[time-nuts] Clock Project Help

[Brooke Clarke]

Hi Robert:

The last clock I did was the PC4, see:
http://www.prc68.com/I/PRC68COM.shtml#07092006

I've been thinking of how to make a sidereal clock that's very accurate.
Things like time of coincidence between sidereal and UTC0 or better UTC1 come 
up. There are very few sources for UTC1.

Have Fun,

Brooke Clarke
http://www.prc68.com

Robert Atkinson wrote:
> Hi Mike have a look at 
> http://www.realhamradio.com/dclock.htm
> http://www.prc68.com/I/LED1PC2.shtml
> and
> http://www.prc68.com/I/PClock.shtml
>  
> Regards,
> Robert G8RPI.
> 
> --- On Wed, 28/10/09, J. Mike Needham <iain_nitro at att.net> wrote:
> 
> 
> From: J. Mike Needham <iain_nitro at att.net>
> Subject: Re: [time-nuts] Clock Project Help
> To: "'Discussion of precise time and frequency measurement'" <time-nuts at febo.com>
> Date: Wednesday, 28 October, 2009, 19:33
> 
> 
> Thanks Hal:
> 
> Yeah, the LCD idea would be fine.  Better would be OLED I think. Digikey is
> one solution, but I am not even sure what embedded system to look into.
> Eventually I want to package these for marketing, so they will become more
> specialized once we get a prototype built, so I wanted to know what makes a
> regular dedicated clock go (IC wise) and then kind of build my controller...
> but I am definitely open to suggestions.
> 
> Thank-you for your help in any case.
> 
> Mike
> 
> 
> 
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of Hal Murray
> Sent: Wednesday, October 28, 2009 1:38 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Clock Project Help
> 
> 
>> Where the problem lies is that I need to find the IC chips for clocks
>> and build a display.
> 
> I'm not sure what you are looking for.  Are you looking for "IC chips" to 
> keep time or to display the time?
> 
> You don't need a special chip to keep time.  Just count CPU cycles.  Most 
> embedded type CPU chips have a way to do that.
> 
> If you run ntpd, it will correct for the error in your crystal.  (makes a 
> good thermometer)
> 
> 
> What type of display do you want?  Aside from Nixies, I can think of two 
> possibilities.  One is LEDs.  The other is LCD.
> 
> There are lots of small LCD modules available.  Typical sizes are 1x20 and 
> 2x20 characters.  They usually come with backlights.   Most of them are 
> really bitmapped.  They just have a built-in font to simplify programming if
> 
> all you want is text.  One of those would make a fine clock display.  You 
> could show the time in a huge font, and put the date and whatever in the 
> leftover space.
> 
> You can get them packaged as a USB module so you could prototype everything 
> from your PC.
> 
> You may be able to get a special LCD designed for a clock, but they will 
> probably be hard to find unless you want to buy a zillion of them.
> 
> 
> 7 segment LED displays are readily available.  You may be able to get one 
> specialized for clocks: 4 digits with a : in the middle.  Or you could build
> 
> your own from single/double packages with discrete LEDs for the :.  Go to 
> Digikey and poke around.
> 
> 
> One for your checklist...  You probably want some sort of photo-transistor
> to 
> sense the ambient light level so you can dim the lighting at night.  (unless
> 
> you want to use the clock as a night light)
> 
> 
> 
>