General > General Technical Chat
electronics like its 1922
jonpaul:
My 2018 IEEE Spectrum reconstruction with 2050 Thyratrons of the 1942 first ADC.
used many (but not all) vintage parts.
Was in IEEE Spectrum February 2019 issue.
Jon
TimFox:
My favorite vintage part there is the hermetically sealed paper capacitor ("2.0 mfd/400 V"), and I appreciate transparency in construction!
When I used "MCAs" (multi-channel analyzers, which analyzed pulse height and displayed the pulses in a histogram) back in the 1970s, I researched the literature and found a model from sometime around 1950 that was built like a pinball machine: the pulse height drove a solenoid that launched ball bearings onto a tilted surface, and the different impulse values resulted in the balls landing in different bins.
The 2050 and 2051 glass-octal thyratrons (2051/VT-109 used in your reconstruction) were commonly used in jukebox mechanisms pre-war.
Kleinstein:
--- Quote from: james_s on October 28, 2022, 11:52:15 pm ---That's pretty impressive. Functional vacuum tubes without the use of a diffusion or turbo pump and not even a getter, I wouldn't have thought they would work at all, much less well enough to be sealed off.
--- End quote ---
After a good bake out by heating the whole system to > 200 C there is very little outgasing. A sealed glass system than does no longer needs contineous pumping. Ideally one would seal off the glass while it is still relatively hot. The tubes in the video do use a getter (the titanium wire on top of the actual tube), though there is not very much of the getter evaporated to the glass wall. If need the getter could be heated even more. Evaporating some titanium is pretty effective in pumping down in the high / UHV vaccuum range, as long as one keeps helium and neon out. Modern 2 stage rotary pumps are not that bad and can be a start for the titanium to work.
jonpaul:
Tim many thanks:
The large plastic caps in lower photo are for the preamp B+ 3 stage RC/HV Zener filter/regulator.
When they fire, Thyratrons induce noise pulses on the B+ which the 100k gain Preamp (2X 6SN7) pickup, causing motorboating.
See the "debugging..unexpected interactions" part of the IEEE Spectrum articles.
Jon
TimFox:
In the lower right-hand corner of the preamp schematic, should the 470 k resistor be to the right of the 100 nF capacitor, to make a voltage doubler?
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