– 5 –
4.0 I
NSTALLING
/C
HANGING THE
B
ATTERIES
1. If strobe is ON, switch the power OFF by pressing and holding the
button (see pages 3 and 4) for 3 seconds.
2. Unscrew the 2 screws at back of the strobe and remove the battery
compartment cover.
3. Insert 3 new, fully charged AAA batteries into the battery
compartment, following the polarity marked on the case.
4. Replace the battery cover and screws.
Do not overtighten.
NOTE:
Disposable or rechargeable (NiMH) batteries may be used.
– 16 –
Step 2:
As the flash rate is lowered, three singular harmonic images
are found.(The first image at 9,600 RPM is rejected because it
is a double image). Point "X" is 7,200, point "Y" is 4,800 and
Point "Z" is 3,600.
Step 3:
To calculate the true RPM, enter these values into one of
the equations shown below. For this example, we will use
equation (6).
RPM
= 2AB(A+B)/(A-B)2
= 2x2,400x1,200x(2,400+1,200)/
(2,400-1,200)2
=
14,400
Where A = (X-Y)
= 7,200 - 4,800
= 2,400
And B = (Y-Z)
= 4,800 – 3,600
= 1,200
Therefore, the true speed of the object is 14,400 RPM. To help further
illustrate this point, the figure below shows the harmonic relationship of
the four images found in this example:
If TWO points, “X” and “Y” are
recorded:
(1) *RPM = XY/(X-Y)
(2) *RPM =Sx(Sx+1)(X-Y)
(3) RPM =S (S -1)(X-Y)
(4) *Sx = Y/(X-Y), rounded
(5) Sy = X/(X-Y), rounded
If THREE points, “X,” “Y” and “Z”
are recorded:
(6) *RPM = 2AB(A+B)/(A-B)2
(7) *A= (X-Y)
(8) *B (Y-Z)
Variations of THREE point formulas:
(9) *RPM = 2PS/D2
(10) P = Product, (A*B)
(11) S = Sum, (A+B)
(12) D = Difference, (A-B)
(13) *Sx = 2(Y-Z)/(X+Z-2Y)
(14) Sy = (X-Z)/(X+Z-2Y)
(15) Sz = 2(X-Y)/(X+Z-2Y)
(16) *Sx = 2B/(A-B)
(17) Sy = (A+B)/(A-B)
(18) Sz = 2A/(A-B)
(19) Sx = 2B/D
(20) Sy = S/D
(21) Sz = 2A/D
Depending on the accuracy desired, either two or three harmonic points
can be found. These points are used in one of the following equations:
Formulas for calculating “Out of Range” RPMs.
Harmonic
FPM/RPM
1/4
1/3
1/2
2/3
5/6
1/1
3,600
4,800
7,200
9,600
12,000
14,400
