Is there a good book for learning about valves/tubes?

suggestions please TIA

Reply to
david eather
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** Your Q is way too broad - the topic of tubes is ENORMOUS while current production involves only a few popular audio types.

FFS tell us what you ACTUALLY wish to know about.

..... Phil

Reply to
Phil Allison

There are loads & loads to choose from. Most of them contain all the basic info. I see no point limiting yourself to one or 2 possibles, see what you can find.

NT

Reply to
Tabby

Dunno exactly what you're looking for, but the suggestions you've gotten so far are for books about designing *with* valves/tubes. Another dimension is the design *of* valves/tubes. If that's what interests you, look up "19

40 RCA Vacuum Tube Design." (There are also later editions.) You can find f ree PDFs on the web. I find the subject fascinating (and who knows, it may be relevant again in a post-apocalyptic world :-) )
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Silvar Beitel
Reply to
Silvar Beitel

Or a post-pandemic world...

Reply to
Pimpom

Good question! I'm wondering what the OP would do if he knew all about tubes? Build a HiFi amp? Guitar amp?

Reply to
gray_wolf

EMP-proof serial computer, definitely. ;)

Cheers

Phil Hobbs

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Reply to
Phil Hobbs

Why does it have to be serial? Why can't it be parallel?

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Grant. . . . 
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Reply to
Grant Taylor

Good question, yes. So far the OP hasn't made clear what he wants to do. In the absence of such clarification, I'd guess that most people who ask the question want to gain enough knowledge about tubes to be able to a) design tube circuits OR b) repair a tube amp OR c) simply understand what the fuss is all about without a specific goal in mind.

Reply to
Pimpom

Takes too many tubes. See the IBM 650.

Cheers

Phil Hobbs

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Reply to
Phil Hobbs

The arithmetic and logical functions are relative easy, but the control functionality (instruction decoding and micro sequencing) is the problem. You need kind of ROM (e.g. a semiconductor diode matrix or core memory). You also need some scratch pad memory, such as core or acoustic (mercury) delay lines.

Reply to
upsidedown

The ENIAC calculator was parallel and had 18000 tubes, early commercial computers were serial (or BCD) with just a few thousand tubes and they even executed a stored program.

Reply to
upsidedown

Y'know, I wonder what kind of performance one of those could do, given modern architectural and electronic knowledge.

A clock frequency somewhat under a MHz seems reasonable, there'd be some tradeoff between tube count and computational power, and with say 16 bit instruction cycles and standard integer ops (logic, arithmetic, and since it's serial, mul and div are pretty cheap) it should be competetive with, say, the Apollo Guidance Computer (~50kIPS) or some very impoverished MCUs (maybe not any 8-bit machines, but those 4-bitters that are still around in some niches).

The memory of course is always going to be the hard part. If you're reluctant to patch in a modern SRAM, you're going to have a hard time doing much of anything else. (Not bad if you find an old core module in working condition, I guess.)

But then, you still need all the support hardware to make use of it. Even just a serial terminal, you either need to get lucky with a surviving vintage one (where "vintage" in this scenario includes any current tech that's surviving?), or make one yourself, which means you're going to need a CRT and support components, rasterizer, character generator, video RAM... All things which existed in various forms back in the day (delay line might be okay for the RAM; and there were CRT-ROMs for drawing characters!), but which weren't exactly corner-store items even back then.

Probably the more realistic scenario is developing a hack-friendly Android OS to use on all those phones that are suddenly less useful without active base stations, and even if a bunch end up dead for various reasons, there's just so many that will survive. Much easier then to keep the battery charged, which, automotive and mains chargers are at least as likely to survive and remain as reliable as they were (which is to say, not always that much heh, but still), and mains inverters and generators, and car batteries and alternators, aren't going away ever so that should be a good enough stopping point. (Engines in turn can be fed by gassified wood, for example.)

Tim

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Reply to
Tim Williams

One thing limiting the speed was the high tube stray capacitances and high impedance levels. Finding tubes with good cathode emissivity might help to design logical circuits with low (say 20-30 V) anode voltages.

Ordinary tubes can have reassemble power gain in grounded grid configuration even at VHF. A grounded grid flip-flop ??

A bit clock above 10 MHz should be possible, so a word add times of a few us should be possible.

You still might find some magnetic core modules.

Of course some shift registers, such as mercury delay lines or 64 us PAL TV delay lines might be used.

A Teletype terminal al should do. One Teletype we used had only semiconductor mains rectifiers and a TO3 power transistor in the 20 mA constant current generator. The data generation and decoding was all electromechanical.

