There are other ways that light can cause unexpected behavior. In 1983 I worked on a process control system whose maiden installation was in a corn processing plant, with lots of big valves and motors being controlled. The cards that did A/D and D/A conversion of control signals had UV erasable EPROMs for their microprocessors. There were a lot of those cards.
One day the plant operators began complaining about the equipment misbehaving on a large scale. The problem went away when the guy taking flash pictures of our equipment stopped taking pictures. We put black tape over the UV lenses. Ob timenuts: This system later had a pulse frequency input card that I connected to the power line. Used the operator's trending display for process variables to watch line frequency change over time. It also had pulse outputs, and a little work got it to play "Daisy, Daisy" like HAL 9000 in "2001: A Space Odyssey." Bill Hawkins -----Original Message----- From: time-nuts [mailto:[email protected]] On Behalf Of Bob kb8tq Sent: Sunday, April 09, 2017 1:34 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] TAPR TICC boxed (input protection) Hi If anybody gets into this sort of thing in the future - There are black / optical blocking die coat materials out there. They are silicone based and quite stable. We used a *lot* of the stuff on watch modules after it was discovered that the watch died when exposed to a heavy dose of sunlight (right through the LCD and into the chip . poof!!) Bob _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
