Old chips

[Paul Koning]

I just received a shipment of parts from Digikey (one of the country's largest distributors). One item is a tube of 74AC241 chips, in DIP packages (the classic black plastic ones with two rows of pins). While those devices have been around for a while, they showed in the catalog as current parts, not obsolete, or "last buy" or supplied by random third parties.

When I looked at the shipping form in the package I noticed it shows the date code for each of the parts I ordered. Most are 2025, as one might expect. But the 74AC241s show a date code of 2013 !

It's a good thing that chips don't get stale. :-)

paul

[Mark Kinsler]

I always liked Digikey, who supplied chips for the digital lab I took around 1980.  I think.  

There was some talk years ago about the lifespans of IC's, but I never heard anything more.  Maybe it'll all rot someday.  And all the bombs will go off and we won't have to worry about it.

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Mark Kinsler

512 East Mulberry Street
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740-503-1973

[Paul Koning]

> On Feb 6, 2026, at 6:53 PM, Mark Kinsler <kins...@gmail.com> wrote:
>
> I always liked Digikey, who supplied chips for the digital lab I took around 1980. I think.
>
> There was some talk years ago about the lifespans of IC's, but I never heard anything more. Maybe it'll all rot someday. And all the bombs will go off and we won't have to worry about it.

Or the sun. I was just reading an article about a recent large solar flare, and a description of the "Carrington event" of 1859. I had heard the name but had no idea of the description; the article spoke of sparking telegraph equipment, enough so to create some fires in some telegraph offices. Anything sufficient to make classic land line telegraph equipment send off sparks would fry any electronics I can think of, with the possible exception of my nice old tube based radios. Pretty mind boggling. The article also talked about putting DC blocks into the neutral connection of large power line transformers to cut the induces currents; it's not clear to me how that is much help. It might protect those transformers but I doubt it will do much to help everyone's home electronics.

paul

[Bob Reite]

AM broadcast transmitters, even modern solid state ones could probably
withstand it. Why? Their output is connected to a tall insulated from
ground (except for a static drain choke which has high enough inductance
so that the transmitted signal does not get shorted out). These towers
get hit by lightning from time to time yet a well designed transmitter
survives.

--
Robert D. Reite
Telecentral Electronics, Inc.

[Dave Typinski]

Home electronics will survive a Carrington-class event* just fine because the
conductors are only a few dozen meters long for house wiring and mm to cm long
in electronic devices. Long haul power transmission lines are hundreds to
thousands(?) of km long -- thus the voltages developed are much greater.

* A very large solar coronal mass ejection (CME) that crashes hard into the
geomagnetic field.

This is why the Carrington event caused long haul telegraph stuff to make a few
sparks and maybe something caught fire, which might be embellishment for
sensationalism. Cotton(?) insulation on the wires and paper dust all over the
office... wouldn't take much to set that stuff ablaze. Or maybe they used
gutta-percha insulation back then. Not sure.

It's the same deal with the nuclear EMP bogey man. Our electronics in central
Florida generally survives the EMP from nearby lightning strikes with no
problem. It'll survive another Carrington event or nuclear EMP too. That
string of streetlights in Hawaii that tripped a breaker during the Starfish
Prime detonation? What they don't say is that the quality of the Hawaiian
electric grid was and still is on par with a third-world nation and that the
offending breaker was probably a hair's breadth away from tripping in the first
place.

But, the power transmission people justifiably worry about CME impacts. Another
Carrington event would ruin everyone's day if power transmission systems aren't
designed to cope with such upsets gracefully.

Did anyone ever figure out for sure what caused that nationwide power outage in
Portugal last year? I know theories have abounded, but I've not seen anything
definitive.
--
Dave

[Mark Kinsler]

One of the (probably classified) books I looked at for my lightning said that any system that can withstand lightning strikes won't be bothered by EMP.  (EMP damage is one of the earliest bogus conspiracy theories.  

There is a famous Mr Homan who has attached his name to one of the firms selling EMP protection for your home, but he'd taken it off last I looked.  Just for fun I laid my transistor radio on one of the sturdy cross-beams of Mississippi State U's 3MV Marx generator and waited for some unrelated tests to begin.  Five of those insane loud discharges failed to stop my radio from playing the hits of the '60's.

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[Paul Koning]

> On Feb 7, 2026, at 3:44 AM, Mark Kinsler <kins...@gmail.com> wrote:
>
> One of the (probably classified) books I looked at for my lightning said that any system that can withstand lightning strikes won't be bothered by EMP. (EMP damage is one of the earliest bogus conspiracy theories.

I remember a Polyphaser catalog that listed some of their surge protectors as particularly suitable for EMP protection. It supposedly had something to do with shorter rise time of the pulse vs. the IEEE standard 8/20 lightning pulse.

> There is a famous Mr Homan who has attached his name to one of the firms selling EMP protection for your home, but he'd taken it off last I looked. Just for fun I laid my transistor radio on one of the sturdy cross-beams of Mississippi State U's 3MV Marx generator and waited for some unrelated tests to begin. Five of those insane loud discharges failed to stop my radio from playing the hits of the '60's.

Interesting. I wonder if a modern laptop computer would fare as well. Perhaps it would. It would be an interesting test.

paul