Atomic Clocks: It is important that they keep good time, Part 1
The clock display on a HP Cesium Standard is a bit of a gimmick. The legend I was told: An Admiral was touring a nuclear submarine, and was being shown the "Atomic Clocks" in the navigation section, and said: "If the Navy is going to pay 40 grand for an atomic clock, I damn well better be able to set my watch by it." And so the need for the clock display was born. (There is likely almost nothing true in that heavily embellished story....)
The 1PPS output, clock display and backup battery were new features added when HP upgraded the 5060A to the 5061A in the early 1970s. The 1PPS circuit was pretty cool. Dividing the 10MHz signal down to a narrow 1 pulse-per-second signal was straightforward, but they added a delay circuit, actuated with a series of thumbwheel 10 position switches, that would allow you to program a delay from 0.1uS to 1 second. Essentially, set the clock (1PPS signal) to match another reference to within one cycle of the 10MHz input, or 100 nano-seconds. The cosmetic human readable display was driven by the delayed 1PPS signal. Since the clock is "only" human readable, their accuracy is essentially +/- 1 second. But those "in the know" realize that when the clock switches to the next second, they are accurate to +/- 100 nano-seconds. The propagation delay through the display electronics would be tactfully unmentioned. That should be good enough for the Admiral.
The first 5061A used an analog style clock manufactured by "Patek Philippe". But it wasn't too many years before Patek Philippe obsoleted the analog electro-mechanical clock, and HP had to design a replacement. This is the more common LED digital display seen on later 5061As. The catch: HP needed to support the old 5061A's that had the analog clock. So the new LED assembly was designed to be backward compatible service and support component too. Some poor engineer had to come up with a solution that fit the electronics in the round hole used by the Patek clock. 3 circular PCAs were used, electrically connected with pins from one PCB to the other, so it would be a drop in replacement. It was a hack of epic proportions. Hard to manufacture, expensive, power hungry. But it worked and was reliable.
As part of the 5061B product, we wanted to cut clean from the baggage of the 5061A past, and didn't have to make all our assemblies backward compatible. My job as a brand new engineer was to design a sensible clock display. Cheaper, easier to build, using less power. (I recall that the power drain from the clock/LED assembly was significant enough to materially impact the battery backup time.)
This was my first ever digital design, and I had a great time coming up with a circuit that would go from 1PPS to a hours, minutes, seconds digital display, including a feature that would allow you to easily set the clock by pushing buttons on the back side of the PCA, by sticking a small screwdriver through the cooling holes on the top cover. I choose to use a LCD display, for its low power. I agonized for weeks on what logic family of digital parts to use. LS-TTL? 4000 CMOS? I eventually choose the 74HC series of CMOS components. They were fairly new to market, which I hoped to indicate they would have a long life, since we were going to build the 5061B "forever". And all the components I needed were catalog parts. (Counters, display drivers, AND gates, etc.)
In my youthful ignorance, I made a few mistakes that Roberto had to clean up later. First, our PC Layout team was experimenting with new auto routing software tools, and choose this design to experiment on. Low frequency, low power, simple. What could go wrong? The auto-routed layout worked fine, even though the routing between the components looked like the output of a random number generator. (If you download the scans of the 5061B manual I uploaded, you can see the random trace routing in the picture of the clock assembly.) Next, I didn't appreciate that the 74HC logic family was pretty fast, with snappy rise and fall times. Capacitive coupling of signals between traces due to fast edges was a foreign concept to me. Finally, in my overzealous quest to save every microwatt in this design, I used 100K resistors for voltage dividers and pull downs, rather than a more sensible 10K or 1K values.
My clock display that worked so nice in all our prototypes (1 sample), turned out to be capable of catching a stray glitch now and then, since the 1PPS signal wound all over the PCB before it was input to the first IC. After a few years of production, some customers complained that the clock would sometimes skip a second.
The Atomic Clock didn't keep accurate time!
I had moved on from PFS production engineering to Frequency Counter Production Engineering Management when this was discovered, and Roberto called me up and gave me hell about my crappy design that he had to clean up with a new PCB layout. New layouts were expensive (a few thousand dollars), and a big deal on a low volume product. To make matters worse, I was now in management, and was by definition incompetent and an idiot. The new manager lobotomy and such. And a traitor or PFS to boot, because I left the team. Roberto was not happy with me. I apologized for my incompetence and thanked him for cleaning up my mess. I managed to hold my tongue and not remind him he was the lead engineer, and had design reviewed and approved all my work.
The moral of the story is clear: If you put a display on an Atomic Clock, it really needs to keep accurate time.
Part two is another clock story, but I'm not the goat this time.
