RODALCO

Hi, I'm new to this Forum but old in electronics, starting with TTL technology 25 years ago in building digital clocks with them based upon 7447, 7490, 7400, 7408 and 7413.
a lot of breadboarding work but great results from it.

I like to know if anyone has built a synchronising CCT to synchronise two pendulum clocks at exactly the same rate.
I know that you have to attach a magnet or piece of soft iron to the pendulum, and put a coil underneath, then trigger it at the correct rate by means of a pulse from an accurate oscillator or from the other clock.
I'm pondering of ways how to approach it.

I collect electric Master and Slave clocks and have 5 German Bürk 3/4 seconds pendelclocks which are very accurate, but I like to keep them going in exact synch. with each other.

Also the Hipp Toggle principle is an option which I'm thinking off as well which is used in a FAVAG clock I have as well.

Any feedback, experience in this field would be greatly appreciated.

Kind Regards Raymond

glenncanada

Reply to Raymond, Auckland, NZ

I have built a system such as you describe: iron "slug" on the bottom of the pendulum rod, with about a 2 mm gap to the top of a vertical-core electromagnet driven by electronics. The pendulum natural frequency is very close to 0.5 Hz, i.e. one tick per second. The electromagnet is turned on for about one-third second, once per second, driven by count-down from the grid frequency (60 Hz here). The surprising thing to me - I'm an ex-professor of electrical engineering - was that no matter how you start the pendulum swinging, it always 'glides' into perfect synchronization with the magnetic pulses! The technical term for this is a stable "limit cycle." So all you would have to do to synchronize two pendulum clocks would be to drive them with the same single electronics circuit.

I would be interested to know if others have constructed such an arrangement.

ljcox

Have you done a search?

I found these by searching on "pendulum":-

http://www.electro-tech-online.com/e...light=pendulum

http://www.electro-tech-online.com/r...light=pendulum

http://www.electro-tech-online.com/e...light=pendulum

There are more so I'll leave you to examine them.

__________________
Len

RODALCO

Thanks for your replies glenncanada and ljcox.

I have been quite busy with my normal job and put this idea to rest for the time being, but with holidays coming i will put some effort in to get this going.
I thought along similar lines. My biggest problem is to source a couple of M5 nuts with a pitch of 0.5 mm instead of 0.8 mm.
I can't get these in New Zealand and in the USA you need to register for a formal account from the traders who sell those nuts.
It looks over the top for a couple of M5 nuts which are probably only worth less than ½ dollar each.
I need to use those to mount the iron slug or bar underneath the pendulum.
For the 3/4 seconds i thought by using a 1 Hz impulse from a acurate 4.19 MHz crystal source to drive a 4017 and every 6 seconds (which is 8 beats) give a short impulse to the pendulums of the 2 clocks concerned.
The coil will be mounted underneath with a small airgap similar as on the FAVAG Hipp toggle clocks.

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There are more ways to get to Rome.

Electricity, Electric clocks, Meters and Trains are great.

ljcox

Have you considered buying a Metric tap and die set?

There are specialist nuts and bolts shops in Melbourne, do you have any friends coming over?

__________________
Len

RODALCO

ljcox, not at the moment Len.

All M5 nuts are with a 0.8mm pitch instead of 0.5mm.
These nuts do exist as in the USA i have seen them for sale at the whole salers via the internet.

__________________
There are more ways to get to Rome.

Electricity, Electric clocks, Meters and Trains are great.

RODALCO

Hi, I succeeded in this pendulum project quite well.

I bought a M5 tapset via Ebay Germany, and made some soft iron retapped nuts which i have hung underneath the pendulum of two different Bürk 3/4 seconds master clocks, which are hanging next to each other.
These have been running perfectly in synch via an external 4.19 MHz quartz oscillator.

I used for the coil an E shape from an old discarded contactor and rewound a new coil to run on about 8 volts, impulsed every 3 seconds, via an 1 second impulse into a 4017 divider, to keep the output pulse within the beat of the 3/4 seconds beat of the clock.

I posted some photo's on an other thread in this forum, of the current arrangement which works well, but as i am in the process of tyding matters up i will take step by step photo's and will add these in the next couple of week or so.

Regards and happy time keeping, Raymond

__________________
There are more ways to get to Rome.

Electricity, Electric clocks, Meters and Trains are great.

wombweller

Ray

Glad to hear you are sorted
Not tried your circuit out just yet as I have neen very busy getting another project for a 30 sec output from a 1 sec input.
Looking forward to seeing the final setup.


Regards Mark
nee. markelectro

bobledoux

If you want to sychro two pendulum why not use one as a master and the other as a slave? The advantage is you improve the accuracy of the system. With proper adjustment you can achieve accuracy of up to a millisecond of error a day. This was the method used to produce the Shortt free pendulum clock that was used in astronomical observatories before the advent of crystal oscillator clocks.

wombweller

Bob


With a gpo. type master clock I have seen this method. One gpo. used as the main clock to work from.Evertime the main clock impulsed the pendulum a relay in another gpo. was trigered.The Relay used was a modified gpo. type relay with a piece of thin metal shim attached to the part of the relay that opens and closes as the relay is energised and de-energised.As the relay closed the shim was brought forwards within the reach of the pendulums swing, as the pendulum hit the shim it gave it enough sprung force to keep it moving.This only happens every time the main or master clock pendulum was impulsed.

Have you seen any other methods?


Mark