Hi Back in the 70’s I was involved in making LCD watches. The whole “photo” issue had not been fully through through. One day our chief marketing guy for the project was driving around in Phoenix AZ. He looks down and notices that his watch is dead. Pops out a spare, puts it on, confirms it it working. Hangs his arm out the window and …. that one is dead as well.
We changed the die coat on the ASIC to an opaque version soon after that … Light does indeed interact with semiconductors. It happens even on circuits that you would not *think* are photo sensitive. Physics is nasty that way …. Bob > On Jan 18, 2016, at 6:45 AM, Poul-Henning Kamp <p...@phk.freebsd.dk> wrote: > > -------- > In message <569bc23a.3030...@arcor.de>, Gerhard Hoffmann writes: > >> LEDs abused as References: > > This is one of the most stupid ideas ever, because LEDs works both ways. > > (Back when LED wrist-watches first came out, people soon discovered > that they would reset themselves when photographed with flash.) > > If you insist on using LEDs as voltage references, the first thing > you need to do is to dip the LED in something which shields it 100% > from incoming light *including infrared* > > -- > Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 > p...@freebsd.org | TCP/IP since RFC 956 > FreeBSD committer | BSD since 4.3-tahoe > Never attribute to malice what can adequately be explained by incompetence. > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