Happy new year,
Hugh Rice
In message <CS1PR8401MB10780BD06FFE6BB5A74DF1BC8C8E0@CS1PR8401MB1078.NAMPRD84.P
ROD.OUTLOOK.COM>, "Rice, Hugh (IPH Writing Systems)" writes:
The clock display on a HP Cesium Standard is a bit of a gimmick.
The legend I was told: An Admiral was touring a nuclear submarine,
and was being shown the "Atomic Clocks" in the navigation section,
and said: "If the Navy is going to pay 40 grand for an atomic
clock, I damn well better be able to set my watch by it."
I once showed the CEO our brand new $100K cisco AGS+ router. It
was kitted out to the hilt with ethernet interfaces, but the front
side he saw had only the orange bridge siloutte and a single green
power LED. He looked at it and then said "For that kind of money,
couldn't they at least make it blink ?"
Some poor engineer had to come up with a solution that fit the
electronics in the round hole used by the Patek clock. 3 circular
PCAs were used, electrically connected with pins from one PCB to
the other, so it would be a drop in replacement. It was a hack
of epic proportions. Hard to manufacture, expensive, power
hungry. But it worked and was reliable.
Well, about that...
http://phk.freebsd.dk/hacks/HP5065A/20151225_clock/index.html
http://phk.freebsd.dk/hacks/HP5065A/20160112_working_clock/index.html
(I still have spare PCBs available)
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
I once showed the CEO our brand new $100K cisco AGS+ router. It
was kitted out to the hilt with ethernet interfaces, but the front
side he saw had only the orange bridge siloutte and a single green
power LED. He looked at it and then said "For that kind of money,
couldn't they at least make it blink ?"
Perhaps this would impress a CEO:
http://leapsecond.com/museum/patek/30-2895_2.jpg
http://leapsecond.com/museum/patek/
(not my Patek Philippe photos; these vintage pieces are beyond my time nut budget)
/tvb
That's an interesting story and history about the clocks. I happen to
have the original type digital one, used in a 5065A. I don't have an
actual 5065A, but many years ago acquired a carcass of one - it was
missing the Rb physics and a few other things, but was a nice box for
re-use.
I eventually used it to repackage and improve a Z3801A GPSDO acquired
later. It turned out to be a good size and layout for this purpose. I
managed to squeeze in the rearranged Z3801A guts, an extra layer of
mu-metal shielding and thermal insulation on the OCXO, and a couple of
12V, 12 A-hr SLA batteries for backup. I used mostly the original power
supply, and put additional supplies and control circuitry inside the
original digital synthesizer box for shielding. The whole front panel
and clock were intact, and I wanted to re-use all that stuff, except
with different functions and labels - I especially like the door in the
center with controls and monitoring functions behind it.
The clock appeared to be a very complicated mess at first, and a helluva
thing to figure out without schematics. I eventually found the
schematics, and the data sheet for the PMOS clock IC, then everything
started to make sense.
It used a buck converter to make the low voltage for the LED display,
which I eliminated since I was making new, cleaner low voltage anyway.
The board also had some simple 1 PPS interface circuitry etc, that I
moved elsewhere, so two boards were left for the clock function - one
for the counting and control, and one for the LEDs. This made the whole
assembly much shallower, and I found that a tin can (6-1/2 oz tuna can,
as I recall) made an excellent shield/cover for it. I punched a bunch of
ventilation holes in it, mechanically mounted it behind the clock
assembly, and ran all the power and signals through feed-through
capacitors.
I also changed the internal LED supply to a variable shunt regulator, to
eliminate pattern-dependent load current. To the outside world, it looks
like a constant-current load, depending on the selected LED brightness,
regardless of the readout value. Finally, I fixed the "6" and "9" tails
on the LED readout. The appearance of the top and bottom segments on
these numbers depend on the particular IC used, and this one didn't have
them. This always bugs me, and I try to make it "proper" according to
me, if possible. It turned out to be very easy to add the tails.
Ed
On Fri, Jan 4, 2019 at 4:15 AM Rice, Hugh (IPH Writing Systems) <
hugh.rice@hp.com> wrote:
The clock display on a HP Cesium Standard is a bit of a gimmick. The
legend I was told: An Admiral was touring a nuclear submarine, and was
being shown the "Atomic Clocks" in the navigation section, and said: "If
the Navy is going to pay 40 grand for an atomic clock, I damn well better
be able to set my watch by it." And so the need for the clock display
was born. (There is likely almost nothing true in that heavily
embellished story....)
