Arbiter Systems 931A, Operation Manual

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instantaneous voltage. The minimum trigger voltage, as a function
of frequency, is shown in the following graph:
NOTE: The minimum rms voltage at 60 Hz is (approx.) 11 volts.
ˆ
“ AC Removed ” configures the timer to trigger on the removal of
an ac voltage, as described above. The point in time at which the
signal last falls below the threshold is interpreted as the trigger.
Slight errors may occur, when using this mode of triggering, that
depend on the instantaneous trigger voltage. However, this error
should not exceed 1 millisecond.
ˆ
“ Contact Open ” configures the timer input to recognize the
opening of an electrical contact as a trigger event. The threshold
is (approx.) 2.9 volts, with a pull-up impedance of (approx.) 47
kilohm to a source voltage of (approx.) 8 volts.
ˆ
“ Contact Closed configures the timer input to recognize the closing
of an electrical contact as a trigger event. The threshold is (approx.)
2.6 volts, with a pull-up impedance of (approx.) 47 kilohm to a
source voltage of (approx.) 8 volts.
3.7.2.5 Select Timer Trigger B
Press the Timer CONFIG key and select Trigger B from the Timer
Configuration Menu and press ENTER. Select the appropriate trigger
signal type for timer “Channel B” from this menu. The choices for input
“B” are exactly the same as those for input “A”. See Section 3.7.2.4.
3.7.3 Timer Measurement Categories
All measurements performed by the timer section of the Model 931A can be
classified as either
time or count measurements. The following paragraphs
describe both categories.
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