the
pendulum completes one full oscillation. Press the Start/Stop key again to begin a new
timing cycle.
Stopwatch: The Manual mode is actually a dual-use function. It provides a means of
manually timing events (like a using a Stopwatch) by pressing the Start/Stop key. It also
allows timing of events using the ME-9207B Free-Fall Adapter and the ME-9259A Laser
Switch, which function via a block/unblock sequence.
Using the Stopwatch: Enter Stopwatch mode and press the Start/Stop key. The
Smart Timer will beep and a “*” will appear on the second line of the LCD. Press
the Start/Stop key again to start the timer. Press the Start/Stop key to stop timing
and display the elapsed time. Press the Start/Stop key again. The old result is
➤ Note: The
picket fence
supplied with the
Smart Timer is
designed to
increase timing
accuracy when
used with
photogates. The
fence has three
sections: the 1 cm
flag, the 5 cm
fence, and the 1
cm fence; one of
these must be
aligned with the
photogate light
path before the
experiment can
proceed.