The 1PPS output, clock display and backup battery were new features added
when HP upgraded the 5060A to the 5061A in the early 1970s. The 1PPS
circuit was pretty cool. Dividing the 10MHz signal down to a narrow 1
pulse-per-second signal was straightforward, but they added a delay
circuit, actuated with a series of thumbwheel 10 position switches, that
would allow you to program a delay from 0.1uS to 1 second. Essentially,
set the clock (1PPS signal) to match another reference to within one cycle
of the 10MHz input, or 100 nano-seconds. The cosmetic human readable
display was driven by the delayed 1PPS signal. Since the clock is "only"
human readable, their accuracy is essentially +/- 1 second. But those
"in the know" realize that when the clock switches to the next second, they
are accurate to +/- 100 nano-seconds. The propagation delay through the
display electronics would be tactfully unmentioned. That should be good
enough for the Admiral.
The first 5061A used an analog style clock manufactured by "Patek
Philippe". But it wasn't too many years before Patek Philippe obsoleted
the analog electro-mechanical clock, and HP had to design a replacement.
Yup -- if anyone happens to have one of the analog style PP clocks that
they would be willing to part with (possibly in trade for some other time
stuff) please let me know -- as well as playing with time, I'm also
interested in watches, and have always wanted to make a desk clock out of
one of the Patek clocks from a 5061...
W
This is the more common LED digital display seen on later 5061As. The
catch: HP needed to support the old 5061A's that had the analog clock. So
the new LED assembly was designed to be backward compatible service and
support component too. Some poor engineer had to come up with a solution
that fit the electronics in the round hole used by the Patek clock. 3
circular PCAs were used, electrically connected with pins from one PCB to
the other, so it would be a drop in replacement. It was a hack of epic
proportions. Hard to manufacture, expensive, power hungry. But it
worked and was reliable.
As part of the 5061B product, we wanted to cut clean from the baggage of
the 5061A past, and didn't have to make all our assemblies backward
compatible. My job as a brand new engineer was to design a sensible clock
display. Cheaper, easier to build, using less power. (I recall that the
power drain from the clock/LED assembly was significant enough to
materially impact the battery backup time.)
This was my first ever digital design, and I had a great time coming up
with a circuit that would go from 1PPS to a hours, minutes, seconds digital
display, including a feature that would allow you to easily set the clock
by pushing buttons on the back side of the PCA, by sticking a small
screwdriver through the cooling holes on the top cover. I choose to use a
LCD display, for its low power. I agonized for weeks on what logic family
of digital parts to use. LS-TTL? 4000 CMOS? I eventually choose the
74HC series of CMOS components. They were fairly new to market, which I
hoped to indicate they would have a long life, since we were going to build
the 5061B "forever". And all the components I needed were catalog parts.
(Counters, display drivers, AND gates, etc.)
In my youthful ignorance, I made a few mistakes that Roberto had to clean
up later. First, our PC Layout team was experimenting with new auto
routing software tools, and choose this design to experiment on. Low
frequency, low power, simple. What could go wrong? The auto-routed
layout worked fine, even though the routing between the components looked
like the output of a random number generator. (If you download the
scans of the 5061B manual I uploaded, you can see the random trace routing
in the picture of the clock assembly.) Next, I didn't appreciate that
the 74HC logic family was pretty fast, with snappy rise and fall times.
Capacitive coupling of signals between traces due to fast edges was a
foreign concept to me. Finally, in my overzealous quest to save every
microwatt in this design, I used 100K resistors for voltage dividers and
pull downs, rather than a more sensible 10K or 1K values.
My clock display that worked so nice in all our prototypes (1 sample),
turned out to be capable of catching a stray glitch now and then, since the
1PPS signal wound all over the PCB before it was input to the first IC.
After a few years of production, some customers complained that the clock
would sometimes skip a second.
The Atomic Clock didn't keep accurate time!
I had moved on from PFS production engineering to Frequency Counter
Production Engineering Management when this was discovered, and Roberto
called me up and gave me hell about my crappy design that he had to clean
up with a new PCB layout. New layouts were expensive (a few thousand
dollars), and a big deal on a low volume product. To make matters worse,
I was now in management, and was by definition incompetent and an idiot.
The new manager lobotomy and such. And a traitor or PFS to boot,
because I left the team. Roberto was not happy with me. I apologized
for my incompetence and thanked him for cleaning up my mess. I managed to
hold my tongue and not remind him he was the lead engineer, and had design
reviewed and approved all my work.
The moral of the story is clear: If you put a display on an Atomic Clock,
it really needs to keep accurate time.
Part two is another clock story, but I'm not the goat this time.
Happy new year,
Hugh Rice
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
--
I don't think the execution is relevant when it was obviously a bad idea in
the first place.
This is like putting rabid weasels in your pants, and later expressing
regret at having chosen those particular rabid weasels and that pair of
pants.
---maf
Yes indeed I also would like one of the analog clocks. But be careful what
you ask for....
I have a friend in Switzerland that does have a 5065 with the analog clock.
