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-boun...@lists.febo.com> on behalf of Steve Allen <s...@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 <s...@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. _______________________________________________ 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.
