Monarch Instrument Nova-Strobe BBL - Manual (Page 7)

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1.1.1 Degree of Rotation Adjustment
The first method is to adjust the flash pulse width for degree of
rotation visible (blur). The user can set this from 0.2 to 14 degrees
out of 360. The higher the setting the brighter the strobe appears
to be but the more blurred the target is. Optimal setting to stop
motion is 1.8 to 3.6°. The number of degrees is a proportional
amount and remains constant as the flash rate increases or decreases.
The strobe automatically calculates how wide the pulse width
should be at different flash rates to keep the blur constant – the
faster the flash rate the narrower the pulse width. The pulse width
equals: (setting in degrees/360) x (1/flash rate in Hz).
Thus the blur remains constant no matter what the flash rate*.
1.1.2 Pulse Duration Adjustment
The second method is to adjust the flash pulse width to a fixed
number of microseconds. Here the user sets the flash pulse width
in microseconds not degrees. As the flash rate increases the pulse
width stays the same and the image will get brighter and more
blurred as the flash width remains constant*. The degree of rotation
visible changes to keep the pulse width of the flash constant*.
*Note: There are two limits maintained by the strobe – the pulse
can never be greater than 3000 µs nor can it exceed 14° of rotation.
The strobe automatically adjusts these values as the flash rate is
increased or decreased to maintain these limits at all times. For
example - at a flash rate of 600 flashes per minute 14° of blur
represents a flash pulse width of 3800 µsec. The Strobe will limit
this value to 3000 µsec or 10.8° of rotation (blur).
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3.2.2 Flash Duration - Microseconds
To view or adjust the flash duration in microseconds
press the
BRIGHT button again after viewing degrees
or press the BRIGHT button twice from normal
operation. The display will show the current
flash duration in microseconds (uSECS) – this
may be calculated from phase degrees set
above. Use the knob to increase or decrease
the flash duration in microseconds. Adjusting the microseconds
will cause this to be the controlling parameter for pulse width. As
the flash rate increases or decreases the strobe will keep the flash
duration at the preset width in microseconds provided this does
not exceed the strobe specifications. Press the
BRIGHT button
to exit the flash duration adjustment.
3.3 Display Units
The display can show the flash rate in revolutions per minute
(RPM) or per second (RPS or Hertz). To switch between
display modes press the
DISPlay button shown right. The
display units will toggle at each press (RPM < > RPS).
4.0 USING THE STROBOSCOPE TO
MEASURE RPM
The primary use for a stroboscope is to stop motion for diagnostic inspection
purposes. However the stroboscope can be used to measure speed (in RPM
/ RPS). In order to do this several factors need to be considered. First, the
object being measured should be visible for all 360° of rotation (e.g. The end
of a shaft). Second, the object should have some unique part on it, like a
bolt, key way or imperfection to use as a reference point. If the object being
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