Also I'm working at the moment on a external very accurate timebase upon a 4.19 MHz crystal, in Crystal oven.

( Pendulum clocks with invar rods are very accurate, but occasionally may drift a couple of seconds a week. )

4.194.304 MHz divide by 22 gives one Herz.

For a 3/4 seconds pendulum i need 4 complete, or 8 half swings for one impulse per 6 seconds. ( I choose this value because i may use it for 2/3 seconds clocks as well )
I have not got a 1 second pendulum clock at the moment because of the hughe shipping costs to New Zealand $1000 NZ or 700$ US .

I'm thinking along the line of using a CMOS 4017 which counts the 1 seconds impulses from the 4017. decode the 6 seconds, and provide a synchronising impulse to the pendulum.
The 1 second impulse is about 0.2 seconds long.
By AND gating the 0.2 and 6 seconds impulse together to a driver transisitor (2N2222) a impulse can be put into the coil to drive the pendulum.

I haven't got this far yet because of 2 young children at home and long working days, and too much time on the forums i admit, but I will get onto it now sooner because of your interest in this great topic too.

This impulse can't be to strong, because the pendulum is already driven through the graham escapement from the electrically wind clockwork.

What country are you from BTW ?

Regards, Raymond

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No-one seems to have mentioned that the natural frequency of the pendulum (ie. it's frequency when it is swinging without the electrical assistance) needs to be as close as possible to the frequency that it is to run at when electrically driven.

Otherwise, it will be impossible to make it sync with the electrical signal from the crystal oscillator (divided down of course).

Instead of a 4017, you could use a presettable counter such as the 74HC161.

This has a synchronous preset. Configure it to preset to 10 (ten) when it reaches 15 (ie. when Tc (pin 15) goes high. It will then be preset to 10 at the next clock pulse. Thus it is a modulo 6 counter.

The advantage of this is that you can use the Tc output (gated with say 0.2 sec) to drive the pendulum pulse.

If you wanted say a modulo 7 counter, then preset to 9, etc.

__________________
Len

 

There is a design that uses the magnetic drive coil as the sensor, as well as the "motor." The pendulum holds a magnet. As the magnet approaches the coil it induces a voltage in the coil. This voltage turns on a switching transistor that discharges a capacitor into the coil to drive the pendulum.

Solarbotics.com sells a "SunSwinger Pendulum Kit" for $30 that is powered by a small solar cell. The drive circuit consists of two transistors, two capacitors, two resistors, a coil, diode and solar cell. You can download the manual for the kit at their website.

This design certainly has promise for driving a clock pendulum.

 

RODALCO

Thanks for the reply.

I have long been interested in master clocks but like you my mind tells me to make one or some of my own.Differance between us is I don't have any Electronic's experiance at all so It's a case of asking those that have what my possibilities are.

I do have a GPO.36 Master with hip n toggle.This is a very good and practical solution BUT!! I did want to try a more electronic route.

Shame you can't get a 1 sec beating master closer to home but keep on trying.
Thanks for everything,if you can help with electro advice for this project I would like to hear from you.

Regards Mark

 

Ray
again thanks thanks for the info.I will read through your post and see what I can pick out of it.but it seems to closer to what I am looking for with my project.

I am from the Uk. but I will swap you places if you like

 

bobledoux

Seems to be a neat little project,just the thing that might start me with the understanding of where to go.

Cheers!!!

 

Thanks for this
all sounds very interesting and could be what I'm after But!! sory there is a lot I don't understand in the explination.If you have the time and could expalin in laymans terms I would be very pleased in hearing from you.

 

Ray
I can sympathise with the fact that Children and Families do take up lots of our time o finding time to work on project can be a little hard.The real vain is the dreaded work,it seems that through your work you have the opportunity to work with Electronics unfortunately I don't.

Again this explination does seem to be closer tho what I'm looking for like (ljcox')explination but could I ask you to explain in laymans terms the parts you dercribe and what they do and are capable of?

Many thanks Mark.
Ps.don't forget about the swap (uk-New zealand) I will throw in a gpo.36

 

I got interested in master/slave clocks when I started looking at the British Synchronome, far away and expensive.

Recently, I purchased an American Standard Electric Company slave clock and built a very simple PIC controller to impulse it once a minute. Over the last couple of months it has been accurate to about a quarter second per month.

The impulse unit operates on a standard 4 mhz crystal at room temperature. I have corrected variations between calculated and actual times by adding and removing clock cycles from the timing loops.

The Microchip simulator has allowed me to count the number of loops required to complete a minute. The current count is 60,000,789 instruction cycles per minute; the PIC uses 4 clock cycles per instruction cycle.

I monitor the clock status every morning by comparing the clock advance pulse to the WWV minute tone. The clock is so accurate that I'd need to compare it to WWV with an oscilloscope to improve it. I'm waiting to see how summer temperatures affect time keeping when the indoor temps rise by about 5 degrees F.

