[time-nuts] Spectracom 8170 -> SWCC clock

[Brooke Clarke]

Hi Jim:

On web page:
http://www.prc68.com/I/SWCC2.shtml#SC

I have data from Henry W. that says 120 V (my memory was wrong on the 200 V) and he says 250 ma.
This will give about 66 times faster response time than using 3 Volts.

I'm spending time on this because with low loop voltage the action is so sluggish that it will barely work or for a 
clock that's not brand new and properly oiled may not work at all.

Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/Brooke4Congress.html


Jim Hickstein wrote:
> On 2012/01/22 15:29, Bob Camp wrote:
>> Hi
>>
>> Teletype loop current as in 20 ma through the coil via a dropping resistor off of 125 vdc.
>
> Value for the dropping resistor?  (I know, I'm an Extra, and I used to design digital circuits, so I should know this 
> stuff.  But I've been in software for a long time.  Let's see.... E over I R.)
>
> I measured the setting coil at the terminals: 11.5 ohms.  To limit 125 VDC to 20mA, this would need an additional 6.2 
> Kohms.  I suppose that represents the metallic circuit back to WU plus a bunch of other 11.5-ohm clocks on the same 
> circuit, plus a compensating resistor back at the head end?
>
> Locally, a D cell (or 3 in series, which I have), with about 200 more ohms, might do.  (Reaches into desk drawer.)  
> Let's see if I still have that bunch of 100-ohm resistors left over from making an ISDN terminator.  Why, yes! 
> Quarter-watt.  P over I E.  90mW.  Eh, it probably won't blow up.
>
> I tried measuring the winding coil, too: 0.1 ohms, but I'm not sure I was getting it in the right place.  And now I've 
> put the face back on the clock. Otherwise I couldn't tell what time it was!  I am really trained to look at that spot 
> on the wall for this information.  While the SWCC was in the hospital (for over a year) I had to buy another clock to 
> put there.  The blank spot was driving me crazy.
>
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