It tends to drive you a bit crazy with the tick of the step so he says. I
may believe that as I used impulse clocks for world time (1 min steps)for
years and have to say it really is annoying. I finally did replace them
with very quite clocks and don't miss the tick at all. There actually is a
tick from the 4 clocks but really low in amplitude. Easily ignored.
Kind of believe I won't be seeing a Patek any time soon.
Great points on the pmos display boy mine are looking ratty so may try the
shunt regulator if you would care to share the mod you did?
Regards
Paul
WB8TSL
On Fri, Jan 4, 2019 at 2:24 PM Warren Kumari warren@kumari.net wrote:
On Fri, Jan 4, 2019 at 4:15 AM Rice, Hugh (IPH Writing Systems) <
hugh.rice@hp.com> wrote:
The clock display on a HP Cesium Standard is a bit of a gimmick. The
legend I was told: An Admiral was touring a nuclear submarine, and was
being shown the "Atomic Clocks" in the navigation section, and said:
"If
the Navy is going to pay 40 grand for an atomic clock, I damn well better
be able to set my watch by it." And so the need for the clock display
was born. (There is likely almost nothing true in that heavily
embellished story....)
The 1PPS output, clock display and backup battery were new features added
when HP upgraded the 5060A to the 5061A in the early 1970s. The 1PPS
circuit was pretty cool. Dividing the 10MHz signal down to a narrow 1
pulse-per-second signal was straightforward, but they added a delay
circuit, actuated with a series of thumbwheel 10 position switches, that
would allow you to program a delay from 0.1uS to 1 second.
Essentially,
set the clock (1PPS signal) to match another reference to within one
cycle
of the 10MHz input, or 100 nano-seconds. The cosmetic human readable
display was driven by the delayed 1PPS signal. Since the clock is
"only"
human readable, their accuracy is essentially +/- 1 second. But those
"in the know" realize that when the clock switches to the next second,
they
are accurate to +/- 100 nano-seconds. The propagation delay through the
display electronics would be tactfully unmentioned. That should be
good
enough for the Admiral.
The first 5061A used an analog style clock manufactured by "Patek
Philippe". But it wasn't too many years before Patek Philippe obsoleted
the analog electro-mechanical clock, and HP had to design a replacement.
Yup -- if anyone happens to have one of the analog style PP clocks that
they would be willing to part with (possibly in trade for some other time
stuff) please let me know -- as well as playing with time, I'm also
interested in watches, and have always wanted to make a desk clock out of
one of the Patek clocks from a 5061...
W
This is the more common LED digital display seen on later 5061As. The
catch: HP needed to support the old 5061A's that had the analog clock.
So
the new LED assembly was designed to be backward compatible service and
support component too. Some poor engineer had to come up with a
solution
that fit the electronics in the round hole used by the Patek clock. 3
circular PCAs were used, electrically connected with pins from one PCB to
the other, so it would be a drop in replacement. It was a hack of epic
proportions. Hard to manufacture, expensive, power hungry. But it
worked and was reliable.
As part of the 5061B product, we wanted to cut clean from the baggage of
the 5061A past, and didn't have to make all our assemblies backward
compatible. My job as a brand new engineer was to design a sensible
clock
display. Cheaper, easier to build, using less power. (I recall that
the
power drain from the clock/LED assembly was significant enough to
materially impact the battery backup time.)
This was my first ever digital design, and I had a great time coming up
with a circuit that would go from 1PPS to a hours, minutes, seconds
digital
display, including a feature that would allow you to easily set the clock
by pushing buttons on the back side of the PCA, by sticking a small
screwdriver through the cooling holes on the top cover. I choose to use
a
LCD display, for its low power. I agonized for weeks on what logic
family
of digital parts to use. LS-TTL? 4000 CMOS? I eventually choose the
74HC series of CMOS components. They were fairly new to market, which I
hoped to indicate they would have a long life, since we were going to
build
the 5061B "forever". And all the components I needed were catalog
parts.
(Counters, display drivers, AND gates, etc.)
In my youthful ignorance, I made a few mistakes that Roberto had to clean
up later. First, our PC Layout team was experimenting with new auto
routing software tools, and choose this design to experiment on. Low
frequency, low power, simple. What could go wrong? The auto-routed
layout worked fine, even though the routing between the components looked
like the output of a random number generator. (If you download the
scans of the 5061B manual I uploaded, you can see the random trace
routing
in the picture of the clock assembly.) Next, I didn't appreciate that
the 74HC logic family was pretty fast, with snappy rise and fall times.
Capacitive coupling of signals between traces due to fast edges was a
foreign concept to me. Finally, in my overzealous quest to save every
microwatt in this design, I used 100K resistors for voltage dividers and
pull downs, rather than a more sensible 10K or 1K values.
