Two Hand Clock, Quartz or 555 timer driven? (1 pulse / minute rather than 1 pulse / second)

Thread Starter

DCraigD

Joined May 1, 2018
6
Greetings, I'm creating some clock driven art where I'm trying to eliminate the constant ticking sound the quartz drive produces. I've found this earlier entry, https://forum.allaboutcircuits.com/threads/help-hacking-a-quartz-clock-im-so-lost.56859/ but it didn't quite draw the conclusions I needed.
For efficiency & accuracy I'm considering a circuit that counts the pulses of a quartz drive, and then either allows, or produces a simultaneous pulse, every 60th occurrence. My other thought would instead use a 555 timer to produce a repetitive pulse ever 60 seconds. I could then easily alter the mechanism from the quartz movement so that the pulse moves the minute hand forward 6 degrees instead of the second.
I'm aware that the "sweeping" second hand quartz movements are considerably quieter, but I'd like to eliminate the physical second hand function entirely if possible.

Would love to hear any suggestion on the issue, Thanks in advance.

Sincerely, DCraigD
 

Alec_t

Joined Sep 17, 2013
10,424
Welcome to AAC!
Forget the 555 if you want accurate time keeping.
A small microprocessor (e.g. PIC) could easily handle the divide-by-60 function, if you have the ability and facilities to program it. Alternatively, an old-school way could use a couple of CD4017 ICs to divide by 10 then by 6.
Would a modified quartz movement have enough torque to drive the relatively heavy minute hand directly?
 

OBW0549

Joined Mar 2, 2015
3,011
For efficiency & accuracy I'm considering a circuit that counts the pulses of a quartz drive, and then either allows, or produces a simultaneous pulse, every 60th occurrence.
This is by far the better choice.

My other thought would instead use a 555 timer to produce a repetitive pulse ever 60 seconds.
You'll have an extremely difficult time getting acceptable accuracy from a 555 timer. Considering the 1% basic timing accuracy of the 555 itself, and using 1% resistors and 5% capacitors in the timer circuit, you could gain or lose up to one and three-quarter hours a day.

People tend not to appreciate just how insanely accurate quartz resonators can be, compared to other electronic components: even a dirt-cheap watch crystal that gains or loses a minute a day is accurate to better than ±0.1%. And one that's within one second per day is accurate to ±0.0012%.
 

dendad

Joined Feb 20, 2016
3,066
Instead of hiding the ticking, why not make it loud, but with a twist?
Have you read the Disk World books?
Lord Vetinari has a loud clock that ticks with an irregular time.
There are a few designs around. Use a PIC or another processor, but have 60 ticks per minute, just vary the timing. It keeps good time per minute, but annoys people :)
One video example....

 

ebp

Joined Feb 8, 2018
2,332
The tick comes from the motor, and on lots of clocks I've seen I think it is probably made much worse because the second hand oscillates - overshoots, bounces back and settles after a few oscillations, all of which rattles the geartrain. Changing the electronic clock source is unlikely to make any difference at all.

There may be some way to modify the drive to the motor to make it quieter, but I don't know what that might be.
 

Thread Starter

DCraigD

Joined May 1, 2018
6
Brilliant!
Thank You all!!
My dream of one tick per minute instead of sixty feels easily doable.



- DCraigD
 

Thread Starter

DCraigD

Joined May 1, 2018
6
Instead of hiding the ticking, why not make it loud, but with a twist?
Have you read the Disk World books?
Lord Vetinari has a loud clock that ticks with an irregular time.
There are a few designs around. Use a PIC or another processor, but have 60 ticks per minute, just vary the timing. It keeps good time per minute, but annoys people :)
One video example....

lol thanks, I currently count 8 quartz tickers clicking from where I sit. The erratic tick clock albeit funny, I'm afraid would be lost in the din. ;-)
 

Thread Starter

DCraigD

Joined May 1, 2018
6
So I think the using a 1 hertz quartz for accuracy with a circuit that responds to every 60th is the way to go. As I research how to create such a circuit, I'd appreciate any ideas you folks have. Thanks, in advance, again.

-DCraigD

PS. I should mention that I'm a novice/tinkerer who self educates when necessary.
 
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