Atomic Clocks: It is important that they keep good time, Part 1
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
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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