My clock display that worked so nice in all our prototypes (1 sample),
turned out to be capable of catching a stray glitch now and then, since
the
1PPS signal wound all over the PCB before it was input to the first IC.
After a few years of production, some customers complained that the clock
would sometimes skip a second.
The Atomic Clock didn't keep accurate time!
I had moved on from PFS production engineering to Frequency Counter
Production Engineering Management when this was discovered, and Roberto
called me up and gave me hell about my crappy design that he had to clean
up with a new PCB layout. New layouts were expensive (a few thousand
dollars), and a big deal on a low volume product. To make matters
worse,
I was now in management, and was by definition incompetent and an idiot.
The new manager lobotomy and such. And a traitor or PFS to boot,
because I left the team. Roberto was not happy with me. I
apologized
for my incompetence and thanked him for cleaning up my mess. I managed
to
hold my tongue and not remind him he was the lead engineer, and had
design
reviewed and approved all my work.
The moral of the story is clear: If you put a display on an Atomic
Clock,
it really needs to keep accurate time.
Part two is another clock story, but I'm not the goat this time.
Happy new year,
Hugh Rice
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
--
I don't think the execution is relevant when it was obviously a bad idea in
the first place.
This is like putting rabid weasels in your pants, and later expressing
regret at having chosen those particular rabid weasels and that pair of
pants.
---maf
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
Paul, what do you mean by the display "looking pretty ratty?" As I
recall, the original buck regulator had regulated output voltage around
5V for the LEDs. and the PMOS clock IC needed something around 12V.
Whatever the LEDs run from, it should be regulated and well filtered. If
the LEDs are dim, it could be the old displays themselves are
deteriorated, or the regulation isn't right, or maybe a bad output
filter cap on the buck converter. If the brightness is OK, but digit or
segment intensities fluctuate with count, then it's probably a
regulation issue.
I used the shunt regulator to isolate the rest of the system from the
large variation (about 3:1) in total LED current with readout values,
and it was possible because I had made lower supplies anyway, via DC-DC
converters. You wouldn't want to linear-regulate all the way down from
the main supply around 24V, to a few V for the LEDs. As I recall, the
peak load is in the 200-300 mA range at good brightness. The efficiency
of the buck converter makes it practical to run this from the normal
supply or battery voltage. I think the original deal was that on power
failure it switched to battery mode, the buck converter was shut off to
shed the LED load, and the clock IC stayed powered up to keep the right
time. The button below the display could force it to show when needed.
Mine will work the same way, when/if I ever finish all the details, but
will have adjustable brightness, and maybe the option of still
indicating time in backup mode, with very dim LED setting.
Ed
Add a tiny speaker so you can simulate the loud 'tick' of the analog clock.
;)
On Fri, Jan 4, 2019 at 4:29 PM ed breya eb@telight.com wrote:
Paul, what do you mean by the display "looking pretty ratty?" As I
recall, the original buck regulator had regulated output voltage around
5V for the LEDs. and the PMOS clock IC needed something around 12V.
Whatever the LEDs run from, it should be regulated and well filtered. If
the LEDs are dim, it could be the old displays themselves are
deteriorated, or the regulation isn't right, or maybe a bad output
filter cap on the buck converter. If the brightness is OK, but digit or
segment intensities fluctuate with count, then it's probably a
regulation issue.
I used the shunt regulator to isolate the rest of the system from the
large variation (about 3:1) in total LED current with readout values,
and it was possible because I had made lower supplies anyway, via DC-DC
converters. You wouldn't want to linear-regulate all the way down from
the main supply around 24V, to a few V for the LEDs. As I recall, the
peak load is in the 200-300 mA range at good brightness. The efficiency
of the buck converter makes it practical to run this from the normal
supply or battery voltage. I think the original deal was that on power
failure it switched to battery mode, the buck converter was shut off to
shed the LED load, and the clock IC stayed powered up to keep the right
time. The button below the display could force it to show when needed.
Mine will work the same way, when/if I ever finish all the details, but
will have adjustable brightness, and maybe the option of still
indicating time in backup mode, with very dim LED setting.
Ed
time-nuts mailing list -- time-nuts@lists.febo.com
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and follow the instructions there.
Bob
Yes indeed click, click, click.
Ed agree with your coment that a 30 or greater year old led may be dimming.
I expect better from HP. Not really.
With respect to the clock it did run off the 24 volt battery and the
display shut down on power failure. There is a button on the front labeled
standard read that you can press to see the time while on battery.
Thank you for the comment.
On Fri, Jan 4, 2019 at 4:38 PM Bob Bownes bownes@gmail.com wrote:
Add a tiny speaker so you can simulate the loud 'tick' of the analog clock.
