In the UK the long term total number of cycles is kept correct.

I have a 1950's clock with a synchronous motor driven by UK 50Hz mains. Keeps virtually perfect time unless the mains fails. I can tell exactly when that occurs though, because the motor doesn't restart automatically: needs a button to be pressed to kick start it.

 

Thanks for the amazing detailed circuit. It will take me a while to absorb it all. I noted the 5V box and its description. Fascinating gadget that is new to me. (I'm of the resistor-capacitor-tube school.) Why the parallel capacitors in the 5V section? It looks like the LEDs are there just as visual confirmation of current in the respective lines.

Where is the compartitor in the circuit?

I guess 390R means 390 Ω and 4K7 means 4.7 KΩ.
The soft switching worked with my old circuitry, so should work with this one too.

I think I can build this! Appreciated.

.
I usually design, and re-design, and re-design, the Circuit as I'm creating the Schematic,
the Comparitor was originally part of the plan in my head,
but then I figured-out that I really didn't need it.

The LEDs are to give a flashing, visual indication that
the Circuit is running, and actively dividing, the 60hz Line Frequency by 1/3600.
( 60-cycles per Second is 3,600 cycles per Minute )
One short flash, once a minute, can leave You wondering, is it really working ?
The LEDs and their associated FETs can be left-out if desired.

The Capacitors are usually known to be a High-Frequency-Ceramic,
and a "Lower-Frequency" Electrolytic-Bulk-Storage-Capacitor,
sorry I didn't make that more clear.
It keeps the Power-Supply nice and quiet when all that High-Speed switching is going on.

"" I guess 390R means 390 Ω and 4K7 means 4.7 KΩ. ""
Correct.

Most of the parts have DigiKey part numbers, and are in stock,
put the part number into a Duck-Duck-Go-Search and all the info,
as well as the Spec-Sheets, are one click away.

The Soft-Start Circuit can be turned all the way down to
the point that it will deliver a hard and fast Square-Wave,
I suggest that You start with the hard setting,
then verify operation,
then experiment with softening it up.

The Output directly from the last 4017 Chip will remain High for 10-Seconds, ( 5-Volts ),
then switch, and remain Low for 50-Seconds, ( zero-Volts ).
Repeat .......
At the maximum "Soft" setting, the Voltage should ramp-up in approx. ~1-Second,
and the Ramp Down my take take as much as ~5-Seconds or more.
I'm telling You this because I still have no idea of how your Escapement-Mechanism works,
and my best guess at designing an R-C-Network for softening-up the pulse
may not result in the desired effect that You need,
so some adjustments in part values may have to be made.
.
.
.

 

https://forum.allaboutcircuits.com/threads/project-24-volt-slave-clock-driver.131160/

Have a look at this thread- it's still clicking away on the wall.

Note that the caps on the 32768 khz crystal are too small, that was aan issue that i remember needing to fix.

 

LowQCab

Thank you for the explanations and additional information. It is all quite fascinating. I worked in an electronics shop more than a half century ago and developed some knowledge and a lot of interest in electronics. We saw printed circuits come in big and my boss dismissed them as junk compared to beautiful hard-wired implementations. Of course he adapted before long, but it's just one illustration of how dramatically things have changed. My mind is reeling a bit from all the new neat stuff that we have now.

I'm looking forward to doing this little project. I'm also curious about how the device will react, and will report back. The load is just a solenoid, an electromagnet. A 10 second hold time should be fine.

I read online about parallel capacitors and understand that now. I don't recall having seen it before.

Thanks again. I have to deal with some other pressing duties and then will order some parts and assemble the driver.

 

https://forum.allaboutcircuits.com/threads/project-24-volt-slave-clock-driver.131160/

Have a look at this thread- it's still clicking away on the wall.

Note that the caps on the 32768 khz crystal are too small, that was aan issue that i remember needing to fix.

Very interesting, and there are some similarities to what I use now. In my current design I trickle-charge a big electrolytic and discharge it once a minute through the solenoid. It worked fine for months but now misses quite often. And that is not good for a clock. Maybe the capacitor has deteriorated, I don't know.

 

the motor doesn't restart automatically: needs a button to be pressed to kick start it.

When I was a kid we had a couple electric clocks that also wouldn't restart automatically.
They had a little knob on that back that was connected to one of the clock shafts and slowly rotated (perhaps about 1rps) with the clock movement.
You just gave it a twist to restart the clock (spin-start).
Interestingly, if you gave it a backwards twist, the clock when then synchronously run backwards, as the motor ran equally well in either direction.

 

I think it must have been some time after the 50s that synchro motors were fitted with a 'ratchet' which prevented them running both ways.

 

Either you have a lousy power system, or you clock, even though it's powered from 60Hz

I have two different clocks that depend on the 60Hz. Both of them keep exact same time. My atomic clock keeps accurate time all the time. The two clocks can gain 3 minutes together over about 5 months. Our electrical grid is probably not so accurate. To some, 60Hz may mean 60.01 is accurate enough. Other clocks don't suffer the same affect.