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Solar powered perpetual grandfather clock.

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Posted by N9WOS on April 23, 2007, 6:24 am
I just had an idea that is soooo good that I just have to share it with
everyone. :-)

I got it while looking at clock movements on


Some nice mechanical movements but the ones that caught my attention is  the
atomic movements. They have ones with a pendulum and/or chime. Think about
it. a grandfather style clock with a swinging pendulum and chime that is
always accurate within a second.

Now here is where the fun starts. They use two batteries in series for a
power source. Around 3V. If you put a set of nicads, or NIMH's in the
movement, and pulled a solar panel/s off of a garden light or a couple, and
used them to charge the batteries in the movement. Put the panels on south
facing side of the house and use telephone cord for the wire running back to
the clock.

It would be many years before you had to change the batteries in that clock.

And you could go even farther. If you changed the battery over to a lithium
battery, and used a solar charger to keep it charge up, think of the run
time for it. A lithium is good for a 1000 full discharge cycles. If it only
discharges the battery around 100ma (or most likely less) a day, you would
be looking at a lifespan of 10000 or so days for an average size LiIon. 30
some years, or more. The battery would probably die from drying out before
that. or the movement would wear out first.

No changing batteries, no winding, no nothing in 30 years.

So your son could be born, graduate high school, graduate college, and have
his children before the clock would stop working.

If the clock stopped working, your children wouldn't know what to do. it
would be a traumatizing experience for them.

Now if you had a solar powered auto winder for a spring wound clock you
could do the same thing. The only difference is you would have to reset the
time once in a while because of clock drift.

He he...... I have dragged together grandfather clocks, atomic clocks,
lithium ion batteries, garden lights and solar power all in one post.......

Good day.......

Posted by Doc O'Leary on April 23, 2007, 11:25 am

I still have a solar powered calculator
<http://www.rskey.org/ec4016.htm>  purchased over 20 years ago that is
still working fine.

Let's hope not.  As much as I love how long my calculator has lasted, it
is still just as replaceable as the clock would be.  More valuable than
the *thing* is the lesson it teaches in buying a quality item that lasts.

Why stop there?  There are all sorts of things that would best be
constructed as "forever" items.  Just looking around me I see low/burst
power items like IR remote controls, smoke detectors, and an electronic
kitchen scale that could easily have been made to work on solar energy
instead of slowly going through batteries.

Perhaps the better question is: what is the power drain threshold for a
device of a certain size such that it makes more sense to use a solar
cell than a battery cell?  Rechargeable are great for the high drain
devices, but I have to wonder why more low drain device didn't opt for
solar like my old calculator did.

My personal UDP list:, 4ax.com, buzzardnews.com, googlegroups.com,
    heapnode.com, localhost, x-privat.org

Posted by Christian Kaiser on April 23, 2007, 12:15 pm
Easy. YOU pay for the batteries, which allows a cheap price, while the solar
cell would make the price higher.

Yet I agree. There are a lot of things running with batteries that needn't.
Solar powered wireless keyboard? ;-) I wouldn't buy the mouse though.

My solar calculator (Casio) is now 27 years old and running fine.


Posted by nicksanspam on April 23, 2007, 5:11 pm

I finally got tired of replacing the 2 C-cells in a clock with a moving
pendulum, so I measured the current (3 volts at 340 microamps) and built
a charge pump like this, viewed in a fixed font:

        0.047 uF @400 V
           ||                      |
           ||               |      |     |
                            |            | 3V
120 VAC                    ---          ---     to clock
                            ^            _
        0.047 uF @400 V     |            |
           ||               |            |

I used two caps in case one shorts and for some ground isolation. The diodes
are 5.1 V zeners ($.29 for 2 at Radio Shack) to limit the clock voltage if
someone unplugs the batteries. This circuit supplies 390 microamps. I hope
to avoid replacing the batteries until their shelf life runs out in 2012 :-)

This could be useful for lots of low-power stuff, eg smoke detectors.


Posted by Neon John on April 23, 2007, 10:44 pm
 On 23 Apr 2007 13:11:53 -0400, nicksanspam@ece.villanova.edu wrote:

Slap a super Cap in there in place of the battery and it probably will
last forever.  Making it just a little more complicated, go to 5 volts
on the cap with a zener to limit the max voltage and use one of the 5
to 3.3 volt single chip switching regulators to feed the clock.  That
way it could ride through long power outages.

they're off the shelf items.  I have them in my house.  They are
standard 9 volt detectors with a little RC network feeding in via a
diode from the line.  The major reason I went with these is that they
use the power line to signal all detectors to alarm when one goes off.
That addresses the problem of a fire in the basement and me in the bed
and not hearing the alarm.  Now all the alarms in the house sound
simultaneously.  The one that actually triggers the alarm flashes the
battery check LED.  Got 'em at Home Depot a few years ago.

Remote controls, smoke alarms, calculators and so on would be
excellent candidate for radionuclide battery power.  Essentially
infinite life.  A very clever design of a smoke detector would use the
ion current itself to power the rest of the thing.  Of course we'd
have to dodge the radiophobes to ever get to that point.

John De Armond
See my website for my current email address
Cleveland, Occupied TN
All great things are simple and many can be expressed in single words:
Freedom, Justice, Honor, Duty, Mercy, Hope.  -Churchill

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