;)
On Fri, Jan 4, 2019 at 4:29 PM ed breya eb@telight.com wrote:
Paul, what do you mean by the display "looking pretty ratty?" As I
recall, the original buck regulator had regulated output voltage around
5V for the LEDs. and the PMOS clock IC needed something around 12V.
Whatever the LEDs run from, it should be regulated and well filtered. If
the LEDs are dim, it could be the old displays themselves are
deteriorated, or the regulation isn't right, or maybe a bad output
filter cap on the buck converter. If the brightness is OK, but digit or
segment intensities fluctuate with count, then it's probably a
regulation issue.
I used the shunt regulator to isolate the rest of the system from the
large variation (about 3:1) in total LED current with readout values,
and it was possible because I had made lower supplies anyway, via DC-DC
converters. You wouldn't want to linear-regulate all the way down from
the main supply around 24V, to a few V for the LEDs. As I recall, the
peak load is in the 200-300 mA range at good brightness. The efficiency
of the buck converter makes it practical to run this from the normal
supply or battery voltage. I think the original deal was that on power
failure it switched to battery mode, the buck converter was shut off to
shed the LED load, and the clock IC stayed powered up to keep the right
time. The button below the display could force it to show when needed.
Mine will work the same way, when/if I ever finish all the details, but
will have adjustable brightness, and maybe the option of still
indicating time in backup mode, with very dim LED setting.
Ed
time-nuts mailing list -- time-nuts@lists.febo.com
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and follow the instructions there.
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To unsubscribe, go to
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and follow the instructions there.
In message 5C2FCFF8.1030803@telight.com, ed breya writes:
Paul, what do you mean by the display "looking pretty ratty?" As I
recall, the original buck regulator had regulated output voltage around
5V for the LEDs. and the PMOS clock IC needed something around 12V.
Whatever the LEDs run from, it should be regulated and well filtered. If
the LEDs are dim, it could be the old displays themselves are
deteriorated, or the regulation isn't right, or maybe a bad output
filter cap on the buck converter.
In my case it was clearly the power-supply, the NS clock chip worked fine.
I simply replaced the entire power-supply board with my own round PCB
with a couple of DC/DC converters and a microcontroller running of
the 5MHz (PPSDIV style) which produces a 1Hz to the NS chip:
http://phk.freebsd.dk/hacks/HP5065A/20160112_working_clock/index.html
I still have a pile of those PCB's in case any of you want one.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
Yes Paul, LEDs wear out over time. By the late 70s and into the 80s, I
think they were improved and perfected to the point where wearout is
very slow and barely noticeable visually, and efficiency is much higher
compared to the oldies. Even opto-couplers are sometimes specified for
LED wearout, in the form of CTR degradation over time.
I don't know what vintage were used in these clocks, but they are fairly
old, and likely have lots of running hours in this application. The ones
in mine still look good, but I did look into replacements way back when
I started - at least for spares in case any crapped out. I don't recall
the part numbers or package style/pinout, but do recall they were
HP-made. Putting more modern ones in would likely improve the display,
and could reduce the power needed to light them - that is, if the
pinouts and styles can be found that readily match up with the oldies. I
think I probably have set aside some of the same types salvaged from
other HP gear from that era, but if enough went bad or I wanted
improvement, I'd look at newer stuff.
Ed
On Fri 2019-01-04T17:05:21-0500 paul swed hath writ:
Ed agree with your coment that a 30 or greater year old led may be dimming.
Not nearly as much as an entirely different clock illumination:
radium watch dial paint
I remember my mom's wind-up travel clock glowing brightly. 50 years
later there is nothing. I brought it into the lab just to check that
it is still radioactive (wouldn't want to have lost that radium
somewhere). It's the zinc sulfide crystals, the radiation damages
them and they stop producing light.
--
Steve Allen sla@ucolick.org WGS-84 (GPS)
UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855
1156 High Street Voice: +1 831 459 3046 Lng -122.06015
Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m
On 5/1/19 6:45 am, paul swed wrote:
Yes indeed I also would like one of the analog clocks. But be careful what
you ask for....
I have a friend in Switzerland that does have a 5065 with the analog clock.
It tends to drive you a bit crazy with the tick of the step so he says. I
may believe that as I used impulse clocks for world time (1 min steps)for
years and have to say it really is annoying. I finally did replace them
with very quite clocks and don't miss the tick at all. There actually is a
tick from the 4 clocks but really low in amplitude. Easily ignored.
I have a few NTP-synced (and PoE powered) analog clocks at home, a pair
Symmetricom branded and a pair Spectracom, both are rebrands from
different companies (Masterclock & Sapling respectively IIRC).
One is a sweep hand, the other step, but both are loud enough to be
annoying if it's particularly quiet.
