15 Feb
2008
15 Feb
'08
10:22 p.m.
On Friday 15 February 2008 10:48, William Donzelli wrote:
(Snip)
For some reason when I read "photocell" earlier on in this thread I started
thinking about CdS and similar stuff, not thinking about _tubes_ per se,
until I hit the last paragraph of this post...
There are a number of different photocell datasheets on my tubes page:
http://www.classiccmp.org/rtellason/tubes.html
Perhaps this info might be useful Some of those real early audio and other
tubes are in there too, though I don't recall offhand if that stuff is dated
or not.
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
I seem to
recall that this was about the biggest problem in getting
Colossus to work in the 1940s; the technology for doing the optical
detection of the tape data just wasn't really 'there' yet, not at any
speed. I think the maximum they managed to get was around 8KHz, but it
wasn't particularly reliable (I think 5KHz was the norm, and it took an
awful lot of initial effort to get that working properly).
I am not sure what the photocells of 1920 were up to, but by 1940 they
were not half bad, with so many being used for FAX service. 8 KHz may
be about right for off the shelf tubes.