Hi

Correct answer:

I don't think there is such a beast. Once you get away from the radio controlled (WWVB etc) clocks the cost goes up quickly.

Also correct, but a bit of a joke answer:

Raspberry PI driving your television set.  Alternatively make the Pi feed control signals to a hacked normal clock.

Bob

On May 27, 2013, at 9:29 AM, Miguel Barbosa Gonçalves m@mbg.pt wrote:

Hi Bob!

On 27 May 2013 14:56, Bob Camp lists@rtty.us wrote:

I don't understand why a microprocessor with an Ethernet controller and a 7
segment display would cost so much to manufacture... I think I'll build my
own.

Good joke :-) I imagine the electricity bill at the end of the month.

I would like to have a clock sync with my super precise stratum 1 servers
:-) what's the point in having them if I can see the time anywhere? :-)

Cheers,
Miguel

I've seen LLCD computer monitors used as clocks.  Seems this would be
the perfect use for a Rasbury Pi. and a cheap monitor. $100 or maybe a
low-end Android tablet.

The way it is more commonly done is you have you computer that is
using NTP produce an IRIG time code.  Then there are any number of
commercial clocks and large digital LED displays that will use IRIG.
IRIG displays are not cheap but they sure are easy to find.

On Mon, May 27, 2013 at 6:29 AM, Miguel Barbosa Gonçalves m@mbg.pt wrote:

--

Chris Albertson
Redondo Beach, California

Hi

On May 27, 2013, at 10:56 AM, Miguel Barbosa Gonçalves m@mbg.pt wrote:

… and that's really my point. You can build one easier than you can buy one.

The Pi isn't all that power hungry. The TV set - yes it's going to be a bit of a hog. Even with the Pi's i/o limitations you should be able to get it to run some sort of low power external display.

Bob

If you want a project, you should be able to get an older Android tablet or
a Chumby 8 for $100 or less and hack it to do what you want.  Hard to beat
the price for the hardware you get.

I'm happy with my OnTime dial clock.

On Mon, May 27, 2013 at 8:14 AM, Bob Camp lists@rtty.us wrote:

On Mon, May 27, 2013 at 7:56 AM, Miguel Barbosa Gonçalves m@mbg.pt wrote:

Don't know about you but I'm always in from of a computer and the time
is one the screen in the upper right corner.

Yes the TV uses a bit of power but you could use a screen that draws
less current and the Pi or other ARM powered computer uses very little
power.  But seriously, IRIG is the standard for local time
distribution it does not have the delay and gitter that NTP over
Ethernet has  It is send via audio frequency so any only twisted pair
phone cable woorks although I've mostly seen then use coax.  NTP
requires a Posix-like OS which means a fairly powerful CPU while time
code can be processed limey with old 74lsxx logic or a tiny $2 uP.
I believe there is a time code generator included in the standard NTP
source distribution in /utils.  The time code software sends the
signal out the audio device at 8KHz sample rate and should be good at
the millisecond level.

In terms of both the amount f power used and accuracy IRIG is better
for this then NTP.

--

Chris Albertson
Redondo Beach, California

On 27 May 2013 16:22, Chris Albertson albertson.chris@gmail.com wrote:

Just checked the Windows taskbar clock and it has a 1 second delay...

At work I use Windows but use Mac OS X at home... but I am looking for a
solution for the Windows platform.

TIA,
Miguel

On Mon, 27 May 2013 14:29:11 +0100, Miguel Barbosa Gonçalves wrote:

This was posted to the group @21-05

http://www.symmetricom.com/lp/gbu/email/time-display-promo-landing-page/?
emailid=GBU078_NTD_Promo_ProdPg&lead_source=Web

http://tinyurl.com/ptopb86

But it's funny ... I think there was a price on that page earlier ...

CFO

Hi

If you are doing this from scratch today, would you go IRIG or would you go RS-485 for a wall clock? Both will drive more cable than you are likely to have in a house. Both are reasonably noise immune. With RS-485 there's less to do. It's a serial stream like any other bunch of "stuff" into a UART.

Some math:

YYMMDDHHMMSSCR  = 13 ASCII characters. With one check byte it would be 14.
A baud rate of 115.4K isn't stretching things on RS-485 or on most UART's these days.
Sent it at 7N1 you have 9 bits per character, 126 bits in the message.
Message takes a bit over 1 ms.

Time it to anywhere in the string and the clock should be within <+/- 2 ms. That's better than I can see on a clock. Better yet, time it to the first (or last) character in the string. More or less a 10X improvement. You could also drop the year / month / day if the clock isn't going to use them.

Take any of the Arduino (or what ever) LED display boards and drive them with something cheap. I doubt the "clock" end plus the drivers would be over $30. I suspect IRIG would cost a bit more once you got it all worked out.

Bob

On May 27, 2013, at 11:03 AM, Chris Albertson albertson.chris@gmail.com wrote: