15 Mar
2020
15 Mar
'20
4:56 a.m.
-----Original Message-----
From: owner-hecnet at Update.UU.SE <owner-hecnet at Update.UU.SE> On
Behalf Of Paul Koning
Sent: 14 March 2020 18:27
To: hecnet at Update.UU.SE
Subject: Re: [HECnet] long term paks
run
On Mar 14, 2020, at 10:26 AM, Thomas DeBellis
<tommytimesharing at gmail.com> wrote:
>
> I think that's an easy case to make for hardware; sooner or later you out of vacuum tubes...
Not as soon as you might think. They are still made. And they can be
made
at home, with practice. Transistors are harder, and
with VLSI you're
dependent on the manufacturers to keep manufacturing.
I demonstrate a replica of a 1948 valve computer.
The builders expected to get 5 years out of it but its now 20 years old
We don't change that many valves but we do run the heaters on half voltage
so they warm up gently
We recently bought some "new old stock" EF50s on E-Bay for ?1 each
I remember some years ago a company that specialized
in making and selling
obsolete germanium transistors.
paul
Dave