Re: Realism fail. :-)

Post #405,587 by TB D 10/23/15 11:15:28 PM Reply	Re: Realism fail. :-) Proper tubes would burn your wrist. They still make tubes - for guitar amps there's nothing quite like em
Post #405,588 by Another Scott 10/23/15 11:19:41 PM Reply	The battery would last about 20 s, also too. :-)
Post #405,609 by static 10/25/15 4:01:20 AM Reply	I know. My dad fixes vintage radios. There are a lot of common tubes still being made. It is interesting to theorise on how tubes could've been miniaturised if transistors hadn't been invented. Wade. Just Add Story http://justaddstory.wordpress.com/
Post #405,616 by Another Scott 10/25/15 10:47:38 AM Reply	People are still working on them... Tubes are very important for high power transmission, e.g., for satellites as well as normal radio. But they're still being worked on for transistor-like functions as well. IEEE Spectrum. Cheers, Scott.
Post #405,617 by Andrew Grygus 10/25/15 11:53:19 AM Reply	Mineaturization: The first step was to reduce the size of the glass bulb from light bulb shape to cylindrical. The next step was to eliminate the base and to reduce the size to less than 2 inches high After that came the sub-mineatures, about 3/8 inch diameter and less than 1-1/2 inches long, with wire leads rather than sockets (thought the leads could be cut short for use in a socket. The specification for these was that they withstand 1000 Gs of acceleration for use in 6 inch gun shell proximity fuses. They were much used in other military applications and avionics. There were some intermediate steps, but the final step I am aware of was ceramic pill shaped tubes about the diameter of a aspirin, but thicker. These were for use in the re-entry warheads for ICBMs, as they could operate at temperatures that melted transistors. All in all, except heat and power consumption, the vacuum tube is far superior to the transistor, able to provide 4 to 6 times the amplification per stage, handle signals at multiple frequencies (1 tube could handle the RF, IF and Audio stages of a radio in some designs). It can also do strange things, like the phantastron oscillator. This was a tube wired into the circuit all wrong that provided an extremely linear saw tooth wave, used as the time base for U.S. radar during WWII. Circuit designers added a few extra components that didn't do anything to confuse analysis should one be captured. But, the greatest advantage for tubes is that they glow in the dark. Transistors don't to that.
Post #405,624 by Ashton 10/25/15 6:28:46 PM Reply	Heh. '6AS6' IIRC, in that Phantastron circuit it was one of my first projects, switching brain from chem-obsession to the wider universe of physics (the root of chem, natch.) I just built the circuit from a "Millman and [Seely?]" text, plugged in my scope 'Eyes' to watch its prestidigitations. Amazing one-tube-trick (though I needed a cathode follower for isolation. i'd used a 'hearing-aid size' sub-min, shielded by a piece of iron pipe! for another hi-Z _input amp necessarily near to a high pulsed field. In the end, though: vac tubes are voltage-controlled devices/xsistors are current-controlled. The FET tries to pretend, but.. You can make the one emulate the other but there Are trade-offs as you mention: heat, vibration/shock and the like, Xsistors rule when you're just flipping boring-#s of bits, for ex. Except when they melt. Or cosmic 'rays' swamp a femtoamp input-Z; then you need Glass. And no dirtied-up silicon alloys. (I loved the book about the Fulcrum Russ fighter brought to Turkey (?) by a defecting pilot. Also Title of his book.) Usians made jokes about the vac. tube prevalence in the design of its critical electronics (maybe sometimes as mere backups.. dunno, never saw a MIG full-schematic diagram.) Then someone mentioned "EMP" and the smarter gigglers ..ceased. Neat quip re the radar nonsense circuits-added, surely a no-brainer idea when one is engaged in Spy-vs-Spy ... but I bet it wasted a lot of EE sleuthing time (by anyone without a properly warped-War-type brain, at the outset.) Like the NoTrueScotsman, wouldn't most EEs say to selves: "no EE would ever create" such a kluge!"--it must be a clever piece I'm missing. (??) ..But you could invest your whole life in trying to keep up with (just the obvious..) extrapolations of the next insanely-great trend in [pick any "field' == a word always a constriction against: ever becoming truly Wise, eh?] Sometimes a one has to Bail outright, to shoe-horn in any smelling of Roses or sniffing out the Numero Uno of brass players, say. Algorithms amuse but they're just recipes for yesterday's schemes, I wot. If I happened to know Everything .?. just the Boltzmann Noise would kill any chance to find correlations; a Cosmic Hee Hee?
Post #405,635 by static 10/26/15 5:43:07 AM Reply	That oscillator sounds like fun! I've seen a circuit that took a CMOS logic chip and wired it funny to get a MOSFET pair for an audio-phaser. Had to be a specific brand, though. Wade. Just Add Story http://justaddstory.wordpress.com/

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