with operating frequency.
Although the light output is
necessarily low power — because of
its repetitive nature — compared to a
one shot Xenon flash, the circuit may
still be used for some photography
tricks. In this instance, the video input
comes in handy.
Connecting the composite video
signal from a camera will synchronize
the flash to the actual frame capture.
As described previously, you may
need to adjust the “Phase Delay”
control to obtain maximum brightness, as observed in the viewfinder.
The water drop sequence in
Figure 7 and the bouncing marble in
Figure 8 were obtained employing
this technique.
You may find that the LED lenses
produce a beam that is perhaps too
narrow (± 3 degrees) for practical
photography usage. Fortunately, the
sub lens shown in Figure 9 (that
attaches to the top of the main lens)
will widen the beam to ± 12 degrees.
Finally, the project may be used in
the free run mode, much like the disco
strobe lights so popular in the ‘70s. So,
load your favorite funky music CDs
and enjoy! NV
■ FIGURE 9. Sub lens.
January 2008 37