I keep one of the sweep-hand ones in my bedroom, and despite living
inner-city where it's rarely quiet, late on a still night I can hear the
motor (and it is annoying).
The step clock is rather louder, but I keep it in my office which has a
much higher noise floor, but even there it can be noticable.
The HP displays were graded for light output. I seem to remember that it was part number dash intensity.
Besides the HP instruments many other devices like the Heathkit H-8 computer used them.
The newer "white" LED's used for illumination still suffer from this.
Jim
From: time-nuts time-nuts-bounces@lists.febo.com on behalf of Steve Allen sla@ucolick.org
Sent: Friday, January 4, 2019 6:57:51 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Atomic Clocks: It is important that they keep good time, Part 1
On Fri 2019-01-04T17:05:21-0500 paul swed hath writ:
Ed agree with your coment that a 30 or greater year old led may be dimming.
Not nearly as much as an entirely different clock illumination:
radium watch dial paint
I remember my mom's wind-up travel clock glowing brightly. 50 years
later there is nothing. I brought it into the lab just to check that
it is still radioactive (wouldn't want to have lost that radium
somewhere). It's the zinc sulfide crystals, the radiation damages
them and they stop producing light.
--
Steve Allen sla@ucolick.org WGS-84 (GPS)
UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855
1156 High Street Voice: +1 831 459 3046 Lng -122.06015
Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
On Fri, Jan 4, 2019 at 6:59 PM Steve Allen sla@ucolick.org wrote:
On Fri 2019-01-04T17:05:21-0500 paul swed hath writ:
Ed agree with your coment that a 30 or greater year old led may be
dimming.
Not nearly as much as an entirely different clock illumination:
radium watch dial paint
I remember my mom's wind-up travel clock glowing brightly. 50 years
later there is nothing.
I used to have a Rolex submariner with a tritium paint based dial -- I
really loved the watch, but the tritium had sufficiently decayed that it
would no longer fluoresce - this didn't affect the utility, but made me
sad.... It was made in ~1989 and marked SWISS T < 25 for "less than 25
milliCurie" (apparently much less, they started out at ~5 milliCurie). In
~2016, the tritium would have decayed to ~1 milliCurie. Tritium paint is
(apparently) no longer legal in the USA, but when I was in Hong Kong I
found someone who had "new" paint, and willing to repaint the face --
unfortunately I didn't have time on that trip to have it done, and when I
went back a few months later the shop had closed down...
There is a (apparently) a group of watch dial enthusiasts who get a
specific brand of tritium based exit sign which has tritium paint embedded
in the plastic (most tritium exit signs are the small gas capsules
instead), grind them up and then extract the paint from the ground plastic
using solvents. I briefly toyed with this idea before deciding this was bad
mojo and sold the watch...
I brought it into the lab just to check that
it is still radioactive (wouldn't want to have lost that radium
somewhere). It's the zinc sulfide crystals, the radiation damages
them and they stop producing light.
Hmmmm. I wonder if that is actually what happens with the tritium paint -
the dial I had would just have a visible glow if I had it in a perfectly
dark room and let my eyes adjust for a while. If the tritium level had
decayed from 5 milliCurie to 1 milliCurie I would have guessed that the
glow should just have been 1/5th of original. The dial would still
fluoresce nicely under UV, so I'm not sure what that means...
W
--
Steve Allen sla@ucolick.org WGS-84 (GPS)
UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat
+36.99855
1156 High Street Voice: +1 831 459 3046 Lng
-122.06015
Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m
time-nuts mailing list -- time-nuts@lists.febo.com
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and follow the instructions there.
--
I don't think the execution is relevant when it was obviously a bad idea in
the first place.
This is like putting rabid weasels in your pants, and later expressing
regret at having chosen those particular rabid weasels and that pair of
pants.
---maf
Interesting. I was wondering this as well now that time-nuts has gotten me
into collecting vintage (pre WWII) chronographs. Some are radium, some not,
most are in need of a good repaint either way.
But I do know that tritium gun sights are also a thing. Are those all
mil-surplus or using some secret source of tritium paint...
BTW, latest acquisition in the Vintage watch collection is a 1916 Waltham,
made nearby, with still a local watch shop specializing in them. Looking
forward to it's arrival.
On Mon, Jan 7, 2019 at 1:48 PM Warren Kumari warren@kumari.net wrote:
On Fri, Jan 4, 2019 at 6:59 PM Steve Allen sla@ucolick.org wrote:
On Fri 2019-01-04T17:05:21-0500 paul swed hath writ:
Ed agree with your coment that a 30 or greater year old led may be
dimming.
Not nearly as much as an entirely different clock illumination:
radium watch dial paint
I remember my mom's wind-up travel clock glowing brightly. 50 years
later there is nothing.
