[time-nuts] Atomic Clocks: It is important that they keep good time, Part 1

[James C Cotton]

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 at lists.febo.com> on behalf of Steve Allen <sla at 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 at 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

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