Janex
Posts: 4
Joined: Thu Dec 28, 2017 11:07 am

Need help with a analog clock upgrade

Thu Dec 28, 2017 11:20 am

Hi. I'm completely new at this forum. But I have a Project With an old analog town clock.
It has been barely working some years ago. But the years has made it unreliable at best.
The clock has been operated With a gear system that is 1:100rpm. My thought was to replace the whole mechanic gear system with a stepper motor with 1:100 gir ratio. I have done some trials with arduino, but not succeded. The clock uses only single action on the pinion for the time (Hour,Minute).
Problem is to get all of this to work, and also implement with RTC.

Has anyone done something like this before?

sprinkmeier
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Re: Need help with a analog clock upgrade

Thu Dec 28, 2017 9:13 pm

Break up the problem.

Do you have the mechanical side sorted out, i.e. the connection to the stepper motor? "town clock" sounds kind of big, this might be a 'non-trivial' problem.

Get a driver board for the stepper motor (i.e. do NOT try to run it directly from GPIO!)

Get the RTC working. Note that RTCs stilll drift, so a network connection (with a time-sync daemon like chrony) or a GPS might be preferable. The network connection will allow monitoring/maintenance as well.

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DougieLawson
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Re: Need help with a analog clock upgrade

Thu Dec 28, 2017 11:23 pm

How are you going to know the position of the hands? You can't set an analog clock without being able to force the mechanism to a known time (12:00) to then step on from there (which is what my MSF 60Hz wall clock does at 01:00 every morning).
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piglet
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Re: Need help with a analog clock upgrade

Thu Dec 28, 2017 11:45 pm

Hopefully not off-topic for this thread (if it is I'll start another one) - but I've been looking for an analogue hand mechanism where the hands (hour/min/second) position can be set/controlled from a pi or microcontroller but have never been able to find one. Any ideas? I can't believe you can't get hold of them - I must be using the wrong search arguments

Janex
Posts: 4
Joined: Thu Dec 28, 2017 11:07 am

Re: Need help with a analog clock upgrade

Fri Dec 29, 2017 6:40 pm

At first with arduino I tried to use an Encoder to set positions for the clockface as each minute resulted en 180degree turn on the old gear mechanism with 1:100 ratio. But eliminating the gearsystem I was hoping to make it easier.
I do not have any of the equipment needed for this plan of mine. But first thoughts were if it would be possible to make this system with RTC and encodersystem implemented to get correct time and position.
It is about 1m diameter clockface. But very easy to move on the axle.

gordon77
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Joined: Sun Aug 05, 2012 3:12 pm

Re: Need help with a analog clock upgrade

Fri Dec 29, 2017 7:46 pm

Doesn't 180degs (1/2turn) for each 1 minute (6deg) mean a ratio of 30:1? 30 turns for 1 hour.

Have you any photos of the mechanism you can show us?

Janex
Posts: 4
Joined: Thu Dec 28, 2017 11:07 am

Re: Need help with a analog clock upgrade

Fri Dec 29, 2017 9:15 pm

I might be a bit off on the math. There are 3 different gear ratios on the old mechanism. It is powered with an old 12VDC 2000rpm motor, that was triggered with a timer.
And geared down to another axle for the 180degree a minute where there was 2 limit switches for sort of minute by minute control. And then the axle to the clock. I have only timed the movement. It's about 3 minutes full power on the motor @ 2000rpm for the 60 minutes rotation on the main axle to the clock face.

Janex
Posts: 4
Joined: Thu Dec 28, 2017 11:07 am

Re: Need help with a analog clock upgrade

Sat Sep 22, 2018 1:08 pm

Still not resolved my little projekt. I am thinking of removing all the old clockwork, and replace it with an Encoder motor.
The clock hands is very easy to move, so there is not a lot of resistanse. Has anyone tried a program for this application?

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