I used to have a Rolex submariner with a tritium paint based dial -- I
really loved the watch, but the tritium had sufficiently decayed that it
would no longer fluoresce - this didn't affect the utility, but made me
sad.... It was made in ~1989 and marked SWISS T < 25 for "less than 25
milliCurie" (apparently much less, they started out at ~5 milliCurie). In
~2016, the tritium would have decayed to ~1 milliCurie. Tritium paint is
(apparently) no longer legal in the USA, but when I was in Hong Kong I
found someone who had "new" paint, and willing to repaint the face --
unfortunately I didn't have time on that trip to have it done, and when I
went back a few months later the shop had closed down...
There is a (apparently) a group of watch dial enthusiasts who get a
specific brand of tritium based exit sign which has tritium paint embedded
in the plastic (most tritium exit signs are the small gas capsules
instead), grind them up and then extract the paint from the ground plastic
using solvents. I briefly toyed with this idea before deciding this was bad
mojo and sold the watch...
I brought it into the lab just to check that
it is still radioactive (wouldn't want to have lost that radium
somewhere). It's the zinc sulfide crystals, the radiation damages
them and they stop producing light.
Hmmmm. I wonder if that is actually what happens with the tritium paint -
the dial I had would just have a visible glow if I had it in a perfectly
dark room and let my eyes adjust for a while. If the tritium level had
decayed from 5 milliCurie to 1 milliCurie I would have guessed that the
glow should just have been 1/5th of original. The dial would still
fluoresce nicely under UV, so I'm not sure what that means...
W
--
Steve Allen sla@ucolick.org WGS-84
(GPS)
UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat
+36.99855
1156 High Street Voice: +1 831 459 3046 Lng
-122.06015
Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
--
I don't think the execution is relevant when it was obviously a bad idea in
the first place.
This is like putting rabid weasels in your pants, and later expressing
regret at having chosen those particular rabid weasels and that pair of
pants.
---maf
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
On Mon, Jan 07, 2019 at 02:21:07PM -0500, Bob Bownes wrote:
Interesting. I was wondering this as well now that time-nuts has gotten me
into collecting vintage (pre WWII) chronographs. Some are radium, some not,
most are in need of a good repaint either way.
You might try International Dial Co -- they repaint watch dials;
if they don't have the die for your dial, they might at least be able to
refer you to someone who does.
But I do know that tritium gun sights are also a thing. Are those all
mil-surplus or using some secret source of tritium paint...
They're not surplus, and you can buy plenty of new sights and
sighting devices containing tritium.
Generally speaking, an artifical sapphire tube is coated with
phosphor, and then filled with the gas. When it's time to replace
the tube, you either replace the sight entirely, or in the case of
hybrid tritium/fiber optic systems like the ACOG, send it back to have
the manufacturer replace the tube, thus refurbishing the sight.
Tritium isn't banned...but tritium lume has definitely fallen
out of favor. I haven't seen any used in new products for about 20
years, and I'd be surprised if it's still made in any significant
quantity. Watches, gun sights, and even magnetic compasses have moved
on to using the gaseous tritium sources.
I don't think this is a bad thing. It's much safer to handle,
without the risk of ingesting or inhaling a beta source.
And radium is not something you want to handle (although I'd
possibly consider going over a radium dial or hands with modern lume --
more to help seal the old radium paint in, than to restore function,
although it will do that. IMHO, the best option is still to have them
professionally repainted.)
The current generation of photoluminescent lumes are quite
bright and long lasting after light exposure -- seriously consider
having any old radium dials and hands stripped and repainted. I had
a WWII watch dial that was over 4,000 cpm, with lots of visible lume
dust present. Nice collectible, but not worth the health risks to
keep original. It's been refinished with modern materials.
--msa
Steve Allen wrote:
I remember my mom's wind-up travel clock glowing brightly. 50 years
later there is nothing. I brought it into the lab just to check that
it is still radioactive (wouldn't want to have lost that radium
somewhere). It's the zinc sulfide crystals, the radiation damages
them and they stop producing light.
Steve, another example of that happening, is in this video by Fran
Blanche, where she tests the clock face of an old radio-clock, showing
that it no longer "glows in the dark" but the radio-active source is
never the less still there !
I have set the start to be at the 15 minute mark, to save watching the
whole mailbag!
https://www.youtube.com/watch?v=0J3cu67SBZY#t=15m
Regards, Geoff (NZ)
This thread is for the topic of hp and atomic clocks.
Time-nuts is not about wristwatches or radium dials, or Rolex or tritium or Waltham, ...
Please take your off-topic tangents elsewhere (there are many wristwatch forums on the internet).
/tvb
Moderator, http://leapsecond.com/time-nuts.htm