VOLTCRAFT DS-01 Notice D'emploi page 22

Image Frequencies (Harmonic Content)
If you flash a moving object with constantly increasing flash frequency, it seems as if
the object moves slowly backwards, then freezes and then moves forward in slow
motion, freezes again, etc. This way, several images appear.
These images appear with mathematical multiples or harmonic content of the actual
rotation speed of the object.
"Frozen" images appear both with whole multiples and fractions of the actual rota-
tion speed of the object. A machine that rotates at 1000 RPM, also seems to ??? at
2.000 (x2), 3000 (x3) etc. as well as at fractions of 500 (
1
(1 / x). (Verb fehlt!!!) Some of these "frozen" images appear as individual images, oth-
2
ers as "multi-images". This is especially important for determining the actual rotation
speed of an object.
Determining the Actual Rotation Speed of an Object
Just like with all stroboscopes, still images appear with the harmonic content of the
actual rotation speed of an object. Here is how you can determine whether this is a
harmonic content or the actual rotation speed.
First some useful tips:
- A good indicator is when you know the approximate rotation speed of the object.
- If the object has an even shape (motor shaft, etc.), you have to attach an identify-
ing marker with paint or adhesive tape, etc.
- An individual image only appears at the actual and half the true rotation speed.
With the button for halving (16) and doubling (15) the image frequency, you can
rapidly and easily determine the actual rotation speed.
Actual rotation speed Flash frequency
1.000 RPM
To be on the safe side, we recommend flashing the object with the
i
respective harmonic content during each measuring of the rotation
speed. This is the only way to make sure that you are dealing with the
actual rotation speed.
1.000 RPM/FPM
2.000 RPM/FPM
500 RPM/FPM
1
/ x), 750 (
2
X2 changeover
switch
2 changeover
switch
3
/ x) and 1.500
4
Frozen image
Individual image
Double image
Individual image
21