[time-nuts] TAPR TICC boxed (input protection)

Bill Hawkins bill.iaxs at pobox.com
Mon Apr 10 23:26:18 EDT 2017

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:time-nuts-bounces at febo.com] On Behalf Of Bob
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)


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!!)


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