Clock Project

I had to read this a couple of times before I got it (I think). If I understand you, you want to use a pendulum of arbitrary length (and arbitrary period) and then have this advance the clock mechanism the correct amount for each swing. For example, say you used a 1 meter long pendulum with a period of 2 seconds. You would want to advance the the clock 2 seconds each cycle. Correct?

Not sure what you mean here, there is nothing vague about the motion of a pendulum.

Bryan Mumford has something like this going, but he uses a pendulum to generate the pulses to an electrical drive system for the hands. He keeps the pendulum going with magnetic impulses. The impulses are triggered by the pendulum itself, so that the pendulum is the thing actually keeping time.

Thanks for the reply, Anthony.

You understood okay, but I was thinking of a complex escapement mechanism that is amusing (?) to watch and has a period of many seconds. Accuracy is not a goal here; the goal is more: "you can keep time with THAT ?"

The latched increment input into a clock driver is the part for which I'm seeking help.

Thanks again.

Marc

Anth> > Would like to build a digital clock with a long-duration mechanical

I'm lost on your description, too. Do you want to _add_ the incremental value to the previously stored value each interval?

Ed

Right, Ed. Time value is incremented by the escapement period time value. (This is true of every mechanical clock, when you think about it.)

I didn't provide detail on the "escapement mechanism" b/c it's not important regarding the portion I need help with. The Increment will be many seconds and you understood perfectly. The "ecapement mechanism" operates over a repeatable-enough period of time and THAT time period will be the "increment".

My own thought since I described the problem is that instead of counters, gates and DIP switches, a small microprocessor chip would be the easy way to program the increment function (especially regarding re-programmability). --probably cheaper, too.

Thanks for responding.

North Coast Igor - Marc

ehsjr wrote:

So conceptually: impulse from escapment-> add N to totalizer is all we have so far. First, flesh out the impulse generator: microswitch, opto, what? Debounce it as needed. You can google "debounce circuit"

Apparently you've already figured out how to come up with N - but why on earth do it that way when you've already decided to use a micro? It can count the time between impulses probably better than you, and with better resolution and no need to gate the value stored in a bunch of dip switches. Just count directly using the micro. That also takes into account any physical abberation in the escapement.

But after impulse from escapment-> add N to totalizer what happens next? Does the value in the totalizer cause something to happen? Seems to me it should, and logically it is something like "is value in totalizer >= X" if yes do something, if no do nothing. Do you want the value to cause the hands to move some particular distance?

You need to do a complete set of specs for what you want to happen. It _has_ to be more than just adding a number to a total or else there is no purpose to doing the addition. I don't mean this as criticsm, but I don't think anyone here wants to drag the specs out of you one at a time. I think that's what I'm doing, and it's not fair of me to waste your time because I just plain don't get it.

Ed

First, you're supposed to bottom-post, to follow the natural flow of the thread.

Given that, google "compound pendulum" - you'll find some really impressive-looking designs for pendulums (pendula?) of practically unlimited period, probably even adjustable ones.

Good Luck! Rich