It seems redundant to use both a pendulum and electronic time keeper to constantly pulse a pendulum which is a good time keeper in its own right. I'd prefer to use Shortt's method of setting the pendulum to run a few seconds slow per day and then use the electronic standard to provide the extra push to keep the times in sync.

See her for more info:

http://www.geocities.com/old_electric_clocks/page02.htm

 

Do you have the data sheet of the 74HC161?

You need this in order to understand what the IC does and my post.

So I suggest you download one and re-read my post.

Then ask any questions that you can't resolve.

Of course, you can do it all in a PIC if you have PIC knowledge and a PIC programmer.

The Modulo of a numbering system is the number of digits it uses.

eg. decimal is modulo ten since it has 12 digits 0, 1 ~ 9.

Binary is Modulo 2 since it has 2 digits, 0 & 1.

Modulo 6 has 6 digits, 0, 1, ~ 5.

The IC counters count in binary but you can make them count in any "Modulo". The digits are coded in binary but can be displayed as numeric digits using a 7 segment display.

For example, a digital clock is working in binary, but it displays the time in decimal. So to make a digital clock you need 2 Modulo 60 counters (one for the seconds and one for the minutes) and either a Modulo 12 or 24 counter for the hours.

There have been plenty of threads on counters in the forum. So do a search for "counter".

__________________
Len

 

Hi, interesting conversation going on re this very interesting topic.

A pendulum masterclock is referred to, in general in the amount of beats per second.

Say for a one second master, one swing is one second, a complete forward and backwards swing takes two seconds.

A 3/4 seconds master takes 1.5 seconds for a complete swing.
To get that to a round seconds value i have to impulse that every 6 or 12 seconds to keep the crystal oscillator in time with the natural swing of the pendulum.

The Hipp toggle has an off set butterfly switch, which operates on the left hand side swing. The contacts close when the arc of the pendulum decreases to the correct amount to close the Hipp Toggle switch via a notch in an attachement to the pendulum rod.
The coil underneath the pendulum attrackts a soft iron bar underneath the pendulum rod, and attracts it at the correct time, increases the arc so the pendulum in motion is clear to swing freely for the next 20 or 25 swings.

An other variety is described below.
The Electrique Brillié master clock impulses every second into the 1/2 second beating pendulum by means of a hairspring contact. Details may be on viredaz electric clocks website Google.

I take a detailed photo off the Hipp toggle on my Favag masterclock and will post it to make it clearer to other interested members.

I work in the Power industry as registered electrician, technician and deal with cable faults, substations, high 11, 22. 33. 66 and 110 kV and low voltage 110, 230, 400 Volts switch gear, control, scada, metering and instrumentation.
Electronics is a hobby of mine and read Silicon chip, Elektor magazines and build things with trial and error sometimes.
I don't know much about PIC's, and like to build projects with discrete components and TTL and CMOS IC's which are cheap and readily available.

Kind regards, Raymond

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www.mypage.bluewin.ch/electric-clocks/


Hope this link works

Regards

Raymond

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Electricity, Electric clocks, Meters and Trains are great.

 

Another clock fanatic besides myself... I'm not sure if I should be amused or concerned LOL.

I have been thinking of a similar project, using the natural pendulum cycle to drive a nixie display...

Anyaway, I am wondering if one of those inexpensive 'perpetual motion' kinetic art toys (example) could be hacked for the drive assembly... It seems to me they operate on the same principle, and using a correct length pendulum would result in the desired period. Myself, I'm hoping to use seconds escapement.

I'm not concerned with absolute accuracy, so long as it is usable.

edit -

If anyone involved with pendulum projects could explain to me the purpose of the pendulum spring, I'd be grateful... Is it simply to avoid the friction associated with a bearing?

 

The pendulum spring has indeed to with avoiding the friction.
A normal bearing or pivot would wear out to fast, or the holes become oval and friction will increase.
The spring steel is well within it's range of flex with the 2 or 3° of the pendulum and not prone to wear.
Considering that one year has 31,536,000 seconds for a one second pendulum, a clock with a 1/2 second pendulum will double that to 63 million.

The pendulum has to be hung with caution and avoid twisting the spring which may break or shear it off.

Under normal working conditions these suspension springs have an almost unlimited lifespan.

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Electricity, Electric clocks, Meters and Trains are great.

 

To drive a nixie display would be a great idea !
a mechanical drive to a classic Nixie tube system is certainly a different approach for a clock.

Have a correct length pendulum, 1, 3/4, 2/3, 1/2 seconds beat.

Drive the pendulum via an electronic Hipp Toggle or Fedchenko system and put output pulses into your 7413 schmitt trigger and counting decades with 7400, 7490 and 74141 IC's or eq.

I'm also still looking for a good and reliable pendulum trigger circuit so any members with knowledge, please post us a link.
The links on Google give you more a completed product to buy instead of any usefull schematics.

Thanks, Raymond

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There are more ways to get to Rome.

Electricity, Electric clocks, Meters and Trains are great.