Have you even been accused of being a clock-watcher? Whether
you have or not, there is a definite risk of being entranced (enchanted?) with
this new LED digital clock. You tend to ignore the central 4-digit display and
just concentrate on that magical circular LED performance.
At the beginning of each minute, each successive LED races
anti-clockwise around the periphery to take up its position as the seconds count
builds up. As the seconds count nears 30, each new LED only has to traverse half
the circle and so each LED makes its circuit slightly slower than the last until
finally, as the count approaches 60, the last few LEDs make the transit very
slowly indeed. But each LED transit around the circle, whether it covers the
whole 360° or just a few, takes exactly one second.
The LED clock comes as a complete kit of parts and includes a double-sided plated-through PC board with a solder mask and silk-screened overlay.
So you find yourself wondering: just what fancy machinations
have been pulled to achieve that? The answer is, of course, that there is a
fancy microcontroller calling all the shots. But even knowing that and having
considered all the programming that must have gone into it, you still tend to
sit there mesmerised by this clock. You just have to see it but be warned – when
you do, you will probably want one!
Apart from that magic circular LED array, this wall clock also
has a 4-digit readout with 12 or 24-hour operation. It also features an alarm
with piezo sound and opto output, a battery backup for time-keeping and alarm
functions, AC mains synchronisation and crystal timebase for precise timing, an
efficient switchmode supply powered by a 12V AC plugpack and a high quality
double-sided, screen-printed and solder-masked PC board with plated-through
holes. What more could you want?
The hours and minutes display consists of the four large digits
in the centre of the clock face. It can be set to display either 12 or 24-hour
time, depending on the position of a single jumper link (JP1). On the righthand
side of the minutes digits is an AM/PM indicator LED and this is active for PM
hours if the 12-hour display mode is chosen.
The timing uses a crystal oscillator for short term accuracy
with the chaser control and is synchronised to the mains AC cycles when present
for long term accuracy.