[time-nuts] HP5065A digital clock info

[EWKehren at aol.com]

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.

Ed

In a message dated 9/27/2011 9:10:25 P.M. Eastern  Standard  Time,
<https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts>EWKehren  at 
aol.com writes:

Sorry  Ed  you are wrong. Hp generates  a 65 Hz signal that advances the
internal prescaler 49 counts and uses the  1 pps output to stop the 65  Hz
output at count 49 and waits for the  internal 1 pps to go to 50  and
advance the
second digit one count.  Sounds crazy but it works,  makes the clock advance
in  perfect  sync with the internal second  generator.
Bert Kehren

In a  message dated 9/27/2011 8:16:43 P.M.  Eastern Standard  Time,
<https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts>eb at  
telight.com writes:

After looking at the manual, I  realized  that I  did look at this
series of parts way back, but  didn't  get the connection  because I
thought it would have to be a  type  that takes 1 Hz input rather  than
50/60 Hz. I see now that they   were used in the "set" mode, bypassing
the internal divide by   50/60.

The clock module I have is the type  with a 555 used as  a  one-shot for
normal operation, or as an oscillator  for fast  setting.  I think this
is probably the newer of the designs,  since  it is   simpler.



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