[time-nuts] Spectracom 8170 -> SWCC clock

Brooke Clarke brooke at pacific.net
Sun Jan 22 17:35:34 EST 2012


Synchronizer coil data at:
http://www.prc68.com/I/SWCC.shtml#SC <- old 2 coil sync
http://www.prc68.com/I/SWCC2.shtml#SC <- newer single coil sync

The WU central office used a 200 VDC supply and the loop drove a number of series connected sync coils.  A large ceramic 
tube variable resistor was used to set the loop current.
It's amazing how much snappier the sync action is when the loop resistance is raised, i.e. shorter time constant/higher 
loop voltage.
I think something like a throwaway camera flash circuit could be charged up maybe a minute before the top of the hour 
and then dumped into the sync coil a few (TBD) ms prior to the exact top of the hour.

Have Fun,

Brooke Clarke

Jim Hickstein wrote:
> On 2012/01/22 14:56, Don Latham wrote:
>> NICE!
>> Measure the resistance of the coil, and see what the current would be
>> with the voltage you want to use. Figure out what the current might have
>> been in the original installation. Ebay has an installation manual at
>> auction for these clocks, may have a description of the driving circuit.
> I hate to pay twenty bucks for a PDF, or to pay twenty bucks just to find out. If it's anything like this:
> http://electric-clocks.com/SWCC/
> ... it doesn't say.  The winding battery, and the setting signal, were supplied, and the installer didn't need to know 
> the specs.  But, then again, I can't afford to experiment too broadly and damage my museum piece.  I think the guy who 
> recently cleaned and repaired the movement tested this coil.  I'll call him back and ask what he put on it.
>> In extremis, measure or estimate the coil wire size and calculate the
>> heat loss for the actuated time with the voltage you want to use.
>> Don
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