Clock

On 02/12/2018 5:36 PM, Paul wrote:
Rene Lamontagne wrote:
On 02/12/2018 1:25 PM, Paul wrote:
Mark Lloyd wrote:
On 02/11/2018 01:08 PM, Peter Percival wrote:
Ken Blake wrote:

If you want to know the time very accurately, of course a digital
clock is more better.

How come?Â* There is nothing about digit clocks that mean that they
can't be wrong.

Sorry, I used the wrong work there. It should be "precision".

However, some clocks are now controlled by internet or radio, and
are more accurate.


The radio are really the best, because you never have
to adjust them. All they need is a source of power, and
they don't need a 60Hz reference to keep time.

The radio that does that, is at low frequency, like 60KHz.
The frequency used, varies with country or locale.
(And this is not GPS either. This works even if GPS
was knocked out. The reason for not using GPS, is the
GPS constellation might not be receive-able inside your house.
60KHz penetrates buildings a lot better.)

You may not get a usable signal during the entire 24 hour day, but
in good circumstances, your "radio clock" is synced at least once
a day. Even if your clock has a 100ppm xtal, it doesn't matter,
because the radio sync will bring it back to where it should be.
You don't have to have an atomic clock in the box.

The antennas used, come two ways. You can use a wire loop with
huge dimensions (i.e. you'd better be on a farm). However,
using ferrite rods, you can make a compact design that
is just as good. The one pictured here, might have been
removed from the back of a commercial wall clock. That's to give
an idea of how big a non-hobbyist one is.

https://electronics.stackexchange.co...-wwvb-receiver


The Russians make the best ferrite rods for this.
Ferrites are available in a number of compositions, and
I don't think there's much commercial interest in making
the rods for this application. But I've seen hobbyists
who claim some Russian-sourced rods worked well.
I've seen some designs, that have multiple ferrite rods
with the wire wrapped around the whole bundle.

This is one of those niche hobbyist activities (if
you want to build your own, rather than buy one). I think
most people who dabble in this, they want the sync info
to be available all day, and that's why they want their
design to be more sensitive than a store-bought one.

If the central transmitter goes down, then no more
sync for you. You're on your own then. An EMP could
easily knock out such a site. Or government cutbacks.

You can also buy the pre-built ones if you want. But you'll
need something to decode the serial output and actually use it.
You know, the rest of your "clock" :-)

https://www.ebay.com/p/3-Pcs-WWVB-60...38#UserReviews


Â*Â*Â* Paul

My La Crosse weather forecast station has a built in one tuned to
WWVB, If I want to set all the other clocks in the house this is the
reference I use.

Rene

Does it have a LED that indicates when the 60KHz carrier is present ?

There is a coverage map for the USA, and the signal strength
contours change with time of day.

Â*Â* Paul


No, it has a Little icon of a satellite dish with waves emanating from it.
If the carrier is not locked in the icon disappears

Rene