Synchronome Slave Clock

[Tmuir]

The other week I went to visit a friend at their shop and they had in for repair the nicest electromechanical slave clock I have ever seen.

It would of been originally installed in a very large area and the dial was about 2 foot across with a lovely wood and brass case.

I was told that the owner wanted it cleaned and serviced and made to run, but he did not have a master clock for it.

I suggested an Arduino with a real time clock module and a relay board should do the job as it only needed a pulse every 30 seconds.

This weekend I was up in my loft and noticed my 'parts' Synchronome clock.

I picked it up a few years ago and the only original part to it is the slave dial mechanism (1909 to 1918) model and the pendulum, everything else is not original (including the dial) and someone had tried to make it work by using a break beam sensor and home wound electromagnets to give it it's impulse. I bought it for the price of a beer as the pendulum rod and weight was worth it alone.

I decided to remove the slave dial and make myself an Arduino Synchronome.

The mechanism was filthy so was given a good clean.

For those familiar with these clocks also note that someone had replaced the coil with a newer one. The resistance of the new coil was 45 ohms whilst the original one would of been around 2.5 ohms, so all my notes on what current to use to run the clock were useless.

After cleaning and replacing the sheet of paper that is on the active surface of the armature I had to spend a lot of time tweaking the placement of the coil to get it to operate correctly as it was slightly too wide.

Once that was sorted through trial and error I worked out that around 6.5 to 7V gave reliable operation of the clock, then it was on to the programming.

After about an hour of struggling to get the program to work correctly I called my 14 year old son who then in about 3 minutes wrote me the code that would get the time from the Real Time Clock module (RTC) and then just looking at the seconds at 00 and 30 seconds it would send a 40 millisecond pulse to the relay.

The clock is now happily ticking every 30 seconds on my bench.

I still need to fit a 450 ohm resistor across the coil to stop arcing on the relay contact but will sort that out tomorrow.

Then it will be time to move the cct off the breadboard onto something more permanent and sort out a dedicated supply for it rather than my bench supply.

Please ignore the mess on my bench. I'm in the process of restoring a late 1930s and a late 1950s bicycle, both made in Australia.

 

 

 

 

 

 

[Tmuir]

The following day my son came up to me and told me we need to improve the coding.

He wants to add a button that when pressed will pulse the clock every second to allow to you adjust the time forward and a second switch to disconnect the relay from the clock.

The reason for the disconnect switch is because this early movement does not have a leaver that you can depress to disengage the locking to allow you to set the time, you must manually push in the armature enough to disengage it, but not so much that it starts to move the wheel forward, this lets the hands free spin allowing you to manually set the time and obviously whilst you are doing this you don't want the relay to pulse the clock.

I know this type of clock is not to everyone's taste but I'm happy because it has got my youngest son for the first time been interested in Horology and if this can be a stepping stone to other clocks so be it.

Maybe once this one is finished, I can get him interested in my IBM clock and we can service and restore that one (and replace the scary 1950s power supply with something more modern and safer).

 

 

Edited June 15, 2021 by Tmuir

[RogerH]

That is a great looking bit of kit - but you're right, the power supply does look scary!! and anything that gets the younger generation involved in clock repair has got to be a good thing.

[Spike63]

Hi, I have the same Synchronome movement  (as in your first photo) but cannot get it it to advance/function correctly. As far as I can tell it appears complete and looks the same as yours. However, when the electro magnet has power it attracts the armature but the ratchet wheel does not move. I don't understand what actually causes the wheel to move and basically whenever power is attached, the armature moves but then moves back to exactly the same position when power is cut. Any idea why the wheel isn't moving? All of the cogs move freely as do the clock hands... Any help would be much appreciated.

[Spike63]

Now sorted this out after much head scratching!