You might have come across the Raspberry Pi story : one of the revised versions had a SMPS control chip that was intended to be buried inside a phone, not exposed on an open pcb.
https://www.raspberrypi.org/forums/viewtopic.php?t=99042 On Mon, Jan 18, 2016 at 3:11 PM, Bob Camp <kb...@n1k.org> wrote: > 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. > _______________________________________________ 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.