Looking for help in synchronizing a wooden geared clock

Hi’
I’ll try to keep the basics short:
I can solder and beyond that know very little about electronics. My forte is more mechanical.

I have successfully built a CNC machine, controlled by the Uno with a CNC shield.

All works well and I now would like to use the CNC to build a wooden geared clock that, importantly, keeps exact time.

I’ll design the clock but would like to use electronics as described on this page http://www.instructables.com/id/A-wood-gear-clock-with-a-unique-drive-mechanism/ to control the swing of the pendulum.

Three questions.

  1. Could Arduino be used to do this?
  2. If yes, is there “off the shelf” code I could use?
  3. Am I away over my head?

I'll appreciate any responses, even if the answer to 3 is "Yes"

Ralph

  1. Yes
  2. On the Instructables site, but would probably have to be modified for your clock
  3. Try it and see. Should be fun.

PS: there is no such thing as "the exact time". The Arduino is not a very good timekeeper due to the low quality resonators usually used.

I can solder . . .

Don't try that on the wooden clock!

Don

Thanks jremington. I'll have a look.

Don. I wooden dream of it but I think I'm falling into a Monty Python "sketch"...

Sketchs are in C++, not Python!

The code posted for the Instructables wooden clock (BTW, one of the very few really decent Instructables I've seen) is highly specific for the MSP430 microprocessor, and is needlessly complicated.

The basic circuitry is quite good, though and the microprocessor could easily be replaced by an Arduino Pro Mini, for example.

If you build the clock and are stuck with the programming, we can help.

Thanks again jremington.

I'll start on the clock and will very likely get back to you.
I'm still looking through the Instructables site.

Ralph

Very cool clock! The microcontroller assisted aspect keeps it fully mechanical. An Arduino could certainly do this, and it should also be possible to improve on the 3 month battery life. As far as accuracy, you can easily add an real time module to the circuit that will keep it accurate as long as the batteries last.

This is sounding good but as a complete moron regarding electronics, I wouldn't know where to start.
I have a spare Arduino Uno lying around that might be used.
The only attraction of using the Texas Launchpad is because the clock website gives me detailed instructions and code.
If someone could give me similar instruction for the Arduino I'd be really grateful.

At the risk of upsetting folks, I have to confess the electronics part of building this clock is really just a means to an end, in getting the clock to keep time.

I've built other wooden clocks but they are notorious for being inaccurate, depending on humidity etc. and this would be a great solution.

Ralph

At the risk of upsetting folks, I have to confess the electronics part of building this clock is really just a means to an end, in getting the clock to keep time.

Don't worry, this is the Arduino forum, not a clock forum.

You don't really need an Arduino. All you need is a crystal controlled mechanism to pulse a coil at the right time, to keep the pendulum with magnet "on track".

You don't really need an Arduino. All you need is a crystal controlled mechanism to pulse a coil at the right time, to keep the pendulum with magnet "on track".

Isn't this exactly what all those inexpensive clocks powered by a single AA battery do. He should be able to start with one of those mechanisms and amplify the signal to drive his larger coil.

Don

Hi
In a clock forum I could, maybe, just about keep up but in this one I'm up to my neck!

I've found a few circuits that can drive or kick a pendulum as it passes over a coil and so keep the clock ticking without the use of weights or mainsprings.

The fascinating thing for me is that this particular clock's electronics can not only keep the clock going but can speed up or slow down the pendulum swing in order to ensure the clock keeps "perfect" time.

The fascinating thing for me is that this particular clock's electronics can not only keep the clock going but can speed up or slow down the pendulum swing in order to ensure the clock keeps "perfect" time.

That is what all electronic clock driving mechanisms do.

The pendulum can and will oscillate at other than its "natural frequency". For this to produce an accurate timekeeper, the pendulum must already have a natural frequency that is close (by your adjustments) to the desired frequency, and then you just give it kicks at the desired frequency.

If you want to delve into the gory details, the pendulum is a driven, damped harmonic oscillator. The "steady state" solution discussed in that link has the same frequency as the driving force.

Thanks for sticking with this post jremington. I really appreciate your input.

Does this mean that I can completely do away with the TI circuitry and use a circuit that I can tune to kick the pendulum at precisely the right moment?

Would this solution also take into account any small changes to the pendulum length and therefore the pendulum period of swing, from things like humidity/heat/or whatever, as any variations would result in inaccuracy?

Think I'll get back to my saw and sandpaper...

Does this mean that I can completely do away with the TI circuitry and use a circuit that I can tune to kick the pendulum at precisely the right moment?

Yes, and you don't need to "tune" a crystal controlled driver.

The inexpensive alarm clocks that move the second hand one step/second have a crystal-controlled stepping motor driver, which could be forced into service for your clock without much effort.

An advantage of a microprocessor based system is that it may have a wider range of convergence, that is, could use some clever tricks to force a pendulum that is far out of sync, back into sync. In addition, the posted software has a set of LEDs that help you tune the pendulum period so that it is already close.

This is all becoming clearer in my head, thanks to your patience and the links you provide.

I'll now have to do a bit of studying...

As a matter of interest, I see the original circuit is being sold on-line.

http://carveshop.com/html/electronics.html

$50 is quite expensive for such a simple circuit, and if 4 D cells last only 2 months, there is a serious problem with the design.

Edit: I see now that the circuit actually powers the movement, rather than just set the timing. So the high energy cost can be attributed to friction in the bearings.

Given my lack of knowledge of electronic stuff but driven by my passion about wooden geared clocks (I know, we all have our little foibles) I really want to build this clock.

I tried to buy the electronic "kit" from the original developer but the site seems to be closed, or at least, it doesn't respond.

If anyone is interested in offering me a ready built circuit for this clock, I would be very interested and happy to recompense them.

Perhaps you should ask a moderator to move your thread to Gigs and Collaborations, which is where folks looking to do freelance design usually look for clients.