The most available analogue dial for PPS clocks is the common quartz
clock movement.
You can leave the unpowered quartz unit in circuit and just connect
to the coil.
The drive is a 5V square wave signal of 0.5 Hz coupled through an
electrolytic capacitor
in the order of 10 - 100mfd. A series resistor of a few hundred ohms
may help.
Each make of clock may need different values to work best, the drive
is the alternating
positive and negative impulse. The original unit may have had a pulse
about 20ms long,
but the square wave drive gives a longer tail. Over-driving is just
as bad as under-driving,
to work well you must optimise the capacitor and resistor.
It is simple to divide the PPS to the square wave, but what is needed
is a simple/surefire
method of adding/removing the leap seconds. Preferably one that works
automatically.
Any ideas?
Neville Michie
On 30/03/2010, at 9:02 AM, Hal Murray wrote:
[email protected] said:
The words "insert a pulse" is what causes the confusion in
conjunction with
leap seconds. There is no extra or missing pulse; no double pulse,
no early
or delayed pulse.
The 1PPS output continues to give a pulse at a 1 Hz rate
regardless if there
is leap second or not. There is never any ambiguity with TAI or
UTC with
respect to the pulses themselves.
Right.
I was commenting about the sub-thread that was expecting an extra
pulse so a
mechanical clock would stay in sync over a leap second event.
Since what's needed is removing a pulse (to allow for the leap
second),
rather than inserting a pulse, I still like the idea of poking a
finger on
the right place in the clock to gum up the works for one tick.
--
These are my opinions, not necessarily my employer's. I hate spam.
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