[mark_in_manc]

I use a master and slaves on this system. It's a 24v pulse, once per minute, which lasts a couple of seconds (though a shorter pulse will work). There are three wires because the system does something odd on the hour - there is a little pip on the back of the minute hand wheel which lifts a switch contact in the slave, and changes which wires are connected to the coil (a semiconductor diode inside the slave is also involved on mine, which may be newer than this one). Also on the hour, some contacts change over in the master, and the thing applies about 10 pulses with a 2 second period (one on, one off). I half remember reading somewhere that the point of this was to bring all the slaves into synchrony once an hour, in case any had dropped a minute here or there - perhaps once that pip makes contact, any further synchonising pulses are redundant.

The master makes quite a clunk when it applies the pulse (via an electromagnet which pulls over a carriage containing a mercury switch) - and 10 big clunks on the hour was too much for a domestic environment! So I slipped some paper between the relevant switch contacts in the master clock, and connected mine up as a 2-wire system. I needed to think about what that little pip was doing inside the slave on the hour, to make that work - and my two slaves generally stay in concert. I have some more movements but no more faces etc - those bits tend to cost money these days!

Hope that's useful. Nice clock - it would be good to keep it original.

M

(oops - crossed with Merlin)

(Looking again - mine only have one electromagnetic ratchet in them, and yours appears (perhaps) to have two. This might have been the way to deal with 'normal' pulses vs 'synchronising' pulses, before semiconductor diodes were available.)