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HANDS-ON TEST & MEASUREMENT
Shutter Time Meter
Accurate to 10 µs
Ton Giesberts
Despite the digital revolution there
continue to be many photographers who still prefer to work with an
‘analogue’ SLR camera. While most of these cameras have a reliable mechanical construction,
after years of use it is worthwhile to check and, if necessary, to adjust the shutter time.
With this circuit we offer the ability to measure the shutter time accurately so that you can
do this calibration yourself.
We have already published a schematic
for a shutter time meter in Elektor Electronics
on an earlier occasion. At that
time (1981), electronics was only just
making an appearance in the world of
photography. These days, it is impossible
to imagine photography without
electronics, when just about everything
is electronically driven. However, the
‘old’ cameras do not have to be written
off just yet. Many an enthusiast swears
50
by their reliable, familiar equipment.
It is obvious that this equipment also
requires maintenance to keep it in optimal
working order. That is why we
now present a revised circuit, which
contains ICs that are more easily available
than the MK50398N, among others,
used in 1981.
We have selected a counter IC from
Maxim, the ICM7217AIPI, which was
originally marketed by Intersil. This IC
has a built-in 4-digit presettable
up/down counter as well as a driver for
four 7-segment displays. In addition
we use a dual BCD counter type
74HC4518 to divide the clock signal.
Circuit description
As already mentioned, we use the
ICM7217. The current source outputs
on this IC would under normal circum-
elektor electronics - 1/2006