Yes, the seconds count really fast in the "Slow" set mode, but the goal in this mode is to set minutes, not seconds. To set the seconds one advances past the current time and uses the "Hold" function to prevent counting until the display is on target. "Fast" set mode clocks the minutes at line frequency to advance hours at a decent rate. FWIW I worked in National's digital apps group around when the MM5311 series was designed, IIRC originally for a Motorola dispatch console. Have a 5314 running in my living room, as it has done faithfully since the early 1970s.
Bob LaJeunesse ________________________________ From: "[email protected]" <[email protected]> To: [email protected] Sent: Wed, September 28, 2011 3:29:14 PM Subject: Re: [time-nuts] HP5065A digital clock info The one you describe is the one I use with my 5313's, would be nice to see how they do it, they must inject the 60 and 600 Hz further up. I do not see how they can set the second digits at 60 Hz they would scroll awful fast. I use a 555 but at 3 Hz, 60 Hz and about 1 KHz. My counter counts down to 1 Hz but can be preset by Tbolt or a thumb wheel device and also has a hold function. That chip family is definitely intended for accurate 1 sec. clocks and combining dividing,synchronizing and setting is not trivial. A PIC could do it,but I do not have the skills. Bert In a message dated 9/28/2011 3:05:51 P.M. Eastern Daylight Time, [email protected] writes: Yes Bert, the "three-board" type uses the counting scheme that you described, but the other type is as I described. On the "two-board" version the "set" mode is permanent, and there is no external counter or logic. The 555 is a normally a one-shot for stretching the narrow 1 PPS pulses from the Rb system, but oscillates at around 60 or 600 Hz (precision not important) during setting, accomplishing the same result. I think this design is the later one - someone at HP may have had a "eureka" moment and realized that this simpler approach could eliminate a board full of logic. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
