oliverb

A quick update on the accuracy of this clock.

The clock has been running now without problems for a couple of months and I have found that I can get it to run within a second a week.

The main problem is adjusting the trimmer capacitor as a fraction of a millimeter will change the clock speed by a large amount.

I have decided to set it to run fast rather than run slow as using the seconds stop switch the time can be reset very quickly.

Brett.

theinfamousbob

If it came down to it, I'd use a PIC/PC and call up time from either an atomic clock station or a sync website...

Just an idea.

-Infamous

__________________
-Ian

oliverb

It would be interesting to see a PIC version of this clock just to see the actual savings in components and time.

There is around 3 days building time in this clock (hard wired without PCB).

I have a PIC controlled atomic clock built from a kit some time back but the LED display is quite dim and is very hard to read in strong light. I had to mount it on a wall facing away from the sun. Also the display seems to flicker a bit.

Mike, K8LH

Can you tell us the number of switches being used and their function as well as the number of outputs and their functions? I couldn't quite get a handle on them from your schematics...

Regards, Mike

<added>

I've also experienced fine tuning problems adjusting the crystal oscillator trimmer capacitor... I ended up using my Ham radio transceiver with its built-in 0.5-ppm timebase to monitor the oscillator frequency while I adjusted the trimmer...

My latest PIC clock project (v2) eliminates the trimmer capacitor in favor of a "software trimmer capacitor" function which is more accurate (6.3 seconds/year) and the 'trim' value is much easier to adjust from the front panel... BTW, the v2 clock uses two chips and standard display multiplexing with PWM brightness control which can be adjusted to be "extremely bright"...

oliverb

Milke
There are the following switches

Set Seconds, Mins and Hours these 3 switches just step the digits up to set the time

Sync Seconds stops the clock to enable it to be synchronised with a precison source

Seconds Reset resets seconds to 00

30 seconds pulse sync synchronises the 30 sec clock pulse with the display (you prob won't need this)

30 second clock Advance & Retard for setting slave clocks
note slaves do not step back so retard just stops 30 sec pulse while advance steps the clocks on at 1 second this is about their max speed.

Chime ON & OFF turns chime off for night time

Chime set Used for setting the chime (prob not required on PIC clock)

The clock has the following outputs

30 second (slave drive)

1 hour relay drive

24 hour relay drive

Chime output to drive a relay

Brett.

Mike, K8LH

Hi Brett,

So it seems a PIC design with the following specs' should suffice?

<1> 6-digit 7-segment display
<2> Crystal oscillator time-base with software 'trimmer' function
<3> 16 switch inputs (can include rotary encoders)
<4> 16 LEDs (can be used for lighted switches, indicators, etc)
<5> 4 relay driver outputs

Would you like to see the 1-chip or the 2-chip design (grin)?

Kind regards, Mike

oliverb

Seeing as we are looking for chip saving etc lets go for the 1 chip design.

Brett.

Mike, K8LH

Let me throw together a quick-n-dirty drawing... Hang in there... Mike...

<added>

ok, here 'tis... sorry it's so crude but I have to leave for work soon... uses all of the I/O pins so no speaker for those nice short beeps used for audible switch feedback and no PWM display brightness control...

Kind regards, Mike

Attached Images

1-chip_masclk.jpg (71.2 KB, 278 views)

oliverb

Mike
Will this design be able to do the hourly chime or do you need an extra chip?
Bret.

Mike, K8LH

You mentioned driving a relay for the Chime... The circuit above has four relay driver outputs... Again, forgive me for the crude drawing... Perhaps the MOSFET "TMR Relay Driver" in the drawing below will be better... Just imagine four of those connected to RA0 through RA3 for your relay outputs... Just change that 5v terminal to 12v if you're using a 12v relay...

Regards, Mike

oliverb

Mike
Sorry Mike by the hourly chime I meant will it chime once for 1 oclock twice for 2 oclock etc.

I presume this is done in "software" on your chip as well as the 30 second pulse.

Brett.

Mike, K8LH

If you want it to chime that way then that's what you'd program it to do... If you decide you'd like 3 or 4 different options for the chime then you'd program it that way, perhaps using additional switches, or using a single switch to change chime modes and 4 LEDs to show you which mode you're in... The programming is the "smarts"... I hope I've stimulated your interest...

Kind regards, Mike

saeeddavish

Dear sir
I want to build a big led digital clock with seconds display.kindly send me a full schematic diagrams of digital led clock.

RODALCO

Great master clock you have build there.
It is an excellent effort you mastered there and a fabulous end result.
I agree with you that the challenge of building something from standard IC's is a lot more fun than putting a PIC IC in it.
OK it's a lot of work but who cares, isn't electronincs a hobby anyway.
I have built about 7 * TTL clocks 10 years ago which serve very accurately in my place or family members places.
A lot of work breadboarding it all together with the 7447, 7490, 7413, 7408 and 7400 IC's.
The hardest part is the suppression of spikes on TTL, because the IC's themself create dips on the 5 Volts DC supply. so decoupling capacitors are recommended for each IC of about 100nF.
I take some pics and will post one or two of them later on.

__________________
There are more ways to get to Rome.

Electricity, Electric clocks, Meters and Trains are great.

abbeystar18

Nice circuit...but i guess it's really complicated...
Great thinking man...hope it's applicable???