Speaking of camera flashes:

In my first job in this industry years ago, I was told of a visit to a=20
large chicken farm by coworkers who were investigating the possibility=20
of creating an egg grading system for them.

In the course of the visit, and before the client could stop it, one of=20
our company personnel snapped a picture with a flash in a large chicken=20
coop, I'm told with hundreds of chickens.

You can imagine what happened next.

:-)

Mark Skeels
Engineer
Competition Electronics, Inc.
TEL: 815-874-8001
FAX: 815-874-8181
www.competitionelectronics.com


Olin Lathrop wrote:
> Marcel Duchamp wrote:
>  =20
>> Light into eprom windows can and usually does affect the operation.  I
>> have seen A/D counts vary when light shines into the window.
>>    =20
>
> One of my earlier PIC projects wasn't working.  As I reached over to put =
a
> scope probe on some pin, it started working.  Then I noticed that just
> moving my hand nearby made it work.  I thought maybe MCLR was floating an=
d
> the capacitance to my hand was making it flip, but MCLR was driven well
> enough.  It finally turned out to be that moving the hand between the PIC
> and the nearby window made it work because that reduced the light hitting
> the die of the JW part.  Since then I always put stickers over the window=
s,
> even if just for short testing.
>
>  =20
>> And once had a system fail in a spectacular fashion from a camera
>> flash
>> going off.  In a development environment, the windows are usually left
>> open ready for another trip through the uv eraser.  A windowed PIC was
>> driving some fets for motor control.  The customer came to see how
>> things were going and whipped out a camera and snapped a photo. Bang!
>> All fets were turned on at once and shorted the nicad battery pack
>> blowing out the fets.
>>    =20
>
> Another PIC project was a rotating LED display.  I had just added the
> feature so that a bunch of units could be strung together and all control=
led
> from a single serial port.  It seemed to work, then everything got shippe=
d
> off to a show in Chicago.  At the show things worked until someone took a
> picture of the booth.  All the displays went down instantly.
>
> We were transmitting data from the base part to the rotating part by IR t=
hru
> the center of the hollow shaft.  This data was just the UART output of th=
e
> transmitter.  It turns out there was a little gap just below the IR recei=
ver
> on the rotating board, and a camera flash was bright enough to get in the=
re
> and be detected.  The flash got interpreted as the reset command.
>
>  =20
>> In a related area, early video camera elements were made from DRAMs
>> with out covers over the chips.
>>    =20
>
> I think that was a later development.  I'm reasonably sure using DRAMs as
> image sensors was pioneered by Bill Yerazunis of the Mitsubishi Electroni=
c
> Research Labs in Cambridge MA in the mid to late 1990s.  You may remember
> him as "Crash" on the NERDS team of some Junkyard Wars episodes.
>
>  =20
--=20
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