[time-nuts] Spectracom 8170 -> SWCC clock

Jim Hickstein jxh at jxh.com
Thu Mar 1 21:18:55 UTC 2012


On 2012/02/22 13:48, Jim Hickstein wrote:
>> What are the chances my EEPROMs would DTRT if I just added an 8255A to this
>> board?

They do.  Socket and 8255A added, signals present on the 50-pin header as 
documented for Option 18, so I'm proceeding with my little TTL circuit to set 
the SWCC clock on the hour.  (Contact me privately if you want criticize my 
schematic.  I'd love to get some help with that, as I haven't done this kind of 
thing for decades.  I'm an Extra, but not an EE.)

This (image) is the 1PPS and seconds-LSB signal, over two seconds.  Sorry for 
the focus.  I could get out the better camera for this, I suppose.  Digikey 
order arrived today.  Whee!!  Now I just have to see if I still remember which 
end of a 14-pin DIP is "up".  (Joke! Some things you just cannot forget, even 
after decades.)

Digikey had everything I needed except the 40-pin DIP package of the 8255A.  But 
I easily found one on eBay.  That makes it an antique.  Copyright 1975.
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