[time-nuts] HP5065A digital clock info

[Robert LaJeunesse]

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: "EWKehren at aol.com" <EWKehren at aol.com>
To: time-nuts at febo.com
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,  
eb at telight.com 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.