Reply to
upsidedown

With Nuvistors and surface-mount passives, you could probably get the clock rate into 100 MHz territory.

Cheers

Phil Hobbs

Reply to
pcdhobbs

Usually the voltages are modest (~100V), so that adequate current can be drawn. Low voltage, you need too much cathode area and capacitance, and your figure of merit (Gm/(Cin+Cout), which has units of frequency) stinks.

And obviously, the FoM doesn't change with scale (length/area of cathode). Though other fixed parameters (like wiring strays) do affect the FoM in-system, so you don't want to use too small of a tube.

They can, but not baseband to VHF. Only a few late era planar types could do that. (Which at the time, were more valuable doing the same ~100MHz bandwidth around a center frequency of some GHz -- pretty good bandwidth even today, to be fair!)

That's the trick. Example:

I happen to have a carton of subminiature (wire lead) 5702s.

These are your basic general purpose / RF, sharp cutoff pentode. 1W max,

5mS at 100V, 10mA.

In an accidentally-grounded-grid arrangement, these like to oscillate around

400MHz; it's the interelectrode ESL+Cp resonant mode I think. (This might happen accidentally, like in a follower type Hartley oscillator, which places its tuning capacitor between grid and ground.) They're perfectly capable of operating at high frequencies; the transit time is a nanosecond or two. (This can be measured with a very low plate load and a fast pulse generator into the grid. The gain in this configuration is pitiful, obviously, but you can indeed see the current changing in that time!)

The capacitances are about 4pF plate and 5pF grid *WHEN COLD*. However the grid capacitance increases when hot -- because the electron cloud has mass, cool huh? -- to more like 9pF. So the total in cascade is 4+9 = 13pF. Plus circuit strays.

That gives a FoM = 5mS / (2*pi*13pF) = 61MHz, which is the no-frills (no peaking) ballpark bandwidth, at unity gain (i.e., a 1/5mS = 200ohm plate load).

In a practical computer, you'd need 1/2 to 1/3 of this (even for a tiny fanout of, well, about as much), and even with peaking (to about double it, give or take how that works in combination with nonlinear loads like diode gates), you're looking at a maximum clock rate for typical gates of maybe

20MHz.

Which, is still pretty promising; that's not much slower than 74HC logic, and faster than CD4000, scarily enough. It does take about a dozen watts to compute even fairly simple logic operations though... ECL's got nothing on this!

Heh, given that those have been obsolete for a while now too -- not hard to find though.

I wonder how much data those store. Let's see, 64us, at a MHz or two bandwidth -- they had to store chroma, modulated I believe, so that's offset on a center frequency? -- suggests 2Mbit/s * 64us = 128 bits. Although that's not actually bits, but baud, and more bits could be encoded given some manner of ADC/DAC system, with adequate SNR and ISI (with whatever ISI compensation can be afforded).

Not bad for, like, a register file, or perhaps more practically, a cache line..?

And since it's modulated, it needs some encoding. PAM perhaps, which would be an easy enough way to transmit 2 bits/symbol (BPASK I guess you might call it?). Probably it would be easy enough making a 4x4 square constellation (4 bits/symbol) too.

Which puts it up around half a kiB, which isn't too shabby. And it would probably match up well enough with a 5702-based (or other tubes of comparable performance) machine.

Downside, now you have to "spin the drum" or whatever; efficient programming gets a lot harder...

(I wonder if anyone's ever written a compiler/optimizer around such a constraint? Certainly very little reason to do so today, but as an academic exercise, maybe interesting.)

Well, I don't know about that. They certainly worked..when they did. How many of them are even around anymore? And of them, how many are basically in parts, or in need of extreme-teardown levels of maintenance? :^)

Definitely mechanical wonders; I've quite enjoyed CuriousMarc's restoration series:

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And absolutely, if you have one in working order -- perfectly compatible with the same old serial frames we've always used, if at rather low baud rates. Just insert RS-232 (or TTL, or..) to 20mA converter, and don't touch the high voltages. :)

Tim

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Seven Transistor Labs, LLC 
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Reply to
Tim Williams

Radiotron for one.

Go here and poke around:

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for example, try: Technical & Engineering > Technical Books > Rider Book Library

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Reply to
Simon S Aysdie

Hmm... Nice pdf. Thanks.

Reply to
Sjouke Burry

Would VFDs be usable for computation? Not just because they're low power & long lived, but also they have matrix-like arrangement of grids & anodes.

NT

Reply to
Tabby

So it's technically possible. It's just not practical.

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Grant. . . . 
unix || die
Reply to
Grant Taylor

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