Children of the Geissler Tube (2023)

One of the most surprising applications for gas tubes in Miller's 01969 book, which I hadn't read before, is capacitive touch control of a 100mA solenoid. His Fig. 6–15 on p. 74 consists of four neon tubes (two T2–27–WR500, two 5AB-B), four resistors, two .001μF capacitors, a 4μF capacitor, a freewheeling diode for the solenoid, and the solenoid itself, and is powered by a 160VDC supply. When you touch the "on" or "off" touchplate, which is grounded through a 5.6MΩ resistor, your body capacitance momentarily provides a path for the 160V to ground before the touchplate capacitor charges up and blocks it. This kicks on the respective T2–27–WR500, which has a series 5AB-B to ground through a 6.8kΩ resistor shared between them. The two series pairs of tubes, connected on the high side through the other cap, form a flip-flop; the "off" pair has a 10kΩ resistor feeding it from the positive supply, while the "on" pair instead is supplied through the solenoid being controlled. When one pair turns on, the big cap couples a negative–going pulse to the other pair to turn it off.

12 low-precision components is pretty good for providing a flip-flop, high-voltage power switching†, capacitive touch sensing, and indicator lights. Miller seems to imply that such circuits were commonplace at the time.

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† I think the circuit is switching 3mA with 50 volts across the solenoid, so a respectable 150mW, even if the 5AB-B is only rated for 0.3mA. The T2-27-1WR500 is rated for 3mA. The 5AB-B has a maintaining voltage of 50–60V, the T2-27-1WR500 of 60–70V, so the voltage left across the series combination of the 10k high-side resistor and the 6.8k low-side resistor is something like 50V when the "off" side of the flip-flop is conducting, and 50V/16.8kΩ is just under 3mA. I assume the solenoid must have comparable resistance.

Yes, agreed. But neon lamps weren't limited to the Bell System; everybody who worked in electronics at the time used them for something, though not as commonly as things like capacitors and resistors.

Microwave gear of course had to use vacuum tubes until transistors got fast enough; as you say, although you can switch a voice signal with a neon lamp, you can't amplify it that way, and microwaves are a million times faster than voice. (Amplifying voice with a saturable inductor, a so-called "magamp", had its day too, though magamps are rarely seen today outside of ATX power supplies.)

But a lot of electronics didn't have to run at microwave frequencies or even voice frequencies; motor frequencies or powerline frequencies were enough.

Which page are you referring to in [2]?

Is your argument that "If a literal translation of a sentence doesn't make sense, then the translation for each word must be wrong?" If so, that's trivial to find counterexamples for:

It's not hard to find Japanese sentences that would literally translate to English as roughly: "O I think it's so cute that you say 'I' (僕) instead of 'I' (私)."

Claiming therefore that translating 僕 and 私 each to the word "I" is always wrong is nonsensical.

If you are making some weaker claim that excludes my example, please fill me in because I couldn't think of one.

The article is right that the vacuum tubes, whose first application were the Edison lighting bulbs, then the Fleming diodes, which evolved directly from the incandescent lighting bulbs, are descendants of the Geissler tubes.

During the evolution of the Geissler tubes, the techniques of making efficient vacuum pumps and of sealing well the glass tubes were developed.

Only when the pumps and the glass tubes had become good enough, it became possible to experiment with the first vacuum tubes, by omitting the filling of the tubes with low-pressure gas.

Without the decades of playing with Geissler tubes there would have never been any incentive to develop the technologies without which making vacuum tubes would have been impossible.

Therefore there is no doubt that what the article says is correct, i.e. that the vacuum tubes are descendants of the low-pressure gas tubes, which were initially known as Geissler tubes.

So the vacuum tubes are a lateral branch of the development of the low-pressure gas tubes. After splitting, both branches have continued to evolve in parallel until they both have been replaced in most of their applications by semiconductor devices.

While vacuum tubes were better known by the general public, because they were present in things like radio receivers or TV sets, which many people owned, in industrial applications gas tubes have always had a similar importance to vacuum tubes.

Even the first electronic counter, which can be considered the ancestor of all electronic computers, has been made with gas tubes, not with vacuum tubes. (The first electronic counters were made to count the pulses from detectors of nuclear or cosmic radiation, for which the existing electro-mechanical counters were too slow. The circuits developed for this application were the basis for the development during WWII of the digital electronic circuits used in the first electronic computers.)