[HN Gopher] One of Fleming's first thermionic diode valves, 1889
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One of Fleming's first thermionic diode valves, 1889
Author : cameron_b
Score : 27 points
Date : 2021-01-14 14:02 UTC (8 hours ago)
(HTM) web link (collection.sciencemuseumgroup.org.uk)
(TXT) w3m dump (collection.sciencemuseumgroup.org.uk)
| tinus_hn wrote:
| These look like characters from a Valve video game. Coincidence?
| jpmattia wrote:
| Cool. I'm old enough that I've actually worked with tubes (final
| amps for 1970s Ham Radios needed too much power to sensibly use
| the solid-state transistors of the day. Also Fender guitar amps
| were just turning solid-state in the late 70s/early 80s, so used
| tube amps were cheaper.)
|
| I would not have guessed that the first ones happened in 1889;
| Anyone have a favorite link for tube history?
| qppo wrote:
| The story I've heard is that the original lightbulbs filled with
| soot and darkened well before they burnt out. Edison guessed the
| soot was coming from the filament and was charged, so he placed a
| charged plate across from the filament to attract the soot before
| it could stick to the glass. It worked, but the bulb was much
| darker than before as the charged plate siphoned a lot of current
| off the filament.
|
| That device would have three conductors, which you can see in the
| photos. Two for the filament, one for the "plate." Later, a
| fourth conductor called the "cathode" was added to be heated by
| the filament (rather than pulling charge directly from the
| filament) to make the first diodes.
|
| There's something funny about how modern active components are
| designed to reduce how much heat they consume, but the first
| active devices required an active heating element to function at
| all.
| mannykannot wrote:
| To call De Forest's audion (now known as a triode) an
| "improvement" of the diode might be technically true, but
| misleading: being able to amplify signals was a quantum leap in
| technological capability, and a necessary precursor to there
| being an electronics industry.
|
| De Forest himself, however, apparently did not understand how his
| audion worked, at least at first, and felt it necessary for it to
| contain some gas. There's an excellent short biography that I
| will post a link to if I can find it...
|
| Edit: This is not the article I had in mind, but it shows that
| initially, De Forest's audion did not have a connection to the
| grid, and also that De Forest was unaware that the triode
| arrangement could be used to amplify, and considered it only an
| improved diode; it was Amstrong who discovered its amplification.
| IIRC (from the other article I have in mind) De Forest was able
| to appropriate the fruits of this seminal discovery by use of his
| audion patents (Armstrong was later screwed over by Sarnoff and
| committed suicide.)
|
| https://history-computer.com/the-audion-history-of-the-audio...
| qppo wrote:
| I don't think it's even technically true, they're fundamentally
| different circuit elements that just share a principle of
| operation. Diodes allow current to flow in one direction
| (rectification), triodes provide a proportional increase in the
| energy of a signal (amplification).
|
| Their shared implementation details mean you can wire a triode
| as a diode but I don't think it's even a _better_ diode.
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